Search results for "Memory disorder"
showing 10 items of 98 documents
Recollection and familiarity in dense hippocampal amnesia: A case study
2004
In the amnesia literature, disagreement exists over whether anterograde amnesia involves recollective-based recognition processes and/or familiarity-based ones depending on whether the anatomical damage is restricted to the hippocampus or also involves adjacent areas, particularly the entorhinal and perirhinal cortices. So far, few patients with well documented anatomical lesions and detailed assessment of recollective and recognition performance have been described. We report a comprehensive neuroanatomical assessment and detailed investigation of the anterograde memory functions of a previously described severe amnesic patient (VC). The results of four previously published neuroradiologic…
Fractionation of memory in medial temporal lobe amnesia
2006
We report a comprehensive investigation of the anterograde memory functions of two patients with memory impairments (RH and JC). RH had neuroradiological evidence of apparently selective right-sided hippocampal damage and an intact cognitive profile apart from selective memory impairments. JC, had neuroradiological evidence of bilateral hippocampal damage following anoxia due to cardiac arrest. He had anomic and "executive" difficulties in addition to a global amnesia, suggesting atrophy extending beyond hippocampal regions. Their performance is compared with that of a previously reported hippocampal amnesic patient who showed preserved recollection and familiarity for faces in the context …
Cannabinoid modulation of hippocampal long-term memory is mediated by mTOR signaling.
2009
Cognitive impairment is one of the most important negative consequences associated with cannabis consumption. We found that CB1 cannabinoid receptor (CB1R) activation transiently modulated the mammalian target of rapamycin (mTOR)/p70S6K pathway and the protein synthesis machinery in the mouse hippocampus, which correlated with the amnesic properties of delta9-tetrahydrocannabinol (THC). In addition, non-amnesic doses of either the mTOR blocker rapamycin or the protein synthesis inhibitor anisomycin abrogated the amnesic-like effects of THC, pointing to a mechanism involving new protein synthesis. Moreover, using pharmacological and genetic tools, we found that THC long-term memory deficits …
The visual orientation memory of Drosophila requires Foraging (PKG) upstream of Ignorant (RSK2) in ring neurons of the central complex
2012
Orientation and navigation in a complex environment requires path planning and recall to exert goal-driven behavior. Walking Drosophila flies possess a visual orientation memory for attractive targets which is localized in the central complex of the adult brain. Here we show that this type of working memory requires the cGMP-dependent protein kinase encoded by the foraging gene in just one type of ellipsoid-body ring neurons. Moreover, genetic and epistatic interaction studies provide evidence that Foraging functions upstream of the Ignorant Ribosomal-S6 Kinase 2, thus revealing a novel neuronal signaling pathway necessary for this type of memory in Drosophila.
Increased hippocampal head diffusivity predicts impaired episodic memory performance in early Alzheimer's disease
2010
Recent neuroanatomical and functional neuroimaging studies indicate that the anterior part of the hippocampus, rather than the whole structure, may be specifically involved in episodic memory. In the present work, we examined whether anterior structural measurements are superior to other regional or global measurements in mapping functionally relevant degenerative alterations of the hippocampus in Alzheimer's disease (AD). Twenty patients with early AD (MMSE 25.7+/-1.7) and 18 healthy controls were studied using magnetic resonance and diffusion-tensor imaging. Using a regions-of-interest analysis, we obtained volumetric and diffusivity measures of the hippocampal head and body-tail-section …
Amygdala-hippocampal atrophy and memory performance in dementia of Alzheimer type.
1997
The aim of the present study was to examine the involvement of brain structures, especially the amygdala-hippocampal complex, in dementia of Alzheimer type (DAT), and to assess the relation of amygdala-hippocampal atrophy with memory dysfunction. 14 patients with DAT and 10 healthy age-matched controls were examined with different neuropsychologic tests including the UCLA-Auditory Verbal Learning Test. MRI was performed with a conventional 1.5-tesla scanner. Atrophy was found in many brain structures of demented subjects in comparison with healthy age-matched controls. The volumes of amygdala-hippocampal complexes and of the temporal lobes of demented subjects were more reduced than the tot…
In the here and now: Short term memory predictions are preserved in Alzheimer's disease
2019
According to neuropsychological models of anosognosia, there is a failure to transfer on-line awareness of dysfunction into a more generalised long term belief about memory function in Alzheimer's disease. This failure results in specific metamemory deficits for global predictions: patients overestimate their performance before the task but are able to monitor their memory performance after having experienced the task. However, after a delay, they are still not able to make accurate predictions. As previous work has mainly focused on long-term memory, the present study investigates this issue in short-term and working memory. Using both global and item-by-item metacognitive judgements in a …
Disordered recognition memory: recollective confabulation.
2013
Recollective confabulation (RC) is encountered as a conviction that a present moment is a repetition of one experienced previously, combined with the retrieval of confabulated specifics to support that assertion. It is often described as persistent deja vu by family members and caregivers. On formal testing, patients with RC tend to produce a very high level of false positive errors. In this paper, a new case series of 11 people with dementia or mild cognitive impairment (MCI) and with deja vu-like experiences is presented. In two experiments the nature of the recognition memory deficit is explored. The results from these two experiments suggest - contrary to our hypothesis in earlier publi…
History repeating itself: Arnaud's case of pathological déjà vu.
2017
International audience; We present a translation of Arnaud's (1896) case report of Patient Louis, a case he describes as having a pathological form of déjà vu. Louis has the delusional belief that the present moment is a repetition of an exact same previous event. Arnaud's paper is critical for two reasons. Firstly, it is amongst the first articles in the scientific literature to describe the déjà vu experience using the term 'déjà vu'. Secondly, the case report of someone with delusional and persistent déjà vu, anticipates recently reported cases with similar symptoms, which are beginning to gain interest as a particular form of memory disorder. We offer a contemporary analysis of Louis an…
Spontaneous confabulation, temporal context confusion and reality monitoring: a study of three patients with anterior communicating artery aneurysms.
2010
AbstractSpontaneous confabulation involves the production of false or distorted memories, and is commonly associated with ventromedial prefrontal damage. One influential theory proposes that the critical deficit is a failure to suppress currently irrelevant memory traces that intrude into ongoing thinking (Schnider & Ptak, 1999). In this study, we report experimental investigations with three spontaneously confabulating patients aimed at exploring this account. Using Schnider and Ptak’s (1999) continuous recognition paradigm, we replicated their experimental results with our patients. However, our data suggest that the critical impairment might be more generalized than a failure to supp…