Neuroscience
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Hyperexcitability of dorsal horn neurons has been shown to play a key role in neuropathic pain following chronic experimental spinal cord injury. With a neonatal in vitro spinal cord injury model, we show that a chemically-induced lesion leads to rapid gain-of-function of sublesional dorsal horn networks biased to hyperexcitation. The expression of the GABA synthetic enzyme GAD65 was significantly reduced at the same level of the spinal cord, suggesting a compromised inhibitory system. We propose that our model could be useful to test early approaches to contrast spinal cord injury-induced central sensitization of dorsal horn circuits.
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Recent data suggest that there may be distinct processing streams emanating from auditory cortical layers 5 and 6 that influence the auditory midbrain. To determine whether these projections have different physiological properties, we injected rhodamine-tagged latex tracer beads into the inferior colliculus of >30-day-old mice to label these corticofugal cells. Whole-cell recordings were performed on 62 labeled cells to determine their basic electrophysiological properties and cells were filled with biocytin to determine their morphological characteristics. ⋯ Quantitative analysis of morphology showed that layer 6 cells are smaller, have a horizontal orientation, and have very long dendrites (>500 μm) that branch profusely both near the soma distally near the pia. Layer 5 corticocollicular cells are large pyramidal cells with a long apical dendrite with most branching near the pial surface. The marked differences in physiological properties and dendritic arborization between neurons in layers 5 and 6 make it likely that each type plays a distinct role in controlling auditory information processing in the midbrain.
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Randomized Controlled Trial
Sensorimotor performance asymmetries predict hand selection.
Handedness is most often measured by questionnaires that assess an individual's preference for using a particular hand to perform a variety of tasks. While such assessments have proved reliable, they do not address the underlying neurobehavioral processes that give rise to the choice of which hand to use. Recent research has indicated that handedness is associated with hemispheric specializations for different aspects of sensorimotor performance. ⋯ We expected that arm choice would be reflected by an interaction between these factors. Our results indicated that removing visual feedback both improved the relative performance of the non-dominant arm and increased the choice to use this arm for targets near midline, an effect that was enhanced for targets requiring larger movement amplitudes. We explain these findings in the context of the dynamic dominance hypothesis of handedness and discuss their implications for the link between hemispheric asymmetries in neural control and hand preference.
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High-mobility group box1 (HMGB1) protein is massively released into the cytoplasm and induces inflammation following various insults such as sepsis, acute cerebral ischemia, and pancreatitis. However, whether HMGB1 can act as an early proinflammatory cytokine to promote inflammation after intracerebral hemorrhage (ICH) is unclear. We explored this question using a rat model of collagenase-induced ICH. ⋯ Administration of ethyl pyruvate decreased the level of HMGB1 and microglia around the hematoma. Ethyl pyruvate also ameliorated ICH-induced neuronal apoptosis, cerebral edema, and neurological impairment. These findings suggest that HMGB1 may act as an early proinflammatory cytokine within the neurovascular unit to mediate inflammation during the acute phase of ICH.
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To maximize reward, we are faced with the dilemma of having to balance the exploration of new response options and the exploitation of previous choices. Here, we sought to determine if the event-related brain potential (ERP) in the P300 time range is sensitive to decisions to explore or exploit within the context of a sequential risk-taking task. Specifically, the task we used required participants to continually explore their options-whether they should "push their luck" and keep gambling or "take the money and run" and collect their winnings. ⋯ Interestingly, these data suggest that participants adopted one of two modes of control on any given trial: a mode where they quickly decided to keep gambling (i.e. exploit), and a mode where they deliberated whether to the take the money they had already won or continue gambling (i.e. explore). Importantly, we found that the amplitude of the ERP in the P300 time range was larger for explorative decisions than for exploitative decisions and, further, was correlated with decision time. Our results are consistent with a recent theoretical account that links changes in ERP amplitude in the P300 time range with phasic activity of the locus coeruleus-norepinephrine system and decisions to engage in exploratory behavior.