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Hippocampal place cells, spatial memory, and synaptic plasticity

was accompanied by impaired spatial memory (but normal nonspatial learning) in these mutants. They also observed that, while CAl pyramidal cells in these mice exhibit place-related activity, spatial specificity of space fields was degraded (4). In a related study, Rotenberg et al. (5) recorded electrical activity from place cells in the CA1 region of transgenic mice that express a mutated Caz+-independent form of CAM kinase II, in which LTP in response to low frequency (5-10 Hz) stimulation is lacking. In these mice, hippocampal place cells exhibit less crisp, and less stable, spatial tuning characteristics. As noted by Rotenberg et al. (5) cognitive maps differ from sensory maps in representing spatial concepts rather than specific sensory stimuli. Irrespective of this, the establishment of cognitive maps in the hippocampus involves synaptic plasticity that is amenable to dissection at the