Neuroscience
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Task execution almost always occurs in the context of reward-seeking or punishment-avoiding behavior. As such, ongoing task-monitoring systems are influenced by reward anticipation systems. In turn, when a task has been executed either successfully or unsuccessfully, future iterations of that task will be re-titrated on the basis of the task outcome. ⋯ Rather, ERP measures suggested that only the magnitude of actual reward or loss was now processed. Reward and task-monitoring processes are clearly dissociable, but interact across very fast timescales to update reward predictions as information about task success or failure is accrued. Careful delineation of these processes will be useful in future investigations in clinical groups where such processes are suspected of having gone awry.
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We examined changes in the variability, frequency composition, and complexity of force signal from subacute to chronic stage of stroke during maintenance of isometric knee extension and compared these parameters between chronic stroke and healthy subjects. The sample included 15 healthy (65±8 years) and 23 chronic stroke subjects (65±14 years, 6-112 months post-stroke) of whom 10 (64±15 years) were also examined 11-22 days post-stroke (subacute stage). The subjects performed isometric knee extension at 10%, 20%, 30%, and 50% of peak torque for 10s (two trials each). ⋯ These results indicate a shift toward lower frequencies and a less complex physiological process underlying force control in chronic stroke. The overall results suggest the improvement in force variability from subacute to chronic stroke but without normalization in the frequency composition and complexity of the force signal. Thus, disordered structure of the force signal remains a marker of impaired motor control long after stroke occurrence despite apparent recovery in force variability.
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The coppery titi monkey (Callicebus cupreus) is a socially monogamous New World primate that has been studied in the field and the laboratory to investigate the behavioral neuroendocrinology of primate pair bonding and parental care. Arginine vasopressin has been shown to influence male titi monkey pair-bonding behavior, and studies are currently underway to examine the effects of oxytocin on titi monkey behavior and physiology. Here, we use receptor autoradiography to identify the distribution of arginine vasopressin 1a receptor (AVPR1a) and oxytocin receptors (OXTR) in hemispheres of titi monkey brain (n=5). ⋯ AVPR1a binding is present throughout the cortex, especially in cingulate, insular, and occipital cortices, as well as in the caudate, putamen, nucleus accumbens, central amygdala, endopiriform nucleus, hippocampus (CA4 field), globus pallidus, lateral geniculate nucleus, infundibulum, habenula, PAG, substantia nigra, olivary nucleus, hypoglossal nucleus, and cerebellum. Furthermore, we show that, in the titi monkey brain, the OXTR antagonist ALS-II-69 is highly selective for OXTR and that the AVPR1a antagonist SR49059 is highly selective for AVPR1a. Based on these results and the fact that both ALS-II-69 and SR49059 are non-peptide, small-molecule antagonists that should be capable of crossing the blood-brain barrier, these two compounds emerge as excellent candidates for the pharmacological manipulation of OXTR and AVPR1a in future behavioral experiments in titi monkeys and other primate species.
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In humans the identification of the primary gustatory cortex (PGC) is still under debate. Neuroimaging studies indicate insula and overlying opercula as the best candidates but the exact position of the PGC within this region is not entirely clear. Moreover, inconsistencies appear when comparing results from studies using functional magnetic resonance imaging (fMRI), and gustatory event-related potentials (gERP), or gustatory event-related magnetic fields (gERMF). fMRI indicates activations in the anterior part of the insula and frontal operculum, while gERP and/or gERMF indicate activations at the transition between the parietal operculum and insula in its posterior part. ⋯ In the present study gERMF and gERP were recorded simultaneously using a whole-head system with 249 magnetometers and 32 electrodes, respectively; taste stimuli were applied using a stimulator providing excellent temporal and spatial control of the stimulus. Separate ERP and ERMF averaged waveforms were derived time-locked to the onset of the taste stimuli. The source analysis for the early time range revealed activity in the left and right anterior and mid part of the insula, where in the later time range the sources were located more in the posterior part of the insula.
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Decreased expression of CHRNA7, the gene encoding the α7(∗) subtype of nicotinic receptor, may contribute to the cognitive dysfunction observed in schizophrenia by disrupting the inhibitory/excitatory balance in the hippocampus. C3H mice with reduced Chrna7 expression have significant reductions in hippocampal α7(∗) receptor density, deficits in hippocampal auditory gating, increased hippocampal activity as well as significant decreases in hippocampal glutamate decarboxylase-65 (GAD65) and γ-aminobutyric acid-A (GABAA) receptor levels. The current study investigated whether altered Chrna7 expression is associated with changes in the levels of parvalbumin, GAD67 and/or GABAA receptor subunits in the hippocampus from male and female C3H Chrna7 wildtype, C3H Chrna7 heterozygous and C3H Chrna7 knockout (KO) mice using quantitative Western immunoblotting. ⋯ Finally, an increase in γ2 subunit protein was found in C3H Chrna7 KO mice with the levels of this subunit again being greater in males than in females. The increases in hippocampal parvalbumin and GAD67 observed in C3H Chrna7 mice are contrary to reports of reductions in these proteins in the postmortem hippocampus from schizophrenic individuals. We hypothesize that the disparate results may occur because of the influence of factors other than CHRNA7 that have been found to be abnormal in schizophrenia.