bioRxiv Subject Collection: Neuroscience's Journal
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Friday, March 1st, 2024
| Time |
Event |
| 3:17a |
Awareness is determined by emotion and gender
Traditionally, consciousness studies focus on domain general cognitive processes rather than on specific information reaching subjective awareness. The present study (N = 45) used visual masking and whole-body images to investigate whether the specific emotional expression as well as gender of the stimuli and of the participants impact awareness. Our results show that participants awareness responses reflect differences in the specific emotion of the stimuli, that these differences are a function of the gender of the stimuli as well as the gender of the participants and that minimal awareness may be associated with emotion specific features of the body images. Overall, we observed that threatening expressions are more easily detected than fearful ones, especially by males presented with male stimuli. Our findings underscore the importance of affective factors for theories of consciousness and underscore the significance of gender differences in emotional processing, often overlooked in past face and body emotion recognition studies. | | 4:39a |
Neurophysiological measures of covert semantic processing in neurotypical adolescents actively ignoring spoken sentence inputs: A high-density event-related potential (ERP) study.
Language comprehension requires semantic processing of individual words and their context within a sentence. Well-characterized event-related potential (ERP) components (the N400 and late positivity component (LPC/P600)) provide neuromarkers of semantic processing, and are robustly evoked when semantic errors are introduced into sentences. These measures are useful for evaluating semantic processing in clinical populations, but it is not known whether they can be evoked in more severe neurodevelopmental disorders where explicit attention to the sentence inputs cannot be objectively assessed (i.e., when sentences are passively listened to). We evaluated whether N400 and LPC/P600 could be detected in adolescents who were explicitly ignoring sentence inputs. Specifically, it was asked whether explicit attention to spoken inputs was required for semantic processing, or if a degree of automatic processing occurs when the focus of attention is directed elsewhere? High-density ERPs were acquired from twenty-two adolescents (7-12 years), under two experimental conditions: 1) individuals actively determined whether the final word in a sentence was congruent or incongruent with sentence context, or 2) passively listened to background sentences while watching a video. When sentences were ignored, N400 and LPC/P600 were robustly evoked to semantic errors, albeit with reduced amplitudes and protracted/delayed latencies. Statistically distinct topographic distributions during passive versus active paradigms pointed to distinct generator configurations for semantic processing as a function of attention. Covert semantic processing continues in neurotypical adolescents when explicit attention is withdrawn from sentence inputs. As such, this approach could be used to objectively investigate semantic processing in populations with communication deficits. | | 4:39a |
An Anatomical and Physiological Basis for Coincidence Detection Across Time Scales in the Auditory System
Coincidence detection is a common neural computation that identifies co-occurring stimuli by integration of inputs. In the auditory system, octopus cells act as coincidence detectors for complex sounds that include both synchronous and sequenced combinations of frequencies. Octopus cells must detect coincidence on both the millisecond and submillisecond time scale, unlike the average neuron, which integrates inputs over time on the order of tens of milliseconds. Here, we show that octopus cell computations in the cell body are shaped by inhibition in the dendrites, which adjusts the strength and timing of incoming signals to achieve submillisecond acuity. This mechanism is crucial for the fundamental process of integrating the synchronized frequencies of natural auditory signals over time. | | 4:39a |
Neuronal ARHGAP8 controls synapse structure and AMPA receptor-mediated synaptic transmission
The aberrant formation and function of neuronal synapses are recognized as major phenotypes in many cases of neurodevelopmental (NDDs) and -psychiatric disorders (NPDs). A growing body of research has identified an expanding number of susceptibility genes encoding proteins with synaptic function. Here, we present the first brain-focused characterization of a potential new susceptibility gene, ARHAGP8, which encodes a Rho GTPase activating protein (RhoGAP). Accumulating evidence suggests that ARHGAP8 plays a pivotal role in the pathogenesis of NPDs/NDDs. We provide the first evidence for ARHGAP8 as a novel player at excitatory synapses, with its synaptic localisation linked to the presence of the developmentally important NMDA receptor subunit GluN2B. By increasing ARHGAP8 levels in hippocampal neurons to mimic the copy number variant found in a subset of patients, we observed reductions in dendritic complexity and spine volume, accompanied by a significant decrease in synaptic AMPA receptor-mediated transmission. These results suggest that ARHGAP8 plays a role in shaping the morphology and function of excitatory synapses, and prompt further investigation of ARHGAP8 as a candidate gene in NDDs/NPDs. |
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