We provide a detailed anatomical tracing of the primate posteromedial cortex (PMC), a term coined for the first time in this publication.
Documented and highlighted a significant problem in cognitive neuroscience research and coined the term "corticocentric myopia".
Provided an overview of findings from 100 years of intracranial brain stimulation.
We recorded directly from the PMC in human subjects. This brain region is one of the key hubs of the default mode network (DMN). We uncovered a rapid surge in high-frequency activity within 150ms as the subjects were cued to rest. Specific neuronal populations in the PMC become active immediately upon the onset of the rest condition, i.e., the rest-induced activation in these neurons probably enables mind wandering rather than being the result of mind-wandering per se. Additionally, these rest active neuronal populations did not respond when the subject was actively recollecting autobiographical memories.
A causal connection between electrical stimulation of the human brain and conscious perception was illustrated through an experiment in which stimulation of the face-activated fMRI sites caused clear distortions in face perception.
Shifts in aperiodic brain activity is the principal source of BOLD signals recorded with fMRI.
Theta-theta phase coherence between PMC and medial temporal lobe during retrieval of self-referential memory processing.
Introducing a new method by which we are able to measure local responses in the human brain during naturalistic setting.
A causal connection established between electrical stimulation of the human dorsal anterior mid-cingulate cortex and generation of a conscious will / emotion/ derive state.
Lateralization of subjective experience: Stimulation of the right hemisphere distorts face perception.
First simultaneous recordings across two nodes of the Default Mode Network (DMN) reveal distinct synchronization of activity and intrinsic connectivity during both task engagement and sleep.
We demonstrated a clear relationship between the magnitude of electrical charge delivered to a brain area and the size of cortical volume stimulated, and the extent of visual sensations reported by the human subjects.
Lateralization of subjective experience has to do with language lateralization and hand dominance.
We replicate the same principles of connectivity and synchronized activity across two regions (nodes) of the brain, this time using arithmetic condition as the task of interest.
We studied the effect of perturbation of one brain region on other sites of the brain and observed a clear difference in terms of the effect of salience network (SN) stimulation and default mode stimulations: Stimulation of the SN nodes affect other regions of the brain mush faster than the stimulation of the DMN nodes.
Stimulation of the ventral PMC causes no changes in the conscious subjective state of the individual.
Seizures originating in the precuneus (dorsal PMC) clearly distorts the individual patient's subjective sense of space.
Simultaneous recordings across different regions of the brain show a clear temporal order of task-evoked activations in dorsal attention network areas of the lateral parietal cortex before deactivations are seen in the medial parietal default mode sites.
By employing direct recordings across multiple brain sites and juxtaposing EEG connectivity and resting-state fMRI connectivity measures within the same individuals, we demonstrated that the connectivity observed between two brain regions at rest (as identified through fMRI) is exclusively present between distinct populations of neurons across the two regions.
Even bilateral stimulation of the human claustrum does not cause any changes in the conscious subjective state.
Epileptic non-lesional brain tissue generates responses to relevant stimuli akin to responses seen in non-epileptic normal brain tissue, but these responses are likely to be "seized" for 100s of milliseconds after the onset of epileptic high frequency oscillations (HFOs).
In three different limbic regions of the brain, we show that the intensity of affective experience is modulated by magnitude of electrical charge delivered to the brain.
Changes in the high frequency broadband activity in the dorsal anterior insula, a brain region implicated in salience processing and alertness, are coupled with changes in the pupil diameter during spontaneous resting state as well as salience-detection task.
We did simultaneous recordings across three regions of interest representing three different brain networks of dorsal attention network (DAN), salience network (SN), and default mode network (DMN). We showed that responses during an attention demanding task appeared fastest in the DAN and then SN sites. Deactivations in the DMN sites occurred significantly later. Lapses of attention (behavioral errors in a demanding task) were marked by distinguishable patterns of both pre- and post-stimulus high frequency activity within each network. Importantly, the magnitude of temporally lagged, negative coupling of such activity between the DAN and DMN (but not SN and DMN) was associated with greater sustained attention performance.
By recording simultaneously across multiple sites within the inferior temporal cortex, we show that the face stimuli triggered responses in clusters of sites (i.e., anatomically localized neuronal populations). Face-responsive sites showed a posterior to anterior gradient in response time (earlier) and selectivity (more face selective). A sparse model focusing on information from the human face-selective sites performed as well as, or better than, anatomically distributed models when discriminating faces from non-faces stimuli. Additionally, we identified the posterior fusiform site as causally the most relevant node for inducing distortion of conscious face processing by direct electrical stimulation.
Ripples (i.e., physiological signature of memory processing in the hippocampus) were documented in the human hippocampus during the retrieval of recent and remote autobiographical events and self-relevant semantic facts. Distributed sites across the neocortical nodes of the default mode network (DMN) exhibited ripple-coupled activations during autobiographical recollection.
We found that if we electrically stimulate a brain region, the effect of such perturbations is more prominent and faster in other brain regions that are located within the same fMRI-identified resting state network than those across different networks. We then showed that the sites within the same resting state networks (compared to sites across two different networks) respond closer in time during a given cognitive task.
In a single subject implanted with intracranial electrodes inside the brain, we documented that focal seizures in the anterior precuneus (aPCU) cause distortions in the sense of bodily self and leads to spatial disorientation and loss of spatial perspective.
Electrical stimulations of the ventromedial hypothalamus in a single patient induced profound feeling of shame, sadness, and fear but not rage or anger. When repeated single electrical pulses were delivered to this hypothalamic sites, we recorded significant evoked responses in the amygdala, hippocampus, ventromedial-prefrontal and orbitofrontal, anterior cingulate, and ventral-anterior and dorsal-posterior insula.
In this review, we highlight the problem of correlational studies and the importance of causal observations in the neuroscience. We also provide a definition of causal experiments and propose a continuum along which to assess the relative strength of causal information from studies of the human brain.
We introduce the method of multi-site thalamic recordings and highlight its clinical utility in determining the more prominent thalamic pathway recruited in seizure propagation in each individual patient.
We offer a detailed map of the effects of electrical stimulation of the human insula. We demonstrate that the subjective effects of stimulations align with the cytoarchitectonic maps of the insula.
In a group of patients implanted with intracranial electrodes, we show that the stimulation of the anterior precuneus (aPCu) causes idiosyncratic distortion of the sense of bodily self. Using repeated single electrical pulse stimulations, and publicly available imaging data from the human connectome project we provide a comprehensive map of (electrophysiological and resting state fMRI) connectivity of this important aPCu region.