Biomaterial Database

Discharge activity of spindle afferents from the gastrocnemius-soleus muscle during head rotation in the decerebrate cat. 1984

R Boyle, and O Pompeiano

The activity of spindle afferents originating from both primary and secondary endings of the isometrically extended (6-8 mm) gastrocnemius-soleus (GS) muscle was recorded in precollicular decerebrate cats during sinusoidal head rotation about the longitudinal axis above a stationary body. In the first group of experiments to test the influence of vestibular volleys on fusimotor neurons, an acute bilateral neck deafferentation at C1-C3 was performed to eliminate possible influences arising from neck receptors; head rotation (0.026 Hz, +/- 15 degrees) induced a weak periodic rate modulation in 6/38 (15.8%) of the tested spindle afferents; the average response gain was 0.18 +/- 0.12, SD imp./s/deg (mean firing rate, 18.9 +/- 2.8 imp./s), and the average phase angle was -43.2 +/- 47.0 degrees, SD lag with respect to ipsilateral side-down displacement of the head (alpha-response pattern). In a second group of experiments head rotation studied after acute bilateral section of VIII cranial nerve, thereby stimulating only neck receptors, failed to influence in a reliable manner the firing rate of 38 additional spindle afferents. In a third group of experiments in which both VIII nerves and cervical dorsal roots were left intact, head rotation induced a response in 7/45 (15.6%) of the tested spindle afferents similar to that observed after cervical deafferentiation and thus depended on stimulation of labyrinth receptors alone. Over the examined frequency range of head rotation from 0.015 to 0.325 Hz (+/- 15 degrees), the response gain of spindle afferents was relatively stable during sinusoidal labyrinth stimulation. For most of the spindle afferents the phase angle of the response elicited at the lower frequencies was related to the direction of head orientation towards the ipsilateral sidedown, thus being attributed to labyrinth volleys originating from macular receptors; at 0325 Hz the stimulus was less effective and some units showed a phase advance relative to head position which was attributed to costimulation of canal receptors. Displacement of the muscle under study obtained by either rotation of the whole animal or body alone beneath a stationary head elicited a periodic modulation of spindle afferent discharge, independent of head orientation or type of preparation, in 51/73 (70%) of the muscle spindles tested; the average response gain was 0.20 +/- 0.19, SD imp./s/deg, and an average phase lead of +14.1 +/- 20.5 degrees, SD with respect to the peak of the ipsilateral side-down displacement of the body or of the animal was observed.(ABSTRACT TRUNCATED AT 400 WORDS)

UI	MeSH Term	Description	Entries
D007758	Ear, Inner	The essential part of the hearing organ consists of two labyrinthine compartments: the bony labyrinthine and the membranous labyrinth. The bony labyrinth is a complex of three interconnecting cavities or spaces (COCHLEA; VESTIBULAR LABYRINTH; and SEMICIRCULAR CANALS) in the TEMPORAL BONE. Within the bony labyrinth lies the membranous labyrinth which is a complex of sacs and tubules (COCHLEAR DUCT; SACCULE AND UTRICLE; and SEMICIRCULAR DUCTS) forming a continuous space enclosed by EPITHELIUM and connective tissue. These spaces are filled with LABYRINTHINE FLUIDS of various compositions.	Labyrinth,Bony Labyrinth,Ear, Internal,Inner Ear,Membranous Labyrinth,Bony Labyrinths,Ears, Inner,Ears, Internal,Inner Ears,Internal Ear,Internal Ears,Labyrinth, Bony,Labyrinth, Membranous,Labyrinths,Labyrinths, Bony,Labyrinths, Membranous,Membranous Labyrinths
D009334	Neck Muscles	The neck muscles consist of the platysma, splenius cervicis, sternocleidomastoid(eus), longus colli, the anterior, medius, and posterior scalenes, digastric(us), stylohyoid(eus), mylohyoid(eus), geniohyoid(eus), sternohyoid(eus), omohyoid(eus), sternothyroid(eus), and thyrohyoid(eus).	Muscle, Neck,Muscles, Neck,Neck Muscle
D009431	Neural Conduction	The propagation of the NERVE IMPULSE along the nerve away from the site of an excitation stimulus.	Nerve Conduction,Conduction, Nerve,Conduction, Neural,Conductions, Nerve,Conductions, Neural,Nerve Conductions,Neural Conductions
D009470	Muscle Spindles	Skeletal muscle structures that function as the MECHANORECEPTORS responsible for the stretch or myotactic reflex (REFLEX, STRETCH). They are composed of a bundle of encapsulated SKELETAL MUSCLE FIBERS, i.e., the intrafusal fibers (nuclear bag 1 fibers, nuclear bag 2 fibers, and nuclear chain fibers) innervated by SENSORY NEURONS.	Muscle Stretch Receptors,Neuromuscular Spindles,Receptors, Stretch, Muscle,Stretch Receptors, Muscle,Muscle Spindle,Muscle Stretch Receptor,Neuromuscular Spindle,Receptor, Muscle Stretch,Receptors, Muscle Stretch,Spindle, Muscle,Spindle, Neuromuscular,Spindles, Muscle,Spindles, Neuromuscular,Stretch Receptor, Muscle
D009475	Neurons, Afferent	Neurons which conduct NERVE IMPULSES to the CENTRAL NERVOUS SYSTEM.	Afferent Neurons,Afferent Neuron,Neuron, Afferent
D002415	Cats	The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)	Felis catus,Felis domesticus,Domestic Cats,Felis domestica,Felis sylvestris catus,Cat,Cat, Domestic,Cats, Domestic,Domestic Cat
D003655	Decerebrate State	A condition characterized by abnormal posturing of the limbs that is associated with injury to the brainstem. This may occur as a clinical manifestation or induced experimentally in animals. The extensor reflexes are exaggerated leading to rigid extension of the limbs accompanied by hyperreflexia and opisthotonus. This condition is usually caused by lesions which occur in the region of the brainstem that lies between the red nuclei and the vestibular nuclei. In contrast, decorticate rigidity is characterized by flexion of the elbows and wrists with extension of the legs and feet. The causative lesion for this condition is located above the red nuclei and usually consists of diffuse cerebral damage. (From Adams et al., Principles of Neurology, 6th ed, p358)	Decerebrate Posturing,Decorticate Rigidity,Decorticate State,Rigidity, Decerebrate,Rigidity, Decorticate,Decerebrate Posturings,Decerebrate Rigidity,Decerebrate States,Decorticate Rigidities,Decorticate States,Posturing, Decerebrate,Posturings, Decerebrate,Rigidities, Decorticate,State, Decerebrate,States, Decerebrate
D004594	Electrophysiology	The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.
D006257	Head	The upper part of the human body, or the front or upper part of the body of an animal, typically separated from the rest of the body by a neck, and containing the brain, mouth, and sense organs.	Heads
D006614	Hindlimb	Either of two extremities of four-footed non-primate land animals. It usually consists of a FEMUR; TIBIA; and FIBULA; tarsals; METATARSALS; and TOES. (From Storer et al., General Zoology, 6th ed, p73)	Hindlimbs