Journal of Neurophysiology

Acetylcholine is a neurotransmitter that plays a variety of roles in the central nervous system. It was previously shown that blocking muscarinic receptors with a non-selective antagonist prevents a form of experience-dependent plasticity termed "spatiotemporal sequence learning" in the mouse primary visual cortex (V1). Muscarinic signaling is a complex process involving the combined activities of five different G-protein coupled receptors, M1-M5, all of which are expressed in the murine brain but differ from each other functionally and in anatomical localization...

Rare disruptions of the transcription factor FoxP1 are implicated in a human neurodevelopmental disorder characterised by autism and/or intellectual disability with prominent problems in speech and language abilities. Avian orthologues of this transcription factor are evolutionarily conserved and highly expressed in specific regions of songbird brains, including areas associated with vocal production learning and auditory perception. Here, we investigated possible contributions of FoxP1 to song discrimination and auditory perception in juvenile and adult female zebra finches...

The CNS may produce the same endpoint trajectory or torque profile with different muscle activation patterns. What differentiates these patterns is the presence of co-contraction, which does not contribute to effective torque generation but allows to modulate joints' mechanical stiffness. While it has been suggested that the generation of force and the modulation of stiffness rely on separate pathways, a characterization of the differences between the synaptic inputs to motor neurons (MNs) underlying these tasks is still missing...

Previous studies suggest that bimanual coordination recruits neural mechanisms that explicitly couple control of the arms, resulting in symmetric kinematics. However, the higher symmetry for actions that require congruous joint motions compared to non-congruous joint motions calls into question the concept of control coupling as a general policy. An alternative view proposes that co-dependence might emerge from an optimal feedback controller that minimizes control effort and costs in task performance. Support for this view comes from studies comparing conditions in which both hands move a shared or independent virtual objects...

Microneurographic recordings of muscle sympathetic nerve activity (MSNA) reflects postganglionic sympathetic axonal activity directed toward the skeletal muscle vasculature. Recordings are typically evaluated for spontaneous bursts of MSNA; however, the filtering and integration of raw neurograms to obtain multi-unit bursts conceals the underlying c-fiber discharge behavior. The continuous wavelet transform with matched mother wavelet has permitted the assessment of action potential discharge patterns, but this approach uses a mother wavelet optimized for an amplifier that is no longer commercially available (University of Iowa Bioengineering Nerve Traffic Analysis System; Iowa NTA)...

Two subtypes of striatal spiny projection neurons, iSPNs and dSPNs, whose axons form the "indirect" and "direct" pathways of the basal ganglia respectively, both make synaptic connections in the external globus pallidus (GPe), but are usually found to have different effects on behavior. Activation of the terminal fields of iSPNs or dSPNs generated compound currents in almost all GPe neurons. To determine whether iSPNs and dSPNs have the same or different effects on pallidal neurons, we studied the unitary synaptic currents generated in GPe neurons by action potentials in single striatal neurons...

Communication between cells in the nervous system is dependent on both chemical and electrical synapses. Factors that can affect chemical synapses have been well studied, but less is known about factors that influence electrical synapses. Retinoic acid, the Vitamin A metabolite, is a known regulator of chemical synapses, but few studies have examined its capacity to regulate electrical synapses. In this study, we determine that retinoic acid is capable of rapidly altering the strength of electrical synapses in an isomer and cell-dependent manner...

At the heart of the prefrontal network is the mediodorsal thalamus (MD). Despite the importance of MD in a broad range of behaviors and neuropsychiatric disorders, little is known about the physiology of neurons in MD. We injected the retrograde tracer cholera toxin subunit B (CTB) into the medial prefrontal cortex (mPFC) of adult wildtype mice. We prepared acute brain slices and used current clamp electrophysiology to measure and compare the intrinsic properties of the neurons in MD that project to mPFC (MD→mPFC neurons)...

The flexibility of the motor system to adjust a planned action before or during the execution of the movement in response to sensory information is critical for preventing errors in motor control. As individuals age, this function declines, leading to an increased incidence of motor errors. While sensory processing and cognitive decline are known contributors to this impairment, here, we test the hypothesis that repetition of context-specific planned actions interferes with the adjustment of feedforward motor commands...

BACKGROUND: Stimuli that potentially require a rapid defensive or avoidance action can appear from the periphery at any time in natural environments. De Wit, Faseyitan, and Coslett (2020) recently reported novel evidence suggestive of a fundamental neural mechanism that allows organisms to effectively deal with such situations. In the absence of any task, motor cortex excitability was found to be greater whenever gaze was directed away from either hand. OBJECTIVE/HYPOTHESIS: If modulation of cortical excitability as a function of gaze location is a fundamental principle of brain organization, then one would expect its operation to be present also outside of motor cortex, such as brain regions involved in perception...

Motor disturbances predominantly characterize hypoxic-ischemic encephalopathy (HIE). Among its intervention methods, Environmental Enrichment (EE) is strictly considered a form of sensory intervention. However, limited research employs EE as a single sensory input intervention to validate outcomes post-intervention. A Sprague-Dawley rat model subjected to left common carotid artery ligation and exposure to oxygen-hypoxic conditions use in this study. EE was achieved by enhancing the recreational and stress-relief items within the cage, increasing the duration of sunlight, colorful items exposure, and introducing background music...

Learning outcome is modified by the degree to which the subject responds and pays attention to specific stimuli. Our recent research suggests that presenting stimuli in contingency with a specific phase of the cardiorespiratory rhythm might expedite learning. Specifically, expiration-diastole (EXP-DIA) is beneficial for learning trace eyeblink conditioning (TEBC) compared to inspiration-systole (INS-SYS) in healthy young adults. The aim of this study was to investigate whether the same holds true in healthy elderly adults (n = 50, aged >70 years)...

The etiology of spaceflight-associated neuro-ocular syndrome (SANS) is a developing field of research, with many current hypotheses receiving varying degrees of support. In this article, three prominent risk factors including zero gravity conditions, extraterrestrial hypercapnic environments, and individual genetic predisposition are described and their pathophysiological pathways are compared. In addition, glymphatic system impairment is explored as a potential mutual endpoint for these pathways in the development of SANS...

This paper evaluates the ethical implications of utilizing artificial intelligence (AI) algorithms in neurological diagnostic examinations. Applications of AI technology have been utilized to aid in the determination of pharmacological dosages of gadolinium for brain lesion detection, localization of seizure foci, and the characterization of large vessel occlusion in ischemic stroke patients. Multiple subtypes of AI- machine learning (AI/ML) algorithms are analyzed as AI-assisted neurology utilizes supervised, unsupervised, artificial neural network (ANN), and deep neural network (DNN) learning models...

A recent study by Tran et al.10 investigated the cellular processes underlying the timing and regulation of oligodendrocyte production, focusing on the role of Notch signaling in the dorsal forebrain of mouse embryos. They found that while Notch signaling is required to specify oligodendrocyte precursor cell fate during embryonic development, over-expression prevents oligodendrogenesis through several mechanisms. This critical review highlights their findings, offering several suggestions for future research investigating the precise spatiotemporal control of Notch signaling throughout the development of the central nervous system...

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that causes motoneuron death. Motoneuron excitability dysfunction in ALS is suspected to contribute to motoneuron degeneration. Therefore, mechanisms underlying excitability dysfunction are being thoroughly investigated. A recent publication from Trajano et al. (Trajano, G. S., Orssatto, L. B. R., McCombe, P. A., Rivlin, W., Tang, L., & Henderson, R. D. The Journal of Physiology , 2023) examined temporal changes to persistent inward currents (PICs) in ALS patients...

To generate a force, the brain activates muscles that act like springs to pull the arm toward a new equilibrium position. The equilibrium position (EP) is central to our understanding of the biological control of viscoelastic muscles. While there is evidence of the EP during the control of limb posture, EPs have not been directly identified when the limb exerts a force against the environment. Here, we asked participants to apply a constant force in one of eight directions against a point-like constraint. This constraint was released abruptly to observe the final position to which the arm converged...

INTRODUCTION: The neural pathways that contribute to force production in humans are currently poorly understood, as the relative roles of the corticospinal tract and brainstem pathways, such as the reticulospinal tract (RST), vary substantially across species. Using functional magnetic resonance imaging (fMRI) we aimed to measure activation in the pontine reticular nuclei (PRN) during different submaximal handgrip contractions to determine the potential role of the PRN in force modulation...

The inferior colliculus (IC) of the midbrain is important for complex sound processing, such as discriminating conspecific vocalizations and human speech. The IC's non-lemniscal, dorsal "shell" region is likely important for this process, as neurons in these layers project to higher-order thalamic nuclei that subsequently funnel acoustic signals to the amygdala and non-primary auditory cortices; forebrain circuits important for vocalization coding in a variety of mammals, including humans. However, the extent to which shell IC neurons transmit acoustic features necessary to discern vocalizations is less clear, owing to the technical difficulty of recording from neurons in the IC's superficial layers via traditional approaches...

The striatum receives projections from multiple regions of the cerebral cortex consistent with the role of the basal ganglia in diverse motor, affective, and cognitive functions. Within the striatum, the caudate receives projections from association cortex including multiple distinct regions of prefrontal cortex. Building on recent insights about the details of how juxtaposed cortical networks are specialized for distinct aspects of higher-order cognition, we revisited caudate organization using within-individual precision neuroimaging initially in two intensively scanned individuals (each scanned 31 times)...