Investigation of cognitive map formation using virtual reality
closed-loop control
Manu S. Madhav*, Ravikrishnan P. Jayakumar^, James J. Knierim*, Noah J. Cowan^
*
The Zanvyl Krieger Mind/Brain Institute, Johns Hopkins University
Department of Mechanical Engineering, Johns Hopkins University
^
Spatial navigation usually involves the formation of a coherent representation of the position
and orientation of an animal or robot within an external framework of landmarks.
Neurophysiological evidence indicates that mammals use both the sensed position of these
landmarks, as well as integrated self-motion cues in the formation of an allocentric “cognitive
map” in the hippocampal region. The two well-known neural correlates of this cognitive map
are place cells and grid cells in rodents[1,2].
Although several cell types have been discovered which encode different aspects of spatial
information, it is unclear how they interact with each other, and integrate various sensory
modalities to form the cognitive map[3]. We believe control theory and system identification,
which have a heritage of being used in automation and robotics, are especially well suited to
exploring the dynamics of the neural circuitry of spatial navigation[4]. We designed and
constructed a virtual reality (VR) apparatus in order to achieve the precise stimulus control and
response observation required to enable these experiments and analyses.
In our VR apparatus, a rodent moves around a circular track under minimal physical constraints,
while multiple electrodes record from populations of place or grid cells. The surrounding visual
scene is controlled in closed-loop in response to the animal’s locomotor output. By
independently perturbing salient visual landmarks and optic flow, and potentially other sensory
modalities, we aim to tease apart the influence of landmark and path integration cues, and
construct quantitative models of the representation of “place” in the brain. Preliminary data
from the apparatus shows that manipulations of the visual landmarks can reliably control the
firing location of place cells, even when the landmarks are radically displaced from their initial
locations.
References
[1] J. O’Keefe and L. Nadel. The hippocampus as a cognitive map. Clarendon Press, Oxford, United
Kingdom, 1978. [2] T. Hafting, M. Fyhn, S. Molden, M.-B. Moser, and E. I. Moser. Microstructure of a spatial map in
the entorhinal cortex. Nature, 436(7052):801–806, Aug 2005. PMID: 15965463. [3] J. O’Keefe and D. H. Conway. Hippocampal place units in the freely moving rat: why they fire
where they fire. Exp Brain Res, 31(4):573–590, Apr 1978. PMID: 658182. [4] Cowan N.J., Ankarali M.M., Dyhr J.P., Madhav M.S., Roth E., Sefati S., Sponberg S., Stamper S.A.,
Fortune E.S., Daniel T.L. 2014. “Feedback control as a framework for understanding tradeoffs in
biology.” Integrative and Comparitive Biology 54: 223–37.