bioRxiv Subject Collection: Neuroscience's Journal

Lateral prefrontal cortex controls interplay between working memory and actions
Humans must often keep multiple task goals in mind, at different levels of priority and immediacy, while also interacting with the environment. We might need to remember information for an upcoming task while engaged in more immediate actions. Consequently, actively maintained working memory (WM) content may bleed into ongoing but unrelated motor behavior. Here, we experimentally test the impact of WM maintenance on action execution, and we transcranially stimulate lateral prefrontal cortex (PFC) to parse its functional contributions to WM-motor interactions. We first created a task scenario wherein human participants (both sexes) executed cued hand movements during WM maintenance. We manipulated the compatibility between WM and movement goals at the trial level and the statistical likelihood that the two would be compatible at the block level. We found that remembering directional words (e.g., "left", "down") biased the trajectory and speed of hand movements that occurred during the WM delay, but the bias was dampened in blocks when WM content predictably conflicted with movement goals. Then we targeted left lateral PFC with two different transcranial magnetic stimulation (TMS) protocols before participants completed the task. We found that an intermittent theta-burst protocol, which is thought to be excitatory, dampened sensitivity to block-level control demands (i.e., proactive control), while a continuous theta-burst protocol, which is thought to be inhibitory, dampened adaptation to trial-by-trial conflict (i.e., reactive control). Therefore, lateral PFC is involved in controlling the interplay between WM content and manual action, but different PFC mechanisms may support different time-scales of adaptive control.

Antagonist actions of CMK-1/CaMKI and TAX-6/Calcineurin along the C. elegans thermal avoidance circuit orchestrate nociceptive habituation
Habituation is a conserved physiological phenomenon, during which responses decrease following repeated exposure to innocuous or noxious stimuli. Impaired nociceptive habituation is associated with several pain conditions in human, but the underpinning molecular mechanisms are only partially understood. In the nematode Caenorhabditis elegans, thermo-nociceptive habituation was previously shown to be regulated by the Ca2+/Calmodulin-dependent protein kinase 1 (named CMK-1), but its downstream effectors were unknown. Here, using in vitro kinase assays coupled with mass-spectrometry-based phosphoproteomics, we empirically identified hundreds of CMK-1 phospho-substrates. Among them, we found that CMK-1 can phosphorylate the calcineurin A (CnA) protein TAX-6 in a highly conserved regulatory domain. Combined genetic and pharmacological manipulations revealed a network of antagonistic actions between CMK-1 and calcineurin pathways in the regulation of the responsiveness of naive worms and their habituation to repeated noxious heat stimuli. We further highlighted multiple places of action of the two signaling pathways in a subset of thermosensory neurons and downstream interneurons mediating avoidance behaviors. As a whole, our study has identified (i) CMK-1 substrate candidates, which will fuel further research on the intracellular actuation of CMK-1-dependent signaling, and (ii) a complex set of antagonistic interactions between CMK-1 and calcineurin signaling operating at distributed loci within a sensory-behavior circuit, acting to adjust baseline thermo-nociception and regulate thermo-nociceptive habituation.

Accept-reject decision-making revealed via a quantitative and ethological study of C. elegans foraging
Decision-making is a ubiquitous component of animal behavior that is often studied in the context of foraging. Foragers make a series of decisions while locating food (food search), choosing between food types (diet or patch choice), and allocating time spent within patches of food (patch-leaving). Here, we introduce a framework for investigating foraging decisions using detailed analysis of individual behavior and quantitative modeling in the nematode Caenorhabditis elegans. We demonstrate that C. elegans make accept-reject patch choice decisions upon encounter with food. Specifically, we show that when foraging amongst small, dispersed, and dilute patches of bacteria, C. elegans initially reject several bacterial patches, opting to prioritize exploration of the environment, before switching to a more exploitatory foraging strategy during subsequent encounters. Observed across a range of bacterial patch densities, sizes, and distributions, we use a quantitative model to show that this decision to explore or exploit is guided by available sensory information, internal satiety signals, and learned environmental statistics related to the bacterial density of recently encountered and exploited patches. We behaviorally validated model predictions on animals that had been food-deprived, animals foraging in environments with multiple patch densities, and null mutants with defective chemosensation. Broadly, we present a framework to study ecologically relevant foraging decisions that could guide future investigations into the cellular and molecular mechanisms underlying decision-making.

Intranasal Lithium Chloride Nanoparticles Inhibit Inflammatory Pyroptosis in Brains and Ameliorate Memory Loss and Depression Behavior in 5xFAD mice
This study compares the changes in lithium concentrations in the brain and blood following the administration of intranasal or oral lithium chloride (LiCl) dissolved in either Ryanodex Formulation Vehicle (RFV) or water, as well as the therapeutic effectiveness and side effects of intranasal versus oral lithium chloride (LiCl) in RFV, and their mechanisms for inhibiting inflammation and pyroptosis in 5xFAD Alzheimers Disease (AD) mice brains. In comparison to oral LiCl in RFV, intranasal LiCl in RFV decreased lithium blood concentrations but increased brain concentrations and duration, resulting in a significantly higher brain/blood lithium concentration ratio than intranasal LiCl in water or oral LiCl in RFV in young adult mice. Intranasal LiCl in RFV robustly protects both memory loss and depressive behavior in both young and old 5xFAD mice, with no side effects or thyroid/kidney toxicity. In fact, intranasal LiCl in RFV protects against age-dependent kidney function impairment in 5xFAD mice. This lithium mediated neuroprotection was associated with its potent effects on the inhibition of InsP3R-1 Ca2+ channel receptor increase, ameliorating pathological inflammation and activation of the pyroptosis pathway, and the associated loss of synapse proteins. Intranasal LiCl in RFV could become an effective and potent inhibitor of pathological inflammation/pyroptosis in the CNS and treat both dementia and depression with no or minimal side effects/organ toxicity, particular in AD.

Cortico-hippocampal interactions underlie schema-supported memory encoding in older adults
Although episodic memory is typically impaired in older adults (OAs) compared to young adults (YAs), this deficit is attenuated when OAs can leverage their rich semantic knowledge, such as their knowledge of schemas. Memory is better for items consistent with pre-existing schemas and this effect is larger in OAs. Neuroimaging studies have associated schema use with the ventromedial prefrontal cortex (vmPFC) and hippocampus (HPC), but most of this research has been limited to YAs. This fMRI study investigated the neural mechanisms underlying how schemas boost episodic memory in OAs. Participants encoded scene-object pairs with varying congruency, and memory for the objects was tested the following day. Congruency with schemas enhanced object memory for YAs and, more substantially, for OAs. FMRI analyses examined how cortical modulation of HPC predicted subsequent memory. Congruency-related vmPFC modulation of left HPC enhanced subsequent memory in both age groups, while congruency-related modulation from angular gyrus (AG) boosted subsequent memory only in OAs. Individual differences in cortico-hippocampal modulations indicated that OAs preferentially used their semantic knowledge to facilitate encoding via an AG-HPC interaction, suggesting a compensatory mechanism. Collectively, our findings illustrate age-related differences in how schemas influence episodic memory encoding via distinct routes of cortico-hippocampal interactions.

Nucleus accumbens astrocytes bidirectionally modulate social behavior
Social behaviors are critical for survival and fitness of a species, and maladaptive social behaviors are frequently associated with neurodevelopmental and psychiatric disorders. As such, the neural circuits and cellular mechanisms driving social behaviors inform critical processes contributing to both health and disease. In particular, the nucleus accumbens (NAc) is a key hub for the integration of both social and non-social information required for successful social interactions and reward motivated behaviors. While astrocytes within the NAc have a recognized role in modulating neural activity, their influence over social behavior is yet undefined. To address this question, we manipulated NAc astrocyte signaling and determined effects on social interactions. NAc core astrocytes bidirectionally influenced social behavior in rats; agonism of astrocyte-specific hM3D(Gq) DREADD receptors increased social interaction time in the social interaction test and increased social preference in the 3-chamber test. Conversely, decreasing intracellular calcium signaling in astrocytes with viral expression of hPMCA reduced both social interaction and social preference in these tests. These results suggest that NAc astrocytes actively participate in the regulation of social behavior and highlight a putative role for astrocytes in disorders characterized by social dysfunction.

Ventrolateral prefrontal cortex in macaques guides decisions in different learning contexts
Flexibly adjusting our behavioral strategies based on the environmental context is critical to maximize rewards. Ventrolateral prefrontal cortex (vlPFC) has been implicated in both learning and decision-making for probabilistic rewards, although how context influences these processes remains unclear. We collected functional neuroimaging data while rhesus macaques performed a probabilistic learning task in two contexts: one with novel and another with familiar visual stimuli. We found that activity in vlPFC encoded rewards irrespective of the context but encoded behavioral strategies that depend on reward outcome (win-stay/lose-shift) preferentially in novel contexts. Functional connectivity between vlPFC and anterior cingulate cortex varied with behavioral strategy in novel learning blocks. By contrast, connectivity between vlPFC and mediodorsal thalamus was highest when subjects repeated a prior choice. Furthermore, pharmacological D2-receptor blockade altered behavioral strategies during learning and resting-state vlPFC activity. Taken together, our results suggest that multiple vlPFC-linked circuits contribute to adaptive decision-making in different contexts.

Basal activation of astrocytic Nrf2 in neuronal culture media: challenges and implications for neuron-astrocyte modelling
As a gate-keeper of anti-oxidant, anti-inflammatory and xenobiotic cell protection mechanisms, the transcription factor Nrf2 has been implicated as a promising therapeutic target for several neurodegenerative diseases, leading to the development of Nrf2 activators targeting Keap1-dependent and independent regulatory mechanisms. This study aimed to evaluate the efficacy of a Keap1-Nrf2 protein-protein interaction disruptor, 18e, in comparison with classical electrophilic Nrf2 activators, CDDO-Me and Dimethylfumarate (DMF), with a view to measuring their effects on neuronal protection using LUHMES neuron-astrocyte co-cultures. Astrocytes play a crucial role in regulating neuronal physiology in health and disease, including Nrf2 neuroprotective responses. As neurons require specific conditions for their differentiation and maintenance, most 2D and 3D co-culture systems use medias containing high glucose and a variety of growth factors, allowing astrocytes to survive without the media negatively impacting neuronal function. Few studies, however, assess the molecular adaptations of astrocytes in response to changes from astrocyte maintenance medias alone, and the potential consequences for neuronal function, which may represent technical rather than physiological changes. Our findings show that while Nrf2 can be effectively activated by 18e, DMF and CDDO-Me in human primary cortical astrocyte monocultures, their efficacy is lost in the LUHMES-astrocyte co-culture, as measured by NQO1 enzymatic activity. Further investigation revealed that the Advanced DMEM/F12-based LUHMES differentiation media maximally induced basal Nrf2 activity in astrocytes alone, in comparison to complete astrocyte maintenance media. Analysis of media components revealed that this was not due tetracycline or high glucose, and was unlikely to be due to REDOX-inducing phenol-red, the concentration of which is comparable across all medias used in our study. Although Neurobasal slightly activated basal Nrf2 compared to astrocyte media, trends toward further activation were observed in the presence of 18e and DMF, suggesting that this media impacts astrocytic Nrf2 responses less than Advanced DMEM/F12. Numerous studies model oxidative stress and neuroinflammation, key features of neurological diseases, using neuronal systems. As Nrf2 is a key regulator of cellular damage, the effects of these stressors could be confounded by cellular environments that maximally activate basal Nrf2, as observed in our experiments. Hence, this study highlights the need for caution in media selection for neuron-astrocyte co-culture modelling, not only for researchers investigating Nrf2 therapeutics, but also for other mechanisms by which astrocytes influence neuronal function in health and disease.

Optogenetic stimulation of dorsal striatum bidirectionally controls seizures
Engagement of the striatum (caudate/putamen) and other basal ganglia nuclei during seizures was first observed over 75 years ago. Basal ganglia output nuclei, and the substantia nigra pars reticulata, in particular, have well-established anti-seizure effects across a large array of experimental models. However, striatal control fo seizures is understudied. To address this gap, we used optogenetic approaches to activate and inactivate neurons in the dorsal striatum of Sprague-Dawley rats submitted to the gamma-butyrolactone (GBL) model of absence epilepsy, amygdala kindling model of temporal lobe epilepsy, and pilocarpine-induced Status Epilepticus (SE). All tests were performed on a within-subject basis. Animals were tested in two different light frequencies (5 Hz and 100 Hz). Open-loop (continuous light delivery) optogenetic activation of the dorsal striatal neurons robustly suppressed seizures in all models. On the other hand, optogenetic silencing of the dorsal striatal neurons increased absence seizure expression and facilitated SE onset but had no effect on kindled limbic seizures. In the GBL model, we also verified if the closed-loop strategy (light delivery in response to seizure detection) would be enough to induce antiseizure effects. On-demand light delivery in ChR2-expressing animals reduced SWD duration, while the same approach in ArchT-expressing animals increased SWD duration. These results demonstrated previously unrecognized anti-absence effects associated with striatal continuous and on-demand neuromodulation. Together, these findings document a robust, bidirectional role of the dorsal striatum in the control of seizure generation and propagation in a variety of seizure models, including focal seizure onset and generalized seizures.

Incorporating buccal mass planar mechanics and anatomical features improves neuromechanical modeling of Aplysia feeding behavior
To understand how behaviors arise in animals, it is necessary to investigate both the neural circuits and the biomechanics of the periphery. A tractable model system for studying multifunctional control is the feeding apparatus of the marine mollusk Aplysia californica. Previous in silico and in roboto models have investigated how the nervous and muscular systems interact in this system. However, these models are still limited in their ability to match in vivo data both qualitatively and quantitatively. We introduce a new neuromechanical model of Aplysia feeding that combines a modified version of a previously developed neural model with a novel biomechanical model that better reflects the anatomy and kinematics of Aplysia feeding. The model was calibrated using a combination of previously measured biomechanical parameters and hand-tuning to behavioral data. Using this model, simulation feeding experiments were conducted, and the resulting behavioral metrics were compared to animal data. The model successfully produces three key behaviors seen in Aplysia and demonstrates a good quantitative agreement with biting and swallowing behaviors. Additional work is needed to match rejection behavior quantitatively and to reflect qualitative observations related to the relative contributions of two key muscles, the hinge and I3. Future improvements will focus on incorporating the effects of deformable 3D structures in the simulated buccal mass.

Viral-mediated Oct4 overexpression and inhibition of Notch signaling synergistically induce neurogenic competence in mammalian Muller glia.
Retinal Muller glia in cold-blooded vertebrates can reprogram into neurogenic progenitors to replace neurons lost to injury, but mammals lack this ability. While recent studies have shown that transgenic overexpression of neurogenic bHLH factors and glial-specific disruption of NFI family transcription factors and Notch signaling induce neurogenic competence in mammalian Muller glia, induction of neurogenesis in wildtype glia has thus far proven elusive. Here we report that viral overexpression of the pluripotency factor Oct4 (Pou5f1) induces transdifferentiation of wildtype mouse Muller glia into bipolar neurons, and stimulates this process synergistically in parallel with Notch loss of function. Single cell multiomic analysis shows that Oct4 overexpression leads to widespread changes in gene expression and chromatin accessibility, inducing activity of both the neurogenic transcription factor Rfx4 and the Yamanaka factors Sox2 and Klf4. This study demonstrates that viral overexpression of Oct4 induces neurogenic competence in wildtype retinal Muller glia, identifying mechanisms that could be used in cell-based therapies for treating retinal dystrophies.

The mechanism and consequences of amyloid-β modulating thiamine pyrophosphokinase-1 expression in microglia
Ample studies attribute cognitive decline in Alzheimer's disease to amyloid-{beta} deposition 1-6. However, brain amyloid-{beta} accumulation that saturates years before the manifestation of clinical symptoms is dissociated with cognitive decline of the disease 7. It is unknown how these two processes are mechanistically linked. In this and our accompanied study, we report that thiamine pyrophosphokinase-1 (TPK) deficiency plays essential roles in both processes via distinct mechanisms. Here we describe that diminished microglia Tpk controls the propagation of amyloid-{beta} plaques. In APP/PS1 transgenic mice, microglia showed elevated Tpk expression at 2-month-old, but reduction in a plaque-centric manner at 8-month-old. Interestingly, lipopolysaccharide, but not amyloid-{beta}, induceed Tpk reduction in cultured microglia. Tpk reduction led to microglia dysfunction, showing volatile motility but reduced phagocytosis and weak response to focal tissue injury, with accumulation of intracellular lipid droplets and abnormal mitochrondria. In Alzheimer's disease mice, microglia-specific knockout of Tpk caused diminished plaque coverage, exacerbated plaque burden and synaptic loss. However, increased plaques were not accompanied by the development of neurofibrillary tangles or brain atrophy, in contrast to the phenotype described in our accompanied paper with neuronal Tpk deletion. In conclusion, plaque-induced inflammation reduces Tpk in microglia, selectively exacerbating the spread of amyloid pathology.

Lateralized cerebellar connectivity differentiates auditory pathways in echolocating and non-echolocating whales
We report the first application of diffusion tractography to a mysticete, which was analyzed alongside three odontocete brains, allowing the first direct comparison of strength and laterality of auditory pathways in echolocating and non-echolocating whales. Brains were imaged post-mortem at high resolution with a specialized steady state free precession diffusion sequence optimized for dead tissue. We conducted probabilistic tractography to compare the qualitative features, tract strength, and lateralization of potential ascending and descending auditory paths in the mysticete versus odontocetes. Tracts were seeded in the inferior colliculi (IC), a nexus for ascending auditory information, and the cerebellum, a center for sensorimotor integration. Direct IC to temporal lobe pathways were found in all animals, replicating previous cetacean tractography and suggesting conservation of the primary auditory projection path in the cetacean clade. Additionally, odontocete IC-cerebellum pathways exhibited higher overall tract strength than in the mysticete, suggesting a role as descending acousticomotor tracts supporting the rapid sensorimotor integration demands of echolocation. Further, in the mysticete, contralateral right IC to left cerebellum pathways were 17x stronger than those between left IC and right cerebellum, while in odontocetes, the laterality was reversed, and left IC to right cerebellum pathways were 2-4x stronger than those between right IC and left cerebellum. The stronger left IC-right cerebellum connectivity observed in odontocetes corroborates the theory that odontocetes preferentially echolocate with their right phonic lips, as the right phonic lips are likely innervated by left-cortical motor efferents that integrate with left-cortical auditory afferents in right cerebellum. This interpretation is further supported by the reversed lateralization of IC-cerebellar tracts observed in the non-echolocating mysticete. We also found differences in the specific subregions of cerebellum targeted by the IC, both between the mysticete and odontocetes, and between left and right sides. This study establishes foundational knowledge on mysticete auditory connectivity and extends knowledge on the neural basis of echolocation in odontocetes.

The transcriptomic landscape of spinal V1 interneurons reveals a role for En1 in specific elements of motor output
Neural circuits in the spinal cord are composed of diverse sets of interneurons that play crucial roles in shaping motor output. Despite progress in revealing the cellular architecture of the spinal cord, the extent of cell type heterogeneity within interneuron populations remains unclear. Here, we present a single-nucleus transcriptomic atlas of spinal V1 interneurons across postnatal development. We find that the core molecular taxonomy distinguishing neonatal V1 interneurons perdures into adulthood, suggesting conservation of function across development. Moreover, we identify a key role for En1, a transcription factor that marks the V1 population, in specifying one unique subset of V1-Pou6f2 interneurons. Loss of En1 selectively disrupts the frequency of rhythmic locomotor output but does not disrupt flexion/extension limb movement. Beyond serving as a molecular resource for this neuronal population, our study highlights how deep neuronal profiling provides an entry point for functional studies of specialized cell types in motor output.

FUS controls muscle differentiation and structure through LLPS mediated recruitment of MEF2 and ETV5
FUS is an RNA binding protein mutated in amyotrophic lateral sclerosis (ALS), a neurodegenerative disease characterized by progressive muscle weakness. We show that ALS-associated FUS mutations lead to ultrastructural defects in muscle of FUS-ALS patients, with disruption of sarcomeres and mitochondria. Studies in mouse and Drosophila models demonstrate an evolutionary-conserved cell autonomous function of FUS in muscle development. Mechanistically, FUS is required for transcription of MEF2 dependent genes, binds to the promoter of genes bound by ETS transcription factors in particular ETV5 and co-activates transcription of MEF2 dependent genes with ETV5. FUS phase separates with ETV5 and MEF2A, and MEF2A binding to FUS is potentiated by ETV5. Last, Etv5 haploinsufficiency exacerbates muscle weakness in a mouse model of FUS-ALS. These findings establish FUS as an essential protein for skeletal muscle structure through its phase separation-dependent recruitment of ETV5 and MEF2, defining a novel pathway compromised in FUS-ALS.

Contrasting Cognitive, Behavioral, and Physiological Responses to Breathwork vs. Naturalistic Stimuli in Reflective Chamber and VR Headset Environments
Background: Virtual reality (VR) and immersive technologies offer mental health benefits, including anxiety reduction, mood enhancement, and cognitive function improvement. Previous research has demonstrated the anxiolytic effects of breathwork and exposure to natural environments, leading to enhanced well-being. Objective: This study examines the effectiveness of rain stimuli and guided breathwork delivered through two distinct systems: MindGym, a reflective chamber, and a traditional VR headset. Methods: Physiological measures, cognitive, and trait and state assessments were collected for 126 participants, randomly assigned to VR (Breathwork), VR (Rain), MindGym (Breathwork), or MindGym (Rain) conditions. Results: Significant improvements were observed across all groups in cognitive performance, anxiety, and mood. The Trail Making Test (RTACC) decreased ({Delta}M=-30.4, W=5443.00, Z=4.32, P.FDR<.001, RBC=.45), Architex Total Speed improved ({Delta}M=-76.4, W=6044.00, Z=7.82, P.FDR<.001, RBC=.84), and anxiety (STAI) reduced ({Delta}M=-3.78, W=5156.50, Z=4.86, P.FDR<.001, RBC=.52). Breathwork conditions showed a greater decrease in breath rate compared to Rain conditions (F(2.48, 208.49)=28.49, P.FDR=.002). Individual differences moderated treatment responses, with MODTAS predicting Awe (b=0.37, SE=0.11, Z=3.28, P.FDR=.004) and Ego Dissolution (b=0.03, SE=0.01, Z=2.98, P.FDR=.015). Openness interacted with stimuli type on anxiety reduction (F(1, 111)=9.58, P.FDR=.038), with higher openness associated with greater anxiety reduction in Breathwork conditions. No significant differences were found between MindGym and VR in effectiveness or immersion. Conclusions: MindGym and VR demonstrated promise as acute anxiolytics, with MindGymgenerated content maintaining effectiveness when translated to VR. This highlights MindGym's potential as a versatile content creation platform for immersive, anxiety-reducing experiences. Individual differences moderated treatment responses, suggesting opportunities for personalized interventions. Future research should explore complex MindGym experiences and adaptation to various delivery systems for accessible, effective anxiety management tools.

Neural basis of collective social behavior during environmental challenge
Humans and animals have a remarkable capacity to collectively coordinate their behavior to respond to environmental challenges. However, the underlying neurobiology remains poorly understood. Here, we found that groups of mice self-organize into huddles at cold ambient temperature during the thermal challenge assay. We found that mice make active (self-initiated) and passive (partner-initiated) decisions to enter or exit a huddle. Using microendoscopic calcium imaging, we found that active and passive decisions are encoded distinctly within the dorsomedial prefrontal cortex (dmPFC). Silencing dmPFC activity in some mice reduced their active decision-making, but also induced a compensatory increase in active decisions by non-manipulated partners, conserving the group's overall huddle time. These findings reveal how collective behavior is implemented in neurobiological mechanisms to meet homeostatic needs during environmental challenges.

Human Neural Organoid Microphysiological Systems Show the Building Blocks Necessary for Basic Learning and Memory
Brain Microphysiological Systems including neural organoids derived from human induced pluripotent stem cells offer a unique lens to study the intricate workings of the human brain. This paper investigates the foundational elements of learning and memory in neural organoids, also known as Organoid Intelligence by quantifying immediate early gene expression, synaptic plasticity, neuronal network dynamics, and criticality to demonstrate the utility of these organoids in basic science research. Neural organoids showed synapse formation, glutamatergic and GABAergic receptor expression, immediate early gene expression basally and evoked, functional connectivity, criticality, and synaptic plasticity in response to theta-burst stimulation. In addition, pharmacological interventions on GABAergic and glutamatergic receptors, and input specific theta-burst stimulation further shed light on the capacity of neural organoids to mirror synaptic modulation and short-term potentiation, demonstrating their potential as tools for studying neurophysiological and neurological processes and informing therapeutic strategies for diseases.

Alpha-synuclein preformed fibril-induced aggregation and dopaminergic cell death in cathepsin D overexpression and ZKSCAN3 knockout mice
alpha-synuclein accumulation is recognized as a prominent feature in the majority of Parkinson disease cases and also occurs in a broad range of neurodegenerative disorders including Alzheimer disease. It has been shown that alpha-synuclein can spread from a donor cell to neighboring cells and thus propagate cellular damage, antagonizing the effectiveness of therapies such as transplantation of fetal or iPSC derived dopaminergic cells. As we and others previously have shown, insufficient lysosomal function due to genetic mutations or targeted disruption of cathepsin D can cause alpha-synuclein accumulation. We here investigated whether overexpression of cathepsin D or knockout (KO) of the transcriptional suppressor of lysosomal biogenesis ZKSCAN3 can attenuate propagation of alpha-synuclein aggregation and cell death. We examined dopaminergic neurodegeneration in the substantia nigra using stereology of tyrosine hydroxylase-immunoreactive cells 4 months and 6 months after intrastriatal injection of alpha-synuclein preformed fibrils or monomeric alpha-synuclein control in control, central nervous system (CNS)-cathepsin D overexpressing and CNS-specific ZKSCAN3 KO mice. We also examined pS129-alpha-synuclein aggregates in the substantia nigra, cortex, amygdala and striatum. The extent of dopaminergic neurodegeneration and pS129-alpha-synuclein aggregation in the brains of CNS-specific ZKSCAN3 knockout mice and CNS-cathepsin D overexpressing mice was similar to that observed in wild-type mice. Our results indicate that neither enhancing cathepsin D expression nor disrupting ZKSCAN3 in the CNS is sufficient to attenuate pS129-alpha-synuclein aggregate accumulation or dopaminergic neurodegeneration.

Flexible Adjustment of Oxytocin Neuron Activity in Mother Mice Revealed by Microendoscopy
Oxytocin (OT) neurons in the hypothalamic paraventricular nucleus (PVH) play an important role in a range of physiological and behavioral processes, including the initiation of milk ejection and the regulation of parental behaviors in mothers. However, their activity patterns at the single-cell level remain poorly understood. Using microendoscopic Ca2+ imaging in freely moving mother mice, we demonstrate highly correlated pulsatile activity among individual OT neurons during lactation. The number of OT neurons engaged in the pulsatile activity, along with the characteristics of individual waveforms, was dynamically modulated by lactation and weaning experiences. Notably, only approximately 10% of the imaged OT neurons exhibited a significantly elevated response during pup retrieval, a hallmark of maternal behaviors, with a magnitude 18 times smaller than that observed during lactation. Collectively, these findings demonstrate the utility of microendoscopic imaging for PVH OT neurons and highlight the flexible adjustments of their individual activity patterns in freely behaving mother mice.

Optical Neuroimage Studio (OptiNiSt): intuitive, scalable, extendable framework for optical neuroimage data analysis
Advancements in calcium indicators and optical techniques have made optical neural recording a common tool in neuroscience. As the volume of optical neural recording data grows, streamlining the data analysis pipelines for image preprocessing, signal extraction, and subsequent neural activity analyses becomes essential. There are a number of challenges in optical neural data analysis. 1) The quality of original and processed data needs to be carefully examined at each step. 2) As there are numerous image preprocessing, cell extraction, and activity analysis algorithms, each with pros and cons, experimenters need to implement or install them to compare and select optimal methods and parameters for each step of processing. 3) To ensure the reproducibility of the research, each analysis step needs to be recorded in a systematic way. 4) For data sharing and meta-analyses, adoption of standard data formats and processing protocols is required. To address these challenges, we developed Optical Neuroimage Studio (OptiNiSt) (https://github.com/oist/optinist), a framework for intuitively creating calcium data analysis pipelines that are scalable, extendable, and reproducible. OptiNiSt includes the following features. 1) Researchers can easily create analysis pipelines by selecting multiple processing modules, tuning their parameters, and visualizing the results at each step through a graphic user interface in a web browser. 2) In addition to common analytical tools that are pre-installed, new analysis algorithms in Python can be easily added. 3) Once a processing pipeline is designed, the entire workflow with its modules and parameters are stored in a YAML file, which makes the pipeline reproducible and deployable on high-performance computing clusters. 4) OptiNiSt can read image data in a variety of file formats and store the analysis results in NWB (Neurodata Without Borders), a standard data format for data sharing. We expect that this framework will be helpful in standardizing optical neural data analysis protocols.

Speed modulations in grid cell information geometry
Grid cells, known for their hexagonal spatial firing patterns, are widely regarded as essential to the brain's internal representation of the external space. Maintaining an accurate internal spatial representation is challenging when an animal is running at high speeds, as its self-location constantly changes. Previous studies of speed modulation of grid cells focused on individual or pairs of grid cells, yet neurons represent information via collective population activity. Population noise covariance can have significant impact on information coding that is impossible to infer from individual neuron analysis. To address this issue, we developed a novel Gaussian Process with Kernel Regression (GKR) method that allows study the simultaneously recorded neural population representation from an information geometry framework. We applied GKR to grid cell population activity, and found that running speed increases both grid cell activity toroidal-like manifold size and noise strength. Importantly, the effect of manifold dilation outpaces the effect of noise increasement, as indicated by the overall higher Fisher information at increasing speeds. This result is further supported by improved spatial information decoding accuracy at high speeds. Finally, we showed that the existence of noise covariance is information detrimental because it causes more noise projected onto the manifold surface. In total, our results indicate that grid cell spatial coding improves with increasing running speed. GKR provides a useful tool to understand neural population coding from an intuitive information geometric perspective.

Deleting PTEN, but not SOCS3 or myelin inhibitors, robustly boosts BRAF-elicited intraspinal regeneration of peripheral sensory axons
Primary sensory axons fail to regenerate into the spinal cord following dorsal root injury leading to permanent sensory deficits. Re-entry is prevented at the dorsal root entry zone (DREZ), the CNS-PNS interface. Current approaches for promoting DR regeneration across the DREZ have had some success, but sustained, long-distance regeneration, particularly of large-diameter myelinated axons, still remains a formidable challenge. We have previously shown that induced expression of constitutively active B-RAF (kaBRAF) enhanced the regenerative competence of injured DRG neurons in adult mice. In this study, we investigated whether robust intraspinal regeneration can be achieved after a cervical DR injury by selective expression of kaBRAF alone or in combination with deletion of the myelin-associated inhibitors or neuron-intrinsic growth suppressors (PTEN or SOCS3). We found that kaBRAF promoted some axon regeneration across the DREZ but did not produce significant functional recovery by two months. Supplementary deletion of Nogo, MAG, and OMgp only modestly improved kaBRAF-induced regeneration. Deletion of PTEN or SOCS3 individually or in combination failed to promote any growth across the DREZ. In marked contrast, simultaneous deletion of PTEN, but not SOCS3, dramatically enhanced kaBRAF-mediated regeneration enabling many more axons to penetrate the DREZ and grow deep into the spinal cord. This study shows that dual activation of BRAF-MEK-ERK and PI3K-Akt-mTOR signaling is an effective strategy to stimulate robust intraspinal DR regeneration.

Intra-hypothalamic circuit orchestrates β-endorphin release following coital ejaculation in male mice
Survey-based evidence suggests that men experience a distinct post-ejaculation affective state1,2, marked by intense pleasure sometimes compared to the euphoric rush from intravenous injection of opioid drugs such as heroin3. However, the intrinsic neural circuit mechanisms underlying the ejaculation-triggered affective state remain unclear. Here, we discovered that Calbindin1-expressing (Calb1+) neurons in the preoptic area (POA) of the hypothalamus, an evolutionarily conserved regulatory region for male mating behavior4, are specifically activated during ejaculation in male mice. Inhibiting POA Calb1+ neurons prolongs mating and delays ejaculation. Importantly, POA Calb1+ neurons transmit the ejaculation signal and activate proopiomelanocortin-expressing (Pomc+) neurons in the arcuate nucleus of the hypothalamus, which show robust and sustained activity lasting for tens of seconds, specifically upon ejaculation. This activity is accompanied by elevated levels of {beta}-endorphins5, opioid peptides secreted by Pomc+ neurons, post-ejaculation in male mice. Optogenetic activation of Pomc+ neurons increases {beta}-endorphins levels and conditioned placed preference, similar to ejaculation. Conversely, intracerebroventricular (i.c.v.) infusion of drugs blocking Pomc neuropeptides signaling eliminates ejaculation-conditioned place preference. Collectively, these results elucidate an intra-hypothalamic circuit from POA Calb1+ neurons to arcuate Pomc+ neurons that coordinate {beta}-endorphin release with ejaculation, shedding light on the neurobiological basis of the post-ejaculation affective state.

Postnatal Development Of Dendritic Morphology And Action Potential Shape In Rat Substantia Nigra Dopaminergic Neurons
Substantia nigra pars compacta (SNc) dopaminergic (DA) neurons are characterized by specific morphological and electrophysiological properties. First, in ~90% of the cases, their axon arises from an axon-bearing dendrite (ABD) at highly variable distances from the soma. Second, they display a highly regular pattern of spontaneous activity (aka pacemaking) and a broad action potential (AP) that faithfully back-propagate through the entire dendritic arbor. In previous studies (Moubarak et al., 2019; Moubarak et al., 2022), we demonstrated that the presence of a high density of sodium current in the ABD and the complexity of this dendrite played a critical role in the robustness of pacemaking and setting the half-width of the AP. In the current study, we investigated the postnatal development of both morphology and AP shape in SNc DA neurons in order to determine when and how the mature electrophysiological phenotype of these neurons was achieved. To do so, we performed electrophysiological recordings of SNc DA neurons at 4 postnatal ages (P3, P7, P14, P21) and fully reconstructed their dendritic and proximal axon morphology. Our results show that several morphological parameters, including the length of the ABD, display abrupt changes between P7 and P14, such that a mature morphology is reached by P14. We then showed that AP shape followed a similar timecourse. Using realistic multicompartment Hodgkin-Huxley modeling, we then demonstrated that the rapid morpho-electrical maturation of SNc DA neurons likely arises from synergistic increases in dendritic length and in somatodendritic sodium channel density.

Role of copper during microglial inflammation
Copper plays crucial roles in various physiological functions of the nervous and immune systems. Dysregulation of copper homeostasis is linked to several diseases, including neurodegenerative diseases. Since dysfunctional microglial immunity can contribute to such diseases, we investigated the role of copper in microglial immunity. We found that both increased and decreased copper levels induced by chemical treatments suppresses lipopolysaccharide (LPS)-mediated inflammation in microglial cells, as determined by RT-qPCR analysis. RNA sequencing (RNA-seq) analysis confirmed that increased copper level reduces the inflammatory response to LPS; however, it also showed that decreased copper level affects genes involved in cell proliferation, transcription, and autophagosome regulation. These findings suggest that copper is vital for maintaining normal immune function in microglia, and both copper excess and deficiency can disrupt microglial immunity.

Ocular hypertension impairs axonal transport in the optic nerve head leading to neurodegeneration in a novel Cre-inducible mouse model of myocilin glaucoma.
Background: Degeneration of optic nerve (ON) axons and loss of retinal ganglion cells (RGCs) are the pathological hallmarks of Primary Open Angle Glaucoma (POAG). Elevation of intraocular pressure (IOP) due to dysfunction of trabecular meshwork (TM) is known to induce neurodegeneration. However, the early pathological events of glaucomatous neurodegeneration are poorly understood due to lack of robust and faithful mouse model that replicates all features of human POAG. Here, we report the generation and characterization of a novel Cre-inducible transgenic mouse model of myocilin (MYOC), the leading known genetic cause of POAG. Using this model, we further explore early pathological events of glaucomatous neurodegeneration due to chronic IOP elevation. Methods: We generated a Cre-inducible transgenic mouse model expressing DsRed-tagged Y437H mutant of human myocilin (Tg.CreMYOCY437H). A single intravitreal injection of helper adenovirus (HAd) 5 expressing empty cassette or Cre was performed in adult Tg.CreMYOCY437H mice, and glaucoma phenotypes including IOP, outflow facility, structural and functional loss of RGCs, ON degeneration, gliosis, and axonal transport deficits were examined at various stages of IOP elevation. Results: An intravitreal injection of HAd5-Cre led to selective MYOC expression in the TM at the level similar to endogenous Myoc. Expression of mutant MYOC induced biochemical and ultrastructural changes in TM leading to reduced outflow facility and significant IOP elevation. Notably, sustained IOP elevation led to significant functional and structural loss of RGCs and progressive ON degeneration. Glaucomatous neurodegeneration was associated with activation of astrocytes and neurodegenerative changes in the optic nerve head (ONH) region. Remarkably, chronic IOP elevation blocked anterograde axonal transport at the ONH prior to axonal degeneration and RGC loss. Interestingly, impaired axonal transport was associated with loss of cytoskeleton proteins including microtubules and neurofilaments resulting into accumulation of mitochondria in the ONH and neuronal dysfunction. Conclusions: Our studies indicate that Cre-inducible Tg.CreMYOCY437H mice recapitulates all glaucoma phenotypes observed in POAG patients. Importantly, sustained IOP elevation impairs axonal transport at ONH leading to glaucomatous neurodegeneration.

Unsupervised alignment reveals structural commonalities and differences in neural representations of natural scenes across individuals and brain areas
Neuroscience research has extensively explored the commonality of neural representations of sensory stimuli across individuals to uncover universal neural mechanisms in the encoding of sensory information. To compare neural representations across different brains, Representational Similarity Analysis (RSA) has been used, which focuses on the similarity structures of neural representations for different stimuli. Despite the broad applicability and utility of RSA, one limitation is that its conventional framework assumes that neural representations of particular stimuli correspond directly to those of the same stimuli in different brains. This assumption excludes the possibility that neural representations correspond differently and limits the exploration of finer structural similarities. To overcome this limitation, we propose to use an unsupervised alignment framework based on Gromov-Wasserstein Optimal Transport (GWOT) to compare similarity structures without presupposing stimulus correspondences. This method allows for the identification of optimal correspondence between neural representations of stimuli based solely on internal neural representation relationships, and thereby provides a more detailed comparison of neural similarity structures across individuals. We applied this unsupervised alignment to investigate the commonality of representational similarity structures of natural scenes, using large datasets of Neuropixels recordings in mice and fMRI recordings in humans. We found that the similarity structure of neural representations in the same visual cortical areas can be well aligned across individuals in an unsupervised manner in both mice and humans. In contrast, we found that the degree of alignment across different brain areas cannot be fully explained by proximity in the visual processing hierarchy alone, but also found some reasonable alignment results, such that the similarity structures of higher-order visual areas can be well aligned with each other but not with lower-order visual areas. We expect that our unsupervised approach will be useful for revealing more detailed structural commonalities or differences that may not be captured by the conventional supervised approach.

Microglia replacement by ER-Hoxb8 conditionally immortalized macrophages provides insight into Aicardi-Goutieres Syndrome neuropathology
Microglia, the brains resident macrophages, can be reconstituted by surrogate cells - a process termed "microglia replacement." To expand the microglia replacement toolkit, we here introduce estrogen-regulated (ER) homeobox B8 (Hoxb8) conditionally immortalized macrophages, a cell model for generation of immune cells from murine bone marrow, as a versatile model for microglia replacement. We find that ER-Hoxb8 macrophages are highly comparable to primary bone marrow-derived (BMD) macrophages in vitro, and, when transplanted into a microglia-free brain, engraft the parenchyma and differentiate into microglia-like cells. Furthermore, ER-Hoxb8 progenitors are readily transducible by virus and easily stored as stable, genetically manipulated cell lines. As a demonstration of this systems power for studying the effects of disease mutations on microglia in vivo, we created stable, Adar1-mutated ER-Hoxb8 lines using CRISPR-Cas9 to study the intrinsic contribution of macrophages to Aicardi-Goutieres Syndrome (AGS), an inherited interferonopathy that primarily affects the brain and immune system. We find that Adar1 knockout elicited interferon secretion and impaired macrophage production in vitro, while preventing brain macrophage engraftment in vivo - phenotypes that can be rescued with concurrent mutation of Ifih1 (MDA5) in vitro, but not in vivo. Lastly, we extended these findings by generating ER-Hoxb8 progenitors from mice harboring a patient-specific Adar1 mutation (D1113H). We demonstrated the ability of microglia-specific D1113H mutation to drive interferon production in vivo, suggesting microglia drive AGS neuropathology. In sum, we introduce the ER-Hoxb8 approach to model microglia replacement and use it to clarify macrophage contributions to AGS.

Development and evaluation of a non-invasive brain-spine interface using transcutaneous spinal cord stimulation
Motor rehabilitation is a therapeutic process to facilitate functional recovery in people with spinal cord injury (SCI). However, its efficacy is limited to areas with remaining sensorimotor function. Spinal cord stimulation (SCS) creates a temporary prosthetic effect that may allow further rehabilitation-induced recovery in individuals without remaining sensorimotor function, thereby extending the therapeutic reach of motor rehabilitation to individuals with more severe injuries. In this work, we report our first steps in developing a non-invasive brain-spine interface (BSI) based on electroencephalography (EEG) and transcutaneous spinal cord stimulation (tSCS). The objective of this study was to identify EEG-based neural correlates of lower limb movement in the sensorimotor cortex of unimpaired individuals and to quantify the performance of a linear discriminant analysis (LDA) decoder in detecting movement onset from these neural correlates. Our results show that initiation of knee extension was associated with event-related desynchronization in the central-medial cortical regions at frequency bands between 4-44 Hz. Our neural decoder using (8-12 Hz), low {beta} (16-20 Hz), and high {beta} (24-28 Hz) frequency bands achieved an average area under the curve (AUC) of 0.83 {+/-} 0.06 s.d. (n = 7) during a cued movement task offline. Generalization to imagery and uncued movement tasks served as positive controls to verify robustness against movement artifacts and cue-related confounds, respectively. With the addition of real-time decoder-modulated tSCS, the neural decoder performed with an average AUC of 0.81 {+/-} 0.05 s.d. (n = 9) on cued movement and 0.68 {+/-} 0.12 s.d. (n = 9) on uncued movement. Our results suggest that the decrease in decoder performance in uncued movement may be due to differences in underlying cortical strategies between conditions. Furthermore, we explore alternative applications of the BSI system by testing neural decoders trained on uncued movement and imagery tasks. By developing a non-invasive BSI, tSCS can be timed to be delivered only during voluntary effort, which may have implications for improving rehabilitation.

Dopamine release in striatal striosome compartments in response to rewards and aversive outcomes during classical conditioning in mice
The striatum consists of two anatomically and neurochemically distinct compartments, striosomes and the matrix, which receive dopaminergic inputs from the midbrain and exhibit distinct dopamine release dynamics in acute brain slices. Striosomes comprise approximately 15% of the striatum by volume and are distributed mosaically. Therefore, it is difficult to selectively record dopamine dynamics in striosomes using traditional neurochemical measurements in behaving animals, and it is unclear whether distinct dynamics play a role in associative learning. In this study, we used transgenic mice selectively expressing Cre in striosomal neurons, combined with a fiber photometry technique, to selectively record dopamine release in striosomes during classical conditioning. Water-restricted mice could distinguish the conditioned stimulus (CS) associated with saccharin water from the air-puff-associated CS. The air-puff-associated CS evoked phasic dopamine release only in striosomes. Furthermore, air puff presentation induced dopamine release to striosomal neurons but suppressed release to putative matrix neurons. These findings suggest that dopamine is released in a differential manner in striosomes and the matrix in behaving animals and that dopamine release in striosomes is preferentially induced by the air-puff-associated CS and air puff presentation. These findings support the hypothesis that striosomal neurons play a dominant role in aversive stimuli prediction.

Brain plasticity for visual words: Elementary school teachers can drive changes in weeks that rival those formed over years
This study aims to investigate the impact of vocabulary acquisition through short-term classroom learning and its relation to broader forms of vocabulary learning through long-term exposure in daily life. Through a two week of "learning sprint" in collaboration with a local elementary school and EEG-Steady State Visual Evoked Potentials (EEG SSVEP) paradigm, we assessed new vocabulary learning in first and second graders within their pedagogical environment. We then compared the results with the word frequency effect, a well-established phenonmenon that reflects long-term vocabulary learning. After two weeks of classroom instruction, newly acquired words elicited neural responses similar to those of high-frequency words, with the effect significantly correlated with children's phonological decoding skills. Additionally, we successfully replicated the word frequency effect using the SSVEP paradigm for the first time. These findings highlight the potential of the "learning sprint" model for conducting neuroscience research in authentic educational settings, thereby fostering a stronger connection between education and neuroscience.

Is there a ubiquitous spectrolaminar motif of local field potential power across primate neocortex?
Mendoza-Halliday, Major et al. 2024 ("The Paper") advocates a local field potential (LFP)-based approach to functional identification of cortical layers during "laminar" (simultaneous recordings from all cortical layers) multielectrode recordings in nonhuman primates (NHPs). The Paper describes a "ubiquitous spectrolaminar motif" in the primate neocortex: 1) 75-150 Hz power peaks in the supragranular layers, 2) 10-19 Hz power peaks in the infragranular layers and 3) the crossing point of their laminar power gradients identifies layer 4 (L4). Identification of L4 is critical in general, but especially for The Paper as the "motif" discovery is couched within a framework whose central hypothesis is that gamma activity originates in the supragranular layers and reflects feedforward activity, while alpha-beta activity originates in the infragranular layers and reflects feedback activity. In an impressive scientific effort, The Paper analyzed laminar data from 14 cortical areas in 2 prior macaque studies and compared them to marmoset, mouse and human data to further bolster the canonical nature of the motif. Identification of such canonical principles of brain operation is clearly a topic of broad scientific interest. Similarly, a reliable online method for L4 identification would be of broad scientific value for the rapidly increasing use of laminar recordings using numerous evolving technologies. Despite The Paper's strengths, and its potential for scientific impact, a series of concerns that are fundamental to the analysis and interpretation of laminar activity profile data in general, and local field potential (LFP) signals in particular, led us to question its conclusions. We thus evaluated the generality of The Paper's methods and findings using new sets of data comprised of stimulus-evoked laminar response profiles from primary and higher-order auditory cortices (A1 and belt cortex), and primary visual cortex (V1). The rationale for using these areas as a test bed for new methods is that their laminar anatomy and physiology have already been extensively characterized by prior studies, and there is general agreement across laboratories on key matters like L4 identification. Our analyses indicate that The Paper's findings do not generalize well to any of these cortical areas. In particular, we find The Paper's methods for L4 identification to be unreliable. Moreover, both methodological and statistical concerns, outlined below and in the supplement, question the stated prevalence of the motif in The Paper's published dataset. After summarizing our findings and related broader concerns, we briefly critique the evidence from biophysical modeling studies cited to support The Paper's conclusions. While our findings are at odds with the proposition of a ubiquitous spectrolaminar motif in the primate neocortex, The Paper already has, and will continue to spark debate and further experimentation. Hopefully this countervailing presentation will lead to robust collegial efforts to define optimal strategies for applying laminar recording methods in future studies.

Comparative study of pre- and post-mortem perfusion of fixative for the quality of neuronal tissue preparation
Transcardiac perfusion of fixative agent is generally recommended for quality preparations for cerebral histology, ensuring rapid and deep penetration in the tissue to preserve the most fragile brain structures. Despite being performed under anesthesia and with proper analgesia, this procedure is cumbersome for the experimenter and raises ethical questions. Recently, alternative protocols have been proposed, based on prior sacrifice of the animal followed by an injection of a fixative agent into the circulation. These so-called post-mortem perfusion protocols should in theory ensure an equivalent quality of tissue fixation, without exposing live animals to a procedure. Before adopting this new method, it is necessary to validate that sample quality is equivalent, ensuring the validity of scientific results. We performed a parallel comparison of several protocols of tissue fixation, by transcardiac or post-mortem perfusion, and measured the impact on the maintenance of axonal structures, dendritic spines, and mitochondrial morphology. Our results showed that histological parameters show variable sensitivity to perfusion condition and fixative used. For instance, axon fragmentation and altered mitochondrial morphology were observed in post-mortem perfusion groups. We furthermore determined that fixation condition had a variable effect on immunostaining, impacting detected expression level or pattern. Our results serve as a guide to orient the experimenter in selecting the best condition for optimal tissue fixation, which minimizes animal suffering while guaranteeing the integrity of the biological results obtained.

Zero-echo time imaging achieves whole brain activity mapping without ventral signal loss in mice
Functional MRI (fMRI) is an important tool for investigating functional networks. However, the widely used fMRI with T2*-weighted imaging in rodents has the problem of signal lack in the lateral ventral area of forebrain including the amygdala, which is essential for not only emotion but also noxious pain. Here, we scouted the zero-echo time (ZTE) sequence, which is robust to magnetic susceptibility and motion-derived artifacts, to image activation in the whole brain including the amygdala following the noxious stimulation to the hind paw. ZTE exhibited higher spatial and temporal signal-to-noise ratios than conventional fMRI sequences. Electrical sensory stimulation of the hind paw evoked ZTE signal increase in the primary somatosensory cortex. Formalin injection into the hind paw evoked early and latent change of ZTE signals throughout the whole brain including the subregions of amygdala. Furthermore, resting-state fMRI using ZTE demonstrated the functional connectivity, including that of the amygdala. These results indicate the feasibility of ZTE for whole brain fMRI, including the amygdala and we first show acute and latent activity in different subnuclei of the amygdala complex after nociceptive stimulation.

Neuronal synchronization in Drosophila
Rhythms are intrinsic to biological processes across temporal and spatial scales. In the brain, the synchronized oscillatory activity of neurons creates collective rhythms that are essential for complex functions. While this is a recognized phenomenon in the mammalian brain, information about insect neuronal synchrony and its underlying mechanisms is scarce. In the fly brain, neuronal oscillations were reported in individual lateral ventral neurons (LNvs), which play a key role in circadian and sleep behaviors. However, it is still unclear whether and how these participate in a collective rhythm. In this work, we perform thorough whole-cell patch clamp recordings of LNvs, and demonstrate consistent membrane potential oscillations. We show that oscillations degrade over time, and disappear upon exposure to an acetylcholine receptor blocker. Together with a flat phase response curve, these results suggest that oscillations are exogenously produced. Prompted by these results, we propose a generic forced oscillator theory that can account for the experimental phase response. The theory further predicts that neurons with similar properties should oscillate in synchrony with zero lags, while neurons with different properties may show coherent oscillations with non-zero lags. We confirm this prediction through simultaneous patch clamp recordings of neuronal pairs, revealing that large LNvs are consistently advanced relative to small LNvs. Additionally, we find that other neurons in the accessory medulla also exhibit coherent membrane potential oscillations, with diverse lags. Our findings suggest the intriguing possibility that brain waves may arise from collective neuronal activity within this region of the fly brain.

Circadian modulation of mosquito host-seeking persistence by Pigment-Dispersing Factor impacts daily biting patterns
Daily rhythms in mosquito attraction to humans are thought to drive biting patterns and contribute to disease transmission dynamics. Behavioral rhythms in many insects are controlled by specialized clock cells in the brain that are coordinated by the neuropeptide Pigment-Dispersing Factor (PDF). We show that female Aedes aegypti mosquitoes with genetically disrupted PDF display altered daily behavioral timing with reduced locomotor activity and biting in the morning. Using an automated behavioral tracking system, we also report that mosquitoes exhibit daily modulation of response persistence to the host cue carbon dioxide and loss of PDF alters this pattern. These findings indicate that PDF regulates temporal features of host-seeking behavior that promote biting success at specific times of day and may underlie blood feeding patterns observed in the field.

Generation of an inducible destabilized-domain Cre mouse line to target disease associated microglia
The function of microglia during progression of Alzheimer's disease (AD) can be investigated using mouse models that enable genetic manipulation of microglial subpopulations in a temporal manner. We developed a mouse strain that expresses destabilized-domain Cre recombinase (DD-Cre) from the Cst7 locus (Cst7DD-Cre) and tested this in 5xFAD amyloidogenic, Ai14 tdTomato cre-reporter line mice. Dietary administration of trimethoprim to induce DD-Cre activity produces long-term labeling in disease associated microglia (DAM) without evidence of leakiness, with tdTomato-expression restricted to cells surrounding plaques. Using this model, we found that DAMs are a subset of plaque-associated microglia (PAMs) and their transition to DAM increases with age and disease stage. Spatial transcriptomic analysis revealed that tdTomato+ cells show higher expression of disease and inflammatory genes compared to other microglial populations, including non-labeled PAMs. This model should allow inducible cre-loxP targeting of DAMs, without leakiness.

Sequestration of oxidative is necessary but not sufficient enough to conclude dopaminergic neuroprotective efficacy of curcumin: Insights from ALSS Drosophila Parkinson disease model
Turmeric is a centuries-old ethnomedicine in Asia. Previously our laboratory demonstrated in the adult life stage-specific (ALSS) Drosophila model of Parkinson disease (PD) that Curcumin (K)-mediated dopaminergic (DAergic) neuroprotection is absent in the transition stage of adult life during which late-onset neurodegenerative disorders like PD sets-in, suggesting its limitation as a therapeutic agent. The present study demonstrates that K can sequester the enhanced levels of brain oxidative stress (OS) during both adult life phases i.e. health and transition stages but confers neuroprotection only during the health phase. However, literature reviews illustrate that efficacy of supposed therapeutic agents was asserted by their ability to sequester OS in only young PD animal models. In this context, it is important to point out that despite encouraging results in animal models, therapeutic efforts to target the general state of OS failed to retard PD progression. To understand this paradigm, we further investigated ALSS regulation of molecular players in the brain of the ALSS fly PD model and discovered that K-mediated differential modulation of adaptive stress response through dFOXO contributes to health phase-specific neuroprotection. These observations suggest that apart from the study of OS markers; it is essential to understand the ALSS regulation of molecular players. The synergistic influence of OS and the ALSS dysfunctional molecular networks could be responsible for the DAergic neurodegeneration in PD. The insights suggest that sequestration of OS by a therapeutic agent is necessary, but inadequate to conclude its neuroprotective efficacy and push it to the next phase of preclinical/clinical evaluation.

Neural Encoding of Direction and Distance across Reference Frames in Visually Guided Reaching
Goal-directed actions require transforming sensory information into motor plans defined across multiple parameters and reference frames. Substantial evidence supports the encoding of target direction in gaze- and body-centered coordinates within parietal and premotor regions. However, how the brain encodes the equally critical parameter of target distance remains less understood. Here, using Bayesian pattern component modeling of fMRI data during a delayed reach-to-target task, we dissociated the neural encoding of both target direction and the relative distances between target, gaze, and hand at early and late stages of motor planning. This approach revealed independent representations of direction and distance along the human dorsomedial reach pathway. During early planning, most premotor and superior parietal areas encoded target distance in single or multiple reference frames and encoded direction. In contrast, distance encoding was magnified in gaze- and body-centric reference frames during late planning. These results emphasize a flexible and efficient human central nervous system that achieves goals by remapping sensory information related to multiple parameters, such as distance and direction, in the same brain areas.

SENP2-based N-terminal truncation of α-synuclein in Lewy pathology propagation
-Synuclein (Syn) is a major component of Lewy bodies (LBs) and Lewy neurites (LNs) which are pathological features of Parkinson's disease (PD) and Dementia with Lewy bodies. In the PD brain, with disease progression, LB/LN formation is propagated from the lower brainstem to the cerebral cortex. Prion-like cell-to-cell seed-transmission has been implicated as an underlying mechanism for Lewy-pathology propagation. However, the biochemical properties and production mechanism of those pathogenic seeds are unelucidated. In this study, we ascertained that the seeds released from pathological neurons that harbour LB/LN-like aggregates have the N-terminally truncated form of Syn. This N-terminal truncation is directly catalysed by SENP2, which is a well-known deSUMOylation enzyme. After SENP2 processing of recombinant Syn, the SDS-resistant high-molecular oligomer formation was promoted in vitro. Inhibition of SENP2 activity suppressed aggregate formation and propagation in cultured neurons and mouse brains. Thus, SENP2 might be a novel therapeutic target in LB diseases.