Abstract:
:Muscles paralyzed by chronic (>1 yr) spinal cord injury fatigue readily. Our aim was to evaluate whether the fatigability of paralyzed thenar muscles (n = 10) could be reduced by the repeated delivery of variable versus constant frequency pulse trains. Fatigue was induced in four ways. Intermittent supramaximal median nerve stimulation (300-ms-duration trains) was delivered at 1) constant high frequency (13 pulses at 40 Hz each second for 2 min); 2) variable high frequency (each second for 2 min). The first two intervals of each variable frequency train were 5 and 20 ms. The remaining pulses were evenly distributed in time across 275 ms. The number of pulses varied for each subject such that the force time integral in the unfatigued state matched that evoked by a constant 40-Hz train; 3) constant low frequency (7 pulses at 20 Hz each second for 4 min); and 4) variable low frequency (each second for 4 min). The pulse pattern was the same as that for variable high frequency except that the force-time integral was matched to that produced by the constant low-frequency stimulation. These same experiments were performed on the thenar muscles of five able-bodied control subjects. The variable high-frequency trains used to fatigue paralyzed and control muscles had an average (+/- SE) of 12 +/- 2 and 10 +/- 1 pulses, respectively. Variable low-frequency trains had 7 +/- 1 and 6 +/- 1 pulses, respectively. Significant mean force declines of comparable magnitude (to 20-25% initial fatigue force or to 13-21% initial 50 Hz force) were seen in paralyzed muscles with all four stimulation protocols. The force reductions in paralyzed muscles were always accompanied by significant increases in half-relaxation time and decreases in force-time integral, irrespective of the stimulation protocol. Significant force decreases also occurred in control muscles during each fatigue test. Again, these force declines were similar whether constant or variable pulse patterns were used at high or low frequencies (to 40-60% initial fatigue force or to 29-36% initial 50 Hz force). The force reductions in control muscles were significantly less than those seen in paralyzed muscles, except when constant high-frequency stimulation was used. The variations in stimulation frequency, pulse pattern, and pulse number used in this study therefore had little influence on thenar muscle fatigue in control subjects or in spinal cord-injured subjects with chronic paralysis.
journal_name
J Neurophysioljournal_title
Journal of neurophysiologyauthors
Thomas CK,Griffin L,Godfrey S,Ribot-Ciscar E,Butler JEdoi
10.1152/jn.01002.2002subject
Has Abstractpub_date
2003-04-01 00:00:00pages
2055-64issue
4eissn
0022-3077issn
1522-1598pii
01002.2002journal_volume
89pub_type
杂志文章abstract::Using extra- and intracellular recording techniques, we investigated the epileptiform activity induced by low concentrations (5 and 10 microM) of bath-applied 4-aminopyridine (4-AP) in the CA3 subfield of rat hippocampal slices. We also studied the effects of 4-AP on the excitatory and inhibitory synaptic conductance ...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.1987.57.6.1911
更新日期:1987-06-01 00:00:00
abstract::Populations of output neurons in the mammalian olfactory bulb (OB) exhibit distinct, widespread spatial and temporal activation patterns when stimulated with odorants. However, questions remain as to how ensembles of mitral/tufted (M/T) neurons in the mammalian OB represent odorant information. In this report, the sin...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.01334.2004
更新日期:2006-03-01 00:00:00
abstract::Both N-methyl-D-aspartate (NMDA) and quisqualate/AMPA-insensitive metabotropic glutamate (mGlu) receptors mediate plasticity induction in neocortex, but their interlaminar distribution in cortical microcircuits is largely unknown. We used (+)(3)H-MK801 and (3)H-glutamate binding plus saturating concentrations of NMDA,...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.2000.84.4.1881
更新日期:2000-10-01 00:00:00
abstract::1. The functional organization of interneurons in spinal laminae III-V was studied in an isolated preparation of hamster dorsal horn with sensory innervation from an excised skin patch. Morphological details of 40 neurons were visualized by intracellular injection of horseradish peroxidase. Active and passive membrane...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.1992.68.5.1746
更新日期:1992-11-01 00:00:00
abstract::The aim of this study was to investigate how humans correct ongoing arm movements while standing. Specifically, we sought to understand whether the postural adjustments in the legs required for online corrections of arm movements are predictive or rely on feedback from the moving limb. To answer this question we measu...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.00944.2010
更新日期:2011-05-01 00:00:00
abstract::1. The graded, synaptic potentials of first-order visual interneurons (lamina monopolar cells) were examined with intracellular recordings. The spatiotemporal properties were characterized with drifting sine wave gratings and annuli. 2. Annulus-elicited inhibition is maximal for annulus-test pulse intervals of approxi...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.1994.71.6.2168
更新日期:1994-06-01 00:00:00
abstract::Reaching movements are subject to noise associated with planning and execution, but precisely how these noise sources interact to determine patterns of endpoint variability in three-dimensional space is not well understood. For frontal plane movements, variability is largest along the depth axis (the axis along which ...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.00495.2011
更新日期:2012-01-01 00:00:00
abstract::As a vital skill in an evolving world, interception of moving objects relies on accurate prediction of target motion. In natural circumstances, active gaze shifts often accompany hand movements when exploring targets of interest, but how eye and hand movements are coordinated during manual interception and their depen...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.00476.2017
更新日期:2018-01-01 00:00:00
abstract::1. Subdivided portions of the cut ventral root innervation of the soleus muscle were electrically stimulated in 14 anesthetized cats. The stimulus trains imposed on these nerves simulated the recruitment and rate-modulation patterns of single motor units recorded during stretch-reflex responses in decerebrate preparat...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.1982.47.5.797
更新日期:1982-05-01 00:00:00
abstract::This study examined the effects of selective inactivation of the cerebellar nuclei in the cat on the control of multijoint trajectories and trajectory adaptation to avoid obstacles. Animals were restrained in a hammock and trained to perform a prehension task in which they reached to grasp a small cube of meat from a ...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.2000.83.4.1886
更新日期:2000-04-01 00:00:00
abstract::Transection of a peripheral nerve results in withdrawal of synapses from motoneurons. Some of the withdrawn synapses are restored spontaneously, but those containing the vesicular glutamate transporter 1 (VGLUT1), and arising mainly from primary afferent neurons, are withdrawn permanently. If animals are exercised imm...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.00892.2014
更新日期:2015-04-01 00:00:00
abstract::Smooth pursuit eye movements stabilize slow-moving objects on the retina by matching eye velocity with target velocity. Two critical components are required to generate smooth pursuit: first, because it is a voluntary eye movement, the subject must select a target to pursue to engage the tracking system; and second, g...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.00197.2015
更新日期:2015-06-01 00:00:00
abstract::The mechanism(s) of olfactory transduction in invertebrates remains to be fully understood. In lobster olfactory receptor neurons (ORNs), a nonselective sodium-gated cation (SGC) channel, a presumptive transient receptor potential (TRP)C channel homolog, plays a crucial role in olfactory transduction, at least in part...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.90903.2008
更新日期:2009-03-01 00:00:00
abstract::In tasks requiring judgments about visual stimuli, humans exhibit repetition priming, responding with increased speed when a stimulus is repeated. Repetition priming might depend on repetition suppression, a phenomenon first observed in monkey inferotemporal cortex (IT) whereby, when a stimulus is repeated, the streng...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.01042.2006
更新日期:2007-05-01 00:00:00
abstract::Despite the well-established contribution of neurohumoral activation to morbidity and mortality in heart failure (HF) patients, relatively little is known about the underlying central nervous system mechanisms. In this study, we aimed to determine whether changes in GABAergic inhibitory and glutamatergic excitatory sy...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.00218.2011
更新日期:2011-09-01 00:00:00
abstract::Experimental and clinical evidence indicates that pain can affect cognitive processes, but the cortical networks involved in pain-cognition interactions are unclear. In this study, we determined the effect of pain on the activity of cortical areas involved in cognition acting as a whole (i.e., a network). Subjects und...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.01210.2006
更新日期:2007-05-01 00:00:00
abstract::To program a goal-directed response in the presence of acoustic reflections, the audio-motor system should suppress the detection of time-delayed sources. We examined the effects of spatial separation and inter-stimulus delay on the ability of human listeners to localize a pair of broadband sounds in the horizontal pl...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.00184.2020
更新日期:2020-12-30 00:00:00
abstract::Recent work has investigated the link between motor learning and sensory function in arm movement control. A number of findings are consistent with the idea that motor learning is associated with systematic changes to proprioception (Haith A, Jackson C, Mial R, Vijayakumar S. Adv Neural Inf Process Syst 21: 593-600, 2...
journal_title:Journal of neurophysiology
pub_type: 杂志文章,随机对照试验
doi:10.1152/jn.00122.2012
更新日期:2012-12-01 00:00:00
abstract::Neurons constituting the pacemaker of circadian rhythms, located in the suprachiasmatic nucleus, generate spontaneous firing patterns that change across the day-night cycle. Their average spontaneous firing rate is considered an important functional marker of clock activity because it is highest during daytime and low...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.1997.78.4.1811
更新日期:1997-10-01 00:00:00
abstract::In contrast to hand movements, the existence of a neural representation of saccade kinematics is unclear. Saccade kinematics is typically thought to be specified by motor error/desired displacement and generated by brain stem circuits that are not penetrable to voluntary control. We studied the influence of instructed...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.00329.2017
更新日期:2017-09-01 00:00:00
abstract::1. The purpose of this study was 1) to characterize the decrease observed in mean firing rates of motor units in the first 8-15 s of isometric constant-force contractions and 2) to investigate possible mechanisms that could account for the ability to maintain force output in the presence of decreasing motor unit firin...
journal_title:Journal of neurophysiology
pub_type: 临床试验,杂志文章
doi:10.1152/jn.1996.76.3.1503
更新日期:1996-09-01 00:00:00
abstract::We characterized the electroresponsive and morphological properties of neurons in the bed nucleus of the stria terminalis (BNST). Previously, Rainnie and colleagues distinguished three cell types in the anterolateral region of BNST (BNST-AL): low-threshold bursting cells (LTB; type II) and regular spiking neurons that...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.00408.2013
更新日期:2013-11-01 00:00:00
abstract::1. Semicircular-canal afferents in the squirrel monkey were characterized by their resting discharge, discharge regularity, sensitivity to galvanic currents delivered to the ear (beta *), the gain (g2Hz), and phase lead (phi 2Hz) of their response to 2-Hz sinusoidal head rotations, and their antidromic conduction velo...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.1995.73.3.1270
更新日期:1995-03-01 00:00:00
abstract::The blood oxygen level-dependent (BOLD) functional magnetic resonance imaging signal arises as a consequence of changes in blood flow and oxygen usage that in turn are modulated by changes in neural activity. Much attention has been given to both theoretical and experimental aspects of the energetics but not to the ne...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.00352.2017
更新日期:2018-03-01 00:00:00
abstract::The last few years have seen an increase in the variety of in vivo experiments used for studying cerebellar physiological mechanisms. A combination of ketamine and xylazine has become a particularly popular form of anesthesia. However, because nonanesthetized control conditions are lacking in these experiments, so far...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.00057.2007
更新日期:2007-09-01 00:00:00
abstract::Following stepping in-place on the surface of a rotating circular treadmill, a subject attempting to step in-place or walk in a straight line across the floor without vision will rotate relative to space. This adaptation, termed podokinetic after-rotation (PKAR), transfers to backward walking following forward walking...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.00588.2001
更新日期:2002-02-01 00:00:00
abstract::The human ventral visual pathway is implicated in higher order form processing, but the organizational principles within this region are not yet well understood. Recently, Lafer-Sousa, Conway, and Kanwisher (J Neurosci 36: 1682-1697, 2016) used functional magnetic resonance imaging to demonstrate that functional respo...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.00358.2016
更新日期:2017-03-01 00:00:00
abstract::GABA(B)-receptor-mediated inhibition was investigated in anatomically identified inhibitory interneurons located at the border between the dentate gyrus granule cell layer and hilus. Biocytin staining was used to visualize the morphology of recorded cells. A molecular layer stimulus evoked a pharmacologically isolated...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.1999.82.3.1438
更新日期:1999-09-01 00:00:00
abstract::In experiments on slices (from 100- to 150-g Sprague-Dawley rats) kept at 33 degreesC, we studied the effects of brief hypoxia (2-3 min) on CA1 neurons. In whole cell recordings from submerged slices, with electrodes containing only KMeSO4 and N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid, and in the presence of...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.1998.80.5.2378
更新日期:1998-11-01 00:00:00
abstract::The recurrent mossy fiber pathway of the dentate gyrus expands dramatically in the epileptic brain and serves as a mechanism for synchronization of granule cell epileptiform activity. It has been suggested that this pathway also promotes epileptiform activity by inhibiting GABA(A) receptor function through release of ...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.2001.85.5.1932
更新日期:2001-05-01 00:00:00