296 research outputs found
[Cerebrospinal fluid levels of HVA and 5-HIAA in epileptic patients: effect of total sleep deprivation]
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Meeting an “impossible challenge” in semantic dementia: outstanding performance in numerical Sudoku and quantitative number knowledge.
No full textThis study describes a follow-up investigation of numerical abilities and visuospatial memory
in a patient suffering from semantic dementia whose progressive decline of semantic memory variably
affected different types of knowledge. Crucially, we investigated in detail her outstanding performance
with Sudoku that has been only anecdotally reported in the previous literature. Method: We tested spatial
cognition and memory, body representation, number processing, calculation, and Sudoku tasks, and we
compared the patient’s performance with that of matched controls. Results: In agreement with the
neuroanatomical data, showing substantial sparing of the parietal lobes in the face of severe atrophy of
the temporal (and frontal) regions, we report full preservation of skills known to be supported by intact
parietal-basal ganglia networks, and impaired knowledge related to long-term stored declarative information
mediated by temporal regions. Performance in tasks sensitive to parietal dysfunction (such as
right–left orientation, finger gnosis, writing, and visuospatial memory) was normal; within the numerical
domain, preserved quantity-based number knowledge dissociated from increasing difficulties with
nonquantitative number knowledge (such as knowledge of encyclopedic and personal number facts) and
arithmetic facts knowledge. Conclusions: This case confirms the relation between numbers and space,
and, although indirectly, their anatomical correlates, underlining which abilities are preserved in the case
of severe semantic loss. In addition, although Sudoku is not inherently numerical, the patient was able
to solve even the most difficult pattern, provided that it required digits and not letters, showing that digits
have, in any case, a specific status
Left but not right temporal involvement in opaque idiom comprehension: a repetitive transcranial magnetic stimulation study
No full textIt has been suggested that figurative language, which includes idioms, is controlled by the right hemisphere. We tested the right hemisphere hypothesis by using repetitive transcranial magnetic stimulation (rTMS) to transiently disrupt the function of the frontal and temporal areas of the right versus left hemisphere in a group of normal participants involved in a task of opaque idiom versus literal sentence comprehension. Forty opaque, nonambiguous idioms were selected. Fifteen young healthy participants underwent rTMS in two sessions. The experiment was run in five blocks, corresponding to the four stimulated scalp positions ( left frontal and temporal and right frontal and temporal) and a baseline. Each block consisted of 16 trials-8 trials with idioms and 8 trials with literal sentences. In each trial, the subject was presented with a written sentence, which appeared on the screen for 2000 msec, followed by a pair of pictures for 2500 msec, one of which corresponded to the sentence. The alternative corresponded to the literal meaning for idioms and to a sentence differing in a detail in the case of literal sentences. The subject had to press a button corresponding to the picture matching the string. Reaction times increased following left temporal rTMS, whereas they were unaffected by right hemisphere rTMS, with no difference between idiomatic and literal sentences. Left temporal rTMS also reduced accuracy without differences between the two types of sentences. These data suggest that opaque idiom and literal sentence comprehension depends on the left temporal cortex
Second-order Raman scattering from linear carbon chains inside multiwalled carbon nanotubes
No full textThe present investigation concerns multiwalled carbon nanotubes synthesized on graphite cathodes by arc discharge in a He atmosphere, either with the insertion of a catalytic Ni-Cr mixture or without catalysts. The morphology of the deposited cathodes was investigated by SEM, while the amount of carbon chains inside multiwalled carbon nanotubes (C@MWCNT) in various regions of the deposited cathodes was revealed by a parallel micro-Raman study, through the analysis of the signal from the Raman bands generated by C@MWCNT in the range 1780-1870 cm(-1) (L bands). In samples obtained by using the catalyst, a very high concentration of linear carbon chains is found in some zones, as indicated by the intensity of the L band, which turns out remarkably stronger than the G band of the host nanotubes. In these zones, the second-order Raman scattering is clearly observed, too. The experimental wavenumber values of the 2 L overtone are slightly lower than the exact doubling of the one-phonon peak wavenumber, and this fact is discussed in terms of the existing theoretical predictions for the chain-mode dispersion curve
Observation of carbidic and graphitic carbon formation from CO in the 10-6 Torr range on Ru(101)
No full textObservation of carbidic and graphitic carbon formation from CO in the 10-5 Torr range on Ru(101)
No full textHomovanillic acid and 5-hydroxyindoleacetic acid in lumbar cerebrospinal fluid of patients with acute cerebrovascular lesion.
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