Biology subjects

Garbarini, F.

Publications and source records attributed to Garbarini, F..

4 recordsLinked to original sources

bioRxiv2024

Electrophysiological responses reveal a dedicated learning mechanism to process salient consonant sounds in human newborns

Isolating relevant sounds in the auditory stream is a crucial feature accomplished by human infants and a pivotal ability for language acquisition. Therefore, it is reasonable to postulate the existence of early mechanisms reorienting attention toward salient acoustic stimuli. Previous studies suggest that infants consider consonant sounds as more salient than dissonant ones, because the former resemble human vocalizations. However, systematic evidence investigating the neural processes underlying consonance tuning in newborns is still scarce. Here, we investigate newborns ability to recognize and learn salient auditory stimuli by collecting Mismatch Responses (MMRs) to consonant and dissonant sounds and by computing the trial-by-trial correlation of the neural signal with Bayesian Surprise (a theoretical measure of learning). We present 22 healthy newborns (40.4 {+/-} 15.8 hours) with a pseudo-random sequence of deviant and standard auditory events, while we record their electroencephalogram. Our results show that newborns exhibit a neural encoding of auditory regularities for all sound types (consonant and dissonant), as demonstrated by the presence of MMRs and significant correlation of the neural signal with Bayesian Surprise. Furthermore, consonant and dissonant sounds elicited MMRs and correlations with Bayesian Surprise of opposite polarities, with consonant auditory stimulation evoking negative responses, reminiscent of an adult-like MMR. Overall, our findings suggest that newborns display a dedicated perceptual learning mechanism for salient consonant sounds. We speculate that this mechanism might represent an evolutionary-achieved neural tuning to detect and learn salient auditory stimuli with acoustic features resembling human vocalizations. SIGNIFICANCE STATEMENTDiscriminating salient sounds in noisy sensory streams is a fundamental ability displayed by human infants, pivotal for acquiring crucial skills including language. Our study shed light on this ability by: (1) investigating perceptual learning mechanisms in newborns with a neurocomputational approach; (2) exploring the role of salient consonant sounds in modulating such mechanisms. Since human vocalizations are often consonant, the presence of a mechanism dedicated to enhance the processing of consonant sounds in newborns would confer evolutionary advantages. Our findings, indicating that newborns possess a dedicated and more refined perceptual learning mechanism to process consonance, corroborates this hypothesis. We speculate that this neural mechanism might facilitate the identification of salient acoustic input and support language acquisition in early infancy.

neuroscience↗

bioRxiv2023

Brain encoding of naturalistic, continuous, and unpredictable tactile events

AbstractStudies employing EEG to measure somatosensory responses have been typically optimized to compute event-related potentials in response to discrete events (ERPs). However, tactile interactions involve continuous processing of non-stationary inputs that change in location, duration, and intensity. To fill this gap, this study aims to demonstrate the possibility of measuring the neural tracking of continuous and unpredictable tactile information. Twenty-seven young adults (females = 15) were continuously and passively stimulated with a random series of gentle brushes on single fingers of each hand, which were covered from view. Thus, tactile stimulations were unique for each participant, and stimulated fingers. An encoding model measured the degree of synchronization between brain activity and continuous tactile input, generating a temporal response function (TRF). Brain topographies associated with the encoding of each finger stimulation showed a contralateral response at central sensors starting at 50 ms and peaking at about 140 ms of lag, followed by a bilateral response at about 240 ms. A series of analyses highlighted that reliable tactile TRF emerged after just 3 minutes of stimulation. Strikingly, topographical patterns of the TRF allowed discriminating digit lateralization across hands and digit representation within each hand. Our results demonstrated for the first time the possibility of using EEG to measure the neural tracking of a naturalistic, continuous, and unpredictable stimulation in the somatosensory domain. Crucially, this approach allows the study of brain activity following individualized, idiosyncratic tactile events to the fingers. Significant StatementThis study expands the current research conducted on neural tracking, opening the exploration of idiosyncratic tactile events and overcoming constraints of laboratory tasks that typically rely on discrete events. We validated a protocol for the ecological investigations of continuous, slow, tactile processing of the hands. The employed approach enriches the possible use of the EEG to characterize somatosensory neural representations of tactile events. Findings unravel coherent neural responses to continuous and naturalistic touch, with sensitivity for digit lateralization and representation.

neuroscience↗

bioRxiv2023

Abstract, modality-specific and experience-dependent coding of affect in the human brain

Emotion and perception are tightly intertwined, as affective experiences often arise from the appraisal of sensory information. Nonetheless, whether the brain encodes emotional instances using a sensory-specific code or in a more abstract manner is unclear. Here, we answer this question by measuring the association between emotion ratings collected during a unisensory or multisensory presentation of a full-length movie and brain activity recorded in typically-developed, congenitally blind and congenitally deaf participants. Emotional instances are encoded in a vast network encompassing sensory, prefrontal, and temporal cortices. Within this network, the ventromedial prefrontal cortex stores a categorical representation of emotion independent of modality and experience, and the posterior superior temporal cortex maps valence using an abstract code. Sensory experience more than modality impacts how the brain organizes emotional information outside supramodal regions, suggesting the existence of a scaffold for the representation of emotional states where sensory inputs during development shape its functioning.

neuroscience↗

bioRxiv2022

A modality independent proto-organization of human multisensory areas

The processing of multisensory information is based upon the capacity of brain regions, such as the superior temporal cortex, to combine information across modalities. However, it is still unclear whether the representation of coherent auditory and visual events does require any prior audiovisual experience to develop and function. In three fMRI experiments, intersubject correlation analysis measured brain synchronization during the presentation of an audiovisual, audio-only or video-only versions of the same narrative in distinct groups of sensory-deprived (congenitally blind and deaf) and typically-developed individuals. The superior temporal cortex synchronized across auditory and visual conditions, even in sensory-deprived individuals who lack any audiovisual experience. This synchronization was primarily mediated by low-level perceptual features and relied on a similar modality-independent topographical organization of temporal dynamics. The human superior temporal cortex is naturally endowed with a functional scaffolding to yield a common representation across multisensory events.

neuroscience↗