Neuronal activity related to visual recognition memory: long-term memory and the encoding of recency and familiarity information in the primate anterior and medial inferior temporal and rhinal cortex.

Recordings of the activity of 2705 single neurones were made in entorhinal and perirhinal cortex, area TG of the temporal lobe, and the inferior temporal cortex both during monkeys' performance of a serial recognition memory task using complex pictures and when monkeys were shown objects. Responses of 120 (9.7%) of the visually responsive neurons recorded were significantly smaller to the second than to the first presentations of unfamiliar stimuli.

The effects of visual stimulation and memory on neurons of the hippocampal formation and the neighboring parahippocampal gyrus and inferior temporal cortex of the primate.

The activity of 736 single neurons was recorded from the hippocampal formation (HF), the rhinal cortex (RH), the medial and anterior inferior temporal cortex (TE), or areas TF and TH of the parahippocampal gyrus (PHG) of monkeys during the performance of a delayed matching to sample task. The results indicate differences between the areas in their contributions to sensory processing and memory. Of the neurons, 55% responded to either the first (S1) and/or the second (S2) of the two successively presented visual stimuli.

Hippocampus and medial temporal cortex: neuronal activity related to behavioural responses during the performance of memory tasks by primates.

Neuronal activity was recorded in the hippocampal formation, the parahippocampal gyrus and medial inferotemporal cortex of monkeys performing memory tasks. In a modified delayed matching to sample task in which 2 sequentially presented stimuli were compared on each trial, a match condition required a right panel press, whereas a non-match condition required a left panel press. The activity of 336/736 (45.

Neuronal evidence that inferomedial temporal cortex is more important than hippocampus in certain processes underlying recognition memory.

Amnesia has been reported to result from combined damage to the amygdala, hippocampus and inferomedial temporal cortex in man and monkey. Evidence is presented that neuronal activity in the monkey inferomedial temporal cortex reflects memory for the previous occurrence of visual stimuli: 26 (15%) of 173 single units responded more strongly to first than to subsequent presentations of unfamiliar stimuli. No such responses were found for neurones recorded in the hippocampus and subicular cortex.