摘要:

FREQUENCY-FOLLOWING responses (FFRs) were elicited by English long vowels (female /a/ and male /e/) in a dichotic listening task. Stimuli were simultaneous and of equal duration, but differing spectra permitted unique identification of vowel components in the compound FFR. Horizontal and vertical montage FFRs were recorded with putative origins in the acoustic nerve and central brain stem, respectively. FFRs obtained during attention to each vowel showed significant effects for the voice fundamental frequency, f0, which is perceptually salient and conveys paralinguistic information such as the sex of the speaker. Amplitudes of f0were larger when vowels were attended than when ignored. These findings provide evidence of short-latency attention effects in humans and suggest that linguistic attention may initially filter inputs based on salient paralinguistic cues.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

WE examined regional cerebral blood flow (rCBF) during a long-term recognition memory task for words in schizophrenic patients and in healthy subjects using positron emission tomography (PET). The task was designed so that performance scores were similar in the patient and control subjects. This memory retrieval task did not increase rCBF in the patients' prefrontal cortex, precuneus and cerebellum as much as it did in the control group. These results point to a dysfunctional corticocerebellar circuit leading to poorly coordinated mental activity (‘cognitive dysmetria’), which could explain the broad range of schizophrenic symptoms. In addition, other brain areas were more activated by the task in the patient group than in the control group and may form a compensatory network performing the memory retrieval task by assisting or replacing the dysfunctional cortico-cerebellar circuit.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

USING ‘jet lag’ paradigms involving phase shifts in the light-dark (LD) cycle, we studied the effects of S-20098 on the circadian clock of a diurnal rodent.Arvicanthis mordax, entrained to a regular LD cycle, were subjected to advance shifts (i.e. 4, 6 or 8 h) in the LD cycle and injected with vehicle or the melatonin agonist S-20098 (20 mg/kg) the day of the shift (and also on subsequent days in the 6 h or 8 h shift paradigms). In each condition, S-20098 accelerated by about 30% resynchronization to the new LD cycle. These data, which are the first to demonstrate the chronobiotic effects of a melatonin agonist in a diurnal rodent, provide new insights for the design of human chronopharmacological protocols.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

QUINIDINE is a long-lived open-channel blocker of the wild-type endplate acetylcholine receptor (AChR). To test the hypothesis that quinidine can normalize the prolonged channel opening events of slow-channel mutants of human AChR, we expressed wild-type AChR and five well characterized slow-channel mutants of AChR in HEK 293 cells and monitored the effects of quinidine on acetylcholine-induced channel currents. Quinidine shortens the longest component of channel opening burst (τ3b) of both wild-type and mutant AChRs in a concentration-dependent manner, and 5 μM quini-dine reduces τ3bof the mutant AChRs to that of wild-type AChRs in the absence of quinidine. Because this concentration of quinidine is attainable in clinical practice, the findings predict a therapeutic effect for quinidine in the slow-channel congenital myasthenic syndrome.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

FLUORESCENT tracers were injected into different regions of the caudate nucleus and HRP-WGA in the substantia nigra of the cat in order to analyse the thalamic distribution of retrogradely labelled thalamostriatal neurones and anterogradely labelled nigrothalamic terminals within the thalamus. Overlapping thalamic territories between the thalamostriatal neurones projecting to areas of the caudate nucleus and the nigrothalamic connections were observed in the rostral nuclei of the central thalamic group (ventral anterior nucleus, ventral anterior-ventral lateral complex and ventral medial nucleus) and, more restricted, in the rostral (rhomboid, paracentral, ventral lateral, dorsal mediodorsal nuclei) and caudal intralaminar nuclei (centromedian–parafascicular complex). This study provides evidence of the existence of thalamic areas in which the input and output of the basal ganglia converge.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE effects of a traumatic neocortical lesion, induced by transcranial cold injury, on brain metabolism and gene expression were examined. The surrounding of the lesions was characterized by increased glucose and lactate levels without major disturbances of protein synthesis or energy state. A transient pH decrease by 0.4 units was noticed 1 h post-injury, which shifted towards alkaline values by 3 h. The metabolic disturbances did not differ between injured animals with spontaneous spreading depressions (SD,n= 14) and those without SD (n= 7). In SD animals, c-fosmRNA was strongly elevated in the injury-remote cortex, buthsp72 mRNA was not enhanced. Thus, in contrast to focal ischemia, the metabolic dysfunction around traumatic cortical lesions is not aggravated by SD.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID