FUNCTIONAL SUB-SPECIALIZATION OF THE RETROSPLENIAL CORTEX IN SPATIAL COGNITION PROCESSES USING ALE META-ANALYSIS

Abstract

cognitive correlates of recent versus remote autobiographical memories in the pre-dementia stage of Alzheimer’s disease (AD). Methods: 20 MCI patients underwent an autobiographical memory test assessing remote (when the patients were 20 to 30 years old) and recent (ten last years) memories. All patients also had a 3T T1 structural MRI and an FDGPET scan, as well as neuropsychological tests assessing semantic autobiographical memory, verbal episodic memory and global cognitive functioning (Mattis). Correlations were then assessed between each of the two autobiographical memory scores and grey matter volume, metabolism and cognitive performances. Results: The score for the remote period correlated with semantic autobiographical memory, verbal episodic memory retrieval and as a trend for the Mattis, whereas the recent period only correlated with verbal episodic memory retrieval. Neuroimaging analyses revealed significant correlations between the remote period and temporal pole and temporo-parietal cortex volume as well as anterior cingulate gyrus metabolism, while the recent period correlated with hippocampus volume and metabolism in the posterior cingulate, medial prefrontal and hippocampal areas. The brain regions related with the recent period showed greater atrophy/hypometabolism in MCI patients compared to controls than those involved in remote memories. Conclusions: The cognitive and neural substrates of recent memories both point to the involvement of relatively pure episodic memory processes involving episodic memory network brain areas. By contrast, remote memories seem to involve other processes and brain regions as well, such as semantic memory processes, consistent with the idea that remote memories tend to semantize with time. The distinct cognitive and cerebral substrates of autobiographical memories according to life periods could explain the differential impairment of recent and remote memories observed in the early stage of AD.