Awasthi, J. | Search bioRxiv

bioRxiv2024

Disruption of the Social Visual Pathway in Autism Spectrum Disorder

The social visual pathway, which diverges from the dorsal pathway at the visual motion area (MT/V5) and runs from posterior down to anterior portions of the superior temporal sulcus (STS), specializes in processing dynamic social information. This study examined resting-state functional connectivity within this pathway in children with autism spectrum disorder (ASD) and typically developing (TD) children. Using data from the ABIDE (Autism Brain Imaging Data Exchange) repository, we found significant underconnectivity between the posterior and middle STS (pSTS-mSTS) in the right hemisphere in children with ASD compared to TD children. Weaker connectivity in this region of the pathway correlated with more severe social impairment symptoms in ASD and reduced social function across both ASD and TD groups. These findings suggest a specific disruption in the right hemisphere social visual pathway in ASD, potentially contributing to social deficits observed in the disorder.

neuroscience↗

bioRxiv2020

Comprehensive Topographical Map of the Serotonergic Fibers in the Mouse Brain

It is well established that serotonergic fibers distribute throughout the brain. Abnormal densities or patterns of serotonergic fibers have been implicated in neuropsychiatric disorders. Although many classical studies have examined the distribution pattern of serotonergic fibers, most of them were either limited to specific brain areas or had limitations in demonstrating the fine axonal morphology. In this study, we utilize transgenic mice expressing GFP under the SERT promoter to map the topography of serotonergic fibers across the rostro-caudal extent of each brain area. We demonstrate previously unreported regional density and fine-grained anatomy of serotonergic fibers. Our findings include: 1) SERT fibers distribute abundantly in the thalamic nuclei close to the midline and dorsolateral areas, in most of the hypothalamic nuclei with few exceptions such as the median eminence and arcuate nuclei, and within the basal amygdaloid complex and lateral septal nuclei, 2) the source fibers of innervation of the hippocampus traverse through the septal nuclei before reaching its destination, 3) unique, filamentous type of straight terminal fibers within the nucleus accumbens, 4) laminar pattern of innervation in the hippocampus, olfactory bulb and cortex with heterogenicity in innervation density among the layers, 5) cortical labelling density gradually decreases rostro-caudally, 6) fibers traverse and distribute mostly within the gray matter, leaving the white fiber bundles uninnervated, and 7) most of the highly labelled nuclei and cortical areas have predominant anatomical connection to limbic structures. In conclusion, we provide novel, regionally specific insights on the distribution map of serotonergic fibers using transgenic mouse.

neuroscience↗