Single low-threshold afferents innervating the skin of the human foot modulate ongoing muscle activity in the upper limbs

2013 ◽  
Vol 109 (6) ◽  
pp. 1614-1625 ◽  
Author(s):  
Leah R. Bent ◽  
Catherine R. Lowrey
Keyword(s):  
Upper Limb ◽  
Muscle Activity ◽  
Reflex Response ◽  
Cutaneous Afferents ◽  
Type I ◽  
Triceps Brachii ◽  
Median Response ◽  
Plantar Surface ◽  
Human Foot ◽  
Low Threshold

We have shown for the first time that single cutaneous afferents in the foot dorsum have significant reflex coupling to motoneurons supplying muscles in the upper limb, particularly posterior deltoid and triceps brachii. These observations strengthen what we know from whole nerve stimulation, that skin on the foot and ankle can contribute to the modulation of interlimb muscles in distant innervation territories. The current work provides evidence of the mechanism behind the reflex, where one single skin afferent can evoke a reflex response, rather than a population. Nineteen of forty-one (46%) single cutaneous afferents isolated in the dorsum or plantar surface of the foot elicited a significant modulation of muscle activity in the upper limb. Identification of single afferents in this reflex indicates the strength of the connection and, ultimately, the importance of foot skin in interlimb coordination. The median response magnitude was 2.29% of background EMG, and the size of the evoked response did not significantly differ among the four mechanoreceptor classes ( P > 0.1). Interestingly, although the distribution of afferents types did not differ across the foot dorsum, there was a significantly greater coupling response from receptors located on the medial aspect of the foot dorsum ( P < 0.01). Furthermore, the most consistent coupling with upper limb muscles was demonstrated by type I afferents (fast and slowly adapting). This work contributes to the current literature on receptor specificity, supporting the view that individual classes of cutaneous afferents may subserve specific roles in kinesthesia, reflexes, and tactile perception.

scholarly journals Modulation of Stretch Reflexes of the Finger Flexors by Sensory Feedback From the Proximal Upper Limb Poststroke

2009 ◽  
Vol 102 (3) ◽  
pp. 1420-1429 ◽  
Author(s):  
Gilles Hoffmann ◽  
Derek G. Kamper ◽  
Jennifer H. Kahn ◽  
William Z. Rymer ◽  
Brian D. Schmit
Keyword(s):  
Upper Limb ◽  
Stretch Reflex ◽  
Sensory Input ◽  
Biceps Brachii ◽  
Elbow Flexion ◽  
Spinal Reflex ◽  
Reflex Response ◽  
Emg Activity ◽  
Triceps Brachii ◽  
Flexor Digitorum

Neural coupling of proximal and distal upper limb segments may have functional implications in the recovery of hemiparesis after stroke. The goal of the present study was to investigate whether the stretch reflex response magnitude of spastic finger flexor muscles poststroke is influenced by sensory input from the shoulder and the elbow and whether reflex coupling of muscles throughout the upper limb is altered in spastic stroke survivors. Through imposed extension of the metacarpophalangeal (MCP) joints, stretch of the relaxed finger flexors of the four fingers was imposed in 10 relaxed stroke subjects under different conditions of proximal sensory input, namely static arm posture (3 different shoulder/elbow postures) and electrical stimulation (surface stimulation of biceps brachii or triceps brachii, or none). Fast (300°/s) imposed stretch elicited stretch reflex flexion torque at the MCP joints and reflex electromyographic (EMG) activity in flexor digitorum superficialis. Both measures were greatest in an arm posture of 90° of elbow flexion and neutral shoulder position. Biceps stimulation resulted in greater MCP stretch reflex flexion torque. Fast imposed stretch also elicited reflex EMG activity in nonstretched heteronymous upper limb muscles, both proximal and distal. These results suggest that in the spastic hemiparetic upper limb poststroke, sensorimotor coupling of proximal and distal upper limb segments is involved in both the increased stretch reflex response of the finger flexors and an increased reflex coupling of heteronymous muscles. Both phenomena may be mediated through changes poststroke in the spinal reflex circuits and/or in the descending influence of supraspinal pathways.

The reflex effects of nonnoxious sural nerve stimulation on human triceps surae motor neurons

1994 ◽  
Vol 71 (5) ◽  
pp. 1897-1906 ◽  
Author(s):  
C. G. Kukulka
Keyword(s):  
Motor Neurons ◽  
Sural Nerve ◽  
Short Latency ◽  
Triceps Surae ◽  
Reflex Response ◽  
Cutaneous Afferents ◽  
Onset Latency ◽  
Human Triceps Surae ◽  
Low Threshold ◽  
Stimulation Of

1. The effects of low-intensity electrical stimulation of the ipsilateral sural nerve on the reflex response of human triceps surae motor neurons were examined in 169 motor units recorded in 11 adult volunteers: 69 units from soleus (SOL), 48 units from lateral gastrocnemius (LG), and 52 units from medial gastrocnemius (MG). The reflex effects were assessed by the peristimulus time histogram (PSTH) technique, categorized according to onset latencies, and the magnitudes of effects were calculated as percent changes in baseline firing rates. 2. Sural stimulation evoked complex changes in motor-unit firing at onset latencies between 28 and 140 ms. The two most common responses seen in all muscles were a short-latency depression (D1) in firing (mean onset latency = 40 ms) in 42% of all units studied and a secondary enhancement (E2) in firing (mean onset latency = 72 ms) in 43% of all units. In LG, the D1 effect represented a mean decrease in firing of 52% which was statistically different from the changes in MG (42% decrease) and SOL (38% decrease). The magnitudes of E2 effects were similar across muscles with an average of 47% increase in firing. 3. No differences were found in the frequencies of occurrence for the enhancements in firing among the muscles studied. The main difference in reflex responses was the occurrence of an intermediate latency depression (D2) in 27% of the LG units with a mean onset latency of 72 ms. 4. Based on estimates of conduction times for activation of low-threshold cutaneous afferents, the short-latency D1 response likely represents an oligosynaptic spinal reflex with transmission times similar to the Ia reciprocal inhibitory pathway. These findings raise the question as to the possibility of low-threshold cutaneous afferents sharing common interneurons with low-threshold muscle afferent reflexes that have identical onset latencies. The complex reflex effects associated with low-level stimulation of a cutaneous nerve indicate a rich assortment of peripheral responses that may influence a given movement. The predominance of a specific effect is most likely determined by the interaction of this input with other peripheral signals and descending commands specific to a given motor task.

scholarly journals The Dynamic Thumb-in-Palm Pattern in Children with Spastic Cerebral Palsy and Its Effects on Upper Limb Function

Children ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 17
Author(s):  
Ja Young Choi ◽  
Dong-Wook Rha ◽  
Seon Ah Kim ◽  
Eun Sook Park
Keyword(s):  
Cerebral Palsy ◽  
Upper Limb ◽  
Multivariable Analysis ◽  
Spastic Cerebral Palsy ◽  
Type I ◽  
Upper Arm ◽  
Limb Function ◽  
Upper Limb Function ◽  
Limb Deformities ◽  
Arm Function

The thumb-in-palm (TIP) pattern is one of the most common upper limb deformities in cerebral palsy (CP). This study was designed to investigate the effect of the dynamic TIP pattern on upper limb function in children with spastic CP. This prospective observational study included a total of 106 children with CP with dynamic TIP. The House TIP classification while grasping small or large objects, Melbourne Assessment of Unilateral Upper Limb Function (MUUL), Shriners Hospital Upper Extremity Evaluation (SHUEE), Zancolli classification for wrist–finger flexor deformity, and degree of swan neck deformity were assessed. Type I was the most common and highest functioning House TIP classification type. However, there were no significant differences in upper arm function between types II, III, and IV. The three components of the SHUEE showed stronger association with MUUL than House TIP and Zancolli classifications. After multivariable analysis, functional use of the wrist–finger and the thumb played a more significant role than the dynamic alignment of the thumb. In conclusion, the House TIP classification is useful to describe the TIP pattern. The SHUEE thumb assessment is a useful tool for reflecting upper arm function. The upper arm function was related more with the associated wrist flexor deformity than dynamic TIP.

scholarly journals Histochemical Characterisation and Gene Expression Analysis of Skeletal Muscles from Maremmana and Aubrac Steers Reared on Grazing and Feedlot Systems

Animals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 656
Author(s):  
Giulia Foggi ◽  
Francesca Ciucci ◽  
Maria Conte ◽  
Laura Casarosa ◽  
Andrea Serra ◽  
...  
Keyword(s):  
Gene Expression ◽  
Physical Activity ◽  
Muscle Fibre ◽  
Skeletal Muscles ◽  
Gene Expression Analysis ◽  
Type I ◽  
Triceps Brachii ◽  
Gene Expressions ◽  
Muscle Properties ◽  
Voluntary Physical Activity

This study aimed to characterise the fibre composition of Triceps brachii (TB) and Semimembranosus (SM) muscles from 20 Maremmana (MA) and 20 Aubrac (AU) steers, and the effect of grazing activity in comparison with feedlot system. The histochemical method was performed with the m-ATPase method with an acid pre-incubation, thus allowing to distinguish type I, IIA, and IIB fibres. Additionally, on total RNA extracted from SM muscle, the expressions of atp1a1, mt-atp6, and capn1 genes were evaluated, in order to find potential associations with muscle fibre histochemical characteristics. In SM muscle, the MA steers had the greater frequency of oxidative fibres (type I and IIA) and the higher atp1a1 expression, in comparison to AU steers. Conversely, AU steers had a greater frequency of type IIB fibres, and the higher capn1 expression. A similar histochemical pattern was observed in TB muscle. The grazing activity was probably insufficient to determine differences both for fibre proportion and size, and gene expressions, except for mt-atp6 expression that was surprisingly highest in feedlot MA in comparison to other steers. These findings further the knowledge of muscle properties belonging to these breeds, and the effect of voluntary physical activity since few studies were available in this regard.

Reflex Responses Induced by Tooth Unloading

2000 ◽  
Vol 84 (2) ◽  
pp. 1088-1092 ◽  
Author(s):  
Kemal S. Türker ◽  
Melissa Jenkins
Keyword(s):  
Local Anesthetic ◽  
Muscle Activity ◽  
Masseter Muscle ◽  
Horizontal Direction ◽  
Reflex Response ◽  
Maxillary Incisor ◽  
Static Force ◽  
Incisor Tooth ◽  
Long Latency ◽  
Unloading Reflex

The reflex response of the masseter muscle to the rapid unloading of a single maxillary incisor tooth was studied. Unloading of a static force of 2 N in the horizontal direction resulted in a short-latency excitation, inhibition, and long-latency excitation of masseter muscle activity occurring at latencies of approximately 13, 20, and 40 ms, respectively, with a corresponding change in bite force occurring slightly later in each case. Following the blocking of periodontal input by the injection of local anesthetic around the stimulated tooth, inhibitory responses were abolished. Therefore, it is concluded that the observed masseteric inhibition was caused by the unloading of periodontal mechanoreceptors and thus that these receptors may contribute to the jaw unloading reflex.

Electrophysiology of globus pallidus neurons in vitro

1994 ◽  
Vol 72 (3) ◽  
pp. 1127-1139 ◽  
Author(s):  
A. Nambu ◽  
R. Llinas
Keyword(s):  
Globus Pallidus ◽  
Input Resistance ◽  
Repetitive Firing ◽  
Type I ◽  
Type Ii ◽  
Low Threshold ◽  
Membrane Oscillations ◽  
Neuronal Type ◽  
A Current ◽  
Membrane Level

1. We investigated the electrical properties of globus pallidus neurons intracellularly using brain slices from adult guinea pigs. Three types of neurons were identified according to their intrinsic electrophysiological properties. 2. Type I neurons (59%) were silent at the resting membrane level (-65 +/- 10 mV, mean +/- SD) and generated a burst of spikes, with strong accommodation, to depolarizing current injection. Calcium-dependent low-frequency (1-8 Hz) membrane oscillations were often elicited by membrane depolarization (-53 +/- 8 mV). A low-threshold calcium conductance and an A-current were also identified. The mean input resistance of this neuronal type was 70 +/- 22 M omega. 3. Type II neurons (37%) fired spontaneously at the resting membrane level (-59 +/- 9 mV). Their repetitive firing (< or = 200 Hz) was very sensitive to the amplitude of injected current and showed weak accommodation. Sodium-dependent high-frequency (20-100 Hz) subthreshold membrane oscillations were often elicited by membrane depolarization. This neuronal type demonstrated a low-threshold calcium spike and had the highest input resistance (134 +/- 62 M omega) of the three neuron types. 4. Type III neurons (4%) did not fire spontaneously at the resting membrane level (-73 +/- 5 mV). Their action potentials were characterized by a long duration (2.3 +/- 0.6 ms). Repetitive firing elicited by depolarizing current injection showed weak or no accommodation. This neuronal type had an A-current and showed the lowest input resistance (52 +/- 35 M omega) of the three neuron types. 5. Stimulation of the caudoputamen evoked inhibitory postsynaptic potentials (IPSPs) in Type I and II neurons. In Type II neurons the IPSPs were usually followed by rebound firing. Excitatory postsynaptic potentials and antidromic responses were also elicited in some Type I and II neurons. The estimated conduction velocity of the striopallidal projection was < 1 m/s (Type I neurons, 0.49 +/- 0.37 m/s; Type II neurons, 0.33 +/- 0.13 m/s).

Long-latency, inhibitory spinal pathway to ankle flexors activated by homonymous group 1 afferents

2014 ◽  
Vol 111 (12) ◽  
pp. 2544-2553 ◽  
Author(s):  
Ephrem T. Zewdie ◽  
Francois D. Roy ◽  
Yoshino Okuma ◽  
Jaynie F. Yang ◽  
Monica A. Gorassini
Keyword(s):  
Muscle Activity ◽  
Corticospinal Tract ◽  
Inhibitory Pathway ◽  
Thoracic Spinal Cord ◽  
Thoracic Spinal ◽  
Long Latency ◽  
Inhibitory Feedback ◽  
Spinal Pathway ◽  
Low Threshold ◽  
Pulse Stimulation

Inhibitory feedback from sensory pathways is important for controlling movement. Here, we characterize, for the first time, a long-latency, inhibitory spinal pathway to ankle flexors that is activated by low-threshold homonymous afferents. To examine this inhibitory pathway in uninjured, healthy participants, we suppressed motor-evoked potentials (MEPs), produced in the tibialis anterior (TA), by a prior stimulation to the homonymous common peroneal nerve (CPN). The TA MEP was suppressed by a triple-pulse stimulation to the CPN, applied 40, 50, and 60 ms earlier and at intensities of 0.5–0.7 times motor threshold (average suppression of test MEP was 33%). Whereas the triple-pulse stimulation was below M-wave and H-reflex threshold, it produced a long-latency inhibition of background muscle activity, approximately 65–115 ms after the CPN stimulation, a time period that overlapped with the test MEP. However, not all of the MEP suppression could be accounted for by this decrease in background muscle activity. Evoked responses from direct activation of the corticospinal tract, at the level of the brain stem or thoracic spinal cord, were also suppressed by low-threshold CPN stimulation. Our findings suggest that low-threshold muscle and cutaneous afferents from the CPN activate a long-latency, homonymous spinal inhibitory pathway to TA motoneurons. We propose that inhibitory feedback from spinal networks, activated by low-threshold homonymous afferents, helps regulate the activation of flexor motoneurons by the corticospinal tract.

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