Biology subjects

Kucewicz, M. T.

Publications and source records attributed to Kucewicz, M. T..

4 recordsLinked to original sources

bioRxiv2026

Cortical high frequency oscillations reflect encoding and retrieval of specific word concepts

High gamma and ripple frequency oscillations are engaged in encoding and recall of memory traces. Tracking specific traces with their signature neural activities across time and various tasks remains a major challenge. Using intracranial electrode recordings from epilepsy patients, we detected bursts of high-frequency oscillations in response to viewing and remembering the same common nouns in two different tasks repeated on subsequent days. We found the lowest word response selectivity of approximately 40% in the visual sensory areas and increasingly higher selectivity in the more anterior associational regions. The same word sets identified as preferred in a screening task triggered selective responses in another task during visual presentation or free recall with no sensory stimulation in the same session, and on the following day. We demonstrate that persistent reactivation of large-scale neuronal assemblies underlying particular concepts is reflected in bursts of high-frequency oscillations in the human cortex.

neuroscience↗

bioRxiv2022

Chronic modulation of human memory and thalamic-hippocampal theta activities.

Electrical stimulation is a powerful therapeutic tool for treating neurologic and neuropsychiatric disorders. Sensing and modulating electrophysiological biomarkers of memory over extended timescales is necessary for tracking and improving memory in humans. Here, we describe results from humans in their natural home environments using a novel, investigational system enabling chronic stimulation and multi-channel recording of anterior thalamic and hippocampal local field potentials during memory tasks. Four people with focal epilepsy performed a free recall verbal memory task repeatedly for up to fifty months on a touch-screen device with wireless signal acquisition with electrophysiology and behavioral data streaming to a cloud environment. Anterior thalamic-hippocampal spectral activities in the theta frequency range were found to correlate with memory processing, to predict task performance, and to be modulated by deep brain stimulation. Our results provide a new biomarker-based technology for chronic remote tracking of memory performance and modulation of the associated neural activities. One Sentence SummaryElectrical stimulation in the anterior thalamic nuclei modulates theta frequency activities and improves human verbal memory performance chronically.

neuroscience↗

bioRxiv2021

Prefrontal cortical contributions to working memory loading, maintenance and recall are parsed by hippocampal-prefrontal oscillatory assembly dynamics

Working memory enables incorporation of recent experience into subsequent decision-making. This processing recruits both prefrontal cortex and hippocampus, where neurons encode task cues, rules and outcomes. However, precisely which information is carried when, and by which neurons, remains unclear. Using population decoding of activity in rat medial prefrontal cortex (mPFC) and dorsal hippocampal CA1, we confirm that mPFC populations lead in maintaining sample information across delays of an operant nonmatch to sample task, despite individual neurons firing only transiently. During sample encoding, distinct mPFC subpopulations joined distributed CA1-mPFC cell assemblies hallmarked by 4-5Hz rhythmic modulation; CA1-mPFC assemblies re-emerged during choice episodes, but were not 4-5Hz modulated. Delay-dependent errors arose when attenuated rhythmic assembly activity heralded collapse of sustained mPFC encoding; pharmacological disruption of CA1-mPFC assembly rhythmicity impaired task performance. Our results map component processes of memory-guided decisions onto heterogeneous CA1-mPFC subpopulations and the dynamics of physiologically distinct, distributed cell assemblies.

neuroscience↗

bioRxiv2021

Independent dynamics of slow, intermediate, and fast intracranial EEG spectral activities during human memory formation

A wide spectrum of brain rhythms are engaged throughout the human cortex in cognitive functions. How the rhythms of various low and high frequencies are spatiotemporally coordinated across the human brain during memory processing is inconclusive. They can either be coordinated together across a wide range of the frequency spectrum or induced in specific bands. We used a large dataset of human intracranial electroencephalography (iEEG) to parse the spatiotemporal dynamics of spectral activities induced during formation of verbal memories. Encoding of words for subsequent free recall activated slow theta, intermediate alpha and beta, and fast gamma frequency power in discrete cortical sites. A majority of the electrode sites recorded activity in only one of these frequencies, except for the visual cortex where spectral power was induced across multiple bands. Each frequency band showed characteristic dynamics of the induced power specific to cortical area and hemisphere. The power of the low, intermediate, and fast activities propagated in distinct spatiotemporal patterns across the visual, temporal and prefrontal cortical areas as the words were presented for encoding. Our results suggest anatomically and temporally distributed spectral activities in the formation of human memory.

neuroscience↗