Biology subjects

Jasmin, K.

Publications and source records attributed to Jasmin, K..

9 recordsLinked to original sources

bioRxiv2025

Spatial coding supports auditory conceptual navigation

Grid cells in human entorhinal cortex encode spatial layouts for real-world navigation, yet their role in conceptual navigation remains unclear. Here we show that mentally transforming tones within a purely auditory pitch-duration space engages spatial circuits, and that such resources are causally necessary. In Experiment 1, participants trained for five days to navigate through a purely conceptual pitch-duration auditory space, then underwent fMRI on Day 6. We observed a six-fold modulation of entorhinal BOLD signals aligned to each participants trajectory angles, similar to grid-cell firing in physical space. Stronger grid-like coding predicted larger training-related gains. In Experiment 2, a new cohort performed the same task under either a spatial or non-spatial interference load. Only the spatial condition selectively disrupted performance on trials requiring mental "movement," indicating a causal reliance on spatial resources. These findings provide evidence that auditory conceptual transformations recruit--and depend on--spatial grid-like computations in the entorhinal-hippocampal system, pointing to a domain-general role for spatial coding in organizing new knowledge along continuous dimensions.

neuroscience↗

bioRxiv2022

Compensation and conversation in autism: atypical connectivity supports typical behavior

BackgroundIt is well-established that individuals with autism show atypical functional brain connectivity. However, the role this plays in behavior, especially in naturalistic social settings, has remained unclear. Some atypical patterns may reflect core deficits, while others may instead compensate for deficits and promote adaptive behavior. Distinguishing these possibilities requires measuring the typicality of spontaneous behavior and determining which connectivity patterns correlate with it. MethodsThirty-nine male participants (19 autism, 20 typically-developed) engaged in 115 spontaneous conversations with an experimenter during fMRI scanning (Jasmin, et al., 2019, Brain). A classifier algorithm was trained to distinguish participants by diagnosis based on 81 semantic, affective and linguistic dimensions derived from their use of language. The algorithms certainty that a participant was in either the autism or typical group was used as a measure of task performance and compared with functional connectivity levels. ResultsThe algorithm accurately classified participants (74%, P = .002), and its scores correlated with clinician-observed autism signs (ADOS) (rs = .56, P = .03). In support of a compensatory role, greater functional connectivity, most prominently between left-hemisphere social communication regions and right inferior frontal cortex, correlated with more typical language behaviour, only for the autism group (rs = .56, P = .01). ConclusionWe report a simple and highly generalizable method for quantifying behavioral performance and neural compensation during complex spontaneous social behavior, without the need for an a priori benchmark. The findings suggest that functional connectivity increases in autism during communication reflect a neural compensation strategy.

neuroscience↗

bioRxiv2021

Prosodic categories in speech are acoustically multidimensional: evidence from dimension-based statistical learning

Segmental speech units such as phonemes are cued by multiple acoustic dimensions (e.g. F0 and duration), but dimensions do not carry equal perceptual weight. The relative perceptual weights of acoustic speech dimensions are not fixed but vary with context. For example, when speech is altered to create an accent in which two acoustic dimensions are correlated in a manner opposite that of long-term experience, the dimension that carries less perceptual weight is down-weighted to contribute less in category decisions. It remains unclear, however, whether this short-term reweighting is limited to segmental categorization, or if it extends to categorization of suprasegmental features which span multiple phonemes, syllables, or words, which would suggest that such "dimension-based statistical learning" is a widespread phenomenon in speech perception. Here we investigated the relative contribution of two acoustic dimensions to word emphasis. Participants categorized instances of a two-word phrase pronounced with typical covariation of fundamental frequency (F0) and duration, and in the context of an artificial accent in which F0 and duration (established in prior research on English speech as primary and secondary dimensions, respectively) covaried atypically. When categorizing accented speech, listeners rapidly down-weighted the secondary dimension (duration) while continuing to rely on the primary dimension (F0). This result indicates that listeners continually track short-term regularities across speech input and dynamically adjust the weight of acoustic evidence for suprasegmental categories. Thus, dimension-based statistical learning appears to be a widespread phenomenon in speech perception extending to both segmental and suprasegmental categorization.

neuroscience↗

bioRxiv2020

Does over-reliance on auditory feedback cause disfluency? An fMRI study of induced fluency in people who stutter.

This study tested the idea that stuttering is caused by over-reliance on auditory feedback. The theory is motivated by the observation that many fluency-inducing situations, such as synchronised speech and masked speech, alter or obscure the talkers feedback. Typical speakers show speaking-induced suppression of neural activation in superior temporal gyrus (STG) during self-produced vocalisation, compared to listening to recorded speech. If people who stutter over-attend to auditory feedback, they may lack this suppression response. In a 1.5T fMRI scanner, people who stutter spoke in synchrony with an experimenter, in synchrony with a recording, on their own, in noise, listened to the experimenter speaking and read silently. Behavioural testing outside the scanner demonstrated that synchronising with another talker resulted in a marked increase in fluency regardless of baseline stuttering severity. In the scanner, participants stuttered most when they spoke alone, and least when they synchronised with a live talker. There was no reduction in STG activity in the Speak Alone condition, when participants stuttered most. There was also strong activity in STG in response to the two synchronised speech conditions, when participants stuttered least, suggesting that either stuttering does not result from over-reliance on feedback, or that the STG activation seen here does not reflect speech feedback monitoring. We discuss this result with reference to neural responses seen in the typical population.

neuroscience↗

bioRxiv2020

Effects of language experience on domain-general perceptual strategies

Speech and music are highly redundant communication systems, with multiple acoustic cues signaling the existence of perceptual categories. This redundancy makes these systems robust to the influence of noise, but necessitates the development of perceptual strategies: listeners need to decide the importance to place on each source of information. Prior empirical work and modeling has suggested that cue weights primarily reflect within-task statistical learning, as listeners assess the reliability with which different acoustic dimensions signal a category and modify their weights accordingly. Here we present evidence that perceptual experience can lead to changes in cue weighting which extend across tasks and across domains, suggesting that perceptual strategies reflect both global biases and local (i.e. task-specific) learning. In two experiments, native speakers of Mandarin (N=45)--where pitch is a crucial cue to word identity--placed more importance on pitch and less importance on other dimensions compared to native speakers of non-tonal languages English (N=45) and Spanish (N=27), during the perception of both second language speech and musical beats. In a third experiment, we further show that Mandarin speakers are better able to attend to pitch and ignore irrelevant variation in other dimensions compared to English and Spanish speakers, and even struggle to ignore pitch when asked to attend to other dimensions. Thus, an individuals idiosyncratic auditory perceptual strategies reflect a complex mixture of congenital predispositions, task-specific learning, and biases instilled by extensive experience in making use of important dimensions in their native language.

neuroscience↗

bioRxiv2019

Reduced functional connectivity between left frontal and right auditory cortices during speech perception in congenital amusia.

Individuals with congenital amusia have a lifelong history of unreliable pitch processing. Accordingly, they downweight pitch cues during speech perception (even large, obvious ones) and instead rely on other dimensions such as duration. We investigated the neural basis for this strategy. During fMRI, individuals with amusia and controls (N=30) matched auditory and visual sentences using pitch and duration cues. A data-driven analysis procedure detected prominent reductions in functional connectivity in the amusia group, between left prefrontal language-related regions (inferior and middle frontal gyrus/DLPFC) and right hemisphere pitch-related regions (auditory and anterior insular cortex). Functional connectivity levels were correlated with prosodic cue weights measured outside the scanner. Furthermore, group differences in functional connectivity between these regions was not present during a control task (passive listening to tones). Our results suggest that individuals compensate for differences in the reliability of perceptual dimensions by regulating functional connectivity between task-relevant frontal and perceptual regions.

neuroscience↗

bioRxiv2019

The Multidimensional Battery of Prosody Perception (MBOPP)

Prosody can be defined as the rhythm and intonation patterns spanning words, phrases and sentences. Accurate perception of prosody is an important component of many aspects of language processing, such as parsing grammatical structures, recognizing words, and determining where emphasis may be placed. Prosody perception is important for language acquisition and can be impaired in language-related developmental disorders. However, existing assessments of prosodic perception suffer from some shortcomings. These include being unsuitable for use with typically developing adults due to ceiling effects, or failing to allow the investigator to distinguish the unique contributions of individual acoustic features such as pitch and temporal cues. Here we present the Multi-Dimensional Battery of Prosody Perception (MBOPP), a novel tool for the assessment of prosody perception. It consists of two subtests - Linguistic Focus, which measures the ability to hear emphasis or sentential stress, and Phrase Boundaries, which measures the ability to hear where in a compound sentence one phrase ends, and another begins. Perception of individual acoustic dimensions (Pitch and Time) can be examined separately, and test difficulty can be precisely calibrated by the the experimenter because stimuli were created using a continuous voice morph space. We present validation analyses from a sample of 57 individuals and discuss how the battery might be deployed to examine perception of prosody in various populations.

neuroscience↗

bioRxiv2018

Overt social interaction and resting state in autism: core and contextual neural features

Conversation is an important and ubiquitous social behavior. Individuals with Autism Spectrum Disorder (autism) without intellectual disability often have normal structural language abilities but deficits in social aspects of communication like pragmatics, prosody, and eye contact. Previous studies of resting state activity suggest that intrinsic connections among neural circuits involved with social processing are disrupted in autism, but to date no neuroimaging study has examined neural activity during the most commonplace yet challenging social task: spontaneous conversation. Here we used functional MRI to scan autistic males (N=19) without intellectual disability and age- and IQ-matched typically developing controls (N=20) while they engaged in a total of 193 face-to-face interactions. Participants completed two kinds of tasks: Conversation, which had high social demand, and Repetition, which had low social demand. Autistic individuals showed abnormally increased task-driven inter-regional temporal correlation relative to controls, especially among social processing regions and during high social demand. Furthermore, these increased correlations were associated with parent ratings of participants social impairments. These results were then compared with previously-acquired resting-state data (56 Autism, 62 Control participants). While some inter-regional correlation levels varied by task or rest context, others were strikingly similar across both task and rest, namely increased correlation among the thalamus, dorsal and ventral striatum, somatomotor, temporal and prefrontal cortex in the autistic individuals, relative to the control groups. These results suggest a basic distinction. Autistic cortico-cortical interactions vary by context, tending to increase relative to controls during Task and decrease during Rest. In contrast, striato- and thalamocortical relationships with socially engaged brain regions are increased in both Task and Rest, and may be core to the condition of autism.

neuroscience↗

bioRxiv2018

Redundancy makes music and speech robust to individual differences in perception

In speech, linguistic information is conveyed redundantly by many simultaneously present acoustic dimensions, such as fundamental frequency, duration and amplitude. Listeners show stable tendencies to prioritize these acoustic dimensions differently, relative to one another, which suggests individualized speech perception strategies. However, it is unclear what drives these strategies, and more importantly, what impact they have on diverse aspects of communication. Here we show that such individualized perceptual strategies can be related to individual differences in perceptual ability. In a cue weighting experiment, we first demonstrate that individuals with a severe pitch perception deficit (congenital amusics) categorize linguistic stimuli similarly to controls when their deficit is unrelated to the main distinguishing cue for that category (in this case, durational or temporal cues). In contrast, in a prosodic task where pitch-related cues are typically more informative, amusics place less importance on this pitch-related information when categorizing speech. Instead, they relied more on duration information. Crucially, these differences in perceptual weights were observed even when pitch-related differences were large enough to be perceptually distinct to amusic listeners. In a second set of experiments involving musical and prosodic phrase interpretation, we found that this reliance on duration information allowed amusics to overcome their perceptual deficits and perceive both speech and music successfully. These results suggest that successful speech - and potentially music - comprehension is achieved through multiple perceptual strategies whose underlying weights may in part reflect individuals perceptual abilities.

neuroscience↗