1,721,241 research outputs found
Perceptual and conceptual priming in amnesic and alcoholic patients
No full textThis study investigated the contribution of perceptual and conceptual processes to the repetition priming effect, and evaluated alternative theoretical positions about repetition priming in amnesic patients. Toward this end, we administered three repetition priming tasks (Stem Completion, Word Identification and Free Association) and an explicit memory task (yes/no Recognition) to amnesic and alcoholic patients, and tested the sensitivity of these tasks to level of processing and to manipulations of presentation modality. Experiment 1 demonstrated that the level of priming in Stem Completion and Free Association (but not in Word Identification) was enhanced by semantic elaboration of the stimuli. Experiment 2 revealed that the magnitude of priming in Word Identification and Stem Completion (but not in Free Association) was larger in the intramodal then in the intermodal condition. Amnesic patients displayed normal perceptual as well conceptual priming. Possible interpretations of these results according to theoretical models that distinguish memory tasks along an explicit-implicit dichotomy (multiple memory system theory), or on the basis of the extent to which they depend upon perceptual or conceptual processing (transfer-appropriate procedures approach), or that assumes a possible contamination of priming performance by explicit strategies of retrieval are discussed
Memory disorders in patients with cerebral tumors
No full textIn patients with cerebral tumors, deficits in declarative episodic memory typically result from damage to structures of the Papez circuit. These deficits can arise directly from the action of the tumor mass or indirectly from the surgical intervention. Memory deficits are also frequently seen in patients who show no direct involvement of the Papez circuit. In these patients, the memory impairment probably results from disruption of frontal lobe functioning (caused by localization of the tumor at this level or disconnection from subcortical afferents). Here, I review the neuropsychological tools used to differentiate amnesic syndromes resulting from lack of consolidation of new memory traces (as a consequence of damage to the Papez circuit) from amnesias resulting from reduced efficiency of elaborative encoding and/or strategic retrieval processes (as a consequence of frontal lobe damage). The clinical and rehabilitative implications of this distinction are briefly discussed
Short-term memory deficits are not uniform in Down and Williams syndromes
No full textNeuropsychological investigation of the development of the mnesic function in mental retardation has primarily focused on evaluating short-term memory (STM). Studies have often documented a reduced verbal short-term memory span in individuals with mental retardation and with Down syndrome in particular, compared to groups of mental age-matched controls. However, recent evidence suggests that verbal short-term memory is not equally impaired in all individuals with mental retardation. Findings in children with Williams syndrome are particularly relevant in this regard. Also, data concerning STM for visual information suggest that visual-object and visual-spatial working memory may be differently compromised in people with mental retardation. In particular, individuals with Williams syndrome exhibit specific difficulties in visual-spatial but not in visual-object working memory tasks compared to typically-developing children matched for mental age. Instead, people with Down syndrome show reduced performance in both visual-spatial and visual-object tests. Taken together, these results reinforce the view that intellectual disability is not a unitary condition characterized by homogeneous slowness of cognitive development but a variety of conditions in which some cognitive functions may be more disrupted than others. The finding that the working memory deficit in individuals with Williams and Down syndrome may be qualitatively differentiated also supports the hypothesis that it is not simply a manifestation of general cognitive impairment but, rather, the expression of a specific deficit of a discrete cognitive ability
Components in the visual processing of known and unknown faces
No full textThis study investigated the neural basis and cognitive mechanisms of disorders affecting the visual processing of human faces. Two patients affected by prosopagnosia (PA), 45 unilateral brain-damaged patients not previously selected for gnosic disturbance, and 52 normal subjects were administered three tasks involving visual matching of unfamiliar faces, identification of famous faces, and age attribution to unknown faces. Results confirmed that the right hemisphere (and particularly the posterior region) is critical for all of the main aspects of facial processing. Neuroradiological and PET examination in both PA patients revealed a lesion in the territory of the right posterior cerebral artery (infero-mesial areas of temporal and occipital lobes). Moreover, group comparisons showed that patients affected by a right posterior lesion obtained the worst scores on all tasks of our battery. Both group comparisons and single-case analyses pointed out that a deficient recognition of familiar faces is generally independent of perceptual disorders and, as such, should be considered mnestic in nature. Disorders in the age attribution, on the contrary, appear to be strictly associated with deficits in the perceptual analysis of unfamiliar faces
Evidence-based practice recommendations for memory rehabilitation.
Full text linkMemory impairment is a common consequence of neurological injury or disease, causing significant disability in everyday life, and is therefore a critical target for rehabilitation intervention. Here we report a review of the available evidence on the efficacy of restitution-oriented therapies and compensatory approaches for memory rehabilitation. A total of 110 studies was systematically classified and analyzed in order to generate evidence-based clinical recommendations for treatment providers. Different key aspects, such as types of brain damage, treatments characteristics and outcome measurements guided the evaluation of the literature as to appraise the potential interaction between patients characteristics, interventions and outcomes. The general conclusion is that memory re-training programs and compensatory approaches are probably effective in ameliorating memory disorders in patients with focal brain lesions, with some evidences of changes in memory functioning extending beyond the trained skills. Externally directed assistive devices and specific learning strategies are effective (with a level D and B of evidence, respectively) in retaining information relevant for daily needs also in patients with degenerative diseases. Some methodological concerns, such as the heterogeneity of subjects, interventions and outcomes studied, may limit the generalization of the present recommendations
Prospective memory functioning in individuals with Parkinson's disease: a systematic review
No full textObjective: There is growing interest in investigating prospective memory (PM) functioning in individuals with Parkinson’s disease (PD) without dementia because evidence suggests that PM may be impaired in this clinical population. This paper reviews current literature on PM functioning in PD patients with the aim of discussing i) the potential contribution of executive and episodic memory disorders to PM impairments, ii) whether PM impairment is an independent disorder in PD or whether it is a sign of mild cognitive impairment (MCI) and iii) the efficacy of cognitive interventions in treating PM disorders in these patients. Method: A search of the relevant literature revealed 21 original research papers and five review/meta-analyses that directly investigated PM abilities in PD samples. Results: Analysis of the reported data revealed that both executive functions and episodic memory are involved in the PM performance of patients with PD. Moreover, sparse evidence suggests that PM is not impaired in all PD patients but, rather, that PM deficits may be specifically associated with MCI. Finally, preliminary findings suggest that cognitive interventions may be effective in improving PM functioning in PD patients with MCI who present a well-established neuropsychological profile. Conclusions: Although some shortcomings of the PM literature on PD patients prevent drawing firm conclusions, this review of current evidence highlights the importance of including PM assessment in the standard neuropsychological evaluation of patients with PD. Moreover, there are indications that ad-hoc cognitive programs applied according to the qualitative cognitive profile of patients could improve their PM abilities
Memory deficits in Alzheimer's patients: a comprehensive review
No full textDespite considerable experimental work on Alzheimer's disease (AD), the underlying cognitive mechanisms as well as the precise localization of neuropathological changes critical for memory loss remains undefined. A review of the neuropsychological literature on long-term memory deficits in AD patients suggests that AD patients display (a) a pervasive deficit of explicit memory, (b) a partial deficiency of implicit memory for verbal and visuoperceptual material (as measured by repetition priming procedures), and (c) a substantial sparing of implicit memory for visuomotor skills. The explicit memory loss is likely a result of encoding as well as consolidation difficulties. A faulty lexical-semantic knowledge structure appears responsible for deficient repetition priming effects. Since neuropathological changes diffusely affect the brain of AD patients, establishing a clear relationship between localization of cerebral lesions and memory deficits is particularly difficult. Nevertheless, data suggest that extensive involvement of the hippocampal-amygdala complex plays a major role in explicit memory loss. Damage to associative cortical areas likely is involved in repetition priming deficits. The relative integrity of primary motor and sensory cortical areas and of the basal ganglia likely subsume, by contrast, the normal learning of visuomotor skills
The contribution of neuropsychological and neuroimaging research to the definition of the neurocognitive correlates of apathy
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Implicit memory is independent from IQ and age but not from etiology: evidence from Down and Williams syndromes
No full textIn the last few years, experimental data have been reported on differences in implicit memory processes of genetically distinct groups of individuals with Intellectual Disability (ID). These evidences are relevant for the more general debate on supposed asynchrony of cognitive maturation in children with abnormal brain development. This study, comparing implicit memory processes in individuals with Williams syndrome (WS) and Down syndrome (DS), was planned to verify the 'etiological specificity' hypotheses pertaining to the skill learning abilities of individuals with ID
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