Neuroscience
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Several lines of evidence indicate group III metabotropic glutamate receptors (mGluRs) have systemic anti-hyperalgesic effects. We hypothesized this could occur through modulation of transient receptor potential vanilloid 1 (TRPV1) receptors on nociceptors. To address this question we performed anatomical studies to determine if group III mGluRs were expressed on cutaneous axons and if they co-localized with TRPV1. ⋯ Finally, the anti-hyperalgesic effect of group III in this paradigm was local and not systemic since intraplantar administration of L-AP-4 in one hind paw did not attenuate nociceptive behaviors following CAP injection in the contralateral hind paw. Adenyl cyclase/cyclic AMP/PKA may be the second messenger pathway linking these two receptor families because intraplantar injection of forskolin (FSK, 10 μM) reduced PWL to heat and L-AP-4 reversed this FSK effect. Taken together, these results suggest group III mGluRs can negatively modulate TRPV1 through inhibition of adenyl cyclase and downstream intracellular activity, blocking TRPV1-induced activation of nociceptors.
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The temporal lobe plays a major role in anxiety and depression disorders and is also of importance for trait anxiety in the non-pathological range. The present study investigates self-report data of personality dimensions linked to trait anxiety in the context of white matter tract integrity in the temporal lobes of the human brain in a large sample of N=110 healthy participants. The results show that especially in men values for fractional anisotropy of several white matter tracts in the temporal lobe of the left hemisphere correlate substantially with individual differences in trait anxiety (depending on the tract investigated between .40 and .49). The present study shows that not only data from functional magnetic resonance imaging (fMRI), but also from structural diffusion tensor imaging (DTI) provide interesting insights into the biological foundation of human personality traits.
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Balance control in Parkinson's disease is often studied using dynamic posturography, typically with serial identical balance perturbations. Because subjects can learn from the first trial, the magnitude of balance reactions rapidly habituates during subsequent trials. Changes in this habituation rate might yield a clinically useful marker. We studied balance reactions in Parkinson's disease using posturography, specifically focusing on the responses to the first, fully unpractised balance disturbance, and on the subsequent habituation rates. ⋯ Higher first trial reactions and a slow habituation rate discriminated Parkinson's patients from controls, but habituated trials did not. Further work should demonstrate whether this also applies to clinical balance tests, such as the pull test, and whether repeated delivery of such tests offers better diagnostic value for evaluating fall risks in parkinsonian patients.
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An altered one carbon cycle (folic acid, vitamin B(12)) and omega 3 fatty acid metabolism during pregnancy can increase the risk for neurodevelopmental disorders in the offspring. Our earlier studies have shown that a maternal diet imbalanced with micronutrients like folic acid, vitamin B(12) reduces levels of brain docosahexaenoic acid (DHA) and neurotrophins in the offspring at birth. The present study examines whether these effects can be reversed by a postnatal diet. ⋯ Brain-derived nerve growth factor (BDNF) and nerve growth factor (NGF) levels were lower in both the vitamin B(12)-deficient groups even after consuming a diet with normal levels of vitamin B(12) during lactation (p<0.05 for all) indicating that the effects of maternal programing with respect to neurotrophins cannot be reversed by a postnatal diet. Our findings for the first time suggest that omega 3 fatty acid supplementation to a micronutrient-imbalanced diet, during pregnancy and lactation protects the levels of BDNF and NGF. This may have significant implications in the development of psychiatric disorders/cognitive deficits in later life.
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This study examined responsiveness to acoustic stimuli among neurons of the basolateral amygdala. While recording from single neurons in awake mustached bats (Pteronotus parnellii), we presented a wide range of acoustic stimuli including tonal, noise, and vocal signals. While many neurons displayed phasic or sustained responses locked to effective auditory stimuli, the majority of neurons (n=58) displayed a persistent excitatory discharge that lasted well beyond stimulus duration and filled the interval between successive stimuli. ⋯ Chemical activation of the medial geniculate body (MG) increased both background and evoked firing. Among 39 histologically localized recording sites, we saw no evidence of topographic organization in terms of temporal response pattern, habituation, or the affect of calls to which neurons responded. Overall, these studies demonstrate that amygdalar neurons in the mustached bat show high selectivity to vocal stimuli, and suggest that persistent firing may be an important feature of amygdalar responses to social vocalizations.