Neuroscience
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Simple cells in the cat primary visual cortex usually have elongated receptive fields (RFs), and their orientation selectivity can be largely predicted by their RFs. As to the relay cells in cats' lateral geniculate nucleus (LGN), they also have weak but significant orientation bias (OB). It is thus of interest to investigate the fine spatiotemporal receptive field (STRF) properties in LGN, compare them with the dynamics of orientation tuning, and examine the dynamic relationship between STRF and orientation sensitivity in LGN. ⋯ Furthermore, biased orientation tuning emerged 20-30 ms earlier than those in the primary visual cortex. These data demonstrated that similar to the primary visual cortex, the orientation sensitivity was closely reflected by the RF properties in LGN. However, the elongated RF and OB in LGN did not originate from the primary visual cortex feedback.
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Aging is associated with a substantial decline in the expression of social behavior as well as increased neuroinflammation. Since immune activation and subsequent increased expression of cytokines can suppress social behavior in young rodents, we examined age and sex differences in microglia within brain regions critical to social behavior regulation (PVN, BNST, and MEA) as well as in the hippocampus. Adult (3-month) and aged (18-month) male and female F344 (N = 26, n = 5-8/group) rats were perfused and Iba-1 immunopositive microglia were assessed using unbiased stereology and optical density. ⋯ When morphological features of microglia were assessed, aged rats exhibited increased soma size in the BNST, MEA, and CA3. Together, these findings provide a comprehensive characterization of microglia number and morphology under ambient conditions in CNS sites critical for the normal expression of social processes. To the extent that microglia morphology is predictive of reactivity and subsequent cytokine release, these data suggest that the expression of social behavior in late aging may be adversely influenced by heightened inflammation.
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Randomized Controlled Trial
The Role of Left Dorsolateral Prefrontal Cortex in Language Processing.
In addition to the role of left frontotemporal areas in language processing, there is increasing evidence that language comprehension and production require cognitive control and working memory resources involving the left dorsolateral prefrontal cortex (DLPFC). The aim of this study was to investigate the role of the left DLPFC in both language comprehension and production. ⋯ However, additional analyses revealed that the polarity of tDCS effects was highly correlated across tasks, implying differential individual susceptibility to the effect of tDCS within participants. Overall, our findings demonstrate that left DLPFC is part of the complex cortical network associated with language processing.
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Semantically congruent sounds can facilitate perception of visual objects in the human brain. However, the manner in which semantically congruent sounds affect cognitive processing for degraded visual stimuli remains unclear. We presented participants with naturalistic degraded images and semantically congruent sounds from different conceptual categories in three modalities: degraded visual only, auditory only, and auditory and degraded visual. ⋯ Our results demonstrate that the visual association cortex and STS/STG are involved in the integration of auditory and degraded visual information. In addition, the pattern classification results imply that semantically congruent sounds may facilitate identification of degraded images in both coarse and fine groups. Importantly, when naturalistic visual stimuli were further subdivided, facilitation through auditory modulation exhibited category selectivity.
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Phospholipase D2 (PLD2), an enzyme involved in vesicle trafficking and membrane signaling, interacts with α-synuclein, a protein known to contribute in the development of Parkinson disease (PD). We previously reported that PLD2 overexpression in rat substantia nigra pars compacta (SNc) causes a rapid neurodegeneration of dopamine neurons, and that α-synuclein suppresses PLD2-induced nigral degeneration (Gorbatyuk et al., 2010). Here, we report that PLD2 toxicity is due to its lipase activity. ⋯ These findings suggest that neither the interaction of PLD2 with dynamin, which has a role in vesicle trafficking, nor the PLD2 interaction with Grb2, which has multiple roles in cell cycle control, chemotaxis and activation of tyrosine kinase complexes, are the primary cause of neurodegeneration. Instead, the synthesis of phosphatidic acid (the product of PLD2), which is a second messenger in multiple cellular pathways, appears to be the key to PLD2 induced neurodegeneration. The fact that α-synuclein is a regulator of PLD2 activity suggests that regulation of PLD2 activity could be important in the progression of PD.