Postencephalitic focal retrograde amnesia after bilateral anterior temporal lobe damage.

BACKGROUND: Marked retrograde amnesia with no or almost no anterograde amnesia is rare. Recently, a combination of ventrolateral prefrontal and temporopolar cortical lesions has been suggested as the cause of such isolated or focal retrograde amnesia. It is also assumed that when the right-sided cortical structures are damaged, autobiographical episodic memories are affected. OBJECTIVE: To search for new anatomic substrates for focal retrograde amnesia. METHODS: We performed extensive neuropsychological tests and obtained detailed neuroimages on a 43-year-old woman who showed a severe, persistent retrograde amnesia but only a limited anterograde amnesia after probable herpes simplex encephalitis. RESULTS: Tests of autobiographical memory revealed that she had a memory loss extending back to her childhood for both semantics and incidents; however, the ability to recall specific episodes appeared much more severely impaired than the ability to recall factual information about her past. The patient also showed profound impairments in recalling public memories; however, her scores improved nearly to a control level on forced-choice recognition memory tasks, although the recall of memories for a decade just before her illness remained mildly impaired. MRI revealed focal pathologies in the temporal poles and the anterior parts of the inferotemporal lobes on both sides, predominantly on the left, with some extension to the anterior parts of the medial temporal lobes. There was additional damage to the left insular cortex and its surrounding structures but no evidence of frontal lobe damage on MRIs or cognitive tests. CONCLUSIONS: A profound retrograde amnesia may be produced by damage to the bilateral temporal poles and anterior inferotemporal lobes in the absence of frontal lobe pathologies, and a dense and persistent episodic old memory loss can arise even with a relatively small lesion in the right anterior temporal lobe if it is combined with extensive damage to the left.     

The influence of seizure frequency on anterograde and remote memory in mesial temporal lobe epilepsy

PurposeSeizure frequency, although considered as an important factor in memory impairment in mesial temporal epilepsy (mTLE), is mostly confounded with other clinical variables, making it unclear to what extent recurrent seizures actually interfere with memory. The present study focuses on the influence of seizure frequency, studied as a main variable, on anterograde and remote memory.MethodsSeventy-one patients with unilateral mTLE were divided into two subgroups, as a function of their seizure frequency (monthly versus weekly seizures). Other seizure-related variables were controlled, namely, lateralisation and type of lesion, age at onset, years of ongoing seizures, etiologic factors, and number of AED. A comprehensive neuropsychological examination, including anterograde memory (verbal and non verbal recognition memory and free recall) tasks together with a large range of tests exploring different domains of remote memory, was carried out.ResultsDespite similar results on IQ, executive functions and attention, the low seizure-frequency group performed significantly better than the high seizure-frequency group on anterograde memory tests. Loss of autobiographical episodes and public-events memory, concomitant with spared personal semantic knowledge, was observed in both patient groups compared with healthy subjects. A worsening effect of high seizure frequency was recorded for autobiographical incidents and news-events memory, but unexpectedly, not for memory for famous people.ConclusionThe study of seizure frequency as the main variable leads us to suggest that high seizure frequency, itself, potentiates the effects of mesial temporal lobe damage on episodic memory deficits.     

Semantic memory functioning and the left temporal lobe

Abstract

The authors report further investigations of patient HA who suffered a head injury in a road traffic accident at the age of 21, which resulted in her left temporal and parietal lobe being largely replaced by cerebrospinal fluid. Despite this devastating lateralized brain damage acquired in adulthood, she presented with relatively normal neurological and neuropsychological functioning, including preservation of verbal memory. Further analysis of her brain structure revealed a preserved strip of inferior and medial left temporal cortex. The focus of the present investigation was to carry out additional studies of HA's semantic memory functioning. Naming, category fluency, visual attribute, superordinate and subordinate knowledge were assessed, as well as both abstract and concrete comprehension, autobiographical memory and knowledge of semantic property information. The results indicate that HA demonstrated relatively normal semantic memory functioning for a woman of her age. It is proposed that the preserved strip of inferotemporal cortex may account for this normative performance, providing further support for the theoretical importance of this region in relation to semantic memory functioning.     

Remote episodic memory deficits in patients with unilateral temporal lobe epilepsy and excisions.

The nature of remote memory impairment in patients with medial temporal lobe damage is the subject of some debate. While some investigators have found that retrograde amnesia in such patients is temporally graded, with relative sparing of remote memories (Squire and Alvarez, 1995), others contend that impairment is of very long duration and that remote memories are not necessarily spared (Sanders and Warrington, 1971; Nadel and Moscovitch, 1997). In this study, remote memory was assessed in 25 patients with unilateral temporal lobe epilepsy and 22 non-neurologically impaired controls using the Autobiographical Memory Interview (Kopelman et al., 1989). Results indicate that patients have impaired personal episodic memory but intact personal semantic memory. The impairment extends even to the most remote time periods in early childhood, long before seizure onset in many patients. As well, patients awaiting temporal lobectomy for control of seizures perform as poorly as those who have already undergone resective surgery. These results support the hypothesis that temporal lobe damage or dysfunction, caused by recurrent seizures or surgical excision, results in extensive retrograde amnesia for personal episodic memories. Interestingly, patients with radiological evidence of hippocampal sclerosis were not significantly more impaired than those without obvious sclerosis. These results indicate that even minimal damage to medial temporal lobes results in significant impairment to autobiographical episodic memory. These findings are more compatible with a memory loss or retrieval deficit rather than a consolidation account of remote memory impairment.     

Semantic knowledge in patient H.M. and other patients with bilateral medial and lateral temporal lobe lesions

We investigated the effects of damage to the medial temporal lobe (MTL) and anterolateral temporal cortex on semantic knowledge. We studied eight male controls, two patients with lesions limited to the hippocampal formation, three postencephalitic patients with extensive MTL lesions and variable damage to the lateral temporal cortex, and patient H.M. (whose lesion is limited mostly to the MTL, but who also has minimal damage to the anterolateral cortex). On 13 tests of semantic memory, patients with lesions limited to the hippocampal formation performed similarly to controls. Postencephalitic patients were mildly to moderately impaired on most tests. Patient H.M.'s performance was impaired on only a few tests and was less severely impaired overall than the three postencephalitic patients. A ranking of test scores showed a direct relationship between impairment and the extent of damage to lateral temporal cortex. These findings, and related findings from other studies, point to the importance of anterolateral temporal cortex for semantic knowledge. Patient H.M. performed uniquely in certain respects. For example, when providing definitions of objects, he made many grammatical errors. In contrast, the other patients with large MTL lesions made no more errors than those made by controls. Considering that H.M.'s lesion, both medially and laterally, is less extensive than the lesions in these other patients, it appears unlikely that his shortcomings in language production are related to his temporal lobe lesion.     

Damage to the default mode network disrupts autobiographical memory retrieval

Functional neuroimaging studies have implicated the default mode network (DMN) in autobiographical memory (AM). Convergent evidence from a lesion approach would help clarify the role of the DMN in AM. In this study, we used a voxelwise lesion-deficit approach to test the hypothesis that regions of the DMN are necessary for AM. We also explored whether the neural correlates of semantic AM (SAM) and episodic AM (EAM) were overlapping or distinct. Using the Iowa Autobiographical Memory Questionnaire, we tested AM retrieval in 92 patients with focal, stable brain lesions. In support of our hypothesis, damage to regions within the DMN (medial prefrontal cortex, mPFC; posterior cingulate cortex, PCC; inferior parietal lobule, IPL; medial temporal lobe, MTL) was associated with AM impairments. Within areas of effective lesion coverage, the neural correlates of SAM and EAM were largely distinct, with limited areas of overlap in right IPL. Whereas SAM deficits were associated with left mPFC and MTL damage, EAM deficits were associated with right mPFC and MTL damage. These results provide novel neuropsychological evidence for the necessary role of parts of the DMN in AM. More broadly, the findings shed new light on how the DMN participates in self-referential processing.     

Impairment of episodic and semantic autobiographical memory in patients with mild cognitive impairment and early Alzheimer's disease

Autobiographical memory includes the retrieval of personal semantic data and the remembrance of incident or episodic memories. In retrograde amnesias, it has been observed that recall of autobiographical memories of recent events is poorer than recall of remote memories. Alzheimer's disease (AD) may also be associated with a temporal gradient (TG) in memory decline, though studies have yielded inconsistent results on this point. They have also yielded inconsistent results on whether AD might differentially affect semantic and episodic remembrance. Here, we compared autobiographical memory of childhood, early adulthood, and recent life among healthy control (HC) subjects, patients with early AD, and patients with amnesic mild cognitive impairment (aMCI). Both the aMCI and AD patients exhibited declines in recall of autobiographical incidents and semantic information. In AD patients, both components of autobiographical memory had a clear TG, with better preservation of memories of childhood than those of early adulthood and recent life. The TG of autobiographical memory decline in AD patients is more compatible with the Cortical Reallocation Theory than with the Multiple Trace Theory of memory consolidation. In contrast to AD patients, aMCI patients exhibited impaired recall of personal facts and autobiographical incidents relating only to recent life. The significant decline in autobiographical memory for recent life that occurred in aMCI patients suggests that deterioration of consolidation of personal facts and events begins with commencement of functional impairment in the hippocampus.     

Anomia in patients with left inferior temporal lobe lesions

Background: Damage to left inferior temporal cortex has been associated with naming deficits resulting either from impaired access to phonological word forms (pure anomia) or from degraded semantic knowledge (semantic anomia). Neuropsychological evidence indicates that pure anomia may follow damage to posterior inferior temporal cortex (BA 37), whereas semantic anomia is associated with damage to more anterior temporal lobe regions (BA 20, 21, 38). By contrast, some investigators have suggested that it is the overall severity of anomia, rather than the nature of the underlying cognitive impairment, that is affected by the anterior extent of the lesion. Aims: To examine the naming performance of patients with left inferior temporal lobe damage and determine whether anterior extension of the lesion influences the nature and/or the severity of the naming impairment. Methods & Procedures: Eight participants with focal damage to left inferior temporal cortex completed a battery of language measures that included confrontation naming, semantic processing, and single‐word reading and spelling. Degree and type of anomia was examined relative to anterior lesion extension using both visual inspection and statistical analyses. Outcomes & Results: Naming performance ranged from unimpaired to severely defective, with only two participants demonstrating an additional mild impairment of semantic knowledge. The underlying mechanism of anomia seemed to be degraded access to phonological word forms in all participants, regardless of lesion configuration. The severity of the naming impairment was positively correlated with anterior extension of the lesion towards the temporal pole, although additional analyses suggested that these findings were significantly influenced by participant age. Naming was not correlated with performance on the nonverbal semantic task or any other demographic variable. Conclusions: The behavioural and neuroanatomical findings provide modest support for the hypothesis that a relationship exists between anterior lesion extension and the severity of concomitant anomia in patients with left inferior temporal lobe damage. The data suggest that such lesions may disconnect relatively preserved semantic knowledge from regions critical for access to phonological word forms. However, additional research is needed to discern to what extent age and individual variability temper these effects.     

Autobiographical memory and executive function in early dementia of Alzheimer type

We studied executive function and autobiographical memory in a cohort of 33 DAT patients [divided into minimal (MMSE 24–30) and mild (MMSE 17–23) groups] and in 30 normal controls. Autobiographical memory, as assessed by autobiographical fluency and the Autobiographical Memory Interview (AMI), was impaired in DAT patients, even those with minimal disease. There was evidence of a gentle temporal gradient on the incident but not the personal semantic component of the AMI, suggesting that the two components are dissociable. Executive function was assessed by two separate dual performance tasks and letter fluency. Although there was a trend for minimal DAT patients to be impaired on executive tasks, this only reached significance for the mild group. Regression analysis suggested that the divided attention component of working memory was involved in the retrieval of personal semantic autobiographical memory, but verbal fluency was more important in the retrieval of autobiographical incidents. There was thus a dissociation in the type of executive function implicated in different subcomponents of autobiographical memory, arguing for subcomponents within executive function and autobiographical memory. The autobiographical memory deficit in DAT reflects, we argue, both impairment in retrieval processes, linked to executive function, and a loss of memory stores.     

The effect of impaired verbal memory retrieval on autobiographical memory across different life periods in schizophrenia

ObjectivesAutobiographical memory (AM) involves recollection of personal events and facts about one's life. Αim of the present study was to investigate AM in schizophrenia patients, and, in particular, patients' ability to recall autobiographical memories after controlling for verbal memory and verbal fluency deficits.MethodParticipants included 40 schizophrenia patients (23 male) and 40 healthy controls (23 male), matched for age, gender, educational level, and premorbid intellectual functioning. Participants' verbal memory (list learning and story recall) and verbal fluency were assessed. AM was evaluated by the Questionnaire of Autobiographical Memory, consisting of the Personal Semantic Memory scale and the Autobiographical Incidents scale. Furthermore, personal incidents' specificity was examined.ResultsSchizophrenia patients showed deficits in verbal memory and verbal fluency, as well as in both semantic and episodic AM compared with healthy controls. Deficits were shown in episodic and semantic memories of events and facts dating to three different life periods (childhood, early adulthood and recent life). Regarding specificity of recalled events, patients reported fewer specific autobiographical incidents than controls. After controlling AM deficits for patients' verbal memory and verbal fluency impairment, it was shown that schizophrenia patients recalled fewer memories of autobiographical incidents dating only to recent life, compared with healthy controls.ConclusionsSchizophrenia patients showed impaired AM after controlling for verbal memory and verbal fluency impairment only in regard with personal episodic memories from recent life. Current findings raise the important issue of cognitive remediation therapy in schizophrenia.     

Patterns of autobiographical memory loss in dementia

BACKGROUND: Several studies have found impaired recall of remote autobiographical memories relative to recent memories in semantic dementia (SD), a pattern opposite to that in Alzheimer's disease (AD). OBJECTIVE: To document dissociation of memory for autobiographical incidents and personal semantic information in individuals with AD, frontotemporal dementia (FTD), and SD. METHODS: The authors administered the Autobiographical Memory Interview to eight individuals with AD, 11 with FTD, eight with SD, and eight normal controls . Autobiographical incidents and personal semantic memory was assessed from three time periods: childhood, early adulthood, and recent life. RESULTS: Individuals with SD recalled more details of autobiographical incidents from the most recent 5 years than from childhood and early adulthood (childhood vs recent life: t(7) = -3.59, p = 0.009; early adulthood vs recent life: t(7) = -4.33, p = 0.003). No difference was found between childhood and early adulthood (t(7) = 1.11, p = 0.305). Recall of personal semantic information was related to the age of the memory with less remembered from earlier time periods (childhood vs recent life: t(7) = -6.52, p < 0.001; childhood vs early adulthood: t(7) = -2.61, p = 0.035; early adulthood vs recent life: t(7) = -9.15, p < 0.001). CONCLUSIONS: SD is a compelling model in which to study the anatomy of episodic memory.     

Retrograde amnesia in patients with diencephalic, temporal lobe or frontal lesions.

Patients with focal diencephalic, temporal lobe, or frontal lobe lesions were examined on various measures of remote memory. Korsakoff patients showed a severe impairment with a characteristic 'temporal gradient', whereas two patients with focal diencephalic damage (and anterograde amnesia) were virtually unimpaired on remote memory measures. Patients with frontal lobe pathology were severely impaired in the recall of autobiographical incidents and famous news events. Patients with temporal lobe pathology showed severe impairment but a relatively 'flat' temporal gradient, largely attributable to herpes encephalitis patients. From recognition and cued recall tasks, it is argued that there is an important retrieval component to the remote memory deficit across all the lesion groups. In general, the pattern of performance by the frontal lobe and temporal lobe groups was closely similar, and there was no evidence of any major access/storage difference between them. However, laterality comparisons across these groups indicated that the right temporal and frontal lobe regions may make a greater contribution to the retrieval of past episodic (incident and event) memories, whereas the left temporal region is more closely involved in the lexical-semantic labelling of remote memories.     

Differential neural activity during search of specific and general autobiographical memories elicited by musical cues

Previous neuroimaging studies that have examined autobiographical memory specificity have utilized retrieval cues associated with prior searches of the event, potentially changing the retrieval processes being investigated. In the current study, musical cues were used to naturally elicit memories from multiple levels of specificity (i.e., lifetime period, general event, and event-specific). Sixteen young adults participated in a neuroimaging study in which they retrieved autobiographical memories associated with musical cues. These musical cues led to the retrieval of highly emotional memories that had low levels of prior retrieval. Retrieval of all autobiographical memory levels was associated with activity in regions in the autobiographical memory network, specifically the ventromedial prefrontal cortex, posterior cingulate, and right medial temporal lobe. Owing to the use of music, memories from varying levels of specificity were retrieved, allowing for comparison of event memory and abstract personal knowledge, as well as comparison of specific and general event memory. Dorsolateral and dorsomedial prefrontal regions were engaged during event retrieval relative to personal knowledge retrieval, and retrieval of specific event memories was associated with increased activity in the bilateral medial temporal lobe and dorsomedial prefrontal cortex relative to retrieval of general event memories. These results suggest that the initial search processes for memories of different specificity levels preferentially engage different components of the autobiographical memory network. The potential underlying causes of these neural differences are discussed.     

Severe amnesia following a unilateral temporal lobe stroke.

A 60 year old right-handed man developed severe amnesia following a left medial temporal stroke as documented by cerebral MRI, MRA and SPECT scans. Neuropsychological evaluation 13 weeks after the stroke showed a profound retrograde amnesia characterised by memory loss for public facts and events over the previous four decades. In addition, autobiographical memory showed selective loss of personal episodic memory with relative preservation of personal semantic memory. The development of this degree of amnesia with these features following a unilateral temporal lobe lesion is unusual. The possible neuroanatomical mechanisms underlying the amnesia and how they relate to current theories of memory loss are discussed.     

Retrograde amnesia after traumatic injury of the fronto-temporal cortex.

An industrial manager had severe retrograde and variable but usually mild anterograde amnesia four years after a head injury. MRI showed damage of both temporal poles and the lateral portion of the right prefrontal cortex. The prefrontal and temporal cortical damage on the right side extended deeply into the white matter while the temporal cortical damage on the left side was much smaller. There was an additional left temporo-parietal lesion. The patient was of average intelligence. His attention, short term memory and learning ability were average or somewhat below average. His old memories were severely affected for the personal-episodic domain and less so for semantic remote memory abilities. Therefore an anatomical dissociation between anterograde and retrograde amnesia is possible at the anterior temporal regions, possibly interacting with the prefrontal cortex; these regions seem necessary for the retrieval of old episodic memories.     

Retrieval of autobiographical memory in Alzheimer's disease: relation to volumes of medial temporal lobe and other structures

The representation of autobiographical memory is distributed over a network of brain structures, with the medial temporal lobe (MTL) at its epicenter. Some believe that, over time, all memories become independent of their MTL component ("consolidation theories"). Others have suggested that this is true only of semantic memory, while episodic aspects of autobiographical memories are dependent on the MTL for as long as they exist, such as multiple trace theory (MTT). In the present study, the volumes of 28 brain regions, including the MTL, and their relation to autobiographical memory were investigated in a group of patients with Alzheimer's disease with varying degrees of retrograde memory loss as assessed by the Autobiographical Memory Interview (AMI). We used the multivariate analysis method of partial least squares (PLS) to assess patterns of atrophy that can lead to retrograde amnesia. We found that different aspects of autobiographical memory were associated with different patterns of tissue loss. Personal semantics were related to a pattern of bilateral anterior and posterior lateral temporal cortex degeneration, more pronounced on the left, as well as right frontal degeneration. Autobiographical event memory ("episodic") was associated with combined atrophy in bilateral MTL and anterior lateral temporal neocortex, more pronounced on the right. This pattern was invariant for memories from childhood, early adulthood, and recent memories, in line with the predictions of MTT, suggesting that MTL tissue is crucial for retrieval of episodic memories regardless of their age.     

Lexical retrieval and semantic knowledge in patients with left inferior temporal lobe lesions

Background: It has been proposed that anomia following left inferior temporal lobe lesions may have two different underlying mechanisms with distinct neural substrates. Specifically, naming impairment following damage to more posterior regions (BA 37) has been considered to result from a disconnection between preserved semantic knowledge and phonological word forms (pure anomia), whereas anomia following damage to anterior temporal regions (BAs 38, 20/21) has been attributed to the degradation of semantic representations (semantic anomia). However, the integrity of semantic knowledge in patients with pure anomia has not been demonstrated convincingly, nor were lesions in these cases necessarily confined to BA 37. Furthermore, evidence of semantic anomia often comes from individuals with bilateral temporal lobe damage, so it is unclear whether unilateral temporal lobe lesions are sufficient to produce significant semantic impairment.

Aims: The main goals of this study were to determine whether anomia following unilateral left inferior temporal lobe damage reflected a loss of semantic knowledge or a post‐semantic deficit in lexical retrieval and to identify the neuroanatomical correlates of the naming impairment.

Methods & Procedures: Eight individuals who underwent left anterior temporal lobectomy (L ATL) and eight individuals who sustained left posterior cerebral artery strokes (L PCA) completed a battery of language measures that assessed lexical retrieval and semantic processing, and 16 age‐ and education‐matched controls also completed this battery. High‐resolution structural brain scans were collected to conduct lesion analyses.

Outcomes & Results: Performance of L ATL and L PCA patients was strikingly similar, with both groups demonstrating naming performance ranging from moderately impaired to unimpaired. Anomia in both groups occurred in the context of mild deficits to semantic knowledge, which manifested primarily as greater difficulty in naming living things than nonliving things and greater difficulty in processing visual/perceptual as opposed to functional/associative semantic attributes. Lesion analyses indicated that both patient groups sustained damage to anterior inferior temporal lobe regions implicated in semantic processing.

Conclusions: These results contribute to a better understanding of the cognitive mechanism of naming impairment in patients with temporal lobe damage and support the notion that pure anomia and semantic anomia represent two endpoints along a continuum of semantic impairment. Unilateral left temporal lobe lesions in our patients resulted in relatively mild semantic deficits that were apparent primarily in lexical production tasks, whereas severe semantic impairment likely requires bilateral temporal lobe damage.     

Damage to the lateral prefrontal cortex impairs familiarity but not recollection

Frontal lobe lesions impair recognition memory but it is unclear whether the deficits arise from impaired recollection, impaired familiarity, or both. In the current study, recognition memory for verbal materials was examined in patients with damage to the left or right lateral prefrontal cortex. Words were incidentally encoded under semantic or phonological orienting conditions, and recognition memory was tested using a 6-point confidence procedure. Receiver operating characteristics (ROCs) were examined in order to measure the contributions of recollection and familiarity to recognition memory. In both encoding conditions, lateral prefrontal cortex damage led to a deficit in familiarity but not recollection. Similar deficits were observed in left and right hemisphere patients. The results indicate that the lateral prefrontal cortex plays a critical role in the monitoring or decision processes required for accurate familiarity-based recognition responses.     

Co-activation of the amygdala, hippocampus and inferior frontal gyrus during autobiographical memory retrieval

Functional MRI was used to investigate the role of medial temporal lobe and inferior frontal lobe regions in autobiographical recall. Prior to scanning, participants generated cue words for 50 autobiographical memories and rated their phenomenological properties using our autobiographical memory questionnaire (AMQ). During scanning, the cue words were presented and participants pressed a button when they retrieved the associated memory. The autobiographical retrieval task was interleaved in an event-related design with a semantic retrieval task (category generation). Region-of-interest analyses showed greater activation of the amygdala, hippocampus, and right inferior frontal gyrus during autobiographical retrieval relative to semantic retrieval. In addition, the left inferior frontal gyrus showed a more prolonged duration of activation in the semantic retrieval condition. A targeted correlational analysis revealed pronounced functional connectivity among the amygdala, hippocampus, and right inferior frontal gyrus during autobiographical retrieval but not during semantic retrieval. These results support theories of autobiographical memory that hypothesize co-activation of frontotemporal areas during recollection of episodes from the personal past.     

Personal semantic and episodic autobiographical memories in Korsakoff syndrome: A comparison of interview methods

Objective: The temporal gradient in patients with Korsakoff’s syndrome has been of particular interest in the literature, as many studies have found evidence for a steep temporal gradient, but others have observed more uniform remote memory impairment across all past time periods. Inconsistencies might be the result of the nature of remote memory impairment under study (i.e., nonpersonal or autobiographical memory) and of methodological differences in the examination of remote memory loss. The aim of this study was to examine whether differences between autobiographical memory interview (AMI) and autobiographical interview (AI) procedures influence the presence of a temporal gradient in semantic and episodic autobiographical memory in Korsakoff patients. Method: The procedure used in the present study combined the AMI and AI into one study session. We compared the performance of 20 patients with Korsakoff’s syndrome and 27 healthy controls. First, participants were asked to recall knowledge from different life periods. Second, participants were asked to recall memories from five life periods. Thirdly, participants were asked to rate their subjective experience of each event recalled on a 5-point scale. Finally, we analyzed the findings in terms of all the memories recalled versus the first memory from each life-period only. Results: Both the AMI and the AI showed a temporally graded retrograde amnesia in the Korsakoff patients for personal semantic and episodic autobiographical memories. The pattern of amnesia in Korsakoff patients was not affected by examining only one event per life-period. Subjective ratings of recalled memories were largely comparable between the groups. Conclusions: The findings were generally consistent across the AMI and AI. Varying the number of events did not affect the pattern of the gradient. Hence, the temporal gradient in Korsakoff patients is not an artefact of either the AMI or the AI method.