Determining affected memory domains in patients with amnestic mild cognitive impairment using computerized and interactive tests.

This study explores different episodic memory domains, namely object, temporal and spatial memory, affected in patients with a clinical diagnosis of single domain amnestic mild cognitive impairment (aMCI). 15 aMCI patients and 25 healthy controls were recruited and tested. Object, spatial, and temporal memory were tested using computerized tasks and again in interactive, real-world tasks. Controls outperformed patients on the object computerized task and showed a trend toward significance for the computerized spatial and temporal tasks, but there was no difference in spatial and temporal memory when using the interactive tasks, indicating the employment of compensatory mechanisms in patients to overcome some of the memory impairments associated with aMCI. These findings highlight that aMCI patients might delay seeking help due to compensatory mechanisms which mask their deficits in real-world situations.

Influence of dorsolateral periaqueductal grey (dlPAG) lesions on contextual conditioning with massed and distributed shock.

Three experiments investigated the conditions under which electrolytic lesions of the dorsolateral periaqueductal grey (dlPAG) facilitate conditioned defensive freezing in the rat (Rattus norvegicus). Experiment 1 found that dlPAG lesions placed before context-shock pairings facilitated conditioned defensive freezing with massed but not distributed shock. No such effect was found in Experiment 2, when the lesions were placed after context-shock pairings. Experiment 3 found that dlPAG lesions facilitated subsequent conditioning with massed but not a single shock. In addition, no differences in sensitivity to thermal or shock pain were evident in lesioned and unlesioned rats. Taken together, these results are consistent with the suggestion that dlPAG activation interferes with the processing of contextual cues during association formation.