Eric Halgren
University of California, San Diego
PhysicsSleep spindleHippocampal formationArtificial intelligencePsychologyNeuroscienceCognitionCognitive psychologyElectrophysiologyCortex (anatomy)EpilepsyTemporal lobeHippocampusComputer scienceBrain mappingElectroencephalographyAudiologyMagnetoencephalographyMedicineBiology
350Publications
89H-index
26.6kCitations
Publications 337
Newest
#1Abdulwahab Alasfour (UCSD: University of California, San Diego)H-Index: 3
Studies in animals have demonstrated a strong relationship between cortical and hippocampal activity, and autonomic tone. However, the extent, distribution, and nature of this relationship have not been investigated with intracranial recordings in humans during sleep. Cortical and hippocampal population neuronal firing was estimated from high gamma band activity (HG) from 70 to 110 Hz in local field potentials recorded from 15 subjects (9 females) during non-rapid eye movement (NREM) sleep. Auto...
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#1Jimmy C. Yang (Harvard University)H-Index: 6
#2Angelique C. Paulk (Harvard University)H-Index: 19
Last. Jong Woo Lee (Brigham and Women's Hospital)H-Index: 21
view all 19 authors...
Abstract null null Objective null Interictal discharges (IIDs) and high frequency oscillations (HFOs) are established neurophysiologic biomarkers of epilepsy, while microseizures are less well studied. We used custom poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) microelectrodes to better understand these markers’ microscale spatial dynamics. null null null Methods null Electrodes with spatial resolution down to 50 µm were used to record intraoperatively in 30 subjects. IIDs’...
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#3Daniel FriedmanH-Index: 72
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#1Erik Kaestner (UCSD: University of California, San Diego)H-Index: 12
#2Thomas Thesen (Comprehensive Epilepsy Center)H-Index: 32
Last. Eric Halgren (UCSD: University of California, San Diego)H-Index: 89
view all 6 authors...
Models of reading emphasize that visual (orthographic) processing provides input to phonological as well as lexical-semantic processing. Neurobiological models of reading have mapped these processes to distributed regions across occipital-temporal, temporal-parietal, and frontal cortices. However, the role of the precentral gyrus in these models is ambiguous. Articulatory phonemic representations in the precentral gyrus are obviously involved in reading aloud, but it is unclear if the precentral...
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#1Christopher Gonzalez (University of California, Berkeley)
#2Xi Jiang (University of California, Berkeley)H-Index: 6
Last. Eric Halgren (University of California, Berkeley)H-Index: 89
view all 4 authors...
In humans, sleep spindles are 10-16 Hz oscillations lasting approximately 0.5-2 s. Spindles, along with cortical slow oscillations, facilitate memory consolidation by enabling synaptic plasticity. Early recordings of spindles at the scalp found anterior channels had overall slower frequency than central-posterior channels. This robust, topographical finding led to dichotomizing spindles as null slow versus null fast, modelled as two distinct spindle generators in frontal versus posterior cortex....
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#1Mila Halgren (MIT: Massachusetts Institute of Technology)H-Index: 1
#2Raphi Kang (MIT: Massachusetts Institute of Technology)H-Index: 1
Last. Orrin Devinsky (NYU: New York University)H-Index: 112
view all 13 authors...
Cortical dynamics obey a 1/f power law, exhibiting an exponential decay of spectral power with increasing frequency. The slope and offset of this 1/f decay reflect the timescale and magnitude of aperiodic neural activity, respectively. These properties are tightly linked to cellular and circuit mechanisms (e.g. excitation:inhibition balance, firing rates) as well as cognitive processes (perception, memory, state). However, the physiology underlying the 1/f power law in cortical dynamics is not w...
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#1Burke Q. Rosen (University of California, Berkeley)H-Index: 10
#2Eric Halgren (University of California, Berkeley)H-Index: 89
The tracts between cortical areas are conceived as playing a central role in cortical information processing, but their actual numbers have never been determined. Here we estimate the absolute number of axons linking cortical areas from a whole-cortex diffusion-MRI (dMRI) connectome, calibrated using the histologically-measured callosal fiber density. Median connectivity is estimated as ~2,700 axons between cortical areas within-hemisphere and ~540 axons interhemispherically, with axons connecti...
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#1Burke Q. Rosen (University of California, Berkeley)H-Index: 10
#2Eric Halgren (University of California, Berkeley)H-Index: 89
A simple method is derived for estimating the absolute number of axons linking cortical areas from a whole-cortex diffusion-MRI (dMRI) connectome. We estimate the conversion factor from dMRI tractography to axons using the histologically-measured callosal fiber density, then allocate axons between regions in proportion to dMRI connectivity. Median connectivity is estimated as ~2,700 axons between cortical areas within-hemisphere and ~540 axons interhemispherically, with axons connecting function...
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#1Ritwik Vatsyayan (UCSD: University of California, San Diego)H-Index: 1
#2Daniel R. Cleary (UCSD: University of California, San Diego)H-Index: 13
Last. Shadi A. Dayeh (UCSD: University of California, San Diego)H-Index: 38
view all 5 authors...
Diagnostic and therapeutic electrical stimulation are increasingly utilized with the rise of neuromodulation devices. However, systematic investigations that depict the practical clinical stimulation paradigms (bipolar, 2-electrode configuration) to determine the safety limits are currently lacking. Further, safe charge densities that were classically determined from conical sharp electrodes are generalized for cylindrical (depth) and flat (surface grid) electrodes completely ignoring geometric ...
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#1Charles W. Dickey (UCSD: University of California, San Diego)H-Index: 4
#2Ilya A. Verzhbinsky (UCSD: University of California, San Diego)H-Index: 5
Last. Eric Halgren (UCSD: University of California, San Diego)H-Index: 89
view all 9 authors...
Hippocampal ripples index the reconstruction of spatiotemporal neuronal firing patterns essential for the consolidation of memories in the cortex during non-rapid eye movement (NREM) sleep. However, it is not known whether ripples are generated in the human cortex during sleep. Here, using human intracranial recordings, we show that ~70ms long ~80Hz ripples are ubiquitous in all regions of the cortex during NREM sleep as well as waking. During waking, cortical ripples occur on local high frequen...
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