Impaired spatial learning after saturation of long-term potentiation.
If information is stored as activity-driven increases in synaptic weights in the hippocampal formation, saturation of hippocampal long-term potentiation (LTP) should impair learning. Here, rats in which one hippocampus had been lesioned were implanted with a multielectrode stimulating array across and into the angular bundle afferent to the other hippocampus. Repeated cross-bundle tetanization caused cumulative potentiation. Residual synaptic plasticity was assessed by tetanizing a naïve test electrode in the center of the bundle. Spatial learning was disrupted in animals with no residual LTP (<10 percent) but not in animals that were capable of further potentiation. Thus, saturation of hippocampal LTP impairs spatial learning.
Moser
E I
EI
Department of Psychology, Norwegian University of Science and Technology, 7034 Trondheim, Norway.
Krobert
K A
KA
Moser
M B
MB
Morris
R G
RG
D000818:Animals; D018891:Dentate Gyrus / Q000502:physiology; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D005071:Evoked Potentials; D019706:Excitatory Postsynaptic Potentials; D006624:Hippocampus / Q000502:physiology*; D017774:Long-Term Potentiation / Q000502:physiology*; D008297:Male; D018782:Maze Learning / Q000502:physiology*; D019580:Perforant Pathway; D051381:Rats; D013569:Synapses / Q000502:physiology; D013746:Tetany