Narinder Kapur

SenseCam: a retrospective memory aid

This paper presents a novel ubiquitous computing device, the SenseCam, a sensor augmented wearable stills camera. SenseCam is designed to capture a digital record of the wearers day, by recording a series of images and capturing a log of sensor data. We believe that reviewing this information will help the wearer recollect aspects of earlier experiences that have subsequently been forgotten, and thereby form a powerful retrospective memory aid. In this paper we review existing work on memory aids and conclude that there is scope for an improved device. We then report on the design of SenseCam in some detail for the first time. We explain the details of a first in-depth user study of this device, a 12-month clinical trial with a patient suffering from amnesia. The results of this initial evaluation are extremely promising; periodic review of images of events recorded by SenseCam results in significant recall of those events by the patient, which was previously impossible. We end the paper with a discussion of future work, including the application of SenseCam to a wider audience, such as those with neurodegenerative conditions such as Alzheimers disease.

Perceptual deficits in amnesia: challenging the medial temporal lobe 'mnemonic' view

Recent animal studies suggest that the medial temporal lobe (MTL), which is thought to subserve memory exclusively, may support non-mnemonic perceptual processes, with the hippocampus and perirhinal cortex contributing to spatial and object perception, respectively. There is, however, no support for this view in humans, with human MTL lesions causing prominent memory deficits in the context of apparently normal perception. We assessed visual discrimination in amnesic cases to reveal that while selective hippocampal damaged patients could discriminate faces, objects, abstract art and colour, they were significantly poorer in discriminating spatial scenes. By contrast, patients with MTL damage, including perirhinal cortex, were significantly impaired in discriminating scenes, faces, and to a lesser extent objects, with relatively intact discrimination of art and colour. These novel observations imply that the human MTL subserves both perceptual and mnemonic functions, with the hippocampus and perirhinal cortex playing distinct roles in spatial and object discrimination, respectively.

Herpes simplex encephalitis: long term magnetic resonance imaging and neuropsychological profile.

The first comprehensive in vivo documentation of the long term profile of pathological and spared tissue is described in a group of 10 patients with a diagnosis of herpes simplex encephalitis, who were left with memory difficulties as a major residual sequel of their condition. With a dedicated MRI protocol, which included high resolution images of temporal lobe and limbic system areas, data are provided on structures that have recently gained importance as anatomical substrates for amnesia. The major features of the lesion profile were: (1) unilateral or bilateral hippocampal damage never occurred in isolation, and was often accompanied by damage to the parahippocampus, the amygdala, specific temporal lobe gyri, and the temporal poles; (2) the insula was always abnormal; (3) neocortical temporal lobe damage was usually unilateral or asymmetric. It never occurred in isolation, and was invariably associated with more medial pathological changes; (4) anterior and inferior temporal lobe gyri were damaged more often and more severely than posterior and superior temporal lobe gyri; (5) pronounced abnormality was often present in the substantia innominata (region of the basal forebrain/anterior perforated substance); (6) there was evidence of significant abnormality in the fornix; (7) there was evidence of damage to the mammillary bodies; (8) thalamic nuclei were affected in around 50% of cases, with damage usually unilateral; (9) frontal lobe damage was present in a few patients, and affected medial areas more than dorsolateral areas; (10) there was some involvement of the striatum, although this was usually unilateral and mild; (11) there was usually limited involvement of the cingulate gyrus and of the parietal and occipital lobes; (12) the cerebellum and brain stem were never damaged. Lesion covariance analysis indicated a close relation between the presence of abnormalities in temporal lobe and limbic-diencephalic regions. Unlike severe head injury, lesions in the temporal pole were not associated with the presence of lesions in the orbitofrontal cortex. Long term neuropsychological impairments were characterised by a dense amnesia in 60% of cases, and a less serve but noticeable anterograde memory impairment in the others. Naming and problem solving deficits were found in a small number of cases. Only two patients were able to return to open employment. Severity of amnesia showed a significant relation with severity of damage to medical limbic system structures such as the hippocampus, with bilateral damage being particularly important. By contrast, there was a minimal relation between memory loss and severity of damage to the thalamus, to lateral temporal lobe areas, or to the frontal lobes.

The syndrome of transient epileptic amnesia

Transient amnesia can be the principal manifestation of epilepsy. This diagnosis, however, is seldom suspected by clinicians and remains controversial. The amnestic attacks are often associated with persistent memory complaints. This study was designed to provide the first description of transient epileptic amnesia in a substantial series of patients.

The use of a wearable camera, SenseCam, as a pictorial diary to improve autobiographical memory in a patient with limbic encephalitis: A preliminary report

This case study describes the use of a wearable camera, SenseCam, which automatically captures several hundred images per day, to aid autobiographical memory in a patient, Mrs B, with severe memory impairment following limbic encephalitis. By using SenseCam to record personally experienced events we intended that SenseCam pictures would form a pictorial diary to cue and consolidate autobiographical memories. After wearing SenseCam, Mrs B plugged the camera into a PC which uploaded the recorded images and allowed them to be viewed at speed, like watching a movie. In the control condition, a written diary was used to record and remind her of autobiographical events. After viewing SenseCam images, Mrs B was able to recall approximately 80% of recent, personally experienced events. Retention of events was maintained in the long-term, 11 months afterwards, and without viewing SenseCam images for three months. After using the written diary, Mrs B was able to remember around 49% of an event; after one month with no diary readings she had no recall of the same events. We suggest that factors relating to rehearsal/re-consolidation may have enabled SenseCam images to improve Mrs Bs autobiographical recollection.

Focal Retrograde Amnesia in Neurological Disease: A Critical Review

The condition of focal retrograde amnesia represents a new and challenging concept to our understanding of human memory disorders. Cases of both permanent and transient focal retrograde amnesia, dating from early clinical descriptions to more recent experimental reports, are critically reviewed. It is concluded that the condition of focal retrograde amnesia does represent a distinct and reliable neurological entity. Four sets of issues are discussed--methodological issues, conceptual issues, anatomical issues and therapeutic issues. Current evidence indicates an important role for temporal lobe structures in mediating focal retrograde amnesia. Both storage and retrieval deficits may contribute to the presence of focal retrograde amnesia, though available evidence points to a greater role for engram destruction/fragmentation rather than disruption of access mechanisms. In general, pharmacological and other therapies have had minimal effects in alleviating focal retrograde amnesia.

Focal Retrograde Amnesia: A Long Term Clinical and Neuropsychological Follow-Up

A patient (E.D.) who had displayed a selective retrograde amnesia in association with transient amnesic episodes (Kapur et al., 1986) was reexamined five years after initial assessment. At the clinical level, his transient amnesic attacks continued, but some of these had clear epileptic features. In addition, EEG investigation indicated temporal lobe abnormality, more prominent in the left temporal region, and supported a clinical diagnosis of temporal lobe epilepsy. Both CT scanning and magnetic resonance imaging were unable to detect the presence of any structural lesion. At the neuropsychological level, there was no evidence of dementia in the form of generalized cognitive dysfunction nor significant deterioration in cognitive functioning since the earlier assessment. Our patient continued to show marked memory loss for public events over the past 20-30 years, in the context of normal or near normal performance on most tests of anterograde memory functioning. While memory for famous scenes and famous faces was markedly impaired, our patients memory for famous cars was within normal limits and his memory for autobiographical events showed only patchy impairment. Although E.D. performed at an average or above average level on most standard tests of anterograde memory functioning, our patient did show evidence of significant memory loss for public events which had occurred over the past ten years (i.e. since the onset of his illness). The possibility is raised that E.D.s memory disorder may represent a form of disconnection syndrome.

Dissociating person-specific from general semantic knowledge: roles of the left and right temporal lobes

The cognitive architecture and neural underpinnings of different semantic domains remains highly controversial. We report two patients with focal temporal lobe atrophy who presented with contrasting and theoretically informative dissociations of person-specific versus general semantic knowledge. Subject J.P. showed severely impaired person-specific semantics, with relative preservation of knowledge about objects and animals, while subject M.A. exhibited the opposite pattern of performance (good knowledge of people in the context of impoverished general semantics). Voxel-based morphometric analysis of MR images in the two cases established predominantly right temporal atrophy associated with J.P.s deficit for person knowledge and predominantly left temporal atrophy in M.A. who was impaired in general conceptual knowledge.

Temporally-specific retrograde amnesia in two cases of discrete bilateral hippocampal pathology.

The role of the hippocampus in retrograde amnesia remains controversial and poorly understood. Two cases are reported of discrete bilateral hippocampal damage, one of which was a rare case of limbic encephalitis secondary to the human herpes virus 6. Detailed memory testing showed marked anterograde memory impairment, but only mild, temporally‐limited retrograde amnesia that covered a period of several years in both autobiographical and factual knowledge domains. The absence of extensive retrograde amnesia in these two cases points to a time‐limited role for the hippocampus in the retrieval of retrograde memories, and suggests that entorhinal, perirhinal, parahippocampal, or neocortical areas of the temporal lobe may be more critical than the hippocampus proper for long‐term retrograde memory functioning. Our findings offer general support to theories of memory consolidation that propose a gradual transfer of memory from hippocampal to neocortical dependency. Hippocampus 1999; 9:247–254.

Intact memory for irrelevant information impairs perception in amnesia

Summary Memory and perception have long been considered separate cognitive processes, and amnesia resulting from medial temporal lobe (MTL) damage is thought to reflect damage to a dedicated memory system. Recent work has questioned these views, suggesting that amnesia can result from impoverished perceptual representations in the MTL, causing an increased susceptibility to interference. Using a perceptual matching task for which fMRI implicated a specific MTL structure, the perirhinal cortex, we show that amnesics with MTL damage including the perirhinal cortex, but not those with damage limited to the hippocampus, were vulnerable to object-based perceptual interference. Importantly, when we controlled such interference, their performance recovered to normal levels. These findings challenge prevailing conceptions of amnesia, suggesting that effects of damage to specific MTL regions are better understood not in terms of damage to a dedicated declarative memory system, but in terms of impoverished representations of the stimuli those regions maintain.