RECOVERY OF FUNCTION PROCESSES IN HUMAN AMNESIA - EVIDENCE FROM TRANSIENT GLOBAL AMNESIA

There are few clues as to the processes that underlie recovery of func tion from human amnesia. Evidence is offered from the perspective of a study of recovery of function during an episode of transient global a mnesia (TGA) that occurred as a complication of a cerebral angiographi c procedure being carried out in a neurosciences centre, and where the re was therefore a unique opportunity to examine acute changes in memo ry function. This allowed us to conduct the first quantitative study w here shrinkage of anterograde and retrograde memory loss was plotted a t four separate intervals throughout the acute recovery process, and a lso 24 hr later. Recovery of retrograde amnesia preceded recovery from anterograde amnesia. Resolution of a naming deficit more closely para lleled recovery from retrograde amnesia rather than anterograde amnesi a. Within retrograde amnesia for public events, there was a temporal g radient of memory loss, with more recent events affected to a greater degree than earlier events. Within anterograde amnesia, picture recogn ition memory preceded recovery of story recall memory. On the basis of these findings, and related observations in the published literature, it is proposed that recovery from some types of human amnesia, such a s that associated with TGA, follows a 'lateral-to-medial' rule-lateral inferotemporal areas that play a major role in retrograde amnesia rec over first from hypometabolism related to the TGA attack, followed by 'interface' areas such as the rhinal and parahippocampal cortices that are considered to have a role in both anterograde and retrograde memo ry functioning, with the last areas to recover physiological integrity being discrete limbic-diencephalic structures such as the hippocampus . (C) 1998 Elsevier Science Ltd. All rights reserved.