Loss of synaptic depression in mammalian anterior cingulate cortex after amputation

Two forms of activity-dependent long-term depression (LTD) in the CNS, as d efined by their sensitivity to the blockade of NMDA receptors, are thought to be important in learning, memory, and development. Here, we report that NMDA receptor-independent LTD is the major form of long-term plasticity in the anterior cingulate cortex (ACC). Both L-type voltage-gated calcium chan nels and metabotropic glutamate receptors are required for inducing LTD. Am putation of a third hindpaw digit in an adult rat induced rapid expression of immediate early genes in the ACC bilaterally and caused a loss of LTD th at persisted for at least 2 weeks. Our results suggest that synaptic LTD in the ACC may contribute to enhanced neuronal responses to subsequent somato sensory stimuli after amputation.