Biology subjects

Soper, D. J.

Publications and source records attributed to Soper, D. J..

4 recordsLinked to original sources

bioRxiv2024

Anxious/depressed individuals exhibit disrupted frontotemporal synchrony during cognitive conflict encoding

BackgroundDepressive disorders are associated with impaired cognitive control, yet the neural mechanisms underlying these deficits remain poorly understood. We used stereotactic EEG (sEEG) in individuals with medically refractory epilepsy to determine whether a history of comorbid depressive symptoms was associated with altered behavioral and neural responses encoding cognitive conflict. MethodssEEGs were recorded from fronto-temporo-limbic regions in 28 participants (age: 35.4{+/-}8.9, female: 15/28) performing a Multi-Source Interference Task (MSIT). Psychiatric histories, neurobehavioral interviews, and symptom ratings were used to categorize participants with a history of depressive symptoms (EDS, n=13), or as epilepsy controls without depression history (n=15). Behavioral, spectral power, and coherence responses to conflict were determined by generalized linear mixed-effects models. Dynamic Causal Modeling (DCM) estimated theta-alpha (4-15Hz) effective connectivity between dorsolateral prefrontal cortex (dlPFC), dorsal anterior cingulate cortex (dACC), and lateral temporal lobe (LTL) during conflict. ResultsEDS participants demonstrated greater conflict-related slowing without difference in accuracy from controls. Conflict elicited distributed fronto-temporo-limbic oscillations in both groups. EDS participants showed greater conflict-related theta/alpha increases in PFC, LTL, and amygdala, and broadband increases in LTL power, and reduced left dlPFC-LTL theta/alpha coherence compared to controls. DCM model estimated effective connectivity from left dlPFCright LTL and left dACCleft LTL was reduced in EDS. ConclusionIncreased oscillatory responses in EDS may reflect a need for greater cognitive resources due to disrupted communication in fronto-temporo-limbic circuits encoding conflict. Our results highlight a role of these circuits in conflict encoding and can inform interventions for improving cognitive control in these populations.

neuroscience↗

bioRxiv2024

Modular Phoneme Processing in Human Superior Temporal Gyrus

Modular organization is fundamental to cortical processing, but its presence is human association cortex is unknown. We characterized phoneme processing with 128-1024 channel micro-arrays at 50-200m pitch on superior temporal gyrus of 7 patients. High gamma responses were highly correlated within [~]1.7mm diameter modules, sharply delineated from adjacent modules with distinct time-courses and phoneme-selectivity. We suggest that receptive language cortex may be organized in discrete processing modules.

neuroscience↗

bioRxiv2021

Large-scale neural recordings with single-cell resolution in human cortex using high-density Neuropixels probes

Recent advances in multi-electrode array technology have made it possible to monitor large neuronal ensembles at cellular resolution. In humans, however, current approaches either restrict recordings to only a few neurons per penetrating electrode or combine the signals of thousands of neurons in local field potential (LFP) recordings. Here, we describe a new probe variant and set of techniques which enable simultaneous recording from over 200 well-isolated cortical single units in human participants during intraoperative neurosurgical procedures using silicon Neuropixels probes. We characterized a diversity of extracellular waveforms with eight separable single unit classes, with differing firing rates, positions along the length of the linear electrode array, spatial spread of the waveform, and modulation by LFP events such as inter-ictal discharges and burst suppression. While some additional challenges remain in creating a turn-key recording system, high-density silicon arrays provide a path for studying human-specific cognitive processes and their dysfunction at unprecedented spatiotemporal resolution.

neuroscience↗

bioRxiv2019

Microscale physiological events on the human cortical surface detected with PEDOT:PSS Electrodes

Despite ongoing advancements in our understanding of the local single-cellular and network-level activity of neuronal populations in the human brain, extraordinarily little is known about their intermediate microscale local circuit dynamics. Here, we utilized ultrahigh density microelectrode arrays and a rare opportunity to perform intracranial recordings across multiple cortical areas in human participants to discover three distinct classes of cortical activity that are not locked to ongoing natural brain rhythmic activity. The first included fast waveforms similar to extracellular single unit activity. The other two types were discrete events with slower waveform dynamics and were found preferentially in upper layers of the grey matter. They were also observed in rodents, non-human primates, and semi-chronic recordings in humans via laminar and Utah array microelectrodes. The rates of all three events were selectively modulated by auditory and electrical stimuli, pharmacological manipulation, and cold saline application and had small causal co-occurrences. These results suggest that with the proper combination of high resolution microelectrodes and analytic techniques it is possible to capture neuronal dynamics that lay between somatic action potentials and aggregate population activity and that understanding these intermediate microscale dynamics may reveal important details of the full circuit behavior in human cognition.

neuroscience↗