Neuroscience
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The classic hypothesis presents the cerebrospinal fluid (CSF) as the "third circulation," which flows from the brain ventricles through the entire CSF system to the cortical subarachnoid space to eventually be passively absorbed into the superior sagittal sinus through arachnoid granulations. The choroid plexus (CP) represents a key organ in the classic CSF physiology and a powerful biological pump, which exclusively secretes CSF. ⋯ The classic hypothesis cannot provide an explanation for these controversies but the recently formulated Bulat-Klarica-Orešković hypothesis can. According to this hypothesis, CSF production and absorption (CSF exchange) are constant and present everywhere in the CSF system, and although the CSF is partially produced by the CP, it is mainly formed as a consequence of water filtration between the capillaries and interstitial fluid.
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Neuroscientific research has made a concerted effort to determine cortical localization using various functional imaging techniques. This approach has undoubtedly yielded important novel anatomical knowledge, albeit at times contradictory, regarding the structural organization of the vestibular cortex. Unfortunately however, this knowledge has not translated to our understanding regarding how neural mechanisms control vestibular function. ⋯ Contrastingly, in the second half of this review, I present previous findings that show how disrupting interhemispheric interactions can modulate the brainstem-mediated vestibular-ocular reflex (VOR). I conclude by speculating why interhemispheric competition induces correlated biases at the cortical and brainstem level respectively. Specifically, I propose that brainstem-mediated vestibulo-spatial and vestibulo-temporal transformations, in addition to coding for head displacement, underpin a generalized cortical magnitude estimation system which the CNS uses to construct dynamic spatio-temporal maps of the physical world, in-turn ensuring spatial orientation.