1/31. Auditory event-related potentials in an amnesic patient with a left temporal lobe lesion. We studied auditory event-related potentials (ERPs) in correlation with Rey's auditory verbal learning test (AVLT) in an amnesic patient with a left temporal lobe lesion. On the AVLT, the number of words recalled was limited to immediate memory capacity (nine words) throughout five trials, and recall after interference was remarkably decreased. In the ERPs, the P300 component was elicited normally, but no N400 component was apparent. Present findings suggest that these two ERP components may be associated with independent processes and support the view that the N400 may index a neural process involved in transfer of information from immediate memory to long-term storage. ( info) |
2/31. Autobiographical recollection and affects of cues in an amnesic patient. The individual described herein (Y.K.) is a pure amnesic patient with severe anterograde amnesia and a selective loss of specific personal episodes in his remote memories. In this study, we examined whether more concrete cues could elicit specificity in his autobiographical memory. It was found that the richness of his autobiographical memory under the condition with probes was significantly higher than condition without probes, although Y.K.'s performance on recalling autobiographical memory was inferior to that of control subjects under both conditions. These results and our previous findings indicate that neither the disorder at the level of the framework's thematic retrieval nor the destruction of individual traces will account for the loss of Y.K.'s autobiographical memory. We suspect that Y.K.'s loss of autobiographical memory may be due to problems in the interface between thematic retrieval frameworks and individual traces. ( info) |
| Background and Purpose-The fornix connects various structures involved in memory. We report a patient with anterograde amnesia after an acute ischemic infarct in the anterior fornix. Case Description-A 71-year-old female with acute-onset amnesia had neuroimaging studies showing ischemic infarction of both columns and the body of the fornix and the genu of the corpus callosum. Neuropsychological evaluation revealed anterograde amnesia without evidence of callosal disconnection. The patient showed marked improvement in her memory function on the follow-up visit. Conclusions-amnesia in this case is likely due to infarction of the anterior fornix structures. ( info) |
| Astrocytomas involving the limbic system are usually unilateral in nature. We report a very unusual case where a low-grade astrocytoma originating in the left temporal lobe spread to the right hippocampus through the hippocampal commissure to cause disabling amnesia and seizures. Some improvement in the memory deficit was facilitated by identification of complex partial status epilepticus. EEG should be performed in all patients with lesions of the limbic system and neuropsychological problems if ongoing seizure activity is not to be missed. ( info) |
5/31. Long-term retrograde amnesia...the crucial role of the hippocampus. For patients with hippocampal pathology, disagreement exists in the literature over whether retrograde amnesia is temporally limited or very extensive depending on whether the anatomical damage is restricted to this structure or also involves additional temporal cortex. We report a comprehensive assessment of retrograde and anterograde memory functions of a severely global amnesic patient (VC). We found that he presented with a remarkably extensive and basically ungraded retrograde amnesia. This impairment profoundly affected four decades preceding the onset of his amnesia and encompassed both non personal and personal facts and events. VC also presented with a severe anterograde amnesia and a deficit in the acquisition of new semantic knowledge in the post-morbid period. Detailed MRI volumetric measurements revealed gross abnormalities in both hippocampi which were markedly shrunken. Of relevance to the debate on retrograde amnesia were the observations that the volumes of both entorhinal cortices and the remainder of both temporal lobes were normal. These data suggest that the hippocampus is critical not only for the efficient encoding and hence normal recall of new information but also for the recall of episodic information acquired before the onset of amnesia. Our results are compatible with the view that retrograde amnesia is both extensive and ungraded when the damage is limited to the hippocampus. ( info) |
6/31. Focal autobiographical amnesia in association with transient epileptic amnesia. Although problems with remembering significant events from the past (e.g. holidays, weddings, etc.) have been reported previously in patients with transient epileptic amnesia (tea), to date there have been no detailed studies of autobiographical memory in patients with this disorder. To investigate this issue, a 68-year-old right-handed man (R.G.) who suffered from tea and reported significant autobiographical memory problems was tested on a battery of neuropsychological tests of anterograde and remote memory. Tests of autobiographical memory revealed that R.G. was unable to evoke detailed autobiographical recollections from a substantial part of his life. By contrast, he performed well on tests of new learning and general knowledge and possessed good personal semantic information about his past. In summary, a distinct form of autobiographical amnesia, which is characterized by loss of experiential remembering of significant events, may be associated with tea. It is proposed that the autobiographical memory deficit seen in the disorder may result from the progressive erasure of cortically based memory representations. This case adds to growing evidence for a dissociation between mechanisms subserving anterograde memory and those required to evoke remote episodic memories. ( info) |
7/31. Severe anterograde amnesia with extensive hippocampal degeneration in a case of rapidly progressive frontotemporal dementia. frontotemporal dementia (FTD) is usually characterized as a spectrum of relatively slowly progressive disorders with largely focal frontal or temporal presentations. The development of clinical and research criteria for discriminating FTD from Alzheimer's disease has relied, in part, on the relative preservation of episodic memory in FTD. We present a patient with FTD who, in addition to the more typical behavioural and language deficits, had a profound anterograde amnesia at the time of diagnosis. neuroimaging confirmed atrophy of frontal and temporal lobes bilaterally, most marked in the anterior left temporal region. At post-mortem, non-Alzheimer pathology resulting in devastating cell loss was revealed in the hippocampi, as well as in the frontal and temporal cortex, thus providing neuroanatomical corroboration of the episodic memory deficit. Progression of the disease was extraordinarily rapid, with just 2 years between reported onset and time of death. This case demonstrates that the pattern of FTD may include severe anterograde amnesia as a prominent and early consequence of the disease. ( info) |
8/31. Preserved recognition in a case of developmental amnesia: implications for the acquisition of semantic memory? We report the performance on recognition memory tests of Jon, who, despite amnesia from early childhood, has developed normal levels of performance on tests of intelligence, language, and general knowledge. Despite impaired recall, he performed within the normal range on each of six recognition tests, but he appears to lack the recollective phenomenological experience normally associated with episodic memory. His recall of previously unfamiliar newsreel events was impaired, but gained substantially from repetition over a 2-day period. Our results are consistent with the hypothesis that the recollective process of episodic memory is not necessary either for recognition or for the acquisition of semantic knowledge. ( info) |
9/31. Profound amnesia and confabulation following traumatic brain injury. amnesia and confabulation may persist following acute aneurysmal hemorrhage of the anterior communicating artery, chronic alcoholic Korsakoff's syndrome, and late-stage dementia of the Alzheimer type. However, there is a paucity of information regarding the persistence of these symptoms following traumatic brain injury. We present the case of JL, a 43-year-old male with persistent and severe anterograde amnesia for verbal and visual information with co-occurring provoked confabulation which persists well into the chronic phase of recovery after a severe traumatic brain injury. Neuropsychological testing at 7 weeks post-injury demonstrated severe anterograde amnesia with co-occurring confabulation. Follow-up testing at 9.5 months post-injury showed persistent and severe anterograde amnesia and provoked confabulation despite superior non-verbal intelligence and above average attentional and perceptual abilities. Late computed tomography showed chronic hypodense regions in the temporal lobes, bilaterally (L > R), and in the region of the left ventrolateral frontal lobe. This case demonstrates that anterograde amnesia and provoked confabulation may persist long after the acute phase of recovery after traumatic brain injury, and also supports previous research which asserts that medial temporal lobe damage must be accompanied by ventral frontal lobe pathology to produce the amnestic-confabulatory syndrome. ( info) |
10/31. Focal retrograde amnesia documented with matching anterograde and retrograde procedures. Focal retrograde amnesia is an unusual and theoretically challenging form of memory disorder. The case of a 65-year-old woman presenting with focal retrograde amnesia is reported. Following a cardiac arrest and subsequent hypoxia she remained in a coma for 24 h with evidence of epileptiform activity during the early recovery period. MR scans, 4 and 7 months post-onset, showed mild bifrontal atrophic changes mainly affecting white matter areas. An [18F]fluorodeoxyglucose resting PET scan 1-year post-onset demonstrated right occipito-temporo-parietal hypometabolism. We were able to document the patient's performance on an extensive range of anterograde and retrograde tests and to monitor her recovery of function by assessing her performance at 4, 12 and 24 months post-onset. Spared anterograde memory was observed on a range of verbal and non-verbal tests, including matched tasks that compared pre-illness and post-illness onset recollections. In contrast, her performance on retrograde memory tests, using detailed autobiographical and public events verbal and photographic tasks, showed a temporally-graded retrograde amnesia, more particularly affecting memory for autobiographical episodes. Possible mechanisms underlying CH's focal retrograde amnesia are discussed in terms of Damasio's time-locked multiregional retroactivation model. ( info) |