Retrograde amnesia in patients with hippocampal, medial temporal, temporal lobe, or frontal pathology

Abstract

There is considerable controversy concerning the theoretical basis of retrograde amnesia (R.A.). In the present paper, we compare medial temporal, medial plus lateral temporal, and frontal lesion patients on a new autobiographical memory task and measures of the more semantic aspects of memory (famous faces and news events). Only those patients with damage extending beyond the medial temporal cortex into the lateral temporal regions showed severe impairment on free recall remote memory tasks, and this held for both the autobiographical and the more semantic memory tests. However, on t-test analysis, the medial temporal group was impaired in retrieving recent autobiographical memories. Within the medial temporal group, those patients who had combined hippocampal and parahippocampal atrophy (H + ) on quantified MRI performed somewhat worse on the semantic tasks than those with atrophy confined to the hippocampi (H − ), but scores were very similar on autobiographical episodic recall. Correlational analyses with regional MRI volumes showed that lateral temporal volume was correlated significantly with performance on all three retrograde amnesia tests. The findings are discussed in terms of consolidation, reconsolidation, and multiple trace theory: We suggest that a widely distributed network of regions underlies the retrieval of past memories, and that the extent of lateral temporal damage appears to be critical to the emergence of a severe remote memory impairment.The neural bases of retrograde amnesia and long-term memory functions remain key issues in cognitive neuroscience. In particular, the time course of medial temporal lobe (MTL) involvement in the storage and retrieval of remote memories has not been resolved. The present study examines performance across a range of measures of remote memory in amnesic patients with focal medial temporal lobe pathology, more widespread temporal lobe damage, and frontal lobe damage. The purpose is to test theoretical predictions concerning the nature of retrograde amnesia.Despite a proliferation of studies on memory and its disorders over the last three to four decades, many of the critical issues are still widely debated (Kopelman 2002(Kopelman , 2006. There are two main theoretical positions currently discussed in the literature regarding the role of MTL structures in the retrieval of remote memories, each of which makes distinct predictions about how remote memory is affected by the physical location and extent of brain damage. According to the consolidation model (ZolaMorgan and Squire 1990; Squire 1992; Squire and Alvarez 1995), episodic (autobiographical events) and semantic memories are processed in the same way, initially dependent on the hippocampal formation, but over time they become represented in the neocortex, independently of medial temporal structures. In contrast, multiple trace theory Moscovitch 1997, 2001;Nadel et al. 2000;Moscovitch et al. 2006) proposes a critical distinction between semantic and episodic memory. Retrieval of episodic (and spatial) memo...

The Fate of Old Memories after Medial Temporal Lobe Damage

“…In addition, remote autobiographical memory was substantially impaired in three other patients, who had damage to one or more cortical areas including the lateral temporal and frontal lobes (Bayley et al, 2005b). Others have also emphasized the importance of lateral temporal and frontal lobe pathology for understanding impaired remote autobiographical memory (Eslinger, 1998;Kapur, 1999;Kopelman et al, 1999;Bright et al, 2006). There is a need for thorough, quantitative anatomical information for all the patients being studied.…”

Detailed recollection of remote autobiographical memory after damage to the medial temporal lobe

“…Further, the available group studies, which come from three different laboratories (11,12,20), have found that remote autobiographical memory is intact when damage is limited to the medial temporal lobe and that impaired autobiographical memory is associated with lateral temporal or frontal lobe pathology.…”

“…One approach has been to use a simple, standardized test like the Autobiographical Memory Interview (9), which asks three questions about each of three different past time periods. Using this test, or a modified version of it, a number of studies have found remote memory to be intact after damage limited to the medial temporal lobe (7,(10)(11)(12)). Yet, a few single-case studies have found remote memory to be impaired (refs.…”

Dissociable Roles for Cortical and Subcortical Structures in Memory Retrieval and Acquisition

“…The effects of subcortical lesions were contrasted with those of selective cortical lesions, because widespread damage limited to cortex may cause relatively greater deficits in retention of preoperatively acquired information than new learning (Thornton et al, 1997;Bright et al, 2006;Browning and Gaffan, 2008). We considered the entorhinal cortex (ERh), because it is unambiguously part of the putative medial temporal lobe memory system (Squire and Zola-Morgan, 1991), yet its involvement in retention and new learning remains unclear, largely because studies in monkeys typically also damage the perirhinal cortex (Leonard et al, 1995;Meunier et al, 1996;Charles et al, 2004).…”