New Findings What is the central question of study? Are corticospinal responses to acute and short-term squat resistance training task-specific? main finding its importance? A single bout increased spinal excitability, but no changes in were noted following 4 weeks despite task-specific increases strength. The present data suggest that processes along pathway knee extensors play a limited role increase strength training. Abstract Neural adaptations subserving have been shown be...

We have recently shown that the CHEK2*1100delC mutation acts as a low penetrance breast cancer susceptibility allele. To investigate if other CHEK2 variants confer an increased risk of cancer, we screened affected individual with from 68 families. Five these individuals were found to harbour germline in CHEK2. Three carried 1100delC variant (4%). One three also missense variant, Arg180His. In two individuals, variants, Arg117Gly and Arg137Gln, identified. These reside within...

Simultaneous recordings were made from gamma (gamma) motor axons and muscle spindle afferents of the medial gastrocnemius (MG) during locomotion in decerebrate cats. The gamma-neurons identified as static or dynamic (gammas gammad) by correlating their behaviour midbrain stimulation with changes afferent responses to stretch. On basis locomotion, gammas neurons could be divided into two groups. One group (type-1) showed strongly smoothly modulated discharge increasing parallel active...

In locomotion, the flexor muscles of leg are mainly concerned with relatively constant task raising foot, whereas extensors have more variable support and propulsion at different speeds. This suggests that way in which fusimotor system works may differ between two muscle groups. Observations previously made static dynamic gamma-motor firing patterns ankle extensor medial gastrocnemius (MG) therefore been repeated tibialis anterior (TA). One or single axons, dissected from a small filament TA...

1. The effects of the muscle‐depolarizing drug succinylcholine (SCh) on stretch responses jaw‐closer muscle spindle afferents were studied in anaesthetized cat. Using ramp and hold stretches repeated every 6 s basic measurements made were: initial frequency (IF), peak (PF) static index (SI), 0.5 after end stretch. Derived from these dynamic difference (DD) = PF‐IF, (DI) PF‐SI (SD) SI‐IF. Increases measures caused by a single I.V. dose SCh (200 micrograms kg‐1) are symbolized prefix delta. 2....

We have studied four different restriction fragment length polymorphisms (RFLPs) for the LDL receptor gene, detected using enzymes StuI, PvuII, ApaLI, and NcoI, in normal subjects patients with familial hypercholesterolaemia (FH) from London. Significant linkage disequilibrium was between all RFLPs. Used together they give a polymorphism information content (PIC) of greater than 0.7 which makes them useful studying inheritance gene more 70% families FH. The NcoI ApaLI RFLPs were found to be...

1. A population of 269 gastrocnemius muscle spindle afferents have been studied in anaesthetized cats for the effects succinylcholine (SCh) on their response to ramp and hold stretches repeated every 6 s. The effectiveness reliability SCh test was improved by prior stimulation at 10 Hz 30 s increase blood flow. 2. Responses assessed from averaged cycle histograms before after a single I.V. dose 200 micrograms kg‐1. As previous studies jaw spindles basic measurements were initial frequency...

Recordings have been made from multiple single muscle spindle afferents medial gastrocnemius (MG) and tibialis anterior (TA) muscles of one hindlimb in decerebrate cats, together with ankle rotation EMG signals, during treadmill locomotion. Whilst the other three limbs walked freely, experimental limb was denervated except for nerves to MG TA secured so that it could rotate only at joint, without any external load. Each afferent characterised by succinylcholine testing regard its intrafusal...

Electrical stimulation over the mastoids or thoracic spinous processes has been used to assess subcortical contribution corticospinal excitability, but responses are difficult evoke in resting lower limbs limited only a few muscle groups. This might be mitigated by delivering stimuli on spinal column, where descending tracts contain greater relative density of motoneurons projecting limb muscles. We investigated activation axons innervating tibialis anterior (TA) and rectus femoris (RF)...

A bout of maximal lengthening contractions is known to produce muscle damage, but confers protection against subsequent damaging bouts, with both tending be lower in older adults. Neural factors contribute this adaptation, the role corticospinal pathway remains unclear. Twelve young (27 ± 5 yr) and 11 adults (66 4 performed two bouts 60 dorsiflexions 2 weeks apart. Neuromuscular responses were measured preexercise, immediately postexercise, at 24 72 h following bouts. The initial resulted...

The aim of this study was to assess differences in motor performance, as well corticospinal and spinal responses transcranial magnetic percutaneous nerve stimulation, respectively, during submaximal isometric, shortening, lengthening contractions between younger older adults. Fifteen [26 yr (SD 4); 7 women, 8 men] 14 [64 3); 5 9 adults performed isometric shortening dorsiflexion on an isokinetic dynamometer (5°/s) at 25% 50% contraction type-specific maximums. Motor evoked potentials (MEPs)...

Eleven families with Noonan syndrome in either two or three generations have been identified. Following the reports of subjects features both and neurofibromatosis type 1, these pedigrees studied using a number probes at 1 locus (17q11). A significantly negative lod score was obtained intragenic probe NF1-C2, suggesting that genes for are not contiguous.

What is the central question of this study? The relationship between motor unit recruitment and firing rate has been related to size corticospinal output with variations in nervous system gain during isometric contractions. However, behaviour incremental torque might differ anisometric contractions owing differences neural control contraction types. main finding its importance? Corticospinal excitability lengthening was smaller compared shortening but increased a similar manner rates...

The purpose of this study was to assess corticospinal excitability soleus (SOL) and tibialis anterior (TA) at a segmental level during passive ankle movement. Four experimental components were performed the effects movement muscle length on (MEP/Mmax) different lengths, subcortical lumbar spinal segments (LEP/Mmax), intracortical inhibition (SICI) facilitation (ICF), H-reflex in SOL TA. In addition, degree fascicle changes between TA assessed subpopulation Fascicles shortened lengthened with...

This study examines the effect of 4 wk high-intensity isometric resistance training on induced tremor in knee extensor muscles. Fourteen healthy volunteers were assigned to either group (n = 7) or nontraining control 7). Induced was assessed by measuring force fluctuations during anisometric contractions against spring loading, whose compliance varied allow for preferential activation short long latency stretch reflex components. Effects under two contraction conditions: relative matching,...

Recordings have been made from 127 single muscle spindle afferents the longissimus lumborum muscles of anaesthetized cats. They characterized by their responses to passive stretch and effects succinylcholine (SCh) sensitivity vibration. The use SCh permitted assessment for each afferent influence bag1 (b1) bag2 (b2) intrafusal fibres. From this, on assumption that all were affected chain (c) fibres, they classified in four groups: b1b2c (41.9%), b2c (51.4%), b1c (1.3%) c (5.4%). All with b1...

We have studied 17 unrelated families from Iceland who familial hypercholesterolaemia (FH), using three different restriction fragment length polymorphisms (RFLPs) of the LDL receptor gene. In one family FH was caused by a 2 kb deletion in gene region exons 9 to 10. The PvuII (intron 15), NcoI (exon 18), and ApaLI 15) RFLPs were used determine haplotypes associated with defective Iceland. Genotypes determined 77 subjects these families, both non-FH. A rare new RFLP detected subjects. Among...

1. Recordings were made from muscle spindle primary afferents medial gastrocnemius and soleus muscles of the cat to study modulating effects varying gamma-motor stimulation frequency at constant length. Stimulus trains had a mean 50 Hz sinusoidally modulated 1 Hz, with an amplitude modulation +/- 5 30 Hz. 2. When dynamic gamma-axons (gamma(d)) selected for their pure effect on bag(1) fibres, they found have very little afferent firing. 3. Static (gamma(s)) tested random stimulus correlation...