Effect of local synaptic strengthening on global activity-wave growth in the hippocampus.
Analysis of a continuum model of the hippocampus shows that strengthening of the synaptic connections within localized regions can convert the global activity-wave properties from decay to growth. These growing waves can play a part in the implantation of long-term memory in the higher brain regions. The wavelength of the fastest-growing mode decreases with increasing local synaptic strength and can be modified by the chemical state as reflected by synaptic sensitivity to stimuli. The temporal period of the response is a constant, equal to twice the delay time exhibited by some of the hippocampal inhibitory neurons ("d-cells"). The value for the period obtained from this relationship and measurement of the delay time agrees with the hippocampal gamma rhythm. For normal hippocampal function the proportion of d-cells is limited to one-third the total number of inhibitory neurons.
Koch
P
P
School of Engineering, New York Institute of Technology, Old Westbury, NY, USA.
Leisman
G
G
D000818:Animals; D005583:Fourier Analysis; D006624:Hippocampus / Q000166:cytology / Q000502:physiology*; D006801:Humans; D008433:Mathematics; D008568:Memory / Q000502:physiology; D008959:Models, Neurological; D009474:Neurons / Q000502:physiology*; D013569:Synapses / Q000502:physiology*