Schematic diagram outlining the possible neural pathways for integration of cutaneous reflex pathways inputs from different nerves of foot during arm and leg remote rhythmic movement (ARM&LEG).

<p>At the center is a simplified interneuronal (IN) reflex pathways in tibialis anterior muscles. Inputs from the sural and tibial nerves have connections onto shared INs (dashed black lines). Excitability of common INs and motoneurons (MNs) are regulated by central commands and peripheral feedback related to LEG (blue square) and ARM (green square) movement. It is possible that individual input arising from each LEG and ARM movement converge “in parallel” onto these putative reflex pathways (dashed lines of blue and green squares) during ARM&LEG movement. TIB n.: tibial nerve. SUR n.: sural nerve. MNs: motoneurons.</p

The effects of galvanic vestibular stimulation (GVS) on ulnar nerve-induced facilitation of motor-evoked potentials in a single subject.

<p>Full-wave rectified and averaged electromyograms (EMGs) in the biceps brachii (BB) muscle after separate ulnar nerve stimulation (NERVE) at 1.0 × the motor threshold of the first dorsal interosseous muscle (<b>A</b>, <b>E</b>, <b>I</b>), separate transcranial magnetic stimulation (TMS) over the contralateral primary motor cortex at 1.1 × the active motor threshold of the BB (<b>B</b>, <b>F</b>, <b>J</b>), and the combination (COMB) of NERVE and TMS (<b>C</b>, <b>G</b>, <b>K</b>). These waveforms were obtained without GVS (left panels), during anodal GVS (middle panels), and during cathodal GVS (right panels) at 2.0 × the perceptual threshold of the head sway. The grey waveforms in <b>C</b>, <b>G</b>, and <b>K</b> represent the summation (SUM) of the averaged EMG waveforms after separate TMS and NERVE. The waveforms in <b>D</b>, <b>H</b>, and <b>L</b> represent the COMB waveforms with the SUM waveforms subtracted.</p

Convergence effect of simultaneous sural and tibial nerve stimulation on TA cutaneous reflex amplitude during ARM&LEG movement.

<p>(A) Full-wave rectified and averaged EMG in TA muscle following simultaneous combined stimulation of sural and tibial nerves (TIB&SUR, red trace), sural alone (SUR, green trace) and tibial alone (TIB, Blue trace) obtained from a single subject. Dashed gray trace: the mathematical summation of EMG traces for individual TIB and SUR nerves stimulation (Algebraic SUM). (B) Grand means (± SD) of the magnitudes of early-latency reflex responses (45–80 ms after stimulation onset) following simultaneous combined stimulation of sural and tibial nerves (Red bar), sural alone (Green bar) and tibial alone (Blue bar) obtained from 12 subjects. Hatched gray bar: mathematical summation of reflex amplitude for individual nerve stimulation (TIB+SUR). * <i>p</i><0.001. Calibration bar = 10 µV.</p

Schematic of the methodology and potential premotoneuronal pathways in the cervical cord.

<p>The wiring pattern is oversimplified for better understanding. Black and red solid lines represent direct (monosynaptic) connections, whereas purple and green dashed lines represent indirect (non-monosynaptic) connections no matter whether its effect is facilitatory or inhibitory. The pyramidal tract volleys (a red arrow) that are produced by transcranial magnetic stimulation (TMS) over the contralateral motor cortex and the afferent volleys (a green arrow) that are produced by electrical stimulation of the ipsilateral ulnar nerve (NERVE) at the wrist converge onto a common cervical interneuron (IN) that projects to motoneurons (MNs) of the biceps brachii (BB) muscle, which results in extra facilitation of motor-evoked potentials (MEPs) in the BB. The TMS and NERVE are timed so that the pyramidal tract and afferent volleys simultaneously arrive at the upper cervical cord. The inputs produced by galvanic vestibular stimulation (GVS) through the bilateral mastoid processes also converge on the IN pool. FDI: first dorsal interosseous muscle, EMG: electromyogram.</p

The effects of galvanic vestibular stimulation (GVS) on the firing probability of single motor units (MUs) after combined motor cortex and ulnar nerve stimulation.

<p><b>A</b>–<b>H</b> show the peristimulus time histograms (PSTHs) of a single MU in the biceps brachii (BB) muscle after separate ulnar nerve stimulation (NERVE) at 1.0 × motor threshold (MT) of the first dorsal interosseous muscle (<b>A</b>, <b>E</b>), separate transcranial magnetic stimulation (TMS) (<b>B</b>, <b>F</b>) over the contralateral primary motor cortex at 1.25 × active motor threshold of the BB, and combined stimulation (COMB) (<b>C</b>, <b>G</b>) in the control (<b>A</b>–<b>D</b>) and anodal GVS conditions (<b>E</b>–<b>H</b>). Each PSTH was obtained after 50 stimuli. The counts in these PSTHs were subtracted by the mean counts during a 50 ms prestimulus period. <b>D</b> and <b>H</b> show differential PSTHs after subtraction of the summed PSTHs after separate stimuli from the PSTHs of the COMB. The number of counts in each bin was normalized by the number of triggers. The vertical dashed line represents the onset of the excitatory peak in the PSTH after separate TMS. The superimposed waveforms in the upper right corner of each PSTH show the MU action potentials (n = 50) obtained from each stimulus trial. <b>I</b>–<b>L</b> indicate the peak counts of the MU firings in the differential PSTHs in the control and anodal GVS conditions obtained from 31 MUs that were investigated with the NERVE set at 1.0 × MT (<b>I</b>, <b>J</b>) and 20 MUs that were investigated with the NERVE set at 0.75 × MT (<b>K</b>, <b>L</b>). The error bars represent 1 standard deviation. The analysis window was set at a predefined period (1.0 ms duration) that started 1.0 ms after the onset of the TMS-induced excitatory peak in the PSTH. **<i>p</i> < 0.01.</p

Typical recordings of EMG activities in AD, VL, MG and TA muscles during ARM&LEG movement for a single subject.

<p>Gray vertical line: stimulation position of ipsilataral side. Dashed lines: flexion phase of movement. Thick lines: extension phase of movement.</p

The pooled data for the effects of galvanic vestibular stimulation (GVS) on the ulnar nerve-induced facilitation of motor-evoked potentials (MEPs) across subjects.

<p>The pooled data for the mean areas of the MEPs in the biceps brachii muscle after separate ulnar nerve stimulation (NERVE), separate transcranial magnetic stimulation (TMS) over the contralateral primary motor cortex, and the combination (COMB) of NERVE and TMS in the control (<b>A</b>, <b>E</b>), anodal GVS (<b>B</b>, <b>F</b>), and cathodal GVS conditions (<b>C</b>, <b>G</b>). <b>D</b> and <b>H</b> show the average of the amount of spatial facilitation in the control and GVS conditions. The areas of the MEPs after the combined stimuli were normalized by the summation of the areas of the MEPs recorded after separate TMS and NERVE. <b>A</b>–<b>D</b> and <b>E</b>–<b>H</b> illustrate the data from experiments involving ulnar nerve stimulation at 1.0 and 0.75 × the motor threshold (MT) of the first dorsal interosseous muscle, respectively. The error bars represent standard errors of the mean. The asterisks indicate a statistically significant difference between conditions (*<i>p</i> < 0.05, **<i>p</i> < 0.01).</p

Experimental tasks in the present study.

<p><b>A</b>–<b>D</b> show the number of subjects, number of test sequences, and stimulus conditions in each experiment. Each block indicates the test sequence used to assess the spatial facilitation effects. The stimulus intensities of the transcranial magnetic stimulation (TMS), ulnar nerve stimulation (NERVE), and galvanic vestibular stimulation (GVS) are indicated within the block. The order of the test sequences was randomly selected. MEP: motor-evoked potential, MT: motor threshold of the first dorsal interosseous muscle, PT: perceptual threshold of GVS-induced head sway, MU: motor unit, AMT: active motor threshold of the biceps brachii muscle.</p

The population-specific <i>F_ST</i> values of three chicken groups.

<p>The population-specific <i>F_ST</i> values of three chicken groups.</p

Three-dimensional structure of the DRD4 protein for domesticated chickens.

<p>The disordered region (arrow) is the region of proline repeats located on the outside of the cell membrane which receives dopamine released from the synaptic cell.</p