Gravity may provide a ubiquitous allocentric reference to the brain's spatial orientation circuits. Here we describe neurons in the macaque anterior thalamus tuned to pitch and roll orientation relative to gravity, independently of visual landmarks. We show that individual cells exhibit two-dimensional tuning curves, with peak firing rates at a preferred vertical orientation. These results identify a thalamic pathway for gravity cues to influence perception, action and spatial cognition.
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http://dx.doi.org/10.1038/nn.4423 | DOI Listing |
Prog Neurobiol
January 2025
Section on Cognitive Neurophysiology and Imaging, National Institute of Mental Health; Bethesda, MD, USA; Neurophysiology Imaging Facility, National Institute of Mental Health, National Institute of Neurological Disorders and Stroke, National Eye Institute; Bethesda, MD, USA. Electronic address:
The macaque cerebral cortex contains concentrations of neurons that prefer faces over inanimate objects. Although these so-called face patches are thought to be specialized for the analysis of facial signals, their exact tuning properties remain unclear. For example, what happens when an object by chance resembles a face? Everyday objects can sometimes, through the accidental positioning of their internal components, appear as faces.
View Article and Find Full Text PDFBackground: The ciliary muscle is known to play a part in presbyopia, but the mechanism has not received a comprehensive review, which this study aims to achieve. We examined relevant articles published from 1975 through 2022 that explored various properties of the muscle and related tissues in humans and rhesus monkeys. These properties include geometry, elasticity, rigidity, and composition, and were studied using a range of imaging technologies, computer models, and surgical methods.
View Article and Find Full Text PDFExp Brain Res
December 2024
Division of Basic Biomedical Sciences, Laboratory of Neurological Sciences, The University of South Dakota, Sanford School of Medicine, Vermillion, SD, USA.
Injury to one cerebral hemisphere can result in paresis of the contralesional hand and subsequent preference of the ipsilesional hand in daily activities. However, forced use therapy in humans can improve function of the contralesional paretic hand and increase its use in daily activities, although the ipsilesional hand may remain preferred for fine motor activities. Studies in monkeys have shown that minimal forced use of the contralesional hand, which was the preferred hand prior to brain injury, can produce remarkable recovery of function.
View Article and Find Full Text PDFJ Neurosci
December 2024
9 Arts Link, AS4-03-39, Singapore 117572.
Working memory updating is an important executive process. Here, we study the single-neuron mechanisms involved in updating versus protecting memory from distractors in the macaque prefrontal cortex. We recorded single-neuron activity from the lateral prefrontal cortex (LPFC) and prearcuate cortex (PAC) while male monkeys performed a task that required them to update their memory of target locations while ignoring distractors.
View Article and Find Full Text PDFEpilepsia
December 2024
Department of Pharmacology and Physiology, Georgetown University, Washington, District of Columbia, USA.
Objective: Area tempestas, a functionally defined region in the anterior piriform cortex, was identified as a crucial ictogenic trigger zone in the rat brain in the 1980s. However, whether the primate piriform cortex can trigger seizures remains unknown. Here, in a nonhuman primate model, we aimed to localize a similar trigger zone in the piriform cortex and, subsequently, evaluated the ability of focal inhibition of the substantia nigra pars reticulata (SNpr) to suppress the evoked seizures.
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