Center for Learning and Memory, Massachusetts Institute of Technology
Effect of LTP/D on the Shape of Receptive Fields: Lessons from the Hippocampus
While there has been some work to understand the effect of patterns of neuronal activity and synaptic plasticity on the size (Mehta et al., PNAS 94, 8918-8921 (1997)) and specificity (Wang et al., Nature, 374, 71-75 (1995)) of receptive fields, little has been done to quantify their effect on the receptive field shape. Here we show that within a few traversals of a familiar environment, a large fraction of hippocampal place fields become asymmetric such that the firing rate of a place cell rises slowly as a rat enters a place field but the firing rate drops off abruptly at the end of the place field. A computational model based on NMDA dependent LTP can explain the results. The model provides a mechanism underlying phase precession in the hippocampal neurons and directional, slanted spatio-temporal receptive fields in the striate cortex. Such asymmetric receptive fields can allow an animal to predict an upcoming event, based on previously experienced patterns of neuronal activity.
This work has been presented in abstract form in the Society for Neuroscience Meeting, 758.3 (1998).