Neuroscience
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Hepatic encephalopathy (HE) represents a brain dysfunction caused by both acute and chronic liver failures, and its severity deeply affects the prognosis of patients with impaired liver function. In its pathophysiology, ammonia levels and glutamatergic system hyperactivity seem to play a pivotal role in the disruption of brain homeostasis. Here, we investigate important outcomes involved in behavioral performance, electroencephalographic patterns, and neurochemical parameters to better characterize the well-accepted animal model of acute liver failure (ALF) induced by subtotal hepatectomy (92% removal of tissue) that produces ALF. ⋯ The hepatectomized rats presented significant motor behavioral changes accompanied by important abnormalities in classical blood laboratory parameters of ALF, and EEG features suggestive of HE and deep disturbances in the brain glutamatergic system. Using an animal model of ALF induced via subtotal hepatectomy, this work provides a comprehensive and reliable experimental model that increases the opportunity for studying the effects of new treatment strategies to be explored in an unprecedented way. It also presents insights into the pathophysiology of HE in a reproducible model of ALF, which correlates important neurochemical and EEG aspects of the syndrome.
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Parkinson's Disease (PD) is a multi-system neurodegenerative disease where approximately 90% of cases are idiopathic. The remaining 10% of the cases can be traced to a genetic origin and research has largely focused on these associated genes to gain a better understanding of the molecular and cellular pathogenesis for PD. The gene encoding vacuolar protein sorting protein 35 (VPS35) has been definitively linked to late onset familial PD following the identification of a point mutation (D620N) as the causal agent in a Swiss family. ⋯ In this review, we examine what is currently known about VPS35, which has pleiotropic effects, as well as proposed mechanisms of pathogenesis by the D620N mutation. A brief survey of other VPS35 polymorphisms is also provided. Lastly, model systems that are being utilized for these investigations and possible directions for future research are discussed.
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Bilingualism is associated with enhancements in perceptual and cognitive processing necessary for juggling multiple languages. Recent psychophysical studies demonstrate bilinguals also show enhanced multisensory processing and more restricted temporal binding windows for integrating audiovisual information. Here, we probed the neural mechanisms of bilinguals' audiovisual benefits. ⋯ Regional activations were associated with an opposite pattern of behaviors: whereas stronger V1 and PAC activity predicted slower behavioral responses, stronger frontal BA10 responses elicited faster judgments. Our results suggest bilinguals' higher precision in audiovisual perception reflects more veridical sensory coding of physical cues coupled with superior top-down gating of sensory information to suppress the generation of false percepts. Findings underscore that the plasticity afforded by speaking multiple languages shapes extra-linguistic brain regions and can enhance audiovisual brain processing in a domain-general manner.
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We used force-matching tasks between the two hands to test predictions of the recently introduced scheme of perception based on the concept of iso-perceptual manifold (IPM) in the combined afferent-efferent space of neural signals. The main hypothesis was that accuracy and variability of individual finger force matching would be worse in a four-finger task compared to one-finger tasks. The subjects produced accurate force levels under visual feedback by pressing with either all four fingers or by one of the fingers of a hand (task-hand). ⋯ Matching hypothetical commands to fingers, rather than finger forces, could be responsible for the consistent force overshoots. Indices of inter-trial variance affecting and unaffecting total force showed strong stabilization of total force in the task-hand but not in the match-hand in support of an earlier hypothesis on the importance of visual feedback for force stabilization. No differences were seen between the right and left hands suggesting that the dynamic dominance hypothesis may not be generalizable to perceptual phenomena.
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Human bipedal balance control is proposed to be the integrated activity of distributed neural areas. There is growing understanding about the cortical involvement in this highly automated behavior. While evidence exists for cortical activity temporally linked to reactive balance control, little is known about the functional interaction of potential cortical regions. ⋯ The results suggest that there might exist a balance control cortical network while standing and rapid, transient, and frequency-specific reorganization occurs in this network during reactive balance control events. This reorganization was characterized by an increased number of short-range connections between neighboring areas and increased strength between connections in delta, theta, alpha, and beta frequency bands during PEP N1 compared to baseline. To our knowledge, this is the first study to report the existence of functional cortical networks during reactive balance control with potential implications on assessing impaired balance associated with various neural diseases.