Brain research
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In this study, the interaction between individual differences in working memory capacity, which were assessed by the Korean version of the California Verbal Learning Test (K-CVLT), and the effects of oculomotor task load on word recall performance are examined in a dual-task experiment. We hypothesized that varying levels of oculomotor task load should result in different demands on cognitive resources. The verbal working memory task used in this study involved a brief exposure to seven words to be remembered, followed by a 30-second delay during which the subject carried out an oculomotor task. ⋯ Subjects with high K-CVLT scores evidenced steady word recall performances, regardless of the type of oculomotor task performed. The concurrent oculomotor performance measured by velocity error did not differ significantly among the K-CVLT groups. However, the high-scoring subjects evidenced smaller phase errors under predictive SPEM conditions than did the low-scoring subjects; this suggests that different resource allocation strategies may be adopted, depending on individuals' working memory capacity.
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Rac1, a protein of the Rho GTPase subfamily, has been implicated in neuronal and spine development as well as the formation of synapses with appropriate partners. Dendrite and spine abnormalities have been implicated in several psychiatric disorders such as Fragile X syndrome, where neurons show a high density of long, thin, and immature dendritic spines. Although abnormalities in dendrites and spines have been correlated with impaired cognitive abilities in mental retardation, the causes of these malformations are not yet well understood. ⋯ We further showed that, in Fmr1 knockout mice, lack of FMRP induces an overactivation of Rac1 in the mouse brain and other organs that have been shown to be altered in Fragile X syndrome. In those animals, pharmacological manipulation of Rac1 partially reverses their altered long-term plasticity. Thus, regulation of Rac1 may provide a functional link among deficient neuronal morphology, aberrant synaptic plasticity and cognition impairment in Fragile X syndrome.
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Current research on empathy for pain emphasizes the overlap in the neural response between the first-hand experience of pain and its perception in others. However, recent studies suggest that the perception of the pain of others may reflect the processing of a threat or negative arousal rather than an automatic pro-social response. It can thus be suggested that pain processing of other-related, but not self-related, information could imply danger rather than empathy, due to the possible threat represented in the expressions of others (especially if associated with pain stimuli). ⋯ Those pictures were primed with own or other faces following the same procedure as in Experiment 1 while ERPs were recorded. Early (N1) and late (P3) cortical responses between pain and no-pain were modulated only in the other-face priming condition. These results support the threat value of pain hypothesis and suggest the necessity for the inclusion of own- versus other-related information in future empathy for pain research.
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Comparative Study
The respective and interaction effects of spinal GRs and MRs on radicular pain induced by chronic compression of the dorsal root ganglion in the rat.
High levels of glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) are colocalized in the substantia gelatinosa. This indicates that the pain pathways appear to be under a strong regulation of these receptors. However, their respective effects on pain behaviors and their interaction remain unclear. ⋯ Moreover, different from intrathecally administered dexamethasone alone [no difference was found between two dose levels of dexamethasone (4 μg=2 μg)], dexamethasone suppresses mechanical allodynia and thermal hyperalgesia in a dose-dependent manner (4 μg>2 μg>vehicle) when combined with spironolactone (3 μg). These findings indicate that both central GRs and MRs play an important role in the regulation of pain behaviors and they have a perplexing interaction with each other. Spironolactone can enhance the analgesic effects of dexamethasone via complex mechanisms.
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The neuroprotective benefit of intra-operative anesthetics is widely described and routinely aimed to invoke electroencephalographic (EEG) silence in anticipation of transient cerebral ischemia. Previous rat survival studies have questioned an additional benefit from achieving EEG silence during transient global cerebral hypoperfusion. Surgical preparation on twelve New Zealand white rabbits under ketamine-propofol anesthesia, included placement of skull screws for bilateral EEG monitoring, skull shaving for laser Doppler probes, and a 5 mm diameter right temporal craniotomy for the NADH probe. ⋯ Compared to controls, the increase in NADH during ischemia was unaffected by EEG silence with either intravenous or intraarterial propofol. We failed to observe any significant additional attenuation of the elevation in NADH levels with propofol induced EEG silence during transient global cerebral hypoperfusion. This is consistent with previous rat survival studies showing that EEG silence was not required for full neuroprotective effects of pentothal anesthesia.