Neuroscience
-
The visual system classifies objects into categories, and distinct populations of neurons within the temporal lobe respond preferentially to objects of a given perceptual category. We can also classify the objects we recognize with the sense of touch, but less is known about the neuronal correlates underlying this cognitive function. To address this question, we performed a multivariate pattern analysis (MVPA) of functional magnetic resonance imagining (fMRI) activity to identify the cortical areas that can be used to decode the category of objects explored with the hand. ⋯ Importantly, we found that categories can also be decoded from the lateral occipital complex (LOC), which is a multimodal region known to be related to the representation of object shape. Furthermore, a hyperalignment analysis showed that activity patterns are similar across subjects. Our results thus indicate that tactile object recognition generates category-specific patterns of activity in a multisensory area known to encode objects, and that these patterns have a similar functional organization across individuals.
-
The Sonic hedgehog (Shh) signaling pathway is recapitulated in response to ischemic injury. Here, we investigated the clinical implications of Shh protein in the ischemic stroke and explored the underlying mechanism. Intracerebroventricular injection of Shh, Cyclopamine, or anti-vascular endothelial growth factor (VEGF) was performed immediately after permanent middle cerebral artery occlusion (pMCAO) surgery and lasted for 7days (d). ⋯ To observe in vitro angiogenesis, rat brain microvascular endothelial cells (RBMECs) were incubated under oxygen glucose deprivation (OGD) for 6h (h) and treated with Shh/anti-VEGF. We found that (1) Shh improved neurological scores and reduced infarct volume, which was blocked by Cyclopamine, (2) Shh improved the microvascular density and promoted angiogenesis and neuron survival in the ischemic boundary zone, (3) Shh enhanced VEGF expression and VEGF antibody could reverse angiogenic and protective effect of Shh in vivo and in vitro. These data demonstrate that the administration of Shh protein could protect brain from ischemic injury, in part by promoting angiogenic repair.
-
Fyn is a non-receptor protein tyrosine kinase that belongs to Src family kinases. Fyn plays a critical role in neuronal migration, but the mechanism remains unclear. ⋯ Moreover, Fyn inhibition increased the length of leading process and decreased the branching number of the migrating cortical neurons. Together, these results indicate that Fyn controls neuronal migration by regulating the cytoskeletal dynamics and multipolar-bipolar transition of newly generated neurons during cortical development.
-
Anxiety is differentially expressed across a continuum of stressful/fearful intensity, influenced by endocannabinoid systems and receptors. The hippocampus plays important roles in the regulation of affective behavior, emotion, and anxiety, as well as memory. Location of Cb1/Cb2 receptor action could be important in determining emotional valence, because while the dorsal hippocampus is involved in spatial memory and cognition, the ventral hippocampus has projections to the PFC, BNST, amygdala, and HPA axis, and is important for emotional responses to stress. ⋯ Escape behavior is associated with reduced Cb2 expression in the dorsal CA1 region, with freezing and escape latency correlated with mRNA levels. Escaping and submitting animals with access to running wheels had increased Cb2 mRNA in dorsal DG/CA1. These results suggest that the Cb2 receptor system is rapidly induced during anxiogenic social interactions plus fear conditioning or exercise; with responses potentially adaptive for coping mechanisms.
-
TRPV4 ion channels have a broad expression profile and were shown to contribute to enhanced pain sensation in inflammation. Directly blocking TRPV4 might run the risk of interfering with normal physiology, and has prompted to explore the interaction with the scaffolding protein AKAP79, an approach successfully used for TRPV1 channels. HEK293t cells express AKAP79, additional transfection did not sensitize human TRPV4. ⋯ A synthetic peptide, resembling these amino acids and extended by a positive region for transmembrane uptake, was tested. Sensitization of TRPV4 responses could be reduced after exposure to this 771-781::TAT peptide but not by a scrambled control peptide. This validates the concept of targeting the interaction between TRPV4 and AKAP79 and controlling increased TRPV4 activity.