Coding of space and time in the entorhinal cortex – Michael Hasselmo

Neurophysiological recordings from brain regions in behaving rodents demonstrate neurons that may code spatial location and elapsed time for memory function. This includes the coding in entorhinal cortex and hippocampus of spatial location by place cells (O'Keefe and Burgess, 1996) and grid cells (Hafting et al., 2005; Stensola et al., 2012). Many of these cells also code the temporal intervals during behavioral tasks (Kraus et al., 2013; 2015). Models of the coding spatial location utilize either integration of running speed and direction or the sensory computation of angle and distance of visual features on environmental boundaries. These models draw on data about the neurons that respond to head direction (Taube et al., 1990), neurons that respond to running speed (Kropff et al., 2015; Hinman et al., 2016) and neurons that respond to environmental boundaries in allocentric coordinates (Solstad et al., 2008; Lever et al., 2009) or that respond to boundaries in egocentric coordinates (Hinman et al., 2017). Experimental data shows that alterations of subcortical input can impair the responses of neurons coding space (Brandon et al., 2011; Winter et al., 2015) and time (Wang et al., 2014). Experimental data and computational modeling have explored potential cortical and subcortical mechanisms for the neural coding of time and space, addressing how network dynamics could contribute to integration of location and time (Burgess et al., 2007; Burak and Fiete, 2009; Howard et al., 2014), or how grid cells and boundary cells alter their coding in response to sensory input about environmental features (Raudies and Hasselmo, 2015; Campbell et al., 2018).