Neurophysiological Evidence for Cognitive Map Formation during Sequence Learning.

Humans deftly parse statistics from sequences. Some theories posit that humans learn these statistics by forming cognitive maps, or underlying representations of the latent space which links items in the sequence. Here, an item in the sequence is a node, and the probability of transitioning between two items is an edge.

Diverse Temporal Dynamics of Repetition Suppression Revealed by Intracranial Recordings in the Human Ventral Temporal Cortex.

Repeated stimulus presentations commonly produce decreased neural responses-a phenomenon known as repetition suppression (RS) or adaptation-in ventral temporal cortex (VTC) of humans and nonhuman primates. However, the temporal features of RS in human VTC are not well understood. To fill this gap in knowledge, we utilized the precise spatial localization and high temporal resolution of electrocorticography (ECoG) from nine human subjects implanted with intracranial electrodes in the VTC.

Fast temporal dynamics and causal relevance of face processing in the human temporal cortex.

We measured the fast temporal dynamics of face processing simultaneously across the human temporal cortex (TC) using intracranial recordings in eight participants. We found sites with selective responses to faces clustered in the ventral TC, which responded increasingly strongly to marine animal, bird, mammal, and human faces. Both face-selective and face-active but non-selective sites showed a posterior to anterior gradient in response time and selectivity.

Mapping human temporal and parietal neuronal population activity and functional coupling during mathematical cognition.

Brain areas within the lateral parietal cortex (LPC) and ventral temporal cortex (VTC) have been shown to code for abstract quantity representations and for symbolic numerical representations, respectively. To explore the fast dynamics of activity within each region and the interaction between them, we used electrocorticography recordings from 16 neurosurgical subjects implanted with grids of electrodes over these two regions and tracked the activity within and between the regions as subjects performed three different numerical tasks. Although our results reconfirm the presence of math-selective hubs within the VTC and LPC, we report here a remarkable heterogeneity of neural responses within each region at both millimeter and millisecond scales.

Electrophysiological Responses in the Ventral Temporal Cortex During Reading of Numerals and Calculation.

Recent evidence suggests that specific neuronal populations in the ventral temporal cortex show larger electrophysiological responses to visual numerals compared with morphologically similar stimuli. This study investigates how these responses change from simple reading of numerals to the active use of numerals in an arithmetic context. We recorded high-frequency broadband (HFB) signals, a reliable measure for local neuronal population activity, while 10 epilepsy patients implanted with subdural electrodes performed separate numeral reading and calculation tasks.

Electrocorticography reveals the temporal dynamics of posterior parietal cortical activity during recognition memory decisions.

Theories of the neurobiology of episodic memory predominantly focus on the contributions of medial temporal lobe structures, based on extensive lesion, electrophysiological, and imaging evidence. Against this backdrop, functional neuroimaging data have unexpectedly implicated left posterior parietal cortex (PPC) in episodic retrieval, revealing distinct activation patterns in PPC subregions as humans make memory-related decisions. To date, theorizing about the functional contributions of PPC has been hampered by the absence of information about the temporal dynamics of PPC activity as retrieval unfolds.

Functional asymmetry between the left and right human fusiform gyrus explored through electrical brain stimulation.

The ventral temporal cortex (VTC) contains several areas with selective responses to words, numbers, faces, and objects as demonstrated by numerous human and primate imaging and electrophysiological studies. Our recent work using electrocorticography (ECoG) confirmed the presence of face-selective neuronal populations in the human fusiform gyrus (FG) in patients implanted with intracranial electrodes in either the left or right hemisphere. Electrical brain stimulation (EBS) disrupted the conscious perception of faces only when it was delivered in the right, but not left, FG.

Corresponding ECoG and fMRI category-selective signals in human ventral temporal cortex.

Functional magnetic resonance imaging (fMRI) and electrocorticography (ECoG) research have been influential in revealing the functional characteristics of category-selective responses in human ventral temporal cortex (VTC). One important, but unanswered, question is how these two types of measurements might be related with respect to the VTC. Here we examined which components of the ECoG signal correspond to the fMRI response by using a rare opportunity to measure both fMRI and ECoG responses from the same individuals to images of exemplars of various categories including faces, limbs, cars and houses.

Intrinsic and task-dependent coupling of neuronal population activity in human parietal cortex.

Human neuroimaging studies have suggested that subregions of the medial and lateral parietal cortex form key nodes of a larger brain network supporting episodic memory retrieval. To explore the electrophysiological correlates of functional connectivity between these subregions, we recorded simultaneously from medial and lateral parietal cortex using intracranial electrodes in three human subjects. We observed electrophysiological co-activation of retrosplenial/posterior cingulate cortex (RSC/PCC) and angular gyrus (AG) in the high-frequency broadband (HFB, or high-gamma) range, for conditions that required episodic retrieval.

Electrical stimulation of the left and right human fusiform gyrus causes different effects in conscious face perception.

Neuroimaging and electrophysiological studies across species have confirmed bilateral face-selective responses in the ventral temporal cortex (VTC) and prosopagnosia is reported in patients with lesions in the VTC including the fusiform gyrus (FG). As imaging and electrophysiological studies provide correlative evidence, and brain lesions often comprise both white and gray matter structures beyond the FG, we designed the current study to explore the link between face-related electrophysiological responses in the FG and the causal effects of electrical stimulation of the left or right FG in face perception. We used a combination of electrocorticography (ECoG) and electrical brain stimulation (EBS) in 10 human subjects implanted with intracranial electrodes in either the left (5 participants, 30 FG sites) or right (5 participants, 26 FG sites) hemispheres.

The will to persevere induced by electrical stimulation of the human cingulate gyrus.

Anterior cingulate cortex (ACC) is known to be involved in functions such as emotion, pain, and cognitive control. While studies in humans and nonhuman mammals have advanced our understanding of ACC function, the subjective correlates of ACC activity have remained largely unexplored. In the current study, we show that electrical charge delivery in the anterior midcingulate cortex (aMCC) elicits autonomic changes and the expectation of an imminent challenge coupled with a determined attitude to overcome it.

Numerical processing in the human parietal cortex during experimental and natural conditions.

Human cognition is traditionally studied in experimental conditions wherein confounding complexities of the natural environment are intentionally eliminated. Thus, it remains unknown how a brain region involved in a particular experimental condition is engaged in natural conditions. Here we use electrocorticography to address this uncertainty in three participants implanted with intracranial electrodes and identify activations of neuronal populations within the intraparietal sulcus region during an experimental arithmetic condition.

A brain area for visual numerals.

Is there a distinct area within the human visual system that has a preferential response to numerals, as there is for faces, words, or scenes? We addressed this question using intracranial electrophysiological recordings and observed a significantly higher response in the high-frequency broadband range (high γ, 65-150 Hz) to visually presented numerals, compared with morphologically similar (i.e., letters and false fonts) or semantically and phonologically similar stimuli (i.

Electrical stimulation of human fusiform face-selective regions distorts face perception.

Face-selective neural responses in the human fusiform gyrus have been widely examined. However, their causal role in human face perception is largely unknown. Here, we used a multimodal approach of electrocorticography (ECoG), high-resolution functional magnetic resonance imaging (fMRI), and electrical brain stimulation (EBS) to directly investigate the causal role of face-selective neural responses of the fusiform gyrus (FG) in face perception in a patient implanted with subdural electrodes in the right inferior temporal lobe.