ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Recent studies have suggested that peripheral tissues in mammals have an autonomous circadian oscillator driven by negative feedback loops consisting of periodical expression of clock genes. In the present study we investigated the mechanism that regulates circadian rhythms in mammalian peripheral tissues, and observed developmental aspects in circadian expression of clock genes in the heart of postnatal rats. Daily expression patterns of clock genes (rPer1,rPer2andBMAL1) and a clock-controlled geneDbpwere examined by Northern blot analysis. Circadian expression ofrPer1,BMAL1andDbpmRNAs started between postnatal day 2 (P2) and P5, butrPer2mRNA did not show rhythmicity until P14. Rhythmic expression of other genes in the heart occurred even in the absence of rhythmicrPer2expression. These findings suggest that in the rat heart, rhythmic expression ofrPer2was not essential to generate circadian rhythmicity at the early postnatal stage. Judging from mRNA rhythms in the heart, it was probably after P20 that rats established the mature circadian system controlling peripheral rhythms.

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

The human thumb is functionally and morphologically different from the other digits, enabling capability for a wide range of movements and for precision grasping. We investigated the reactivity of the magnetic ∼20 Hz motor cortex rhythm by stimulating thumb and middle finger electrically and by quantifying the poststimulus rebounds. The level of the ∼20 Hz rhythm level was significantly higher after thumb than middle finger stimulation. In contrast, the somatosensory 20-ms responses were stronger after middle finger than the thumb stimulation. We found an inverse thumb/middle finger ratio between the 20 ms responses and the reactivity of the ∼20 Hz motor cortex rhythm. Thus the sensorimotor processing differs for thumb and middle finger in the human primary motor and somatosensory cortices.

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Orphanin FQ is a novel opioid family member, which is densely localized in the hypothalamus, a region of the brain important for the control of reproduction. This study tested the hypothesis that orphanin FQ might regulate the secretion of gonadotropin-releasing hormone, the key central regulator of the ovulatory cycle. To test this hypothesis, we used rat hypothalamic fragments and immortalized gonadotropin-releasing hormone neurons (GT1-7)in vitroand examined whether orphanin FQ would inhibit forskolin-induced gonadotropin-releasing hormone release. The studies revealed that orphanin FQ potently and dose-dependently inhibits forskolin-induced gonadotropin-releasing hormone release from rat hypothalamic fragments. In contrast, orphanin FQ had no effect on gonadotropin-releasing hormone release from GT1-7 neurons. Reverse transcriptase-polymerase chain reaction analysis further revealed that the orphanin FQ receptor, ORL-1 is expressed in hypothalamic fragments, but not in GT1-7 neurons. Together, these findings are the first to suggest a role for orphanin FQ in the regulation of gonadotropin releasing hormone secretion.

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

We recorded event-related potentials (ERPs) in 2-month-old infants in two different states of alertness: awake and asleep. Syllables varying in vowel duration (longvsshort) were presented in an oddball paradigm, known to elicit a mismatch brain response. ERPs of both groups showed a mismatch response reflected in a positivity followed by a frontal negativity. While the positivity was present as a function of the stimulus type (present for long deviants only), the negativity varied as a function of the state of alertness (present for awake infants only). These data indicate a functional separation between precognitive and cognitive aspects of duration mismatch essential for the distinction between long and short vowels during early infancy.

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Dysfunctional emotion processing is a key aspect of many neuropsychiatric disorders. This dysfunction may be due to an abnormal magnitude of neural substrate activation during emotion processing or due to an altered time course of the neural substrate response. To better understand the temporal characteristics of the neural substrate activation underlying implicit emotion processing, nine healthy female controls were repeatedly exposed to pictures of affective faces while performing a gender identification task in an fMRI. As the salience of the stimuli decreased with repeated exposure, brain areas implicated in a right hemispheric spatial attention network (including the posterior parietal cortex (BA 40) and the frontal eye fields (BA 6)) habituated while brain areas lateralized to the left hemisphere (including the angular gyrus (BA 39), posterior superior temporal gyrus (BA 39) and insula (BA 13)) sensitized. These results provide strong evidence that the time course of activation is a critical component when assessing the function of neural substrates underlying emotion processing (specifically whether habituation is altered) in neuro-psychiatric patients.

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

The present study investigated whether 2- to 6-year-old children with Williams syndrome can form new object categories based on either visual or verbal information alone. Children were presented with six triads of objects. In each triad, two objects either shared visual properties, or were given the same name. Following the presentation of each triad, categorization based on the shared visual or verbal property was evaluated through object manipulation. While the children categorized the objects according to visual cues, they failed to use the verbal cues. These results contrast with previous research showing that typically developing toddlers, who were much younger than the children with Williams syndrome and much less advanced in their vocabulary development, could perform both types of categorization. The present study hence supports the claim that vocabulary acquisition in Williams syndrome develops atypically.

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Microinjection is one of the most useful and important methods in cellular neurobiology. However, direct insertion and retraction of a capillary produce physical stresses inside cells that make it difficult to apply on small and fragile cells, especially the central nervous system (CNS) neurons. In this study, we developed a novel method called MALC (microinjection method assisted with laser activated chromophore) to avoid this disadvantage of the conventional method. In MALC, a capillary is just attached on cell surface, and combination of a newly developed photosensitizer with a laser pointing system makes the plasma membrane permeable to molecules. This novel method can expand the application of the microinjection method and realize molecular manipulations inside CNS neurons.

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

It is believed that aggressive attacks are activated by a downward stimulatory stream that includes the medial amygdala, hypothalamic attack area, and periaqueductal grey. However, the hypothalamic attack area (from which attacks can be induced by electrical stimulation) sends projections to the forebrain, the significance of which is unknown. Here we report that the unilateral stimulation of the hypothalamic attack areaper seinduced an unilateral c-Fos activation of most brain nuclei involved in attack, and that attacks occurred only when cortical regions were also activated, and the activation of the medial amygdala and hypothalamic attack area were bilateral. This suggests that the hypothalamic attack area not only transmits information to lower brain structures but also activates forebrain structures involved in attack.

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID