scholarly journals Movement Reduces the Dynamic Response of Muscle Spindle Afferents and Motoneuron Synaptic Potentials in Rat

2004 ◽  
Vol 91 (5) ◽  
pp. 2164-2171 ◽  
Author(s):  
Valerie K. Haftel ◽  
Edyta K. Bichler ◽  
T. Richard Nichols ◽  
Martin J. Pinter ◽  
Timothy C. Cope
Keyword(s):  
Dynamic Response ◽  
Stretch Reflex ◽  
Muscle Spindles ◽  
Triceps Surae ◽  
History Dependence ◽  
Muscle Stretch ◽  
Initial Burst ◽  
Synaptic Potentials ◽  
Probable Effect ◽  
Triceps Surae Muscles

Among the mechanisms that may result in modulation of the stretch reflex by the recent history of muscle contraction is the history dependence observed under some conditions in the response properties of muscle spindles. The present study was designed to test one report that in successive trials of muscle stretch-release, spindle afferent firing during stretch, i.e., the dynamic response shows no history dependence beyond the initial burst of firing at stretch onset. Firing responses of spindle afferents were recorded during sets of three consecutive trials of triangular stretch-release applied to triceps surae muscles in barbiturate-anesthetized rats. All 69 spindle afferents fired more action potentials (spikes) during the dynamic response of the first trial, excluding the initial burst, than in the following two trials. The reduced dynamic response (RDR) was nearly complete after trial 1 and amounted to an average of ∼12 fewer spikes (16 pps slower firing rate) in trial 3 than in trial 1. RDR was sensitive to the interval between stretch sets but independent of stretch velocity (4–32 mm/s). RDR was reflected in the synaptic potentials recorded intracellularly from 16 triceps surae α-motoneurons: depolarization during muscle stretch was appreciably reduced after trial 1. These findings demonstrate history dependence of spindle afferent responses that extends throughout the dynamic response in successive muscle stretches and that is synaptically transmitted to motoneurons with the probable effect, unless otherwise compensated, of modulating the stretch reflex.

Beta-contributions to fusimotor action in triceps surae muscles of decerebrated cats

1987 ◽  
Vol 57 (2) ◽  
pp. 574-595 ◽  
Author(s):  
S. E. Grill ◽  
W. Z. Rymer
Keyword(s):  
Muscle Force ◽  
Discharge Rate ◽  
Muscle Spindles ◽  
Triceps Surae ◽  
Medial Gastrocnemius ◽  
Gamma Activity ◽  
Response Patterns ◽  
Two Measures ◽  
Triceps Surae Muscles ◽  
Stimulation Of

The discharge of spindle afferents from medial gastrocnemius and soleus muscles was recorded in the decerebrated cat preparation, under isometric conditions and during ramp and hold stretches. Motor output was varied systematically by manual stimulation of the contralateral hindlimb. Twenty-six of 34 afferents showed response patterns consistent with enhancement of dynamic and/or static fusimotor input with increasing muscle force. To establish whether force-related fusimotor effects were mediated at least partly by beta-input, beta-innervation to these same spindles was sought, using a ventral root stimulation protocol. Twenty-three of the 34 afferents were shown to receive beta-innervation, which was most often static in type. For two measures of fusimotor action, the slope of the afferent dynamic rate-length relation and the discharge rate measured during the last portion of ramp stretch, significant increases in the measure, which paralleled increases in muscle force, made it statistically more likely that the afferent received beta-innervation. Our measures did not successfully predict the type of beta-input (beta-static or beta-dynamic). Procaine block of gamma-fibers produced substantial reductions in fusimotor effect in seven spindle afferents (although modest residual fusimotor effects were detectable for 3/7 afferents). The severity of these reductions indicates that beta-action probably requires concurrent gamma-input to the spindle in order to be effective. In support of this possibility, the fusimotor effects of electrical stimulation of single beta-fibers were greatly reduced for five out of six afferents during procaine block of gamma-fibers, compared with the beta-effects recorded when modest levels of spontaneous gamma-activity were present. We conclude that beta-innervation to muscle spindles of triceps surae is common and that this innervation exerts significant fusimotor effects. It appears likely that beta-motoneurons are able to produce both static and dynamic effects above extrafusal threshold, but that the actions require on-going gamma-activity in order to be effective.

Frequency analysis of stretch reflex and its main subsystems in triceps surae muscles of the cat.

1970 ◽  
Vol 33 (6) ◽  
pp. 713-749 ◽  
Author(s):  
N P Rosenthal ◽  
T A McKean ◽  
W J Roberts ◽  
C A Terzuolo
Keyword(s):  
Frequency Analysis ◽  
Stretch Reflex ◽  
Triceps Surae ◽  
Triceps Surae Muscles

scholarly journals Intrinsic Properties and Reflex Compensation in Reinnervated Triceps Surae Muscles of the Cat: Effect of Activation Level

2003 ◽  
Vol 90 (3) ◽  
pp. 1537-1546 ◽  
Author(s):  
Clotilde M.J.I. Huyghues-Despointes ◽  
Timothy C. Cope ◽  
T. Richard Nichols
Keyword(s):  
Mechanical Properties ◽  
Stretch Reflex ◽  
Full Range ◽  
Motor Units ◽  
Triceps Surae ◽  
Type I ◽  
Initial Stiffness ◽  
Decerebrate Cat ◽  
Reflex Action ◽  
Triceps Surae Muscles

The manner in which activation levels influence intrinsic muscular properties and contributions of the stretch reflex were studied in homogeneous soleus (SOL) and heterogeneous gastrocnemius (G) muscles in the decerebrate cat. Intrinsic mechanical properties were represented by the initial stiffness of the muscle, measured prior to reflex action, and by the tendency of the muscle to yield during stretch in the absence of the stretch reflex. Stiffness regulation by the stretch reflex was evaluated by measuring the extent to which reflex action reduces yielding and the extent to which stiffness depends on background force. Intrinsic mechanical properties were measured in muscles deprived of effective autogenic reflexes using the method of muscular reinnervation. Reinnervated muscles were recruited to force levels comparable to those achieved during natural locomotion. As force declined during crossed-extension reflexes in reinnervated and intact muscles, initial stiffness declined according to similar convex trajectories. The data did not support the hypothesis that, for a given force level, initial stiffness is greatest in populations of predominantly type I motor units. Incremental stiffness (Δ f/Δ l) of both G and SOL increased in the presence of the stretch reflex. Yielding of SOL (ratio of incremental to initial stiffness) substantially decreased in the presence of the stretch reflex over the full range of forces. In reflexive G, yielding significantly decreased for low to intermediate forces, whereas at higher forces, yielding was similar irrespective of the presence or absence of the stretch reflex. The stretch reflex regulates stiffness in both homogeneous and heterogeneous muscles.

scholarly journals Stretch reflex gain in cat triceps surae muscles with compliant loads

2002 ◽  
Vol 545 (3) ◽  
pp. 1027-1040 ◽  
Author(s):  
Sophie J. De Serres ◽  
David J. Bennett ◽  
Richard B. Stein
Keyword(s):  
Stretch Reflex ◽  
Triceps Surae ◽  
Reflex Gain ◽  
Triceps Surae Muscles

scholarly journals Changes in muscle spindle firing in response to length changes of neighboring muscles

2016 ◽  
Vol 115 (6) ◽  
pp. 3146-3155 ◽  
Author(s):  
Hiltsje A. Smilde ◽  
Jake A. Vincent ◽  
Guus C. Baan ◽  
Paul Nardelli ◽  
Johannes C. Lodder ◽  
...  
Keyword(s):  
Muscle Spindle ◽  
Muscle Spindles ◽  
Triceps Surae ◽  
Connective Tissues ◽  
Muscle Belly ◽  
Intact Muscle ◽  
Muscle Compartment ◽  
Synergistic Muscles ◽  
Length Changes ◽  
Triceps Surae Muscles

Skeletal muscle force can be transmitted to the skeleton, not only via its tendons of origin and insertion but also through connective tissues linking the muscle belly to surrounding structures. Through such epimuscular myofascial connections, length changes of a muscle may cause length changes within an adjacent muscle and hence, affect muscle spindles. The aim of the present study was to investigate the effects of epimuscular myofascial forces on feedback from muscle spindles in triceps surae muscles of the rat. We hypothesized that within an intact muscle compartment, muscle spindles not only signal length changes of the muscle in which they are located but can also sense length changes that occur as a result of changing the length of synergistic muscles. Action potentials from single afferents were measured intra-axonally in response to ramp-hold release (RHR) stretches of an agonistic muscle at different lengths of its synergist, as well as in response to synergist RHRs. A decrease in force threshold was found for both soleus (SO) and lateral gastrocnemius afferents, along with an increase in length threshold for SO afferents. In addition, muscle spindle firing could be evoked by RHRs of the synergistic muscle. We conclude that muscle spindles not only signal length changes of the muscle in which they are located but also local length changes that occur as a result of changing the length and relative position of synergistic muscles.

scholarly journals Muscle proprioceptors in adult rat: mechanosensory signaling and synapse distribution in spinal cord

2017 ◽  
Vol 118 (5) ◽  
pp. 2687-2701 ◽  
Author(s):  
Jacob A. Vincent ◽  
Hanna M. Gabriel ◽  
Adam S. Deardorff ◽  
Paul Nardelli ◽  
Robert E. W. Fyffe ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Mammalian Species ◽  
Movement Control ◽  
Triceps Surae ◽  
Muscle Stretch ◽  
Adult Rat ◽  
Afferent Projections ◽  
Female Wistar Rats ◽  
Triceps Surae Muscles ◽  
Passive Muscle

The characteristic signaling and intraspinal projections of muscle proprioceptors best described in the cat are often generalized across mammalian species. However, species-dependent adaptations within this system seem necessary to accommodate asymmetric scaling of length, velocity, and force information required by the physics of movement. In the present study we report mechanosensory responses and intraspinal destinations of three classes of muscle proprioceptors. Proprioceptors from triceps surae muscles in adult female Wistar rats anesthetized with isoflurane were physiologically classified as muscle spindle group Ia or II or as tendon organ group Ib afferents, studied for their firing responses to passive-muscle stretch, and in some cases labeled and imaged for axon projections and varicosities in spinal segments. Afferent projections and the laminar distributions of provisional synapses in rats closely resembled those found in the cat. Afferent signaling of muscle kinematics was also similar to reports in the cat, but rat Ib afferents fired robustly during passive-muscle stretch and Ia afferents displayed an exaggerated dynamic response, even after locomotor scaling was accounted for. These differences in mechanosensory signaling by muscle proprioceptors may represent adaptations for movement control in different animal species. NEW & NOTEWORTHY Muscle sensory neurons signal information necessary for controlling limb movements. The information encoded and transmitted by muscle proprioceptors to networks in the spinal cord is known in detail only for the cat, but differences in size and behavior of other species challenge the presumed generalizability. This report presents the first findings detailing specializations in mechanosensory signaling and intraspinal targets for functionally identified subtypes of muscle proprioceptors in the rat.

scholarly journals The Muscle Stretch Reflex throughout the Menstrual Cycle

2014 ◽  
Vol 46 (3) ◽  
pp. 600-609 ◽  
Author(s):  
ELLEN CASEY ◽  
FARAH HAMEED ◽  
YASIN Y. DHAHER
Keyword(s):  
Menstrual Cycle ◽  
Stretch Reflex ◽  
Muscle Stretch

Dynamic Force Responses in Electrically Stimulated Triceps Surae Muscles: Effects of Fatigue and Temperature

1999 ◽  
Vol 23 (5) ◽  
pp. 436-439 ◽  
Author(s):  
Dietmar Rafolt ◽  
Eugen Gallasch ◽  
Winfried Mayr ◽  
Hermann Lanmuller
Keyword(s):  
Triceps Surae ◽  
Dynamic Force ◽  
Triceps Surae Muscles

Receptor Mechanisms Underlying Heterogenic Reflexes Among the Triceps Surae Muscles of the Cat

1999 ◽  
Vol 81 (2) ◽  
pp. 467-478 ◽  
Author(s):  
T. Richard Nichols
Keyword(s):  
Triceps Surae ◽  
Spinal Reflex ◽  
Medial Gastrocnemius ◽  
Entire Group ◽  
Passive Components ◽  
Mechanical Coupling ◽  
Golgi Tendon Organs ◽  
Reflex Pathways ◽  
Tendon Organs ◽  
Triceps Surae Muscles

Receptor mechanisms underlying heterogenic reflexes among the triceps surae muscles of the cat. The soleus (S), medial gastrocnemius (MG), and lateral gastrocnemius (LG) muscles of the cat are interlinked by rapid spinal reflex pathways. In the decerebrate state, these heterogenic reflexes are either excitatory and length dependent or inhibitory and force dependent. Mechanographic analysis was used to obtain additional evidence that the muscle spindle primary ending and the Golgi tendon organ provide the major contributions to these reflexes, respectively. The tendons of the triceps surae muscles were separated and connected to independent force transducers and servo-controlled torque motors in unanesthetized, decerebrate cats. The muscles were activated as a group using crossed-extension reflexes. Electrical stimulation of the caudal cutaneous sural nerve was used to provide a particularly strong activation of MG and decouple the forces of the triceps surae muscles. During either form of activation, the muscles were stretched either individually or in various combinations to determine the strength and characteristics of autogenic and heterogenic feedback. The corresponding force responses, including both active and passive components, were measured during the changing background tension. During activation of the entire group, the excitatory, heterogenic feedback linking the three muscles was found to be strongest onto LG and weakest onto MG, in agreement with previous results concerning the strengths of heteronymous Ia excitatory postsynaptic potentials among the triceps surae muscles. The inhibition, which is known to affect only the soleus muscle, was dependent on active contractile force and was detected essentially as rapidly as length dependent excitation. The inhibition outlasted the excitation and was blocked by intravenous strychnine. These results indicate that the excitatory and inhibitory effects are dominated by feedback from primary spindle receptors and Golgi tendon organs. The interactions between these two feedback pathways potentially can influence both the mechanical coupling between ankle and knee.

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