Operant conditioning of primate spinal reflexes: the H-reflex

1987 ◽  
Vol 57 (2) ◽  
pp. 443-459 ◽  
Author(s):  
J. R. Wolpaw
Keyword(s):  
Operant Conditioning ◽  
H Reflex ◽  
Spinal Reflexes ◽  
Triceps Surae ◽  
Spinal Reflex ◽  
Control Mode ◽  
Response Threshold ◽  
Reflex Amplitude ◽  
Emg Amplitude ◽  
Spinal Stretch Reflex

The study of primate memory substrates, the CNS alterations which preserve conditioned responses, requires an experimental model that fulfills two criteria. First, the essential alterations must be in a technically accessible location. Second, they must persist without input from other CNS regions. The spinal cord is the most technically accessible and readily isolated portion of the primate CNS. Recent work has demonstrated that the spinal stretch reflex (SSR), the initial, wholly segmental response to muscle stretch, can be operantly conditioned and suggests that this conditioning may produce persistent spinal alteration. The present study attempted similar operant conditioning of the H-reflex, the electrical analog of the SSR. The primary goals were to demonstrate that spinal reflex conditioning can occur even if the muscle spindle is removed from the reflex arc and to demonstrate conditioning in the lumbosacral cord, which is far preferable to the cervical cord for future studies of neuronal and synaptic mechanisms. Nine monkeys prepared with chronic fine-wire triceps surae (gastrocnemius and soleus) electromyographic (EMG) electrodes were taught by computer to maintain a given level of background EMG activity. At random times, a voltage pulse just above M response (direct muscle response) threshold was delivered to the posterior tibial nerve via a chronically implanted silicon nerve cuff and elicited the triceps surae H-reflex. Under the control mode, reward always followed. Under the HR increases or HR decreases mode, reward followed only if the absolute value of triceps surae EMG from 12 to 22 ms after the pulse (the H-reflex interval) was above (HR increases) or below (HR decreases) a set value. Monkeys completed 3,000-6,000 trials/day over study periods of 2-3 mo. Background EMG and M response amplitude remained stable throughout data collection. H-reflex amplitude remained stable under the control mode. Under the HR increases mode (5 animals) or HR decreases mode (4 animals), H-reflex amplitude (EMG amplitude in the H-reflex interval minus background EMG amplitude) changed appropriately over at least 6 wk. Change appeared to occur in two phases: an abrupt change within the first day, followed by slower change, which continued indefinitely. Change occurred in all three triceps surae muscles (medial and lateral gastrocnemii and soleus). Under the HR increases mode, H-reflex amplitude rose to an average of 213% of control, whereas under the HR decreases mode it fell to an average of 68% of control. The results demonstrate that the H-reflex can be operantly conditioned.(ABSTRACT TRUNCATED AT 400 WORDS)

Memory traces in primate spinal cord produced by operant conditioning of H-reflex

1989 ◽  
Vol 61 (3) ◽  
pp. 563-572 ◽  
Author(s):  
J. R. Wolpaw ◽  
C. L. Lee
Keyword(s):  
Spinal Cord ◽  
Operant Conditioning ◽  
Internal Control ◽  
H Reflex ◽  
Triceps Surae ◽  
Reflex Response ◽  
Reflex Amplitude ◽  
Memory Traces ◽  
Spinal Stretch Reflex ◽  
Root Stimulation

1. Study of memory traces in higher animals requires experimental models possessing well-localized and technically accessible memory traces--plasticity responsible for behavioral change, not dependent on control from elsewhere, and open to detailed investigation. Our purpose has been to develop such a model based on the wholly spinal, largely monosynaptic path of the spinal stretch reflex. Previous studies described operant conditioning of this reflex and of its electrical analog, the H-reflex. In this study, we sought to determine whether conditioning causes changes in the spinal cord that affect the reflex and are not dependent on continued supraspinal influence, and thus qualify as memory traces. 2. Sixteen monkeys underwent chronic conditioning of the triceps surae H-reflex. Eight were rewarded for increasing H-reflex amplitude (HR increases mode), and eight were rewarded for decreasing it (HR decreases mode). In each animal, the other leg was an internal control. Over several months of conditioning, H-reflex amplitude in the conditioned leg rose in HR increases animals and fell in HR decreases animals. H-reflex amplitude in the control leg changed little. 3. After HR increases or HR decreases conditioning, each animal was deeply anesthetized and surgically prepared. The reflex response to supramaximal dorsal root stimulation was measured from the triceps surae nerve as percent of response to supramaximal ventral root stimulation, which was the maximum possible response. Data from both legs were collected before and for up to 3 days after thoracic (T9-10) cord transection. The animal remained deeply anesthetized throughout and was killed by overdose. 4. The reflex asymmetries produced by conditioning were still present several days after transection removed supraspinal influence: reflexes of HR increases animals were significantly larger in HR increases legs than in control legs and reflexes of HR decreases animals were significantly smaller in HR decreases legs than in control legs. 5. Reflex amplitude was much greater in the control legs of anesthetized HR decreases animals than in the control legs of anesthetized HR increases animals. 6. Chronic conditioning had at least two effects on the spinal cord. The first effect, task-appropriate reflex asymmetry, was evident both in the awake behaving animal and in the anesthetized transected animal. The second effect, larger control leg reflexes in HR decreases than in HR increases animals, was evident only in the anesthetized animal. By removing supraspinal control, anesthesia and transection revealed a previously hidden effect of conditioning.(ABSTRACT TRUNCATED AT 400 WORDS)

Operant conditioning of H-reflex in freely moving rats

1995 ◽  
Vol 73 (1) ◽  
pp. 411-415 ◽  
Author(s):  
X. Y. Chen ◽  
J. R. Wolpaw
Keyword(s):  
Operant Conditioning ◽  
H Reflex ◽  
Response Amplitude ◽  
Primate Research ◽  
Sprague Dawley ◽  
Initial Value ◽  
Reflex Amplitude ◽  
Nerve Cuff ◽  
Spinal Stretch Reflex ◽  
Experimental Use

1. Primates can increase or decrease the spinal stretch reflex and its electrical analogue, the H-reflex (HR), in response to an operant conditioning task. This conditioning changes the spinal cord itself and thereby provides an experimental model for defining the processes and substrates of a learned change in behavior. Because the phenomenon has been demonstrated only in primates, its generality and theoretical implications remain unclear, and its experimental use is restricted by the difficulties of primate research. In response to these issues, the present study explored operant conditioning of the H-reflex in the rat. 2. Seventeen Sprague-Dawley rats implanted with chronic electromyographic (EMG) recording electrodes in one soleus muscle and nerve cuff stimulating electrodes on the posterior tibial nerve were rewarded (either with medial forebrain bundle stimulation or food) for increasing (HRup conditioning mode) or decreasing (HRdown conditioning mode) soleus H-reflex amplitude without change in background EMG or M response (direct muscle response) amplitude. 3. H-reflex amplitude changed appropriately over 3-4 wk. Under the HRup mode, it rose to an average of 158 +/- 54% (mean +/- SD) of initial value, whereas under the HRdown mode it fell to an average of 67 +/- 11% of initial value. Background EMG and M response amplitude did not change. 4. Operant conditioning of the H-reflex in the rat appears similar in rate and final magnitude of change to that observed in the monkey.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Operant Conditioning of Reciprocal Inhibition in Rat Soleus Muscle

2006 ◽  
Vol 96 (4) ◽  
pp. 2144-2150 ◽  
Author(s):  
Xiang Yang Chen ◽  
Lu Chen ◽  
Yi Chen ◽  
Jonathan R. Wolpaw
Keyword(s):  
Spinal Cord ◽  
Operant Conditioning ◽  
Reciprocal Inhibition ◽  
H Reflex ◽  
Spinal Reflex ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Cord Injury ◽  
Rat Soleus Muscle ◽  
Spinal Stretch Reflex

Operant conditioning of the H-reflex, the electrical analog of the spinal stretch reflex (SSR), induces activity-dependent plasticity in the spinal cord and might be used to improve locomotion after spinal cord injury. To further assess the potential clinical significance of spinal reflex conditioning, this study asks whether another well-defined spinal reflex pathway, the disynaptic pathway underlying reciprocal inhibition (RI), can also be operantly conditioned. Sprague-Dawley rats were implanted with electromyographic (EMG) electrodes in right soleus (SOL) and tibialis anterior (TA) muscles and a stimulating cuff on the common peroneal (CP) nerve. When background EMG in both muscles remained in defined ranges, CP stimulation elicited the TA H-reflex and SOL RI. After collection of control data for 20 days, each rat was exposed for 50 days to up-conditioning (RIup mode) or down-conditioning (RIdown mode) in which food reward occurred if SOL RI evoked by CP stimulation was more (RIup mode) or less (RIdown mode) than a criterion. TA and SOL background EMG and TA M response remained stable. In every rat, RI conditioning was successful (i.e., change ≥20% in the correct direction). In the RIup rats, final SOL RI averaged 171± 28% (mean ± SE) of control, and final TA H-reflex averaged 114 ± 14%. In the RIdown rats, final SOL RI averaged 37 ± 13% of control, and final TA H-reflex averaged 60 ± 18%. Final SOL RI and TA H-reflex sizes were significantly correlated. Thus like the SSR and the H-reflex, RI can be operantly conditioned; and conditioning one reflex can affect another reflex as well.

scholarly journals Electrocorticographic activity over sensorimotor cortex and motor function in awake behaving rats

2015 ◽  
Vol 113 (7) ◽  
pp. 2232-2241 ◽  
Author(s):  
Chadwick B. Boulay ◽  
Xiang Yang Chen ◽  
Jonathan R. Wolpaw
Keyword(s):  
Sensorimotor Cortex ◽  
Afferent Input ◽  
H Reflex ◽  
Spinal Reflex ◽  
Emg Activity ◽  
Adult Rats ◽  
Frequency Spectra ◽  
Emg Amplitude ◽  
Spinal Stretch Reflex ◽  
The Impact

Sensorimotor cortex exerts both short-term and long-term control over the spinal reflex pathways that serve motor behaviors. Better understanding of this control could offer new possibilities for restoring function after central nervous system trauma or disease. We examined the impact of ongoing sensorimotor cortex (SMC) activity on the largely monosynaptic pathway of the H-reflex, the electrical analog of the spinal stretch reflex. In 41 awake adult rats, we measured soleus electromyographic (EMG) activity, the soleus H-reflex, and electrocorticographic activity over the contralateral SMC while rats were producing steady-state soleus EMG activity. Principal component analysis of electrocorticographic frequency spectra before H-reflex elicitation consistently revealed three frequency bands: μβ (5–30 Hz), low γ (γ1; 40–85 Hz), and high γ (γ2; 100–200 Hz). Ongoing (i.e., background) soleus EMG amplitude correlated negatively with μβ power and positively with γ1 power. In contrast, H-reflex size correlated positively with μβ power and negatively with γ1 power, but only when background soleus EMG amplitude was included in the linear model. These results support the hypothesis that increased SMC activation (indicated by decrease in μβ power and/or increase in γ1 power) simultaneously potentiates the H-reflex by exciting spinal motoneurons and suppresses it by decreasing the efficacy of the afferent input. They may help guide the development of new rehabilitation methods and of brain-computer interfaces that use SMC activity as a substitute for lost or impaired motor outputs.

scholarly journals Effect of cervicolumbar coupling on spinal reflexes during cycling after incomplete spinal cord injury

2018 ◽  
Vol 120 (6) ◽  
pp. 3172-3186 ◽  
Author(s):  
R. Zhou ◽  
B. Parhizi ◽  
J. Assh ◽  
L. Alvarado ◽  
R. Ogilvie ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
H Reflex ◽  
Spinal Reflexes ◽  
Incomplete Spinal Cord Injury ◽  
Reflex Amplitude ◽  
Arm Cycling ◽  
Cord Injury ◽  
Leg Cycling ◽  
Cycling Training

Spinal networks in the cervical and lumbar cord are actively coupled during locomotion to coordinate arm and leg activity. The goals of this project were to investigate the intersegmental cervicolumbar connectivity during cycling after incomplete spinal cord injury (iSCI) and to assess the effect of rehabilitation training on improving reflex modulation mediated by cervicolumbar pathways. Two studies were conducted. In the first, 22 neurologically intact (NI) people and 10 people with chronic iSCI were recruited. The change in H-reflex amplitude in flexor carpi radialis (FCR) during leg cycling and H-reflex amplitude in soleus (SOL) during arm cycling were investigated. In the second study, two groups of participants with chronic iSCI underwent 12 wk of cycling training: one performed combined arm and leg cycling (A&L) and the other legs only cycling (Leg). The effect of training paradigm on the amplitude of the SOL H-reflex was assessed. Significant reduction in the amplitude of both FCR and SOL H-reflexes during dynamic cycling of the opposite limbs was found in NI participants but not in participants with iSCI. Nonetheless, there was a significant reduction in the SOL H-reflex during dynamic arm cycling in iSCI participants after training. Substantial improvements in SOL H-reflex properties were found in the A&L group after training. The results demonstrate that cervicolumbar modulation during rhythmic movements is disrupted in people with chronic iSCI; however, this modulation is restored after cycling training. Furthermore, involvement of the arms simultaneously with the legs during training may better regulate the leg spinal reflexes.NEW & NOTEWORTHY This work systematically demonstrates the disruptive effect of incomplete spinal cord injury on cervicolumbar coupling during rhythmic locomotor movements. It also shows that the impaired cervicolumbar coupling could be significantly restored after cycling training. Actively engaging the arms in rehabilitation paradigms for the improvement of walking substantially regulates the excitability of the lumbar spinal networks. The resulting regulation may be better than that obtained by interventions that focus on training of the legs only.

scholarly journals Acquisition of a simple motor skill: task-dependent adaptation and long-term changes in the human soleus stretch reflex

2019 ◽  
Vol 122 (1) ◽  
pp. 435-446 ◽  
Author(s):  
N. Mrachacz-Kersting ◽  
U. G. Kersting ◽  
P. de Brito Silva ◽  
Y. Makihara ◽  
L. Arendt-Nielsen ◽  
...  
Keyword(s):  
Operant Conditioning ◽  
Stretch Reflex ◽  
Conditioning Session ◽  
H Reflex ◽  
Reflex Change ◽  
Reflex Pathways ◽  
Term Change ◽  
Neurologically Normal ◽  
Spinal Stretch Reflex

Changing the H reflex through operant conditioning leads to CNS multisite plasticity and can affect previously learned skills. To further understand the mechanisms of this plasticity, we operantly conditioned the initial component (M1) of the soleus stretch reflex. Unlike the H reflex, the stretch reflex is affected by fusimotor control, comprises several bursts of activity resulting from temporally dispersed afferent inputs, and may activate spinal motoneurons via several different spinal and supraspinal pathways. Neurologically normal participants completed 6 baseline sessions and 24 operant conditioning sessions in which they were encouraged to increase (M1up) or decrease (M1down) M1 size. Five of eight M1up participants significantly increased M1; the final M1 size of those five participants was 143 ± 15% (mean ± SE) of the baseline value. All eight M1down participants significantly decreased M1; their final M1 size was 62 ± 6% of baseline. Similar to the previous H-reflex conditioning studies, conditioned reflex change consisted of within-session task-dependent adaptation and across-session long-term change. Task-dependent adaptation was evident in conditioning session 1 with M1up and by session 4 with M1down. Long-term change was evident by session 10 with M1up and by session 16 with M1down. Task-dependent adaptation was greater with M1up than with the previous H-reflex upconditioning. This may reflect adaptive changes in muscle spindle sensitivity, which affects the stretch reflex but not the H reflex. Because the stretch reflex is related to motor function more directly than the H reflex, M1 conditioning may provide a valuable tool for exploring the functional impact of reflex conditioning and its potential therapeutic applications. NEW & NOTEWORTHY Since the activity of stretch reflex pathways contributes to locomotion, changing it through training may improve locomotor rehabilitation in people with CNS disorders. Here we show for the first time that people can change the size of the soleus spinal stretch reflex through operant conditioning. Conditioned stretch reflex change is the sum of task-dependent adaptation and long-term change, consistent with H-reflex conditioning yet different from it in the composition and amount of the two components.

scholarly journals Changes in H-Reflex Amplitude During Massage of Triceps Surae in Healthy Subjects

1990 ◽  
Vol 12 (2) ◽  
pp. 55-59 ◽  
Author(s):  
Moreno Morelli ◽  
Derek E. Seaborne ◽  
S. John Sullivan
Keyword(s):  
Healthy Subjects ◽  
H Reflex ◽  
Triceps Surae ◽  
Reflex Amplitude

Sway-dependent modulation of the triceps surae H-reflex during standing

2008 ◽  
Vol 104 (5) ◽  
pp. 1359-1365 ◽  
Author(s):  
Craig D. Tokuno ◽  
S. Jayne Garland ◽  
Mark G. Carpenter ◽  
Alf Thorstensson ◽  
Andrew G. Cresswell
Keyword(s):  
Postural Sway ◽  
Center Of Pressure ◽  
H Reflex ◽  
Triceps Surae ◽  
Quiet Standing ◽  
Electromyographic Activity ◽  
Experimental Conditions ◽  
Reflex Amplitude ◽  
Independent Effects ◽  
Spinal Excitability

Previous research has shown that changes in spinal excitability occur during the postural sway of quiet standing. In the present study, it was of interest to examine the independent effects of sway position and sway direction on the efficacy of the triceps surae Ia pathway, as reflected by the Hoffman (H)-reflex amplitude, during standing. Eighteen participants, tested under two different experimental protocols, stood quietly on a force platform. Percutaneous electrical stimulation was applied to the posterior tibial nerve when the position and direction of anteroposterior (A-P) center of pressure (COP) signal satisfied the criteria for the various experimental conditions. It was found that, regardless of sway position, a larger amplitude of the triceps surae H-reflex (difference of 9–14%; P = 0.005) occurred when subjects were swaying in the forward compared with the backward direction. The effects of sway position, independent of the sway direction, on spinal excitability exhibited a trend ( P = 0.075), with an 8.9 ± 3.7% increase in the H-reflex amplitude occurring when subjects were in a more forward position. The observed changes to the efficacy of the Ia pathway cannot be attributed to changes in stimulus intensity, as indicated by a constant M-wave amplitude, or to the small changes in the level of background electromyographic activity. One explanation for the changes in reflex excitability with respect to the postural sway of standing is that the neural modulation may be related to the small lengthening and shortening contractions occurring in the muscles of the triceps surae.

scholarly journals New evidence of corticospinal network modulation induced by motor imagery

2016 ◽  
Vol 115 (3) ◽  
pp. 1279-1288 ◽  
Author(s):  
Sidney Grosprêtre ◽  
Florent Lebon ◽  
Charalambos Papaxanthis ◽  
Alain Martin
Keyword(s):  
Evoked Potentials ◽  
Motor Imagery ◽  
Motor Evoked Potentials ◽  
Static Condition ◽  
Mental Simulation ◽  
Voluntary Contraction ◽  
H Reflex ◽  
Triceps Surae ◽  
Subcortical Structures ◽  
Reflex Amplitude

Motor imagery (MI) is the mental simulation of movement, without the corresponding muscle contraction. Whereas the activation of cortical motor areas during MI is established, the involvement of spinal structures is still under debate. We used original and complementary techniques to probe the influence of MI on spinal structures. Amplitude of motor-evoked potentials (MEPs), cervico-medullary-evoked potentials (CMEPs), and Hoffmann (H)-reflexes of the flexor carpi radialis (FCR) muscle and of the triceps surae muscles was measured in young, healthy subjects at rest and during MI. Participants were asked to imagine maximal voluntary contraction of the wrist and ankle, while the targeted limb was fixed (static condition). We confirmed previous studies with an increase of FCR MEPs during MI compared with rest. Interestingly, CMEPs, but not H-reflexes, also increased during MI, revealing a possible activation of subcortical structures. Then, to investigate the effect of MI on the spinal network, we used two techniques: 1) passive lengthening of the targeted muscle via an isokinetic dynamometer and 2) conditioning of H-reflexes with stimulation of the antagonistic nerve. Both techniques activate spinal inhibitory presynaptic circuitry, reducing the H-reflex amplitude at rest. In contrast, no reduction of H-reflex amplitude was observed during MI. These findings suggest that MI has modulatory effects on the spinal neuronal network. Specifically, the activation of low-threshold spinal structures during specific conditions (lengthening and H-reflex conditioning) highlights the possible generation of subliminal cortical output during MI.

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