1,721,078 research outputs found
The impact of lexical-semantic impairment and of executive dysfunction on the word reading performance of patients with probable Alzheimer dementia
No full textThe influence of lexical-semantic impairment and of executive dysfunction on word naming performance was investigated in a group of patients with probable Alzheimer dementia (AD). The patients, who varied in the severity of the illness, were tested in a word naming task where they had to read aloud Italian three-syllable words with a dominant or subordinate stress pattern. These types of words have been shown to interact with frequency in normal adults J. Exp. Psychol.: Hum. Percept. Perform. 18 (4) (1992) 987, so that the effect of the subordinate stress pattern (slower reading times) is only apparent for low frequency words. The frequency and stress effects on accuracy increased across dementia severity levels. Regression analyses showed that the impairment in reading low frequency words with subordinate stress depended largely on the level of lexical-semantic impairment, measured by a test of semantic memory and comprehension. Implications for the current reading models are discussed
Intramodal somaesthetic recognition disorders following right and left hemisphere damage
No full textA dissociation between apperceptive and associative processing after right and left hemisphere damage, respectively, has been suggested for visual, auditory and visuo-tactile matching tasks. This study was aimed at testing for this dissociation in a purely somaesthetic task. Forty consecutive patients with recent right and left hemispheric vascular lesions and 10 normal controls were studied. The groups were compared on two intramodal somaesthetic matching tasks, consisting of either meaningless shapes (apperceptive recognition) or meaningful objects (associative recognition). In normal controls, no significant difference was found either between the two tests, indicating a similar degree of difficulty, or between hands. An analysis of variance indicated a differential impairment of the two hemisphere-damaged groups on the two tests in comparison with normal controls. Right hemisphere lesions impaired the apperceptive, but not the associative, task, while the reverse occurred after left hemisphere lesions. This double dissociation between side of hemispheric lesion (right and left) and level of recognition impairment (apperceptive and associative) extends the results reported for other sensory modalities to intramodal tactile recognition matching. © 1995 Oxford University Press
Naming From Definition, Semantic Relevance and Feature Type: The Effects of Aging and Alzheimer's Disease
No full textSomesthetic-Visual Matching Disorders in Right and Left Hemisphere-Damaged Patients
No full textForty-nine patients with recent right (RHD) and left (LHD) hemispheric vascular lesions were compared on a task of somesthetic-visual matching of meaningful objects and of meaningless shapes. A selective impairment for shapes was found in RHD subjects, while LHD patients were impaired in object matching. This double dissociation conforms to the classical distinction between apperceptive and associative agnosia, and extends to the somesthetic modality the “double dissociation” between left and right hemispheric lesions and associative and apperceptive recognition disorders, which has been found in other modalities of agnosia. © 1991, Masson Italia Periodici s.r.l. Milano. All rights reserved
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
rTMS for PTSD: induced merciful oblivion or elimination of abnormal hypermnesia?
No full textNeuroimaging studies and experimental data suggest that symptoms of posttraumatic stress disorder (PTSD) are associated with dysfunctions of neural circuits linking prefrontal cortex and the limbic system that have a role in autobiographic episodic memory. High-frequency repetitive transcranial magnetic stimulation (rTMS) of the right dorsolateral prefrontal cortex (DLPFC) has been suggested to be beneficial to patients with PTSD, transiently alleviating re-experiencing as well as avoidance reactions and associated anxiety symptoms. In healthy humans, converging evidence suggests that rTMS of the right DLPFC interferes with episodic memory retrieval. Hence, we hypothesize that daily applications of rTMS in PTSD patients may reduce access to the set of autobiographical stored events, that, if re-experienced, may cause the overt PTSD symptoms
Brain functional correlates of episodic memory using an ecological free recall task
Full text linkEpisodic Memory (EM) allows us to revive a past event through mental time-travel. The neural correlates of memories recollection have been identified in hippocampal regions and multiple neocortical areas, but few neuroimaging studies have used an ecological task such as a free recall of a structured story. Using an ecological fMRI-free recall (FR) task, we aimed to investigate the relevant recruitment of the brain networks associated with the story recollection process and its performance. Fourteen healthy participants listened to a brief story and were tested for Immediate-Recall (IR), a task that is widely used in a neuropsychological evaluation. Then, the subjects under-went an fMRI session, where they had to perform a free recall (FR) of the story subvocally. Finally, the participants were tested for Delayed-Recall (DR). IR and DR scores were significantly (r = 0.942; p < 0.001) correlated. FR enhanced the activity of the Language, the Left Executive Control, the De-fault Mode and the Precuneus brain networks, with the strongest BOLD signal localized in the left Angular Gyrus (AG) (p < 0.05; FWE-corrected). Furthermore, the story recall performance covaried with specific network activation patterns and the recruitment of the left anterior/posterior AG cor-related, respectively, with higher/lower performance scores (p > 0.05). FR seems to be a promising task to investigate ecologically the neural correlates of EM. Moreover, the recruitment of the anterior AG might be a marker for an optimal functioning of the recall process. Preliminary outcomes lay the foundation for the investigation of the brain networks in the healthy and pathological elderly population during FR
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