Biology subjects

Perrachione, T. K.

Publications and source records attributed to Perrachione, T. K..

7 recordsLinked to original sources

bioRxiv2026

Selectivity for high-level language processing is highly localized in individual brains

Some aspects of human behavior and cognition depend on focal and selective cortical areas, such as the frontal eye fields or fusiform face area, while others, like semantic knowledge, are broadly distributed across the cortex. Whether higher-level cognitive functions like language can also be highly localized has been a longstanding matter of debate. Here, we provide multiple lines of evidence that receptive language in the brain is subserved by a network of discrete, focal, and uniquely language-selective areas when examining individual brains. Using precision neuroimaging, we observed highly circumscribed patches of cortex that are distinctly selective for language, uniquely consistent in their response properties during language processing, and highly reliable in their anatomical locations within individuals (though variable in location across individuals). These findings indicate that language regions in the brain are characterized by unique functional profiles and sharp boundaries, consistent with the systems neuroscience definition of true "cortical areas."

neuroscience↗

bioRxiv2026

Neurodiversity in the brain: More variable localization of face regions in autism

A fundamental principle in human neuroscience is that the brain is organized into distinct functional regions specialized for particular processes. These functional regions develop early and are shaped by sensory experiences. Strikingly, the precise location of these functional regions is relatively consistent across individuals, with specific regions found in stereotyped locations with respect to the macroanatomy (e.g., particular sulci and gyri). An important question is how flexible this functional neuroanatomy is, particularly in neurodevelopmental disorders like autism which are characterized by atypical brain development and behavior. Here, we investigated this question by focusing on the organization of the face-processing network -- a well-characterized system of regions that are reliably localized across neurotypical individuals, including, famously, the fusiform face area. Using precision fMRI, we identified subject-specific face-sensitive regions in the brains of autistic and neurotypical adults, and assessed their topographical alignment across individuals. Face regions in autism were globally and highly variably displaced - located farther from their expected locations in the brain relative to much more homogenous localization in neurotypical adults. Autistic individuals whose face regions were more displaced had greater sociocommunicative challenges. In contrast, the spatial organization of object-sensitive regions was not affected. These findings suggest that the spatial organization of the face network is atypical in autism, with behaviorally meaningful increased variability in the precise location of face-sensitive areas, and highlights the importance of individualized approaches in neuroimaging. Significance StatementThe human brain is organized into specialized functional regions positioned in remarkably consistent locations across individuals. It is unclear how altered neurodevelopment affects this organization. Using precision fMRI, we found that autism was characterized by globally and highly variably displaced face-sensitive functional brain regions. Atypical spatial organization of these regions was associated with greater sociocommunicative difficulties. In contrast, the spatial organization of object-sensitive regions did not differ in autism. These findings reveal that functional neuroanatomy in autism is altered in category-specific ways, with direct relevance to core sociocommunicative features of the condition. This work underscores the importance of individualized brain mapping in neuroimaging and may shed light on inconsistent findings in previous group-level neuroimaging studies.

neuroscience↗

bioRxiv2025

Systematic bias in surface area asymmetry measurements from automatic cortical parcellations

Anatomical asymmetry is a hallmark of the human brain and may reflect hemispheric differences in its functional organization. Widely used software like FreeSurfer can automate neuroanatomical measurements and facilitate studies of hemispheric asymmetry. However, patterns of surface area lateralization measured using FreeSurfer are curiously consistent across diverse samples. Here, we demonstrate systematic biases in these measurements obtained from the default processing pipeline. We compared surface area asymmetry measured from reconstructions of original brains vs. the same scans after flipping their left-right orientation. The default pipeline returned implausible asymmetry patterns between the original and flipped brains: Many structures were always left- or right-lateralized. Notably, these biases occur prominently in key speech and language regions. In contrast, manual labeling and curvature-based parcellations of key structures both yielded the expected reversals of left/right lateralization in flipped brains. We determined that these biases result from discrepancies in how regional labels are defined in the left vs. right hemisphere in the default cortical parcellation atlases. These biases are carried into individual parcellations because the FreeSurfer parcellation algorithm prioritizes vertex correspondence to the template atlas relative to individual neuroanatomical variation. We further demonstrate several straightforward, bias-free approaches to measuring surface area asymmetry, including using symmetric registration templates and parcellation atlases, vertex-wise analyses, and within-subject curvature-based parcellations. These results highlight theoretical concerns about using only the default processing stream to make inferences about population-level brain asymmetry and underscore the need for validating bias-free neuroanatomical measurements, particularly when studying regions where structural lateralization may underlie functional lateralization.

neuroscience↗

bioRxiv2024

Musical training does not enhance neural sound encoding at early stages of the auditory system: A large-scale multisite investigation

Musical training has been associated with enhanced neural processing of sounds, as measured via the frequency following response (FFR), implying the potential for human subcortical neural plasticity. We conducted a large-scale multi-site preregistered study (n > 260) to replicate and extend the findings underpinning this important relationship. We failed to replicate any of the major findings published previously in smaller studies. Musical training was related neither to enhanced spectral encoding strength of a speech stimulus (/da/) in babble nor to a stronger neural-stimulus correlation. Similarly, the strength of neural tracking of a speech sound with a time-varying pitch was not related to either years of musical training or age of onset of musical training. Our findings provide no evidence for plasticity of early auditory responses based on musical training and exposure.

neuroscience↗

bioRxiv2021

Electrophysiological correlates of perceptual prediction error are attenuated in dyslexia

A perceptual adaptation deficit often accompanies reading difficulty in dyslexia, manifesting in poor perceptual learning of consistent stimuli and reduced neurophysiological adaptation to stimulus repetition. However, it is not known how adaptation deficits relate to differences in feedforward or feedback processes in the brain. Here we used electroencephalography (EEG) to interrogate the feedforward and feedback contributions to neural adaptation as adults with and without dyslexia viewed pairs of faces and words in a paradigm that manipulated whether there was a high probability of stimulus repetition versus a high probability of stimulus change. We measured three neural dependent variables: expectation (the difference between prestimulus EEG power with and without the expectation of stimulus repetition), feedforward repetition (the difference between event-related potentials (ERPs) evoked by an expected change and an unexpected repetition), and feedback-mediated prediction error (the difference between ERPs evoked by an unexpected change and an expected repetition). Expectation significantly modulated prestimulus theta- and alpha-band EEG in both groups. Unexpected repetitions of words, but not faces, also led to significant feedforward repetition effects in the ERPs of both groups. However, neural prediction error when an unexpected change occurred instead of an expected repetition was significantly weaker in dyslexia than the control group for both faces and words. These results suggest that the neural and perceptual adaptation deficits observed in dyslexia reflect the failure to effectively integrate perceptual predictions with feedforward sensory processing. In addition to reducing perceptual efficiency, the attenuation of neural prediction error signals would also be deleterious to the wide range of perceptual and procedural learning abilities that are critical for developing accurate and fluent reading skills.

neuroscience↗

bioRxiv2021

Similarity in sensory modality and information domain impair processing in a dual-task context: Evidence from behavior, pupillometry, and EEG

Project AbstractMaking sense of our environment requires us to extract simultaneous temporal and spatial information from multiple sensory modalities, particularly audition and vision. This sensory information can be stored in working memory (WM) to guide future actions, at which point it must be safeguarded against interference from ongoing sensory processing. Recent fMRI research has uncovered regions in human frontal cortex well-suited to coordinate this interplay between attention and WM for multisensory and multidimensional information. Which of these brain regions are engaged depends on both the sensory modality of the input and the information domain of the task, forming the basis of two complementary networks specialized for auditory/temporal and visual/spatial processing. Motivated by the functional specializations of these networks, we examined whether similarity in sensory modality and information domain modulates neural and perceptual interference between two concurrent tasks. Participants stored temporal or spatial information about auditory or visual stimuli in WM, and on some trials, performed an intervening temporal or spatial auditory task during WM retention. WM recall and auditory perceptual judgments were impaired when the two tasks relied on the same sensory modality and/or information domain. Pupil dilations were also larger in these conditions, indicating increased cognitive effort. Event-related potentials (ERPs) revealed a neural signature of domain-based interference that was masked by behavioral ceiling effects. These results demonstrate that modality and information domain jointly affect how task information is represented in WM, and concomitantly, how tasks engage the complementary auditory-temporal and visual/spatial cognitive control networks.

neuroscience↗

bioRxiv2021

Talker discontinuity disrupts attention to speech: Evidence from EEG and pupillometry

Speech is processed less efficiently from discontinuous, mixed talkers than one consistent talker, but little is known about the neural mechanisms for processing talker variability. Here, we measured psychophysiological responses to talker variability using electroencephalography (EEG) and pupillometry while listeners performed a delayed recall of digit span task. Listeners heard and recalled seven-digit sequences with both talker (single- vs. mixed-talker digits) and temporal (0- vs. 500-ms inter-digit intervals) discontinuities. Talker discontinuity reduced serial recall accuracy. Both talker and temporal discontinuities elicited P3a-like neural evoked response, while rapid processing of mixed-talkers speech led to increased phasic pupil dilation. Furthermore, mixed-talkers speech produced less alpha oscillatory power during working memory maintenance, but not during speech encoding. Overall, these results are consistent with an auditory attention and streaming framework in which talker discontinuity leads to involuntary, stimulus-driven attentional reorientation to novel speech sources, resulting in the processing interference classically associated with talker variability.

neuroscience↗