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At least 865 records · Page 48Linked to original sources
PubMed1977

Dynamic relations between natural vestibular inputs and activity of forelimb extensor muscles in the decerebrate cat. I. Motor output during sinusoidal linear accelerations.

Decerebrate cats were subjected to sinusoidal linear accelerations along the animal's horizontal and vertical axes, while recording the EMG activity of both triceps brachii muscles. This activity was found to be sinusoidally modulated in response to the accelerations and thus phase and gain relations between motor output and input acceleration could be obtained. They were found to be the same for accelerations along each of the three axes. In particular the gain dropped by 14-20 dB over a frequency range from 0.2 to 1.0 Hz and the phase of the motor output showed a lag of 40-60 degrees at 1.0 Hz. Thus, it was concluded that (1) the dynamic behavior of utricular and saccular receptors is the same, (2) the changes in motor activity observed during accelerations along the vertical axis are mostly due to the activation of saccular afferents, and (3) the motor output cannot simply result from vestibular afferent activities being relayed directly to the spinal motoneurons via the vestibulo-spinal tracts.

Acceleration↗
PubMed1977

Dynamic relations between natural vestibular inputs and activity of forelimb extensor muscles in the decerebrate cat. III. Motor output during rotations in the vertical plane.

Decerebrate cats with the spinal cord sectioned at low thoracic levels were subjected to sinusoidal rotations in the vertical plane, while recording the EMG activity of both triceps brachii muscles. The applied stimulus activated utricular and saccular receptors as well as the vertical semicircular canals. Using results presented in preceding papers 2,3, namely the dynamic response characteristics of the motor output to macular inputs and the fact that the responses to otolith and canal stimulation summate linearly 3, it is deduced that the dynamic characteristics of the motor output in response to stimulation of the vertical canals are the same as those to horizontal canal stimulation. The implication of these findings vis-à-vis the problem of central processing of vestibular inputs and the problem of postural stability is discussed.

Acceleration↗
PubMed1985

Burst discharges of pontine reticular neurons in relation to forelimb stepping of thalamic and high spinal cats.

The paralemniscal pontine reticular neurons (PLRF) exhibited burst discharges when thalamic cats stepped on the moving treadmill, during stepping induced by mesencephalic locomotor region (MLR) stimulation, fictive locomotion by MLR stimulation after immobilization and during MLR stimulation after transection at the C2 level. These results imply that MLR stimulation can evoke burst discharge within the brainstem which may obtain alternating limb movements via descending tract to the cervical cord.

Animals↗
PubMed1988

Recurrent inhibition in the cat distal forelimb.

The pattern of recurrent pathways from motor axon collaterals to motoneurones has been investigated in the spinal cord of anaesthetized cats with intracellular techniques. Only recurrent inhibitory postsynaptic potentials (RIPSPs) were observed so far. They were very pronounced between the mechanical synergists acting at the elbow. The triceps muscles received substantial effects also from the extensor carpi ulnaris (ECU) and from palmar-located medialis (M) and ulnaris (Ul) muscles. The effects were much smaller in the motor nuclei acting on the wrist (ECU, EC radialis (ECR]. The motor nuclei to the muscles acting on the phalanges (extensor digitorum communis and lateralis, extensor indicis proprius, and abductor pollicis longus (EDC, EDL, EIP, APL] neither received nor emitted any recurrent effects, which may indicate a lack of the recurrent system in these distal motor nuclei. A comparison of the recurrent pattern with the distribution of monosynaptic excitation from large muscles spindle afferents (Ia) shows that there is a partial overlap of both systems only at the elbow joint.

Action Potentials↗