AN FMRI STUDY OF DIFFERENTIAL PERIRHINAL AND PREFRONTAL CORTEX ACTIVATION DURING FAMILIARITY/RECENCY DISCRIMINATION

초록

Studies of amnesia in humans and of ablation and neuronal recording in monkeys have suggested that the perirhinal cortex of the temportal lobe is crucial to the familiarity discrimination component of recognition memory. However, fMRI studies have often failed to find differential activation of perirhinal cortex when subjects view novel or familiar stimuli(Shacter et al.(1998), Neruon 20:185-195). Haemodynamic responses associated with the viewing by 6 young healthy female volunteers of novel,familiar or recentlu presented pictures of objects were measured using an fMRI scanner(1.5T GE Signa; SPM96 software). Prior to scanning, subjects were made familiar with a mixtureof transport-related pictures (targets reqiring a key press response) and other pictures(non-targets).During scanning subjects viewde an series of novel and familiar target and non-targer pictures.The picture-encoding task was associated with increased fMRI signals in prefrontal cortex and perirhinal cortex.In perirhinal cortex the greatest increase was for presentations of novek target pictures, with there being smaller increases for repeated presentations of these novel pictures or for presentations of familiar target pictures.In prefrontal cortex the opposite pattern was seen,the activations being least for the novel targets.these signal changes closely parallel changes in the responses of neurones recorded in monkey perirhinal and prefrontal cortex during the performance of a familiarity discrimination task(Xiang and Brown(1998)Neuropharmacol. 37:657-676;(1999)Eur.J.Neruosci.11:152P).