Biology subjects

Chow, H. M.

Publications and source records attributed to Chow, H. M..

6 recordsLinked to original sources

bioRxiv2026

Fixel-wise Differences in White Matter Fiber-bundle Cross-section identified in Children who Stutter

Developmental stuttering has been repeatedly linked to decreased white matter integrity and structural connectivity differences in major white matter tracts. Prior diffusion-weighted MRI studies reporting such white matter structural differences involved voxel-averaged tensor measures (e.g., fractional anisotropy (FA)). A well-acknowledged limitation of this approach, however, has been that it cannot resolve distinct fiber populations within crossing-fiber regions. Fixel-based analysis addresses this limitation by quantifying individual fiber populations within a voxel and providing complementary measures of fiber density (FD), fiber-bundle cross-section (FC), and their combined measure (FDC).Here we applied Fixel-based analysis to diffusion MRI data from 171 children aged 3 - 13 years, including 84 children who stutter and 87 typically developing controls, to test whether white-matter differences associated with developmental stuttering were expressed as differences in FD, FC, and FDC and whether these measures show group-specific age-related patterns. We evaluated this at both the whole-brain level and within a priori white-matter tracts.FC, but not FD or FDC, showed significant Group and Group by Age effects, indicating that white-matter differences were primarily expressed in fiber-bundle macrostructure. Tract-of-interest analyses identified developmental differences in bilateral arcuate fasciculus FC that remained significant across tracts, with controls showing greater age-related increases in FC than children who stutter. Additional FC differences were observed across corticospinal and thalamocortical pathways, although these tract-wise effects were less robust to across-tract correction. These findings suggest that white-matter differences in developmental stuttering are prominently expressed in fiber-bundle macrostructure rather than fiber density and highlight divergent development of bilateral arcuate pathways. FBA provides fiber-specific information that complements conventional tensor-based diffusion measures and may improve characterization of white-matter development in childhood stuttering.

neuroscience↗

bioRxiv2026

Neural subtypes in developmental stuttering

Developmental stuttering is a complex neurodevelopmental disorder characterized by disfluent speech. At the individual level, the behavioral manifestations of stuttering vary considerably, likely reflecting heterogeneity in underlying neural mechanisms. In this study, we examined individual-specific differences in the brains of children who stutter (CWS), by implementing normative modeling, a framework that quantifies how an individual deviates from an age- and sex-matched reference population. We applied this approach to identify individual-specific structural brain atypicalities using gray and white matter volumes. These volumes were derived from MRI scans from a large mixed-longitudinal dataset of 235 and 240 scans from CWS and fluent controls respectively, aged between 3 and 12 years. Individual deviation maps capturing these atypicalities were then used to cluster CWS into subtypes based on similarities in their neuroanatomical profiles. This analysis identified four neural subtypes with distinct neuroanatomical atypicalities relative to fluent controls. The key findings were a basal ganglia-thalamo-cerebellar subtype associated with higher stuttering severity and lower rates of recovery, and a white matter subtype characterized by mild severity and a higher likelihood of recovery. The remaining two subtypes showed cerebellar differences alongside alterations in brain regions involved in sensorimotor integration. Moreover, cerebellar volume atypicalities were present in all four subtypes, indicating that cerebellar alterations were present across otherwise distinct neural profiles and may represent a shared neuroanatomical feature of stuttering. These findings indicate that examining individual-specific neural differences and subtyping based on patterns of neural atypicalities provides valuable insight into the heterogeneity of developmental stuttering and represents a promising direction for improving our understanding of the disorder.

neuroscience↗

bioRxiv2023

Smooth Pursuit Inhibition Reveals Audiovisual Enhancement of Fast Movement Control

The sudden onset of a visual object or event elicits an inhibition of eye movements at latencies approaching the minimum delay of visuomotor conductance in the brain. Typically, information presented via multiple sensory modalities, such as sound and vision, evokes stronger and more robust responses than unisensory information. Whether and how multisensory information affects ultra-short latency oculomotor inhibition is unknown. In two experiments, we investigate smooth pursuit and saccadic inhibition in response to multisensory distractors. Observers tracked a horizontally moving dot and were interrupted by an unpredictable visual, auditory, or audiovisual distractor. Distractors elicited a transient inhibition of pursuit eye velocity and catch-up saccade rate within [~]100 ms of their onset. Audiovisual distractors evoked stronger oculomotor inhibition than visual-or auditory-only distractors, indicating multisensory response enhancement. Multisensory response enhancement magnitudes were equal to the linear sum of responses to component stimuli. These results demonstrate that multisensory information affects eye movements even at ultra-short latencies, establishing a lower time boundary for multisensory-guided behaviour. We conclude that oculomotor circuits must have privileged access to sensory information from multiple modalities, presumably via a fast, subcortical pathway.

neuroscience↗

bioRxiv2020

Look where you go: characterizing eye movements toward optic flow

When we move through our environment, objects in the visual scene create optic flow patterns on the retina. Even though optic flow is ubiquitous in everyday life, it is not well understood how our eyes naturally respond to it. In small groups of human and non-human primates, optic flow triggers intuitive, uninstructed eye movements to the patterns focus of expansion (Knoll, Pillow & Huk, 2018). Here we investigate whether such intuitive oculomotor responses to optic flow are generalizable to a larger group of human observers, and how eye movements are affected by motion signal strength and task instructions. Observers (n = 43) viewed expanding or contracting optic flow constructed by a cloud of moving dots radiating from or converging toward a focus of expansion that could randomly shift. Results show that 84% of observers tracked the focus of expansion with their eyes without being explicitly instructed to track. Intuitive tracking was tuned to motion signal strength: saccades landed closer to the focus of expansion and smooth tracking was more accurate when dot contrast, motion coherence, and translational speed were high. Under explicit tracking instruction, the eyes aligned with the focus of expansion more closely than without instruction. Our results highlight the sensitivity of intuitive eye movements as indicators of visual motion processing in dynamic contexts.

neuroscience↗

bioRxiv2019

Linking lysosomal enzyme targeting genes and energy metabolism with altered gray matter volume in children with persistent stuttering

Developmental stuttering is a childhood onset neurodevelopmental disorder with an unclear etiology. Subtle changes in brain structure and function are present in both children and adults who stutter. It is a highly heritable disorder, and up to 12-20% of stuttering cases may carry a mutation in one of four genes involved in mannose-6-phosphate mediated protein intracellular trafficking. To better understand the relationship between genetic factors and brain structural changes, we used gene expression data from the Allen Institute for Brain Science (AIBS) and voxel-based morphometry (VBM) to investigate the spatial correspondence between gene expression patterns and differences in gray matter volume (GMV) between children with persistent stuttering (n=26, 87 scans) and their fluent peers (n=44, 139 scans). We found that expression patterns of two stuttering-related genes (GNPTG and NAGPA) in the brain exhibit a strong positive spatial correlation with the magnitude of GMV differences between groups. Further gene set enrichment analyses revealed that genes whose expression was highly correlated with the GMV differences were enriched for glycolysis and oxidative metabolism in mitochondria. Although the results are correlational and cannot inform us about underlying casual mechanisms, our results suggest a possibility that regions with high expression level of genes associated with stuttering may be particularly vulnerable to the effect of alterations in these genes. This effect may be further exacerbated by the relatively high energy utilization in those brain during the period of a sharp increase in brain energy utilization, which coincides with a period of rapid language development and the onset of stuttering during childhood.

neuroscience↗

bioRxiv2018

A Sensory Processing Hierarchy for Thermal Touch: Thermal Adaptation Occurs Prior to Thermal-Tactile Integration

The brain consistently faces a challenge of whether and how to combine the available information sources to estimate the properties of an object explored by hand. Thermal referral (TR) is a phenomenon that demonstrates how thermal and tactile modalities coordinate to resolve inconsistencies in spatial and thermal information. When the middle three fingers of one hand are thermally stimulated, but only the outer two fingers are heated (or cooled), thermal uniformity is perceived across three fingers. This illusory experience of thermal uniformity in TR compensates for the discontinuity in the thermal sensation across the sites in contact. The neural loci of TR is unclear. While TR reflects the diffuse nature of the thermoceptive system, its similarities to perceptual filling-in and its facilitative role in object perception also suggest that TR might involve inference processes associated with object perception. To clarify the positioning of this thermo-tactile interaction in the sensory processing hierarchy, we used perceptual adaptation and Bayesian decision modelling techniques. Our results indicate that TR adaptation takes place at a peripheral stage where information about temperature inputs are still preserved for each finger, and that the thermal-tactile interaction occurs after this stage. We also show that the temperature integration across three fingers in TR is consistent with precision weighted averaging effect - Bayesian cue combination. Altogether, our findings suggest that for the sensory processing hierarchy of thermal touch, thermal adaptation occurs prior to thermo-tactile integration, which combines thermal and tactile information to give a unified percept to facilitate object recognition.\n\nSignificance StatementThermal touch refers to the perception of temperature of objects in contact with the skin and is key to object recognition based on thermal cues. While object perception is an inference process involving multisensory inputs, thermal referral (TR) is an illusion demonstrating how the brains interpretation of object temperature can deviate from physical reality. Here we used TR to explore the processing hierarchy of thermal touch. We show that adaptation of thermal perception occurs prior to integration of thermal information across tactile locations. Further, we show that TR results from simple averaging of thermal sensation across locations. Our results illuminate the flexibility of the processing that underlies thermal-tactile interactions and facilitates object exploration and identification in our complicated natural environment.

neuroscience↗