Summary
The activity of single neurons within the hand area of the precentral motor cortex of primates was recorded during the performance of a maintained precision grip between the thumb and forefinger. The finger opposition forces were exerted against a strain gauge which allowed force changes to be studied under near isometric conditions. Task performance required the generation of a force ramp (the dynamic phase) and thereafter the maintenance of a stable force for one second (the static phase). Intracortical stimulation through the recording electrode was used to verify that the recordings were made from the appropriate somatotopographic area of the motor cortex.
From a total of 221 recorded neurons, 76 were found to be either activated or deactivated during performance of the task. Among the 51 activated neurons, most discharged at higher frequencies during the dynamic phase, than during the static phase. The discharge of some of these neurons could be related to both force (F) and rate of force change (df/dt) whereas certain others could only be correlated with df/dt. The change in discharge frequency for these neurons generally occurred prior to the onset of EMG activity. Eight neurons were more active during maintained force than during the force ramp. The discharge frequency could not be correlated with df/dt and only one showed a significant positive relation to force. The change in discharge frequency for these neurons either coincided or occurred after the onset of EMG activity.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Asanuma, H., Rosén, I.: Topographical organization of cortical efferent zones projecting to distal forelimb muscles in the monkey. Exp. Brain Res. 14, 243–256 (1972)
Brown, M.C., Crowe, A., Matthews, P.B.C.: Observations on the fusimotor fibres of the tibialis posterior muscle of the cat. J. Physiol. (Lond.) 177, 140–159 (1965)
Clough, J.F.M., Phillips, C.G., Sheridan, J.D.: The short-latency projection from the baboon's motor cortex to fusimotor neurons of the forearm and hand. J. Physiol. (Lond.) 216, 257–279 (1971)
Evarts, E.V.: Relation of discharge frequency to conduction velocity in pyramidal tract neurons. J. Neurophysiol. 28, 216–228 (1965)
Evarts, E.V.: Pyramidal tract activity associated with a conditioned hand movement in the monkey. J. Neurophysiol. 29, 1011–1027 (1966)
Evarts, E.V.: Relation of pyramidal tract activity to force exerted during voluntary move ment. J. Neurophysiol. 31, 14–27 (1968)
Evarts, E.V.: Activity of pyramidal tract neurons during postural fixation. J. Neurophysiol. 32, 375–385 (1969)
Evarts, E.V.: Precentral and postcentral cortical activity in association with visually trig gered movement. J. Neurophysiol. 37, 373–381 (1974)
Gillies, J.D.: Motor unit discharges during isometric contraction in man. J. Physiol. (Lond.) 223, 36–37P (1972)
Hepp-Reymond, M.-C., Wiesendanger, M.: Unilateral pyramidotomy in monkeys: Effect on force and speed of a conditioned precision grip. Brain Res. 36, 117–131 (1972)
Hepp-Reymond, M.-C., Trouche, E., Wiesendanger, M.: Effects of unilateral and bilateral pyramidotomy on a conditioned rapid precision grip in monkeys (Macaca fascicularis). Exp. Brain Res. 21, 519–527 (1974)
Humphrey, D.R., Schmidt, E.M., Thompson, W.D.: Predicting measures of motor perform ance from multiple cortical spike trains. Science 170, 758–762 (1970)
Koeze, T.H., Phillips, C.G., Sheridan, J.D.: Thresholds of cortical activation of muscle spindles and motoneurones of the baboon's hand. J. Physiol. (Lond.) 195, 419–449 (1968)
Landgren, S., Phillips, C.G., Porter, R.: Cortical fields of origin of the monosynaptic pyramidal pathways to some motoneurones of the baboon's hand and forearm. J. Physiol. (Lond.) 161, 112–125 (1962)
Murphy, J.T., Wong, Y.C., Kwan, H.C.: Distributed feedback systems for muscle control. Brain Res. 71, 495–505 (1974)
Phillips, C.G.: Motor apparatus of the baboon's hand. Proc. roy. Soc. B 173, 141–174 (1969)
Phillips, C.G., Porter, R.: The projection to motoneurones of some muscle groups of baboon's forelimb. In: Physiology of the Spinal Neurones, Progress in Brain Research, Vol. 12, 222–245. (J.C. Eccles and J.P. Schade, Eds.). Amsterdam: Elsevier 1964
Phillips, C.G., Powell, T.P.S., Wiesendanger, M.: Projection from low-threshold muscle afferents of hand and forearm to area 3a of baboon's cortex. J. Physiol. (Lond.) 217, 419–446 (1971)
Rosén, L, Asanuma, H.: Peripheral afferent input to the forelimb area of the monkey motor cortex: Input-output relations. Exp. Brain Res. 14, 257–273 (1972)
Rispal-Padel, L., Latreille, J.: The organization of projections from the cerebellar nuclei to the contralateral motor cortex in the cat. Exp. Brain Res. 19, 36–60 (1974)
Schmidt, E.M., Jost, R.G., Davis, K.K.: Reexamination of the force relationship of cortical cell discharge patterns with conditioned wrist movements. Brain Res. 83, 213–223 (1975)
Shapovalov, A.I., Karamian, O.A., Kurchavyi, G.G., Repina, Z.A.: Synaptic actions evoked from the red nucleus on the spinal alpha-motoneurons in the rhesus monkey. Brain Res. 32, 325–348 (1971)
Shapovalov, A.I., Kurchavyi, G.G.: Effects of trans-membrane polarization and TEA injec tion on monosynaptic actions from motor cortex, red nucleus and group Ia afferents on lumbar motoneurons in the monkey. Brain Res. 82, 49–67 (1974)
Tanji, J.: Activity of neurons in cortical area 3a during maintenance of steady postures by the monkey. Brain Res. 88, 549–553 (1975)
Vallbo, A.B.: Afferent discharge from human muscle spindles in non-contracting muscles. Steady state impulse frequency as a function of joint angle. Acta physiol. scand. 90, 303–318 (1974a)
Vallbo, A.B.: Human muscle spindle discharge during isometric voluntary contractions. Amplitude relations between spindle frequency and torque. Acta physiol. scand. 90, 319–336 (1974b)
Wiesendanger, M.: Input from muscle and cutaneous nerves of the hand and forearm to neu rones of the precentral gyrus of baboons and monkeys. J. Physiol. (Lond.) 228, 203–219 (1973)
Yumiya, H., Kubota, K., Asanuma, H.: Activities of neurons in area 3a of the cerebral cortex during voluntary movements in the monkey. Brain Res. 78, 169–177 (1974)
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Smith, A.M., Hepp-Reymond, M.C. & Wyss, U.R. Relation of activity in precentral cortical neurons to force and rate of force change during isometric contractions of finger muscles. Exp Brain Res 23, 315–332 (1975). https://doi.org/10.1007/BF00239743
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00239743