Jun, S. C. | Search bioRxiv

bioRxiv2021

Revealing the Physiological Origin of Event-Related Potentials using Electrocorticography in Humans

The scientific and clinical value of event-related potentials (ERPs) depends on understanding the contributions to them of three possible mechanisms: (1) additivity of time-locked voltage changes; (2) phase resetting of ongoing oscillations; (3) asymmetrical oscillatory activity. Their relative contributions are currently uncertain. This study uses analysis of human electrocorticographic activity to quantify the origins of movement-related potentials (MRPs) and auditory evoked potentials (AEPs). The results show that MRPs are generated primarily by endogenous additivity (88%). In contrast, P1 and N1 components of AEPs are generated almost entirely by exogenous phase reset (93%). Oscillatory asymmetry contributes very little. By clarifying ERP mechanisms, these results enable creation of ERP models; and they enhance the value of ERPs for understanding the genesis of normal and abnormal auditory or sensorimotor behaviors.

neuroscience↗

bioRxiv2019

Effect of sinusoidal electrical cortical stimulation on brain cells

BackgroundElectrical cortical stimulation is often used in patients with neurological disorders but it is unclear how it modulates different types of brain cells. ObjectiveThe aim of this study was to determine the effect of sinusoidal electrical brain stimulation (SEBS) on different types of brain cells and to identify the exact types of brain cells that are stimulated. MethodsThe study subjects were 40 male Sprague Dawley rats (weight 300-350 g; age 9 weeks). SEBS was delivered continuously at frequencies of 20, 40, 60, or 100 Hz to the sensory parietal cortex using epidurally placed electrodes for 1 week. Transverse rat brain tissue sections were immunolabeled with calmodulin-dependent protein kinase II and parvalbumin (PV) antibodies and with c-Fos for counting of activated excitatory and inhibitory neurons. Computer simulation was performed to cross-validate the frequency-specific cell stimulation results. ResultsInhibitory neurons were more excited than excitatory neurons after epidural EBS. Most excitatory neural activity was evoked at 40 Hz (p<0.05) and most inhibitory neuronal activity was evoked at 20 Hz (p<0.01). The contralateral sensory cortex was activated significantly more at 40 Hz (p<0.05) and the corticothalamic circuit at 20 Hz (p<0.001). Stimulation-induced excitatory and inhibitory neuronal activation was widest at 20 Hz. ConclusionsEpidural electrical stimulation targets both excitatory and inhibitory neurons and the related neural circuits. Further exploration is needed to identify circuits that promote the plasticity needed for recovery in patients with specific neurological diseases. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=90 SRC="FIGDIR/small/855395v1_ufig1.gif" ALT="Figure 1"> View larger version (17K): org.highwire.dtl.DTLVardef@3fbad8org.highwire.dtl.DTLVardef@3dad5org.highwire.dtl.DTLVardef@113fbe9org.highwire.dtl.DTLVardef@ffa066_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗