1,721,028 research outputs found
The role of prefrontal cortex in sentence comprehension: a rTMS study
No full textUsing repetitive transcranial magnetic stimulation (rTMS), we investigated the role of the
left and right dorsolateral prefrontal cortex (DLPFC) in sentence comprehension. Subjects
were required to judge which of the two pictures correctly matched the meaning of active
and passive semantically reversible sentences (subject–verb–object); the incorrect picture
did not match the sentence in term of lexical items (semantic task) or agent–patient structure
(syntactic task). The subjects performed the task while a series of magnetic stimuli
were applied to the left or right DLPFC. When rTMS was applied to the left DLPFC, the subjects’
performance was delayed only for the semantic task, while rTMS applied to the right
DLPFC slowed the processing of syntactic information. The results of this experiment provide
direct evidence of a double dissociation between the rTMS effects and the type of task,
which may reflect a differential hemispheric involvement of working memory resources
during sentence comprehension
La memoria episodica nell’invecchiamento fisiologico uno studio con stimolazione magnetica transcranica ripetitiva (rTMS).
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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
EFNS guidelines on cognitive rehabilitation: report of an EFNS task force. Members of the Task Force on Cognition Rehabilitation
No full textDisorders of language, spatial perception, attention, memory, calculation and praxis are
a frequent consequence of acquired brain damage [in particular, stroke and traumatic
brain injury (TBI)] and a major determinant of disability. The rehabilitation of aphasia
and, more recently, of other cognitive disorders is an important area of neurological
rehabilitation. We report here a review of the available evidence about effectiveness of
cognitive rehabilitation. Given the limited number and generally low quality of randomized
clinical trials (RCTs) in this area of therapeutic intervention, the Task Force
considered, besides the available Cochrane reviews, evidence of lower classes which was
critically analysed until a consensus was reached. In particular, we considered evidence
from small group or single cases studies including an appropriate statistical evaluation of
effect sizes. The general conclusion is that there is evidence to award a grade A, B or C
recommendation to some forms of cognitive rehabilitation in patients with neuropsychological
deficits in the post-acute stage after a focal brain lesion (stroke, TBI). These
include aphasia therapy, rehabilitation of unilateral spatial neglect (ULN), attentional
training in the post-acute stage after TBI, the use of electronic memory aids in memory
disorders, and the treatment of apraxia with compensatory strategies. There is clearly a
need for adequately designed studies in this area, which should take into account specific
problems such as patient heterogeneity and treatment standardization
Serial study of neuropsychological performance and gadolinium-enhanced MRI in MS
No full textMany multiple sclerosis patients show cognitive decline, although no definite correlation between brain demyelination at MRI and neuropsychological performance has been found so far. We submitted a group of nine relapsing-remitting, mildly disabled patients to both serial gadolinium-DTPA enhanced MRI and neuropsychological evaluation in a follow up period of three months. Despite the great variability in acute lesions' load, no overall decline in test, performance was found. Furthermore, in selected cases whose test scores declined at follow up, no concordance with the new lesion load was found
Age-related functional changes of prefrontal cortex in long-term memory. A repetitive transcranial magnetic stimulation (rTMS) study.
No full textNeuroimaging findings suggest that the lateralization of prefrontal cortex activation associated with episodic memory performance is
reduced by aging. It is still a matter of debate whether this loss of asymmetry during encoding and retrieval reflects compensatory
mechanisms or de-differentiation processes. We addressed this issue by the transient interference produced by repetitive transcranial
magnetic stimulation (rTMS), which directly assesses causal relationships between performance and stimulated regions. We compared
the effects of rTMS (a rapid-rate train occurring simultaneously to the presentation of memoranda) applied to the left or right dorsolateral
prefrontal cortex (DLPFC) on visuospatial recognition memory in 66 healthy subjects divided in two classes of age (45 and50 years).
In young subjects, rTMS of the right DLPFC interfered with retrieval more than left DLPFC stimulation. The asymmetry of the effect
progressively vanished with aging, as indicated by bilateral interference effects on recognition performance. Conversely, the predominance
of left DLPFC effect during encoding was not abolished in elders, thus probing its causal role for encoding along the life span.
Findings confirm that the neural correlates of retrieval modify along aging, suggesting that the bilateral engagement of the DLPFC has a
compensatory role on the elders’ episodic memory performance
Hemispheric asymmetries during episodic memory. An rTMS study along physiological ageing
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