The Department of Psychology Distinguished Scholar Lecture Series is a three-day public lecture series sponsored by the Department of Psychology, Faculty of Arts and Faculty of Science. Each year the Department invites a renowned psychologist to present three one-hour lectures. The event is normally scheduled in the fall.
The 40th Annual Distinguished Scholar Lecturer Series
Dr. Michael Hasselmo: How we remember - Brain Mechanisms of Episodic Memory
October 18, 19, 20 2017 @ 3:30pm
Natural Resources Engineering building 2-003 (NRE 2-003)
Dr. Hasselmo is interested in medial temporal lobe memory circuits and the relevance of oscillatory activity, but also neuromodulation to the specific forms of memory exhibited by these circuits. His studies involve multiple levels of investigation including behaviour and neurophysiology (and their combinations) in both humans and animals, as well as computational modeling of both oscillatory processes and their relevance to the neurobiology of memory.
Everyone is welcome.
If you would like to meet with Dr. Hasselmo during his visit please contact Clayton Dickson (firstname.lastname@example.org).
Lecture 1: Neural coding of space and time for episodic memory
Episodic memory is defined as memory for events occurring at a specific time and place. Neurophysiological recordings from brain regions in behaving rodents demonstrate neuron response properties that may code space and time for episodic memory. This includes the coding of space by grid cells in entorhinal cortex (Moser and Moser, 2008) and place cells in hippocampus, and coding of temporal intervals by time cells in both regions (Kraus et al., 2013; 2015). Experimental data indicates potential mechanisms for the neural coding of time and space. Inactivation of input from the medial septum influences network oscillatory dynamics such as theta rhythm, and impairs the responses of neurons coding space (Brandon et al., 2011) and time (Wang et al., 2014). These effects on the coding of space and time may involve modulation of cellular neural mechanisms of resonance and rebound spiking (Dickson et al., 2000; Giocomo et al., 2007; Shay et al., 2015). Models demonstrate how intrinsic properties may contribute to coding of space and time.
Lecture 2: Cholinergic neuromodulation and episodic memory
A wide range of behavioral studies indicate that the neuromodulator acetylcholine plays an important role in regulating the encoding of episodic memories, whereas low levels of acetylcholine could be important for consolidation of memories. Cellular effects of acetylcholine (reviewed in Hasselmo, 2006) indicate that cholinergic modulation may enhance encoding by increasing the spiking response to afferent input and enhancing the modification of synapses that store associations. Acetylcholine also induces persistent spiking activity that could actively maintain information for encoding. Acetylcholine causes a robust presynaptic inhibition of glutamate release at excitatory feedback synapses in most cortical regions. Computational modeling demonstrates how this presynaptic inhibition could enhance encoding by preventing interference from retrieval of previously stored associations mediated by excitatory feedback. Acetylcholine levels show a dramatic decrease during quiet waking and slow-wave sleep (reviewed in Hasselmo, 1999), resulting in an enhancement of excitatory cortical feedback that could underlie the consolidation of episodic memory traces into semantic representations in neocortical structures.
Lecture 3: A model of episodic memory
The third talk in the series will address a model of episodic memory that focuses on coding of spatiotemporal trajectories that bring together representations of time cells, grid cells, place cells and head direction cells, with modulatory regulation of encoding and retrieval dynamics. The talk will also review modeling of the potential mechanism of influence of visual stimuli on grid cells (Raudies and Hasselmo, 2015) and the encoding of associations between spatial representations and visual stimuli. In addition, this talk will address the potential role of these same circuits in memory-guided goal-directed spatial behavior (Erdem and Hasselmo, 2014).