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Theta oscillations (3—8 Hz) in the human brain have been linked to perception, cognitive control and spatial memory, but their relation to the motor system is less clear. We tested the hypothesis that theta oscillations coordinate distributed behaviorally relevant neural representations when initiating voluntary movement using intracranial electroencephalography (iEEG) recordings from 9 patients (n = 490 electrodes) as they performed a simple instructed movement task. Using high frequency activity (70-200 Hz) as a marker of local spiking activity, we identified electrodes that were positioned near neural populations that showed increased activity during instruction and movement. We found that theta synchrony was widespread throughout the brain but was increased near regions that showed movement-related increases in neural activity. These results support the view that theta oscillations are a general property of brain activity that may also have a specific role in coordinating widespread neural activity when initiating voluntary movement. New and Noteworthy: Whereas theta oscillations in the human brain have been extensively related to a wide range of perceptual and cognitive functions, there is only limited data linking theta oscillations to motor systems. In this study, we use intracranial EEG to show that theta oscillations (3—8 Hz) are widespread throughout the brain but further increased near movement-related neural populations during instructed movement. Our results provide a link between theta oscillations and motor systems.

The hippocampus is integral to working and episodic memory and is a central region of interest in diseases affecting these processes. Pig models are widely used in translational research and may provide an excellent bridge between rodents and nonhuman primates for CNS disease models because of their gyrencephalic neuroanatomy and significant white matter composition. However, the laminar structure of the pig hippocampus has not been well characterized. Therefore, we histologically characterized the dorsal hippocampus of Yucatan miniature pigs and quantified the cytoarchitecture of the hippocampal layers. We then utilized stereotaxis combined with single-unit electrophysiological mapping to precisely place multichannel laminar silicon probes into the dorsal hippocampus without the need for image guidance. We used in vivo electrophysiological recordings of simultaneous laminar field potentials and single-unit activity in multiple layers of the dorsal hippocampus to physiologically identify and quantify these layers under anesthesia. Consistent with previous reports, we found the porcine hippocampus to have the expected archicortical laminar structure, with some anatomical and histological features comparable to the rodent and others to the primate hippocampus. Importantly, we found these distinct features to be reflected in the laminar electrophysiology. This characterization, as well as our electrophysiology-based methodology targeting the porcine hippocampal lamina combined with high-channel-count silicon probes, will allow for analysis of spike-field interactions during normal and disease states in both anesthetized and future awake behaving neurophysiology in this large animal.