Biology subjects

Norman, Y.

Publications and source records attributed to Norman, Y..

4 recordsLinked to original sources

bioRxiv2025

Sensorimotor Theta Oscillations Coordinate Speech Movements

Fluent speech depends on precisely timed motor commands that coordinate rapid transitions between successive articulatory gestures. Using direct cortical recordings, we identified a prominent sensorimotor theta oscillation (6-10 Hz) that supports this coordination. During articulation, premotor speech circuits exhibited enhanced theta phase coherence, with elevated population activity near theta troughs. The oscillations frequency remained remarkably stable across varying speech rates and cognitive states, consistent with an intrinsically generated rhythm. Vocal-tract kinematics revealed pulse-like movements at 6-10 Hz, tightly coupled to cortical theta phase. At a mesoscopic scale, theta cycles structured sequential sensorimotor activations encoding articulatory gestures, with syllable identity optimally decodable following theta troughs. These findings identify theta oscillations as an intrinsic timing mechanism that coordinates the distributed and synergistic motor control underlying fluent speech.

neuroscience↗

bioRxiv2023

Hippocampal Ripples linked to Declarative Memory Judgments in Children

Intracranial studies have demonstrated significant roles for hippocampal ripples in human declarative memory. Yet, the developmental trajectory and contribution of ripples to memory processes in children remain unknown. We studied hippocampal ripple activity using intracranial recordings in 14 children (age: 6-14) undergoing epilepsy monitoring. After watching a pink panther cartoon twice, participants engaged in an old/new recognition test, determining whether events portrayed in short (4s) videoclips stemmed from the cartoon they had just viewed. Our results reveal a significant rise in ripple rate during successful recognition of familiar events. An anticipatory decline in ripple rate preceded recognition errors. Interestingly, when participants viewed the cartoon passively during the initial full-length screenings, the overall temporal pattern of ripple activation remained consistent across repetitions, and significantly distinct from explicit recognition. We conclude that hippocampal ripples in children play a key role in declarative memory, supporting the explicit identification of previously encountered events.

neuroscience↗

bioRxiv2022

Perceptual stability reflected in neuronal pattern similarities in human visual cortex

The magnitude of neuronal activation is commonly considered a critical factor for conscious perception of visual content. However, this dogma contrasts with the phenomenon of rapid adaptation, in which the magnitude of neuronal activation drops dramatically in a rapid manner, while the visual stimulus and the conscious experience it elicits remain stable. Here we report that the profiles of multi-site activation patterns and their relational geometry -i.e. the similarity distances between activation patterns, as revealed using iEEG recordings, are sustained during extended stimulation despite the major magnitude decrease. These results are compatible with the hypothesis that conscious perceptual content is associated with the neuronal pattern profiles and their similarity distances, rather than by the overall activation magnitude, in human visual cortex.

neuroscience↗

bioRxiv2018

Face-selective units in human ventral temporal cortex reactivate during free recall

Properties of face-responsive individual neurons in the human ventral temporal cortex (VTC) have yet to be studied, and their role in conscious perception remains unknown. To explore this, we implanted microelectrodes into the VTCs of eight human subjects undergoing invasive epilepsy monitoring. Most (26 of 33) category-selective units showed specificity for face stimuli, with a range of response profiles. Different face exemplars evoked consistent and discriminable responses in the population of units sampled. During a free recall task, face-selective units selectively reactivated in the absence of visual stimulation during the 2-second window prior to face recall events. Furthermore, the identity of the recalled face could be predicted by comparing activity preceding recall events to activity evoked by visual stimulation.

neuroscience↗