RT Journal Article
SR Electronic
T1 Hippocampal Network Dynamics Constrain the Time Lag between Pyramidal Cells across Modified Environments
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 13448
OP 13456
DO 10.1523/JNEUROSCI.3824-08.2008
VO 28
IS 50
A1 Kamran Diba
A1 György Buzsáki
YR 2008
UL http://www.jneurosci.org/content/28/50/13448.abstract
AB The hippocampus provides a spatial map of the environment. Changes in the environment alter the firing patterns of hippocampal neurons, but are presumably constrained by elements of the network dynamics. We compared the neural activity in CA1 and CA3 regions of the hippocampus in rats running for water reward on a linear track, before and after the track length was shortened. A fraction of cells lost their place fields and new sets of cells with fields emerged, indicating distinct representation of the two tracks. Cells active in both environments shifted their place fields in a location-dependent manner, most notably at the beginning and the end of the track. Furthermore, peak firing rates and place-field sizes decreased, whereas place-field overlap and coactivity increased. Power in the theta-frequency band of the local field potentials also decreased in both CA1 and CA3, along with the coherence between the two structures. In contrast, the theta-scale (0–150 ms) time lags between cell pairs, representing distances on the tracks, were conserved, and the activity of the inhibitory neuron population was maintained across environments. We interpret these observations as reflecting the freedoms and constraints of the hippocampal network dynamics. The freedoms permit the necessary flexibility for the network to distinctly represent unique patterns, whereas the dynamics constrain the speed at which activity propagates between the cell assemblies representing the patterns.