Abstract
Neurons of the medial entorhinal cortex (MEC) provide spatial representations critical for navigation. In this network, the periodic firing fields of grid cells act as a metric element for position. The location of the grid firing fields depends on interactions between self-motion information, geometrical properties of the environment and nonmetric contextual cues. Here, we test whether visual information, including nonmetric contextual cues, also regulates the firing rate of MEC neurons. Removal of visual landmarks caused a profound impairment in grid cell periodicity. Moreover, the speed code of MEC neurons changed in darkness and the activity of border cells became less confined to environmental boundaries. Half of the MEC neurons changed their firing rate in darkness. Manipulations of nonmetric visual cues that left the boundaries of a 1D environment in place caused rate changes in grid cells. These findings reveal context specificity in the rate code of MEC neurons.
Highlights
Grid cells of the medial entorhinal cortex (MEC) fire at several locations organized as a grid of equilateral triangles (Hafting et al, 2005)
We investigated whether the firing rate of MEC neurons changed significantly when visual landmarks were eliminated
The results presented so far indicate that the firing rate of MEC neurons is modulated by the presence of visual landmarks
Summary
Grid cells of the medial entorhinal cortex (MEC) fire at several locations organized as a grid of equilateral triangles (Hafting et al, 2005). The repetitive nature of the firing fields suggests that grid cells are an important metric element of a neuronal system involved in spatial navigation (Hafting et al, 2005; McNaughton et al, 2006; Burgess et al, 2007). Computational models suggest that grid cells integrate heading direction and traveled distance (Fuhs, 2006; McNaughton et al, 2006; Burgess et al, 2007; Burak and Fiete, 2009). On the other hand, could be estimated from the firing rate of speed cells located in the MEC (Kropff et al, 2015). As expected from an internal speedometer, the increase of the firing rate of speed cells as a function of running velocity is preserved across different environments (Kropff et al, 2015)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
