Cornelis Wiersma Visiting Professor of Neurobiology Seminar

Title: Inhibitory engrams and the flexible control of cognition.

Abstract:

The brain encodes information in the form of excitatory cell assemblies whose activities can be modulated by familiarity, context or intention. Our work on Drosophila olfactory behavior indicates that habituation, the reduced behavioral response to familiar odorants, arises from the creation of matched inhibitory masks (inhibitory engrams) that silence responses to assemblies encoding familiar odorants. In combination with additional observations on organisms ranging from molluscs to humans, these observations lead to a framework in which inhibitory engrams support flexible cognition across neural systems and animal species. The model proposes that inhibitory engrams: a) drive and maintain behavioral habituation; (b) allow memories to be stored in silent, quiescent forms; and, (c) through upstream disinhibitory mechanisms, are lifted from ensembles encoding relevant percepts or recalled memories.  I will discuss different types of inhibitory engrams, mechanisms by which they are regulated, possible roles for sleep-phases in their formation as well as the potential relevance of their dysregulation to dreams, hallucinations and mental health.