Neuroscience
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Difficulties in realizing persistent neurogenesis, inabilities in modeling pathogenesis of most cases, and a shortage of disease material for screening therapeutic agents restrict our progress to overcome challenges presented by neurodegenerative diseases. We propose that reprogramming primary somatic cells of patients into induced pluripotent stem cells (iPSCs) provides a new avenue to overcome these impediments. ⋯ In this review, we introduce efficient approaches to generate iPSCs and distinct iPSCs differentiation stages, and critically discuss paradigms of iPSCs technology application to investigate neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD). Although iPSCs technology is in its infancy and faces many obstacles, it has great potential in helping to identify therapeutic targets for treating neurodegenerative diseases.
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Despite modern imaging techniques, assessing and localizing changes in brain activity during whole-body exercise is still challenging. Using an active electroencephalography (EEG) system in combination with source localization algorithms, this study aimed to localize brain cortical oscillations patterns in the motor cortex and to correlate these with surface electromyography (EMG)-detected muscular activity during pedaling exercise. Eight subjects performed 2-min isokinetic (90 rpm) cycling bouts at intensities ranging from 1 to 5 Wkg(-1) body mass on a cycle ergometer. ⋯ More importantly, the oscillations in cortical activity within the motor cortex were significantly correlated with EMG activity during the high-intensity cycling bouts. This study demonstrates that it is possible to localize oscillations in brain cortical activity during moderate- to high-intensity cycling exercise using EEG in combination with source localization algorithms, and that these oscillations match the activity of the active muscles in time and amplitude. Results of this study might help to further evaluate the effects of central vs. peripheral fatigue during exercise.
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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.
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Dopamine (DA) plays fundamental roles as a neurotransmitter and neuromodulator in the central nervous system. How DA modulates the electrical excitability of individual neurons to elicit various behaviors is of great interest in many systems. The buccal ganglion of the freshwater pond snail Helisoma trivolvis contains the neuronal circuitry for feeding and DA is known to modulate the feeding motor program in Helisoma. ⋯ Using the cell culture system, we demonstrated that the strong hyperpolarization was inhibited by the D2 receptor antagonist sulpiride and the phospholipase C (PLC) inhibitor U73122, indicating that DA affected the membrane potential of B5 neurons through the activation of a D2-like receptor and PLC. Further studies revealed that the DA-induced hyperpolarization was inhibited by the K channel blockers 4-aminopyridine and tetraethylammonium, suggesting that K channels might serve as the ultimate target of DA signaling. Through its modulatory effect on the electrical activity of B5 neurons, the release of DA in vivo may contribute to a neuronal output that results in a variable feeding motor program.
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This study investigated the modular control of complex locomotor tasks that require fast changes in direction, i.e., cutting manoeuvres. It was hypothesized that such tasks are accomplished by an impulsive (burst-like) activation of a few motor modules, as observed during walking and running. It was further hypothesized that the performance in cutting manoeuvres would be associated to the relative timing of the activation impulses. ⋯ The variability in timing between impulses across subjects was greater for cutting manoeuvres than for running. The timing difference between M2 and M3 in the cutting manoeuvres was significantly associated to W-Abs (r(2)=0.45) whereas the timing between M3 and M4 was associated to W-Prp (r(2)=0.43). These results suggest that complex locomotor tasks can be achieved by impulsive activation of muscle groups, and that performance is associated to the specific timing of the activation impulses.