Here and below, plots shows firing rate as a function of the rat's location while it explores for randomly scattered food. Similar outcomes to experimental fields i-iii are illustrated: inhibition of firing (i) doubling of existing field in presence of barrier (ii, the most common outcome) double place field induced by presence of the barrier (iii). Three simulated place fields from the Boundary Vector Cell (BVC) model in 65cm square environments with and without the 40cm barrier. Three outcomes inserting a barrier are illustrated: (i) inhibition of firing (ii-iii) doubling of field with duplicate on either side of the barrier (the most common outcome) (iv) firing unaffected by the barrier (less common).
Third column: final 10 minute trial, barrier removed. Second column: first 10 minutes of 40 minute second trial, after the insertion of a 40cm barrier. Place fields of 4 place cells (i-iv) in three successive trials in a 65cm square walled environment. The relationship between neurophysiological results in rats and spatial behaviour in humans is discussed.Įffect of barrier insertion on real and simulated place fields. Simulations are compared to experimental data on the firing of place cells under geometrical manipulations to their environment. Finally, we extend the model to include experience-dependent modification of connection strengths through a BCM-like learning rule - the size and sign of strength change is influenced by historic activity of the postsynaptic cell.
The boundary update#
We review and update computational simulations predicting the location of human search within a virtual environment of variable geometry, assuming that boundary vector cells provide one of the input representations of location used in mammalian spatial memory. Preliminary experimental results are presented concerning the effects of addition or removal of environmental boundaries on place cell firing and evidence that boundary vector cells may exist in the subiculum.
We review evidence for the boundary vector cell model of the environmental determinants of the firing of hippocampal place cells.
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