Neuroscience
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Anhedonia, or the inability to experience positive feelings is a hallmark of depression. However, few animal models have relied on decreased positive affect as an index of susceptibility to depression. Rats emit frequency-modulated ultrasonic vocalizations (USVs), designated as "positive" calls in the 50-kHz range. ⋯ However, if a bLR is accompanied by another bLR, there is a significant increase in 50-kHZ USVs emitted by this phenotype. bHRs emitted increases in 50-kHZ UVSs upon first exposure to EC, whereas bLRs showed a similar increase only after repeated exposure. bLRs' increase in positive affect after chronic EC was coupled with significant positive correlations between corticosterone levels and c-fos mRNA in the accumbens. Conversely, a decline in the rate of positive calls in bHRs after chronic EC was associated with a negative correlation between corticosterone and accumbens c-fos mRNA. These studies demonstrate that inborn differences in emotionality interact with the environment to influence positive affect and underscore the potential interaction between glucocorticoids and the mesolimbic reward circuitry in modulating 50-kHz calls.
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Schizophrenia is a severe condition that has been associated with functional abnormalities in dopaminergic (DA) neurons of the ventral tegmental area (VTA). Neurokinin-3 receptors (NK3Rs) of the tachykinin family of neuropeptides modulate the activity of VTA DA neurons and might be involved in DA abnormalities relevant to schizophrenia. Recent work from our lab showed that systemic injection of the dopamine D1/D2 receptor agonist apomorphine in rats, which mimics schizophrenia-like behaviors in humans, also evoked a redistribution of NK3Rs in DA neurons of the rat VTA. ⋯ In non-TH, presumably GABAergic neurons of the VTA, the NK3R densities in somata and dendrites were not significantly changed by apomorphine with or without SB222200. The results suggest that the NK3R antagonist SB222200 is effective against the apomorphine-evoked NK3R internalization in VTA DA dendrites, but does not prevent nuclear NK3R trafficking in VTA DA neurons. These results might have important implications in targeting NK3R antagonists in basic or clinical studies.
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Randomized Controlled Trial
Illumination influences working memory: an EEG study.
Illumination conditions appear to influence working efficacy in everyday life. In the present study, we obtained electroencephalogram (EEG) correlates of working-memory load, and investigated how these waveforms are modulated by illumination conditions. We hypothesized that illumination conditions may affect cognitive performance. ⋯ The fact that the illumination condition affects brain activity but not behavioral performance suggests that the lighting conditions used in the present study did not influence the performance stage of behavioral processing. Nevertheless, our findings provide objective evidence that illumination conditions modulate brain activity. Further studies are necessary to refine the optimal lighting parameters for facilitating working memory.
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Thyrotropin-releasing hormone (TRH), a neuropeptide contained in neural terminals innervating brainstem vagal motor neurons, enhances vagal outflow to modify multisystemic visceral functions and food intake. Type 2 diabetes (T2D) and obesity are accompanied by impaired vagal functioning. We examined the possibility that impaired brainstem TRH action may contribute to the vagal dysregulation of food intake in Goto-Kakizaki (GK) rats, a T2D model with hyperglycemia and impaired central vagal activation by TRH. ⋯ Fasting-induced Fos expression accompanying endogenous brainstem TRH action decreased by 66% and 91%, respectively, in the nucleus tractus solitarius (NTS) and the dorsal motor nucleus of the vagus (DMV) in GK rats, compared to Wistar rats. Refeeding abolished fasting-induced Fos-expression in the NTS, while that in the DMV remained in Wistar but not GK rats. These findings indicate that dysfunctional brainstem TRH-elicited vagal impairment contributes to the disturbed food intake in T2D GK rats, and may provide a pathophysiological mechanism which prevents further weight gain in T2D and obesity.
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Deep brain stimulation (DBS) has become the standard surgical procedure for advanced Parkinson's disease (PD). Recently, the pedunculopontine tegmental nucleus (PPN) has emerged as a potential target for DBS in patients whose quality of life is compromised by freezing of gait and falls. To date, only a few groups have published their long-term clinical experience with PPN stimulation. ⋯ To this end, the Bar nucleus area was analysed in mouse, monkey and human tissues, paying particular attention to the anatomical position in humans, where it has been largely overlooked. Results confirm that anatomical location renders the Bar nucleus susceptible to influence by the PPN DBS lead or to diffusion of electrical current. This may have an undesirable impact on the quality of life of patients.