Excessive excitation is hypothesized to cause motoneuron (MN) degeneration in amyotrophic lateral sclerosis (ALS), but actual proof of hyperexcitation vivo missing, and trials based on this concept have failed. We demonstrate, by single-MN electrophysiology, that, contrary expectations, excitatory responses evoked sensory brainstem inputs are reduced MNs presymptomatic mutSOD1 mice. This impairment correlates with disrupted postsynaptic clustering Homer1b, Shank, AMPAR subunits. Synaptic...

Transcranial direct current stimulation (tDCS) affects neurons at both cortical and subcortical levels. The effects involve several descending motor systems but appeared to be relatively weak, as only small increases in the amplitude of subcortically initiated volleys a minute shortening latencies these were found. aim present study was therefore evaluate consequences facilitation on ensuing muscle activation. experiments carried out deeply anaesthetized rats without neuromuscular blockade....

Resistance training, with repeated short-term and high-intensity exercises, is responsible for an increase in muscle mass force. The aim of this study was to determine whether such training induces adaptations the electrophysiological properties motoneurons innervating trained muscles relate these adaptive changes previous observations made on motor unit contractile properties. performed adult male Wistar rats. Animals from group were subjected a 5-wk voluntary progressive weight-lifting...

In many neurological conditions, early-stage neural circuit adaption can preserve relatively normal behaviour. some diseases, spinal motoneurons progressively degenerate yet movement is initially preserved. We therefore investigated whether these neurons and associated microcircuits adapt in a mouse model of progressive motoneuron degeneration. Using combination

The main aim of the present study was to examine what extent long-lasting subcortical actions transcranial direct current stimulation (tDCS) may be related its presynaptic actions. This investigated in red nucleus, where tDCS recently demonstrated facilitate transmission between interpositorubral and rubrospinal neurons. Changes excitability preterminal axonal branches neurons close were during after (0.2 mA) applied over sensorimotor cortical area deeply anaesthetized rats cats. As a...

Direct current (DC) potently increases the excitability of myelinated afferent fibers in dorsal columns, both during DC polarization these and a considerable (>1 h) postpolarization period. The aim present study was to investigate whether similarly long-lasting changes nerve columns may be evoked by field potentials following stimulation peripheral afferents subthreshold epidurally applied pulses. experiments were performed deeply anesthetized rats. effects monitored volleys stimulated...

Spinal polarization evoked by direct current stimulation [trans-spinal (tsDCS)] is a novel method for altering spinal network excitability; however, it remains not well understood. The aim of this study was to determine whether tsDCS influences motoneuron activity. Twenty Wistar rats under general pentobarbital anesthesia were subjected 15 min anodal (n = 10) or cathodal 0.1 mA intensity, and the electrophysiological properties their motoneurons intracellularly measured before, during, after...

Recently, it has been shown that spinal cord polarization considerably modulates motoneuron activity, with certain observed changes in membrane and firing properties outlasting the duration of polarization. The purpose this study was to determine whether repeated sessions transcutaneous transspinal direct current stimulation (tsDCS) induce adaptive properties. In study, adult male Wistar rats under isoflurane anesthesia were subjected anodal (n = 6) or cathodal tsDCS (100 μA, 15 min) 5 days...

Abstract The purpose of this study was to determine whether altered serum and/or muscle concentrations brain-derived neurotrophic factor (BDNF) can modify the electrophysiological properties spinal motoneurons (MNs). This conducted in wild-type and Bdnf heterozygous knockout rats (HET, SD-BDNF). Rats were divided into four groups: control, knockout, control trained, trained. latter two groups underwent moderate-intensity endurance training increase BDNF levels hindlimb muscles. other factors...

The study aimed at determining the influence of a whole body vibration (WBV) on electrophysiological properties spinal motoneurons. WBV training was performed adult male Wistar rats, 5 days week, for wk, and each daily session consisted four 30-s runs 50 Hz. Motoneuron were investigated intracellularly during experiments deeply anesthetized animals. experimental group subjected to seven control nine rats. treatment induced no significant changes in passive membrane However, WBV-evoked...

Trans-spinal direct current stimulation (tsDCS) is a novel neuromodulatory technique that has been used during neurological rehabilitation and sports to modulate muscle activation. However, the physiological mechanisms underly long-lasting functional effects of polarization are not yet fully understood, nor their relationships with specific neuronal populations. The acute facilitatory depressive anodal cathodal on motoneurons have recently demonstrated, aim this study was determine whether...

Abstract Homeostatic feedback loops are essential to stabilize the activity of neurons and neuronal networks. It has been hypothesized that, in context Amyotrophic Lateral Sclerosis (ALS), an excessive gain might hyper- or hypo-excite motoneurons (MNs) contribute pathogenesis. Here, we investigated how neuromodulation MN intrinsic properties is homeostatically controlled presymptomatic adult SOD1(G93A) mice age-matched control WT mice. First, determined that β2 β3-adrenergic receptors, which...

Abstract Ipsilateral actions of pyramidal tract ( PT ) neurons are weak but may, if strengthened, compensate for deficient crossed following brain damage. The purpose the present study was to examine whether transcranial direct current stimulation tDCS can strengthen ipsilateral iPT actions; in particular, those relayed by reticulospinal co‐excited axon collaterals fibres descending and contralateral (co medial longitudinal fascicle MLF ). effects were assessed acute experiments on deeply...

Whole body vibration (WBV) is often applied as an alternative method for strength training or to prevent muscle force decrease. In this study, we evaluated the influence of WBV on Ia monosynaptic input from spindles because tonic reflex responsible enhancement activity observed after WBV. The aim was investigate whether repeated activation during may result in altered synaptic excitation motoneurons. performed adult male Wistar rats, 5 days/wk, wk, and each daily session consisted four 30-s...

The purpose of the study was to determine effects 5-week whole-body vibration (WBV) on contractile parameters and force–frequency relationship functionally isolated motor units rat medial gastrocnemius muscle: fast fatigable (FF), fatigue-resistant (FR), slow (S). Moreover, myosin heavy chain isoform content quantified. Following WBV, maximum tetanic force FF increased by ∼25%. twitch half-relaxation time in all types contraction FR were shortened. twitch-to-tetanus ratio decreased curves...

Several studies have reported differences in the morphological characteristics of motoneurons and contractile properties motor units male female rats. However, spinal motoneuron activity between sexes are not well understood. This study investigates electrophysiological α-motoneurons Wistar rats under pentobarbital anaesthesia. Fast slow types tibial were recorded intracellularly 15 rats, measured parameters compared statistically using two-way ANOVA Tukey post hoc tests. The membrane...

Intracellular recording of spinal motoneurons in vivo provides a "gold standard" for determining the cells' electrophysiological characteristics intact network and holds significant advantages relative to classical vitro or extracellular techniques. An advantage intracellular recordings is that this method can be performed on adult animals with fully mature nervous system, therefore many observed physiological mechanisms translated practical applications. In methodological paper, we describe...

Abstract An imbalance between cells’ intrinsic excitability and synaptic excitation levels is the basis of spinal motoneuron (MN) pathophysiology in Amyotrophic Lateral Sclerosis. Recently, a restoration deficient Ia MNs was achieved by applying acute trans-spinal direct current stimulation (tsDCS) to presymptomatic SOD1 G93A mice. Here we investigate whether two-week repeated tsDCS applied animals can provoke MN neuroplasticity reduce disease burden. Anodal, cathodal or sham polarisation...

Abstract Male and female rats differ in muscle fibre composition, related motor unit contractile properties, spindle density but not number. On the other hand, their motoneurons' intrinsic excitability firing properties are similar. The aim of this study was to investigate whether apparent sex differences body mass force influence proprioceptive input from spindles motoneurons. Medial gastrocnemius motoneurons were investigated intracellularly deeply anaesthetised male rats. Monosynaptic Ia...

Spinal alpha-motoneurons are classified in several types depending on the contractile properties of innervated muscle fibers. This diversity is further displayed different levels vulnerability distinct motor units to neurodegenerative diseases such as Amyotrophic Lateral Sclerosis (ALS). We summarize recent data suggesting that, contrary excitotoxicity hypothesis, most vulnerable hypoexcitable and experience a reduction their firing prior symptoms onset ALS. suggest that dysregulation...