Neuroscience
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Recently, it has been shown that short-term monocular deprivation in adult humans can temporally shift the ocular dominance in favor of the deprived eye. It is not clear whether this form of ocular dominance plasticity can be explained by cortical contrast adaptation, which is known to be orientationally selective. Here we show that if only one eye is deprived of a limited band of orientations for a short period of 2.5 h, the deprived eye's contribution to binocular function at all orientations rather than just those corresponding to the previously deprived orientations is strengthened. This isotropic enhancement is quite different from the orientational enhancement previously reported and suggests a separate neuroplastic mechanism specific to binocular function.
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Cluster of differentiation 36 (CD36) belongs to the class B scavenger receptor family. CD36 is a glycoprotein found on the surface of various cell types and has been implicated in the mechanism of numerous central nervous system (CNS) diseases. However, the relationship between CD36 and epilepsy remains unknown. ⋯ Whole-cell patch-clamp technique exhibited a decreased frequency of action potentials (APs) in the hippocampal slices of CD36-/- mice. In addition, local field potential (LFP) analysis further indicated that CD36 deletion reduced the frequency and duration of epileptiform-like discharges. These results revealed that CD36 deficiency could produce an antiepileptic effect and could provide new insight into antiepileptic treatment.
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If one eye is patched for a period of 2.5 h in human adults, transient changes in sensory eye dominance result with the previously patched eye's contribution being strengthened. Similar changes result from opaque and translucent occlusion suggesting that it is the deprivation of contrast not luminance information that drives these transient shift of sensory eye dominance. ⋯ With further control experiments we show that this deprivation effect critically depends on the absolute luminance of each eye rather than the relative interocular luminance imbalance. These results indicate that changes in contrast gain at an early, monocular stage of the pathway can result in the transient shift of sensory eye dominance.
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Afferent chorda tympani (CT) fibers innervating anterior tongue fungiform papillae have neuron cell bodies in the geniculate ganglion (GG). To characterize electrophysiological and receptive field properties, we recorded extracellular responses from single GG neurons to lingual application with chemical, thermal and mechanical stimuli. Receptive field size was mapped by electrical stimulation of individual fungiform papillae. ⋯ The receptive field sizes for CHEMICAL, and CHEMICAL/THERMAL neurons averaged five papillae exceeding the field size of THERMAL and TACTILE neurons which averaged about two papillae. Detailed analysis of the receptive field of CHEMICAL/THERMAL neurons revealed that within one field only a subset of the fungiform papillae making up the receptive field responded to the cold stimuli, whereas the other papillae responded only to chemical stimuli. These finding demonstrate that fungiform papilla are complex sensory organs with a multisensory function suggesting a unique role in detecting and sampling food components prior to ingestion.
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Transient receptor potential melastatin 8 (TRPM8) is a nonselective cation channel that primarily detects the innocuous cold. In pathological conditions, TRPM8 plays a role in the development of cold hyperalgesia/allodynia. Nerve growth factor (NGF) is an important mediator involved in various pain disorders. ⋯ It was inferred that LAMP-2 was involved in the vesicular transport of TRPM8. Pharmacological blockade of the proteasome with MG132 led to a further increase in NGF-induced TRPM8 expression, indicating that the proteasome system played a pivotal role in the degradation of TRPM8. Our findings provide novel insight into the signaling pathways involved in NGF-mediated TRPM8 upregulation and its reversion to the normal state.