Neuroscience
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Socially housed monkeys have been used as a model to study human diseases. The present study examined behavioral, physiological and neurochemical measures as predictors of social rank in 16 experimentally naïve, individually housed female cynomolgus monkeys (Macaca fascicularis). The two behavioral measures examined were novel object reactivity (NOR), as determined by latency to touch an opaque acrylic box placed in the home cage, and locomotor activity assessed in a novel open-field apparatus. ⋯ The two measures that correlated with eventual social rank were CSF 5-HIAA concentrations, which were significantly higher in the animals who eventually became subordinate, and latency to touch the novel object, which was significantly lower in eventual subordinate monkeys. Measures of 5-HT function did not change as a consequence of social rank. These data suggest that levels of central 5-HIAA and measures of novel object reactivity may be trait markers that influence eventual social rank in female macaques.
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The current study aimed at investigating the processing of prosodic hierarchical boundaries in Mandarin Chinese sentences using electroencephalography, mainly focused on the following questions: (1) whether prosodic boundaries at different levels could evoke the closure positive shift reflecting prosodic boundary perception; (2) what were the differences between them at latency, amplitude and topography; (3) whether this positive component was modified by the variations of acoustic cues (e.g. pause). Main results were: (1) As the previous studies indicated, intonational phrases elicited the closure positive shift as a marker of online speech structuring; (2) phonological phrases evoked the same positive effect with shorter onset latency and somewhat lower amplitude; (3) when the pauses in the vicinity of prosodic boundaries were entirely removed, the original latency difference between the two conditions disappeared, which clearly demonstrated the influence of pause on prosodic boundary processing; (4) prosodic word boundaries only induced amplitude variation waving around the baseline, which was more positive compared with the one elicited by syllable boundaries. The present results indicated that listeners were very sensitive to both intonational phrase boundaries and phonological phrase boundaries.
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There is consensus that muscarinic and nicotinic receptors expressed in vestibular hair cells and afferent neurons are involved in the efferent modulation of the electrical activity of the afferent neurons. However the underlying mechanisms of postsynaptic control in neurons are not well understood. In our work we show that the activation of muscarinic receptors in the vestibular neurons modulates the potassium M-current modifying the activity of afferent neurons. ⋯ The erg-channel blocker E-4031 did not significantly modify the M-current amplitude. In current-clamp experiments, linopirdine, XE-991, and oxotremorine-M modified the discharge response to current pulses from single spike to multiple spiking, reducing the adaptation of the electrical discharge. Our results indicate that large soma-size cultured vestibular-afferent neurons (most probably calyx-bearing neurons) express the M-current and that the modulation of this current by activation of muscarinic-receptor reduces its spike-frequency adaptation.
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Orexin (hypocretin) peptides are known to depolarize rat thalamic paraventricular nucleus (PVT) neurons by suppression of one or more undefined potassium conductances. Here, we investigated a contribution of TWIK-related acid-sensitive K(+) (TASK) channels to the resting membrane potential and orexin-induced depolarization of PVT neurons, using patch clamp recording techniques in brain slice preparations. Upon exposure to an acidic (pH 6.3) extracellular solution, PVT neurons displayed membrane depolarization. ⋯ Although responsiveness to orexins was preserved under each of the above conditions, the amplitude of the orexin B (0.5 microM)-induced inward current was depressed in the acidic solution and in the presence of anandamide, remained largely unchanged in the alkaline solution, and was enhanced by isoflurane when compared with that in normal artificial cerebrospinal solution. We conclude that pH-sensitive potassium channels, TASK-1 and TASK-3 channels, contribute substantially to the resting membrane conductance(s) and excitability in PVT neurons. The observations that orexin-induced currents were affected by putative TASK-specific drugs in a manner predictable from their effects on TASK channels also suggest that the orexin-induced excitation in PVT neurons is mediated by closure of TASK channels.
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Selective serotonin reuptake inhibitors (SSRIs), such as Prozac, are used to treat mood disorders. SSRIs attenuate (i.e. desensitize) serotonin 1A (5-HT(1A)) receptor signaling, as demonstrated in rats through decreased release of oxytocin and adrenocorticotropin hormone (ACTH) following 5-HT(1A) receptor stimulation. Maximal therapeutic effects of SSRIs for treatment of mood disorders, as well as effects on hypothalamic 5-HT(1A) receptor signaling in animals, take 1 to 2 weeks to develop. ⋯ Pretreatment with PTX to the PVN before peripheral injections of 17-beta-estradiol 3-benzoate completely prevented the reduction of the oxytocin response to the 5-HT(1A) receptor agonist, (+)-8-hydroxy-2-dipropylaminotetralin (DPAT). Treatment with the selective GRP30 agonist, G-1, attenuated 5-HT(1A) receptor signaling in the PVN as measured by an attenuated oxytocin (by 29%) and ACTH (by 31%) response to DPAT. This study indicates that a putative extra-nuclear estrogen receptor, GPR30, may play a role in estradiol-mediated attenuation of 5-HT(1A) receptor signaling, and potentially in accelerating the effects of SSRIs in treatment of mood disorders.