Time-modulated enhancing of the fronto-parietal circuits in the very-old elders.

Several studies have shown that memory circuits can be reorganised as a function of age. Brain magnetic activity evoked by a memory task was recorded in 19 healthy elderly subjects divided into two groups, a young-elder group (mean age of 62) and senior-elder group (mean age of 76). The young-elder group showed greater activity over the left medial temporal lobe in the late latency windows (between 400 and 800 ms) than the senior-elder group. The senior-elder group showed an initial increased activity (between 150 and 400 ms) over the complex of motor areas, followed by an increased activity in the left temporo-parietal cortex at the late latency window. These results revealed a reorganization of brain networks supporting memory in the eldest subjects. Furthermore, these circuits are reorganised in a time-dependent manner, meaning the rehearsal articulatory process active in the early time window followed by a phonological storage and recognition process in the late latency window.