Early impairment of long-term depression in the perirhinal cortex of a mouse model of Alzheimer's disease.

Visual recognition memory is early impaired in Alzheimer's disease. Long-term depression of synaptic transmission in the perirhinal cortex is critically involved in this form of memory. We found that synaptic transmission was impaired in perirhinal cortex slices obtained from 3-month-old Tg2576 mice, and that 3,000 pulses at 5 Hz induced long-term depression in perirhinal cortex slices from age-matched control mice, but not in those from Tg2576 mice. To our knowledge, these data provide the first evidence of synaptic transmission and long-term depression impairment in the perirhinal cortex in an animal model of Alzheimer's disease, and the earliest synaptic deficit in Tg2576 mice.