KAORI TAKEHARA, University of Toronto
Title: Formation and remodeling of temporal bridges in the medial prefrontal cortex
Ebbinghaus Empire Series 2015-2016
VIDEO RECORDING OF TALK
Abstract: Cognitive phenomena such as episodic memory, working memory, and goal directed behavior all rely on the ability to link information across time. In this talk, I will present evidence suggesting that the rat medial prefrontal cortex (mPFC; a homologue of the anterior cingulate cortex in humans) plays an important role in detecting and encoding correlations between stimuli that are disconnected in time. I will first show neurophysiological data suggesting that mPFC neurons encode temporal relationships between stimuli by sustaining their firing rates during intervening intervals. Over multiple weeks of experiences, the sustained firings retain its specificity for stimulus relationships common across experiences while becoming less selective for physical stimulus feature specific to each experience. In addition, the mPFC re-uses this generalized representation to encode the same relationship of stimulus pair presented in a novel environment. I will then show that the mPFC also exhibits strong theta and beta rhythms during the interval between stimulus pairs, and that the amplitude of these oscillations is predictive of memory success. Furthermore, a manipulation that induces these particular oscillatory dynamics enables the formation of stimulus associations separated by intervals substantially longer than rats can normally learn. Based on these findings, I will discuss a view that the mPFC detects relevant stimulus relationships by using its generalized representations of stimulus sequences encountered in the past.
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