PNI Faculty Search Seminars

Abstract:
In this talk I will discuss my lab’s research using direct brain recordings from neurosurgical patients to understand the neural basis of spatial navigation and episodic memory in humans.  The goal of this work is to explain the functional electrophysiology of the human medial temporal lobe (MTL) to show how our brain supports complex spatial and memory demands and to identify potential differences compared to animals.  First, I will describe the human single-neuron activity that underlies spatial navigation. Here, I show evidence of human place and grid cells, whose activity represents the current location during navigation. These single-neuron patterns remap in relation to subjects’ high-level cognitive states, suggesting that the human MTL supports more than a purely spatial map of the environment.  Second, I will describe task-related network oscillations in the human MTL. I show that the human MTL shows two distinct patterns of large-scale 'theta' oscillations, at ~8 and ~3 Hz, that correlate with spatial and memory processes, respectively. The existence of these two patterns suggests a potential key functional difference compared to simpler animals, where a single oscillatory pattern generally dominates. Finally, by examining the large-scale properties of neural activity during these tasks, I will show that neuronal oscillations are traveling waves, propagating continuously across the cortex following predictions of coupled-oscillator models. This suggests that oscillations at various frequencies have a broad role in spatially organizing large-scale cortical patterns to support cognition. I conclude by discussing future directions for my work, in which I will continue to investigate how neural activity in the human MTL extends the principles suggested by animal model systems.