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Psychological Medicine Feb 2023Little is known about the neural correlates of dissociative amnesia, a transdiagnostic symptom mostly present in the dissociative disorders and core characteristic of...
BACKGROUND
Little is known about the neural correlates of dissociative amnesia, a transdiagnostic symptom mostly present in the dissociative disorders and core characteristic of dissociative identity disorder (DID). Given the vital role of the hippocampus in memory, a prime candidate for investigation is whether total and/or subfield hippocampal volume can serve as biological markers of dissociative amnesia.
METHODS
A total of 75 women, 32 with DID and 43 matched healthy controls (HC), underwent structural magnetic resonance imaging (MRI). Using Freesurfer (version 6.0), volumes were extracted for bilateral global hippocampus, cornu ammonis (CA) 1-4, the granule cell molecular layer of the dentate gyrus (GC-ML-DG), fimbria, hippocampal-amygdaloid transition area (HATA), parasubiculum, presubiculum and subiculum. Analyses of covariance showed volumetric differences between DID and HC. Partial correlations exhibited relationships between the three factors of the dissociative experience scale scores (dissociative amnesia, absorption, depersonalisation/derealisation) and traumatisation measures with hippocampal global and subfield volumes.
RESULTS
Hippocampal volumes were found to be smaller in DID as compared with HC in bilateral global hippocampus and bilateral CA1, right CA4, right GC-ML-DG, and left presubiculum. Dissociative amnesia was the only dissociative symptom that correlated uniquely and significantly with reduced bilateral hippocampal CA1 subfield volumes. Regarding traumatisation, only emotional neglect correlated negatively with bilateral global hippocampus, bilateral CA1, CA4 and GC-ML-DG, and right CA3.
CONCLUSION
We propose decreased CA1 volume as a biomarker for dissociative amnesia. We also propose that traumatisation, specifically emotional neglect, is interlinked with dissociative amnesia in having a detrimental effect on hippocampal volume.
Topics: Humans; Female; Dissociative Identity Disorder; Hippocampus; Magnetic Resonance Imaging; Amnesia; Biomarkers
PubMed: 34165068
DOI: 10.1017/S0033291721002154 -
Cortex; a Journal Devoted To the Study... Jun 1994This paper challenges the idea that memory is the special function of any single brain structure, an idea that developed from clinical cases of amnesia that had lesions... (Review)
Review
This paper challenges the idea that memory is the special function of any single brain structure, an idea that developed from clinical cases of amnesia that had lesions in and around the hippocampus. There are many instances of amnesia and other evidence of memory functions in brain areas that do not involve the hippocampus. The evidence that medial temporal lobe lesions in animals produce uncontaminated memory deficits is reviewed and rejected, as well as the evidence that the memory task used in these experiments has any special relationship to the hippocampus. It is proposed that memory is not the function of any one structure, but is a part of local neuronal operations carried out in all cortical areas where the information to be remembered is processed and perceived. If this suggestion is correct, then a local lesion will cause a loss of local function and the memory for that function.
Topics: Amnesia; Brain Damage, Chronic; Brain Mapping; Hippocampus; Humans; Mental Recall; Neural Pathways; Neurons; Temporal Lobe
PubMed: 7924350
DOI: 10.1016/s0010-9452(13)80198-0 -
Neuropsychologia Aug 2018During conversation, people integrate information from co-speech hand gestures with information in spoken language. For example, after hearing the sentence, "A piece of...
During conversation, people integrate information from co-speech hand gestures with information in spoken language. For example, after hearing the sentence, "A piece of the log flew up and hit Carl in the face" while viewing a gesture directed at the nose, people tend to later report that the log hit Carl in the nose (information only in gesture) rather than in the face (information in speech). The cognitive and neural mechanisms that support the integration of gesture with speech are unclear. One possibility is that the hippocampus - known for its role in relational memory and information integration - is necessary for integrating gesture and speech. To test this possibility, we examined how patients with hippocampal amnesia and healthy and brain-damaged comparison participants express information from gesture in a narrative retelling task. Participants watched videos of an experimenter telling narratives that included hand gestures that contained supplementary information. Participants were asked to retell the narratives and their spoken retellings were assessed for the presence of information from gesture. For features that had been accompanied by supplementary gesture, patients with amnesia retold fewer of these features overall and fewer retellings that matched the speech from the narrative. Yet their retellings included features that contained information that had been present uniquely in gesture in amounts that were not reliably different from comparison groups. Thus, a functioning hippocampus is not necessary for gesture-speech integration over short timescales. Providing unique information in gesture may enhance communication for individuals with declarative memory impairment, possibly via non-declarative memory mechanisms.
Topics: Acoustic Stimulation; Aged; Amnesia; Female; Gestures; Hippocampus; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Male; Middle Aged; Psychomotor Performance; Speech
PubMed: 29932960
DOI: 10.1016/j.neuropsychologia.2018.06.012 -
Intensive & Critical Care Nursing Aug 2017This review aims to use thematic analysis to explore and synthesise evidence of the actual or potential reported effects of diaries on the psychological rehabilitation... (Review)
Review
AIM
This review aims to use thematic analysis to explore and synthesise evidence of the actual or potential reported effects of diaries on the psychological rehabilitation and recovery of discharged critical care patients.
BACKGROUND
Evidence suggests that whilst admission to critical care may save patient lives, the psychological aftermath can damage a patient's recovery and these needs must be met. Patient diaries are one potential intervention to aid patients understand their critical illness and fill memory gaps caused by sedation, thus reducing psychological distress post-discharge. Prospective patient diaries are increasing in popularity amongst critical care units in the United Kingdom, however there is little evidence base to support their use or understand their effects.
METHOD
A literature review using systematic methods was undertaken of studies relating to the effects of diaries on discharged patients. Thematic analysis enabled the generation and synthesis of themes.
RESULTS
Three themes arose from the generated codes: 1) Reclaiming ownership of lost time. 2) Emphasising personhood. 3) Fear and frustration. The diary intervention was shown to have a largely positive impact on survivors' psychological rehabilitation. However, caution should be exercised as recipients could find the contents painful and emotional. Diaries should be embedded within a robust critical care follow-up plan.
CONCLUSION
This review suggests that diaries have the potential to form one aspect of rehabilitation and make a positive impact on patients' recovery. More research is indicated to fully evaluate the effects of diaries on their recipients.
Topics: Adult; Amnesia; Critical Illness; Family; Female; Humans; Intensive Care Units; Male; Medical Records; Survivors; United Kingdom
PubMed: 28363594
DOI: 10.1016/j.iccn.2017.03.002 -
Philosophical Transactions of the Royal... Sep 2001Memory is sometimes a troublemaker. Schacter has classified memory's transgressions into seven fundamental 'sins': transience, absent-mindedness, blocking,... (Review)
Review
Memory is sometimes a troublemaker. Schacter has classified memory's transgressions into seven fundamental 'sins': transience, absent-mindedness, blocking, misattribution, suggestibility, bias and persistence. This paper focuses on one memory sin, misattribution, that is implicated in false or illusory recognition of episodes that never occurred. We present data from cognitive, neuropsychological and neuroimaging studies that illuminate aspects of misattribution and false recognition. We first discuss cognitive research examining possible mechanisms of misattribution associated with false recognition. We also consider ways in which false recognition can be reduced or avoided, focusing in particular on the role of distinctive information. We next turn to neuropsychological research concerning patients with amnesia and Alzheimer's disease that reveals conditions under which such patients are less susceptible to false recognition than are healthy controls, thus providing clues about the brain mechanisms that drive false recognition. We then consider neuroimaging studies concerned with the neural correlates of true and false recognition, examining when the two forms of recognition can and cannot be distinguished on the basis of brain activity. Finally, we argue that even though misattribution and other memory sins are annoying and even dangerous, they can also be viewed as by-products of adaptive features of memory.
Topics: Amnesia; Brain; Humans; Memory; Repression, Psychology
PubMed: 11571030
DOI: 10.1098/rstb.2001.0938 -
The Western Journal of Medicine Feb 1990A wide variety of conditions seen in medical practice can produce memory impairment (amnesia). Normal aging, depression, and anxiety are commonly associated with memory... (Review)
Review
A wide variety of conditions seen in medical practice can produce memory impairment (amnesia). Normal aging, depression, and anxiety are commonly associated with memory difficulties, as are many neurologic conditions. Systemic illnesses can impair memory by injuring vulnerable limbic regions sensitive to hypoxia or hypoglycemia. Commonly used over-the-counter and prescription medications can likewise cause amnesia. These conditions disrupt memory in characteristic ways. Recent studies suggest that immediate, recent, and remote memory functions have different neuroanatomic substrates, as do the processes of registration, retention, and retrieval. New classifications have emerged to explain the evidence for multiple memory subsystems. The neuropharmacology of memory now includes several peptides in addition to cholinergic and noradrenergic pathways. Critical limbic regions have been discovered that mediate memory consolidation, and neuronal mechanisms such as long-term potentiation are being implicated in the unique capacity of these areas to permit new learning to take place.
Topics: Adrenocorticotropic Hormone; Age Factors; Amnesia; Brain Injuries; Epilepsy; Humans; Lorazepam; Multiple Sclerosis
PubMed: 2154898
DOI: No ID Found -
Journal of Neurology, Neurosurgery, and... Apr 1998To clarify the clinical and neuropsychological aspects of transient epileptic amnesia (TEA) based on 10 personally studied cases as well as review of 21 previously... (Review)
Review
OBJECTIVES
To clarify the clinical and neuropsychological aspects of transient epileptic amnesia (TEA) based on 10 personally studied cases as well as review of 21 previously published cases; and to propose tentative diagnostic criteria for the diagnosis of TEA.
METHODS
All 10 patients and informants underwent a standardised clinical interview. The radiological and neurophysiological (EEG) data were also reviewed in all cases. The diagnosis of transient epileptic amnesia was made on the basis of the following criteria: (1) there was a history of recurrent witnessed episodes of transient amnesia; (2) cognitive functions other than memory were judged to be intact during typical episodes by a reliable witness; (3) there was evidence for a diagnosis of epilepsy. This evidence was provided by either (a) wake or sleep EEG, or (b) the co-occurrence of other seizure types (if their roughly concurrent onset or close association with episodes of transient amnesia suggested a connection), or (c) a clear cut response to anticonvulsant therapy, or by a combination of these three factors. In addition all patients were administered a comprehensive neuropsychological test battery designed to assess verbal and non-verbal anterograde memory and retrograde memory for famous personalities and personal events. Their results were compared with those of 25 age and IQ matched normal controls.
RESULTS
TEA usually begins in later life, with a mean age of 65 years in this series. Episodes are typically brief, lasting less than one hour, and recurrent, with a mean frequency of three a year. Attacks on waking are characteristic. Repetitive questioning occurs commonly during attacks. The anterograde amnesia during episodes is, however, often incomplete so that patients may later be able to "remember not being able to remember". The extent of the retrograde amnesia during attacks varies from days to years. Most patients experience other seizure types compatible with an origin in the temporal lobes, but transient amnesia is the only manifestation of epilepsy in about one third of patients. Epileptiform abnormalities arising from the temporal lobes are most often detected on interictal sleep EEG. Despite normal performance on tests of anterograde memory, many patients complain of persistent interictal disturbance of autobiographical memory, involving a significant but variable loss of recall for salient personal episodes. The epochs affected may predate the onset of epilepsy by many years.
CONCLUSIONS
TEA is an identifiable syndrome and comprises episodic transient amnesia with an epileptic basis, without impairment of other aspects of cognitive function. Future studies should consider the question of whether TEA reflects ictal activity or a postictal state, and the mechanism of the persistent autobiographical amnesia. It is hypothesised that the latter may result in part from impairment of very long term memory consolidation as a result of epileptic activity in mesial temporal structures.
Topics: Aged; Aged, 80 and over; Amnesia; Anticonvulsants; Case-Control Studies; Electroencephalography; Epilepsy; Female; Humans; Male; Middle Aged; Neuropsychological Tests; Recurrence
PubMed: 9576532
DOI: 10.1136/jnnp.64.4.435 -
Revista de Neurologia Feb 2002The literature on clinical and physiophatologic characteristics of the spectrum of memory disorders in childhood is reviewed in this article.
OBJECTIVE
The literature on clinical and physiophatologic characteristics of the spectrum of memory disorders in childhood is reviewed in this article.
DEVELOPMENT
There are only a few detailed reports of permanent specific memory disorders in children. Early anoxo ischaemic bihippocampal injuries can cause a selective permanent impairment of episodic daily life memory with preservation of semantic learning and general intelligence; this dissociation has been related to partial hippocampal damage whilst the entorhinal, parahippocampal and prefrontal cortices, which are critical to systematized memorizing and work memory, keep normal. Biological psychiatry research has shown that early childhood amnesias after psychological maltreatment or abuse could be related to damage in neuronal systems which support memory, caused by glutamatergic cascade. Both severe bilateral hippocampal sclerosis (also mediated by toxic neurotransmitters) in early malignant epilepsies, and massive bilateral damage of mesial temporal lobes due to herpex virus encephalitis or Reye's syndrome, cause severe amnesic deficits, frequently accompanied by absence of any language development and autism with features of Klüver-Bucy syndrome. There are also on record some examples of Korsakoff's syndrome in children with midfossa tumors.
CONCLUSIONS
All types of classical amnesias described in adults have been observed in children. Developmental amnesias are probably more frequent than currently presumed. It must be paid special attention to selective autobiographical memory impairments in individuals who underwent a partial bihippocampal damage in perinatal or early postnatal periods; they are to be distinguished from, although it may coexist with, other clinical situations such as attention deficit disorder or semantic pragmatic disorder.
Topics: Adult; Amnesia; Brain; Child; Humans
PubMed: 12447800
DOI: No ID Found -
Hippocampus Nov 2014We often engage in counterfactual (CF) thinking, which involves reflecting on "what might have been." Creating alternative versions of reality seems to have parallels...
We often engage in counterfactual (CF) thinking, which involves reflecting on "what might have been." Creating alternative versions of reality seems to have parallels with recollecting the past and imagining the future in requiring the simulation of internally generated models of complex events. Given that episodic memory and imagining the future are impaired in patients with hippocampal damage and amnesia, we wondered whether successful CF thinking also depends upon the integrity of the hippocampus. Here using two nonepisodic CF thinking tasks, we found that patients with bilateral hippocampal damage and amnesia performed comparably with matched controls. They could deconstruct reality, add in and recombine elements, change relations between temporal sequences of events, enabling them to determine plausible alternatives of complex episodes. A difference between the patients and control participants was evident, however, in the patients' subtle avoidance of CF simulations that required the construction of an internal spatial representation. Overall, our findings suggest that mental simulation in the form of nonepisodic CF thinking does not seem to depend upon the hippocampus unless there is the added requirement for construction of a coherent spatial scene within which to play out scenarios.
Topics: Adult; Amnesia; Female; Hippocampus; Humans; Imagination; Male; Mental Recall; Middle Aged; Narration; Neuropsychological Tests; Thinking
PubMed: 24978690
DOI: 10.1002/hipo.22323 -
The Primary Care Companion For CNS... May 2023
Topics: Humans; Suicide, Attempted; Charcoal; Amnesia
PubMed: 37146431
DOI: 10.4088/PCC.22cr03386