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. Author manuscript; available in PMC: 2012 May 4.
Published in final edited form as: Science. 2011 Nov 4;334(6056):623–628. doi: 10.1126/science.1209236

Figure 1. Hippocampal Synaptic Plasticity.

Figure 1

A. The rodent hippocampus can be dissected out and cut into transverse slices (B) preserving all three synaptic pathways. In the perforant pathway (purple), axons from the entorhinal cortex project to form synapses (red circles) on dendrites of dentate granule cells; in the mossy fiber pathway (green), dentate granule axons synapse on CA3 pyramidal neuron dendrites; and in the Schaffer collateral pathway (brown), CA3 axons synapse on CA1 dendrites. The dentate, CA3 and CA1 cell bodies form discrete somatic layers (dark blue lines), projecting axons and dendrites into defined regions. Electrodes can be used to stimulate axonal afferents and record from postsynaptic follower cells, as illustrated for the Schaffer collateral (CA3-CA1) pathway. Test stimuli elicit a stable synaptic response in the follower cell, measured as a excitatory post-synaptic potentials (EPSP, Ci). Trains of high frequency stimulation (HFS) or low frequency stimulation (LFS) to the axonal fibers produce sustained increases or decreases, respectively of the EPSP amplitude in response to subsequent test stimuli (C and D). These forms of plasticity are known as long-term potentiation (LTP) and long-term depression (LTD). Figure adapted from (56).