bioRxiv Subject Collection: Neuroscience's Journal
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Wednesday, June 19th, 2024
| Time |
Event |
| 8:33a |
A network correspondence toolbox for quantitative evaluation of novel neuroimaging results
Decades of neuroscience research has shown that macroscale brain dynamics can be reliably decomposed into a subset of large-scale functional networks, but the specific spatial topographies of these networks and the names used to describe them can vary across studies. Such discordance has hampered interpretation and convergence of research findings across the field. To address this problem, we have developed the Network Correspondence Toolbox (NCT) to permit researchers to examine and report spatial correspondence between their novel neuroimaging results and sixteen widely used functional brain atlases, consistent with recommended reporting standards developed by the Organization for Human Brain Mapping.
The atlases included in the toolbox show some topographical convergence for specific networks, such as those labeled as "default" or "visual". Network naming varies across atlases, particularly for networks spanning frontoparietal association cortices. For this reason, quantitative comparison with multiple atlases is recommended to benchmark novel neuroimaging findings.
We provide several exemplar demonstrations using the Human Connectome Project task fMRI results and UK Biobank independent component analysis maps to illustrate how researchers can use the NCT to report their own findings through quantitative evaluation against multiple published atlases. The NCT provides a convenient means for computing Dice coefficients with spin test permutations to determine the magnitude and statistical significance of correspondence among user-defined maps and existing atlas labels. The NCT also includes functionality to incorporate additional atlases in the future. The adoption of the NCT will make it easier for network neuroscience researchers to report their findings in a standardized manner, thus aiding reproducibility and facilitating comparisons between studies to produce interdisciplinary insights. | | 8:33a |
Theta-burst stimulation over primary somatosensory cortex modulates tactile acuity of tongue
BackgroundEmerging studies in humans have established the modulatory effects of repetitive transcranial magnetic stimulation (rTMS) over primary somatosensory cortex (S1) on somatosensory cortex activity and perception. However, to date, research in this area has primarily focused on the hand and fingers, leaving a gap in our understanding of the modulatory effects of rTMS on somatosensory perception of the orofacial system and speech articulators.
ObjectiveThe present study aimed to examine the effects of different types of theta-burst stimulation--continuous TBS (cTBS), intermittent TBS (iTBS), or sham--over the tongue representation of left S1 on tactile acuity of the tongue.
MethodsIn a repeated-measures design, fifteen volunteers participated in four separate sessions, where cTBS, iTBS, sham, or no stimulation was applied over the tongue representation of left S1. Effects of TBS were measured on both temporal and spatial perceptual acuity of tongue using a custom vibrotactile stimulator.
ResultsCTBS significantly impaired spatial amplitude threshold at the time window of 16-30 minutes after stimulation, while iTBS improved it at the same time window. The effect of iTBS, however, was smaller than cTBS. In contrast, neither cTBS nor iTBS had any effect on the temporal discrimination threshold.
ConclusionsThe current study establishes the validity of using TBS to modulate somatosensory perception of the orofacial system. Directly modifying somatosensation in the orofacial system has the potential to benefit clinical populations with abnormal tactile acuity, improve our understanding of the role of sensory systems in speech production, and enhance speech motor learning and rehabilitation.
HighlightsO_LITheta-burst stimulation (TBS) can modulate somatosensation in the orofacial system
C_LIO_LIcTBS over S1 impaired spatial acuity of tongue
C_LIO_LIiTBS over S1 improved spatial acuity of tongue
C_LI | | 9:46a |
The transcriptomic and spatial organization of telencephalic GABAergic neuronal types
The telencephalon of the mammalian brain comprises multiple regions and circuit pathways that play adaptive and integrative roles in a variety of brain functions. There is a wide array of GABAergic neurons in the telencephalon; they play a multitude of circuit functions, and dysfunction of these neurons has been implicated in diverse brain disorders. In this study, we conducted a systematic and in-depth analysis of the transcriptomic and spatial organization of GABAergic neuronal types in all regions of the mouse telencephalon and their developmental origins. This was accomplished by utilizing 611,423 single-cell transcriptomes from the comprehensive and high-resolution transcriptomic and spatial cell type atlas for the adult whole mouse brain we have generated, supplemented with an additional single-cell RNA-sequencing dataset containing 99,438 high-quality single-cell transcriptomes collected from the pre- and postnatal developing mouse brain. We present a hierarchically organized adult telencephalic GABAergic neuronal cell type taxonomy of 7 classes, 52 subclasses, 284 supertypes, and 1,051 clusters, as well as a corresponding developmental taxonomy of 450 clusters across different ages. Detailed charting efforts reveal extraordinary complexity where relationships among cell types reflect both spatial locations and developmental origins. Transcriptomically and developmentally related cell types can often be found in distant and diverse brain regions indicating that long-distance migration and dispersion is a common characteristic of nearly all classes of telencephalic GABAergic neurons. Additionally, we find various spatial dimensions of both discrete and continuous variations among related cell types that are correlated with gene expression gradients. Lastly, we find that cortical, striatal and some pallidal GABAergic neurons undergo extensive postnatal diversification, whereas septal and most pallidal GABAergic neuronal types emerge simultaneously during the embryonic stage with limited postnatal diversification. Overall, the telencephalic GABAergic cell type taxonomy can serve as a foundational reference for molecular, structural and functional studies of cell types and circuits by the entire community. | | 9:46a |
Functional segregation of conversational production and comprehension when using word predictability
The extent to which the language production and comprehension systems overlap remains debated. We address this debate using a dataset where participants engaged in unscripted conversations, while scanned with fMRI. Word predictability was hypothesized to rely on different processes, depending on whether the word was uttered or heard. We employed the information-theoretic measure of surprisal (the negative log probability of a word occurring, given the preceding context) as a parametric modulator, controlling for the words overall frequency. The results for production surprisal revealed activation in the left superior and inferior frontal gyri and motor areas. A large bilateral cluster in the posterior part of the medial prefrontal cortex extended from the supplementary motor area to the anterior cingulate cortex. The results for comprehension surprisal replicated findings from non-conversational contexts, showing involvement of the bilateral superior temporal gyrus/sulcus, presumably supporting bottom-up processes for prediction error detection. Importantly, no overlap in the neural infrastructure of production and comprehension was observed, suggesting that word predictability processes in production and comprehension differ. We suggest that while the comprehension system handles prediction errors, the production system minimizes these errors through adaptation, all to achieve successful communication. | | 9:46a |
Adolescent maturation of cortical excitation-inhibition balance based on individualized biophysical network modeling
The balance of excitation and inhibition is a key functional property of cortical microcircuits which changes through the lifespan. Adolescence is considered a crucial period for the maturation of excitation-inhibition balance. This has been primarily observed in animal studies, yet human in vivo evidence on adolescent maturation of the excitation-inhibition balance at the individual level is limited. Here, we developed an individualized in vivo marker of regional excitation-inhibition balance in human adolescents, estimated using large-scale simulations of biophysical network models fitted to resting-state functional magnetic resonance imaging data from two independent cross-sectional (N = 752) and longitudinal (N = 149) cohorts. We found a widespread relative increase of inhibition in association cortices paralleled by a relative age-related increase of excitation, or lack of change, in sensorimotor areas across both datasets. This developmental pattern co-aligned with multiscale markers of sensorimotor-association differentiation. The spatial pattern of excitation-inhibition development in adolescence was robust to inter-individual variability of structural connectomes and modeling configurations. Notably, we found that alternative simulation-based markers of excitation-inhibition balance show a variable sensitivity to maturational change. Taken together, our study highlights an increase of inhibition during adolescence in association areas using cross sectional and longitudinal data, and provides a robust computational framework to estimate microcircuit maturation in vivo at the individual level. | | 9:46a |
Transcranial Direct Current Stimulation over the Posterior Parietal Cortex Increases Non-target Retrieval during Visual Working Memory
Accurate visual working memory (VWM) requires precise content-context binding. Previous studies have revealed a close relationship between the posterior parietal cortex (PPC) and feature binding during VWM, this study further examined their causal relationship through three transcranial direct current stimulation (tDCS) experiments. In Experiment 1 (N = 57), participants underwent three sessions of tDCS separately, including PPC stimulation, occipital cortex stimulation, and sham stimulation, and completed a series of delayed estimation tasks for orientations before and after stimulation. Results showed that tDCS over PPC selectively prolonged recall response time (RT) and increased the probability of non-target responses (a.k.a. failure of feature binding). In Experiment 2 (N = 29), combining metacognition estimation during the task, we further investigated whether the effects of PPC stimulation on RT and increased probability of non-target responses were attributed to more mis-binding (i.e., participants self-reported "remembered" in non-target responses) or informed guessing (participants self-reported "forgotten" in non-target responses). We replicated the main findings in Experiment 1, and we also observed greater tDCS effects of PPC on RT in informed guessing trials than mis-binding trials while comparable effects on non-target response rates in these two types of trials. In Experiment 3 (N = 28), we then examined whether the effects of tDCS over PPC specifically influenced the memory retrieval process by using a change detection task. We found that PPC stimulation did not influence the recognition RT or accuracy. Together, this study provides causal evidence supporting the involvement of PPC in feature binding during VWM retrieval.
Significance StatementVisual working memory (VWM) enables humans to temporarily store and process visual information, which requires accurate binding of items to their unique context. Accumulating studies posited that the posterior parietal cortex (PPC) is closely related to this binding process, the current study further examined their causal relationship. Through three strictly within-subject well-designed non-invasive neural stimulation experiments, we found that PPC stimulation selectively increased response time (RT) and binding error during VWM. Moreover, we found these changes were modulated by individual metacognition and only occurred during memory recall instead of recognition. Together, our results provided strong evidence that PPC is causally involved in the binding process during visual working memory retrieval. |
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