-
Hippocampus Feb 2018Hippocampal involvement in learning and remembering relational information has an extensive history, often focusing specifically on spatial information. In humans,...
Hippocampal involvement in learning and remembering relational information has an extensive history, often focusing specifically on spatial information. In humans, spatial reconstruction (SR) paradigms are a powerful tool for evaluating an individuals' spatial-relational memory. In SR tasks, participants study locations of items in space and subsequently reconstruct the studied display after a short delay. Previous work has revealed that patients with hippocampal damage are impaired both in overall placement accuracy as well as on a specific measure of relational memory efficacy, "swaps" (i.e., when the relative location of two items is reversed). However, the necessity of the hippocampus for other types of spatial-relational information involved in reconstruction behaviors (e.g., where in the environment and relative to which other items an item was located) have not yet been investigated systematically. In this work, three patients with hippocampal damage and nine healthy matched comparison participants performed an SR task. An analysis framework was developed to independently assess three first-order types of relations: (1) memory for the binding of specific item identities to locations, (2) memory for arrangement of items in relation to each other or the environment bounds, regardless of memory for the item identity, and (3) higher-order, compound relational errors (i.e., errors involving multiple pieces of relational information). Reconstruction errors were evaluated to determine the degree to which patients and comparisons differed (or not) on each type of spatial-relational information. Data revealed that the primary group difference in performance was for identity-location information. However, when the locations of items were evaluated without regarding the identities, no group difference was found in the number of item placements to studied locations. The present work provides a principled approach to analysis of SR data and clarifies our understanding of the types of spatial relations impaired in hippocampal damaged.
Topics: Amnesia; Analysis of Variance; Brain Mapping; Female; Hippocampus; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Male; Middle Aged; Neuropsychological Tests
PubMed: 29232494
DOI: 10.1002/hipo.22819 -
Annual Review of Psychology 2016The lesion-deficit model dominates neuropsychology. This is unsurprising given powerful demonstrations that focal brain lesions can affect specific aspects of cognition.... (Review)
Review
The lesion-deficit model dominates neuropsychology. This is unsurprising given powerful demonstrations that focal brain lesions can affect specific aspects of cognition. Nowhere is this more evident than in patients with bilateral hippocampal damage. In the past 60 years, the amnesia and other impairments exhibited by these patients have helped to delineate the functions of the hippocampus and shape the field of memory. We do not question the value of this approach. However, less prominent are the cognitive processes that remain intact following hippocampal lesions. Here, we collate the piecemeal reports of preservation of function following focal bilateral hippocampal damage, highlighting a wealth of information often veiled by the field's focus on deficits. We consider how a systematic understanding of what is preserved as well as what is lost could add an important layer of precision to models of memory and the hippocampus.
Topics: Amnesia; Hippocampus; Humans
PubMed: 26361051
DOI: 10.1146/annurev-psych-122414-033739 -
Journal of the Neurological Sciences Sep 2021
Topics: Amnesia, Transient Global; COVID-19; Diagnosis, Differential; Hippocampus; Humans; SARS-CoV-2
PubMed: 34280604
DOI: 10.1016/j.jns.2021.117562 -
Anesthesiology Jun 2022
Topics: Amnesia; Conscious Sedation; Humans; Hypnosis; Hypnotics and Sedatives; Midazolam; Receptors, GABA; gamma-Aminobutyric Acid
PubMed: 35482970
DOI: 10.1097/ALN.0000000000004234 -
Scandinavian Journal of Pain Dec 2019As professional health care personnel we are well educated in anatomy, physiology, clinical medicine and so forth. Our patients present with various symptoms and signs... (Review)
Review
As professional health care personnel we are well educated in anatomy, physiology, clinical medicine and so forth. Our patients present with various symptoms and signs that we use this knowledge to diagnose and treat. But sometimes the patient case contradicts our knowledge. Since the patient is the terrain and our knowledge is the map, these patient cases are anomalies that give us the opportunity to update our maps. One such anomaly is how time restricted amnesia can improve or even eradicate an underlying chronic pain condition and eliminate the patient's dependence on daily opioid consumption. In this short communication I will use amnesia as a starting point to briefly review chronic pain from a learning and memory perspective. I will introduce, for many readers, new concepts like degeneracy and criticality, and together with more familiar concepts like habits and brain network activity, we will end with overarching principles for how chronic pain treatment in general can be crafted and individualized almost independently of the chronic pain condition at hand. This introductory article is followed by a review series that elaborates on the fundamental biological principles for chronic pain, treatment options, and testing the theory with real world data.
Topics: Amnesia; Analgesics, Opioid; Chronic Pain; Female; Humans; Learning; Neuronal Plasticity; Pain Management
PubMed: 31661437
DOI: 10.1515/sjpain-2019-0100 -
Neuroscience and Biobehavioral Reviews Feb 2021The medial diencephalon, in particular the mammillary bodies and anterior thalamic nuclei, has long been linked to memory and amnesia. The mammillary bodies provide a... (Review)
Review
The medial diencephalon, in particular the mammillary bodies and anterior thalamic nuclei, has long been linked to memory and amnesia. The mammillary bodies provide a dense input into the anterior thalamic nuclei, via the mammillothalamic tract. In both animal models, and in patients, lesions of the mammillary bodies, mammillothalamic tract and anterior thalamic nuclei all produce severe impairments in temporal and contextual memory, yet it is uncertain why these regions are critical. Mounting evidence from electrophysiological and neural imaging studies suggests that mammillothalamic projections exercise considerable distal influence over thalamo-cortical and hippocampo-cortical interactions. Here, we outline how damage to the mammillary body-anterior thalamic axis, in both patients and animal models, disrupts behavioural performance on tasks that relate to contextual ("where") and temporal ("when") processing. Focusing on the medial mammillary nuclei as a possible 'theta-generator' (through their interconnections with the ventral tegmental nucleus of Gudden) we discuss how the mammillary body-anterior thalamic pathway may contribute to the mechanisms via which the hippocampus and neocortex encode representations of experience.
Topics: Amnesia; Animals; Anterior Thalamic Nuclei; Humans; Mammillary Bodies; Memory; Neural Pathways
PubMed: 33309908
DOI: 10.1016/j.neubiorev.2020.11.031 -
Disease Models & Mechanisms May 2018Amnesia - the loss of memory function - is often the earliest and most persistent symptom of dementia. It occurs as a consequence of a variety of diseases and injuries....
Amnesia - the loss of memory function - is often the earliest and most persistent symptom of dementia. It occurs as a consequence of a variety of diseases and injuries. These include neurodegenerative, neurological or immune disorders, drug abuse, stroke or head injuries. It has both troubled and fascinated humanity. Philosophers, scientists, physicians and anatomists have all pursued an understanding of how we learn and memorise, and why we forget. In the last few years, the development of memory engram labelling technology has greatly impacted how we can experimentally study memory and its disorders in animals. Here, we present a concise discussion of what we have learned about amnesia through the manipulation of engrams, and how we may use this knowledge to inform novel treatments of amnesia.
Topics: Amnesia; Animals; Disease Models, Animal; Humans; Memory Disorders; Mental Recall
PubMed: 29784659
DOI: 10.1242/dmm.035055 -
Social Cognitive and Affective... Oct 2020Does the tendency to adjust appraisals of ourselves in the past and future in order to maintain a favourable view of ourselves in the present require episodic memory? A...
Does the tendency to adjust appraisals of ourselves in the past and future in order to maintain a favourable view of ourselves in the present require episodic memory? A developmental amnesic person with impaired episodic memory (HC) was compared with two groups of age-matched controls on tasks assessing the Big Five personality traits and social competence in relation to the past, present and future. Consistent with previous research, controls believed that their personality had changed more in the past 5 years than it will change in the next 5 years (i.e. the end-of-history illusion), and rated their present and future selves as more socially competent than their past selves (i.e. social improvement illusion), although this was moderated by self-esteem. Despite her lifelong episodic memory impairment, HC also showed these biases of temporal self-appraisal. Together, these findings do not support the theory that the temporal extension of the self-concept requires the ability to recollect richly detailed memories of the self in the past and future.
Topics: Adult; Amnesia; Female; Humans; Memory, Episodic; Mental Recall; Personality; Self Concept
PubMed: 32734306
DOI: 10.1093/scan/nsaa105 -
Psychonomic Bulletin & Review Apr 2023Re-exposure to elements of prior experiences can create opportunities for inducing amnesia for those events. The dominant theoretical framework posits that such... (Review)
Review
Re-exposure to elements of prior experiences can create opportunities for inducing amnesia for those events. The dominant theoretical framework posits that such re-exposure can result in memory destabilization, making the memory representation temporarily sensitive to disruption while it awaits reconsolidation. If true, such a mechanism that allows for memories to be permanently changed could have important implications for the treatment of several forms of psychopathology. However, there have been contradictory findings and elusive occurrences of replication failures within the "reconsolidation" field. Considering its potential relevance for clinical applications, the fact that this "hot" research area is being dominated by a single mechanistic theory, and the presence of unexplainable contradictory findings, we believe that it is both useful and timely to critically evaluate the reconsolidation framework. We discuss potential issues that may arise from how reconsolidation interference has typically been deducted from behavioral observations, and provide a principled assessment of reconsolidation theory that illustrates that the theory and its proposed boundary conditions are vaguely defined, which has made it close to impossible to refute reconsolidation theory. We advocate for caution, encouraging researchers not to blindly assume that a reconsolidation process must underlie their findings, and pointing out the risks of doing so. Finally, we suggest concrete theoretical and methodological advances that can promote a fruitful translation of reminder-dependent amnesia into clinical treatment.
Topics: Humans; Memory; Amnesia; Memory Consolidation
PubMed: 36085236
DOI: 10.3758/s13423-022-02173-2 -
Brain : a Journal of Neurology Sep 2017There are very few case series of patients with acute psychogenic memory loss (also known as dissociative/functional amnesia), and still fewer studies of outcome, or...
There are very few case series of patients with acute psychogenic memory loss (also known as dissociative/functional amnesia), and still fewer studies of outcome, or comparisons with neurological memory-disordered patients. Consequently, the literature on psychogenic amnesia is somewhat fragmented and offers little prognostic value for individual patients. In the present study, we reviewed the case records and neuropsychological findings in 53 psychogenic amnesia cases (ratio of 3:1, males:females), in comparison with 21 consecutively recruited neurological memory-disordered patients and 14 healthy control subjects. In particular, we examined the pattern of retrograde amnesia on an assessment of autobiographical memory (the Autobiographical Memory Interview). We found that our patients with psychogenic memory loss fell into four distinct groups, which we categorized as: (i) fugue state; (ii) fugue-to-focal retrograde amnesia; (iii) psychogenic focal retrograde amnesia following a minor neurological episode; and (iv) patients with gaps in their memories. While neurological cases were characterized by relevant neurological symptoms, a history of a past head injury was actually more common in our psychogenic cases (P = 0.012), perhaps reflecting a 'learning episode' predisposing to later psychological amnesia. As anticipated, loss of the sense of personal identity was confined to the psychogenic group. However, clinical depression, family/relationship problems, financial/employment problems, and failure to recognize the family were also statistically more common in that group. The pattern of autobiographical memory loss differed between the psychogenic groups: fugue cases showed a severe and uniform loss of memories for both facts and events across all time periods, whereas the two focal retrograde amnesia groups showed a 'reversed' temporal gradient with relative sparing of recent memories. After 3-6 months, the fugue patients had improved to normal scores for facts and near-normal scores for events. By contrast, the two focal retrograde amnesia groups showed less improvement and continued to show a reversed temporal gradient. In conclusion, the outcome in psychogenic amnesia, particularly those characterized by fugue, is better than generally supposed. Findings are interpreted in terms of Markowitsch's and Kopelman's models of psychogenic amnesia, and with respect to Anderson's neuroimaging findings in memory inhibition.
Topics: Adult; Aged; Amnesia; Amnesia, Retrograde; Craniocerebral Trauma; Depression; Family Conflict; Female; Humans; London; Male; Memory, Episodic; Middle Aged; Neuropsychological Tests; Self Concept; Young Adult
PubMed: 29050391
DOI: 10.1093/brain/awx186