22 October 2021 - 22 October 2021
2:00PM - 3:00PM
This seminar is hosted by the Psychology Department at Durham University
Neurophysiological recordings in cortical structures in behaving rodents demonstrate potential coding of space and time for episodic memory and goal-directed behavior. Extensive data shows coding of spatial location in entorhinal cortex and hippocampus by grid cells and place cells, which also code temporal intervals in a behavioral task, firing as time cells when a rat runs on a treadmill (Kraus et al., 2013; 2015; Mau et al., 2018).
Computational modeling shows how time cells may arise from exponential decay of neural activity on multiple time scales (Liu et al., 2019). Coding of space could involve either path integration or sensory transformations. In support of path integration, subcortical inputs to cortex appear to contribute to the cortical coding of running speed (Hinman et al., 2016) and head direction (Taube et al., 1990), which could be combined for coding of location by path integration.
Consistent with this, inactivation of input from the medial septum impairs the spatial selectivity of grid cells (Brandon et al., 2011). However, recent data shows inaccurate coding of speed on short intervals (Dannenberg et al., 2019) and indicate that few cells code movement direction for path integration (Raudies et al., 2015). This suggests that transformation of sensory input may be more important for computing location. Data shows coding of environmental boundaries in egocentric coordinates in the dorsomedial striatum and retrosplenial cortex (Hinman et al., 2019; Alexander et al., 2020). This fits with a modeling framework (Byrne, Becker, Burgess, 2007; Bicanski and Burgess, 2018) in which egocentric coding of barriers combined with head direction can generate allocentric coding of environmental barriers (Lever et al., 2009; Poulter et al., 2021) and locations. These different neural mechanisms could mediate the encoding of spatial location of agents and objects and the time of events in episodic memory.
Director of the Center for Systems Neuroscience, Boston University
Dr. Hasselmo's research uses neurophysiological recording and computer modeling to link the dynamics of cortical circuits to memory-guided behavior. Dr. Hasselmo is a member of numerous scientific journal editorial boards. He is a section editor at the journal Hippocampus and in 2012 he published a book on episodic memory with MIT Press. He is the former chair of the NIH Neurobiology of Learning and Memory study section (LAM).