Summary
The cortical projections to neck muscle motoneurons were studied in normal subjects by electrical and magnetic transcranial brain stimulation. After magnetic stimulation with a large coil, motor evoked potentials were present in about 20% of relaxed and 100% of contracting neck muscles. The latency of these responses was short: about 7 ms in the sternomastoid and splenius and 9 ms in the trapezius muscles. Subtraction of the M-wave latency after stimulation of the accessory nerve at the skull base resulted in a central latency of about 4.5 ms. We suggest that rapid cortical projections connect with neck muscle motoneurons mono or disynaptically. The latency difference between the responses after electrical and magnetic stimulation was smaller in neck than in limb muscles but similar to that seen in masticatory muscles. A small magnetic coil was used to study the pattern of functional lateralization of cortical projections to neck muscle motoneurons; the projections for the sternomastoid and splenius are bilateral but predominantly contralateral, whereas those for the trapezius are exclusively contralateral.
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References
Amassian V, Quirk GJ, Stewart M (1990) A comparison of cortico-spinal activation by magnetic coil and electrical stimulation of monkey motor cortex. EEG Clin Neurophysiol 77:390–401
Alstermark B, Pinter M, Sasaki S (1983a) Brainstem relay of dysynaptic pyramidal EPSPs to neck motoneurons in the cat. Brain Res 259:147–150
Alstermark B, Pinter M, Sasaki S (1983b) Converge on reticulospinal neurons mediating contralateral pyramidal disynaptic EPSPs to neck motoneurons. Brain Res 259:151–154
Benecke R, Meyer BV, Schonle Conrad B (1988) Transcranial magnetic stimulation of the human brain: responses in muscles supplied by cranial nerves. Exp Brain Res 71:623–632
Berardelli A, Inghilleri M, Manfredi M, Zamponi V, Cecconi V, Dolce G (1987) Cortical and cervical stimulation after hemispheric infarction. J Neurol Neurosurg Psychiat 50:732–737
Berardelli A, Inghilleri M, Cruccu G, Manfredi M (1990) Descending volley after electrical and magnetic transcranial stimulation in man. Neurosci Lett 112:54–58
Brodal A (1957) The cranial nerves — Anatomy and anatomoclinical correlation. Blackwell, Oxford, England, p 57
Cruccu G, Berardelli A, Inghilleri M, Manfredi M (1989) Functional organization of the trigeminal motor system in man: a neuro-physiological study. Brain 112:1333–1350
Cruccu G, Berardelli A, Inghilleri M, Manfredi M (1990) Corticobulbar projections to upper and lower facial motoneurons. A study by magnetic transcranial stimulation in man. Neurosci Lett 117:68–73
Day BL, Rothwell JC, Thompson PD, Dick JPR, Cowan JMA, Berardelli A, Marsden CD (1987) Motor cortex stimulation in intact man. II. Multiple descending volleys. Brain 110:1191–1210
Day BL, Dressler D, Maertens de Noorhout A, Marsden CD, Nakashima K, Rothwell JC, Thompson PD (1989) Electric and magnetic stimulation of human cortex: surface EMG and single motor unit responses. J Physiol 412:449–473
Edgley SM, Eyre JA, Lemon RN, Miller JSG (1990) Direct activation of corticospinal neurons by electromagnetic stimulation in anaesthetized and conscious monkeys. J Physiol 425:301–320
Gandevia SC, Rothwell JC (1987) Activation of the human diaphragm from the motor cortex. J Physiol 384:109–118
Gandevia SC, Applegate C (1988) Activation of neck muscles from the human motor cortex. Brain 111:801–813
Hess CW, Mills KR, Murray NMF (1987) Responses in small hand muscles from magnetic stimulation of the human brain. J Physiol 388:397–419
Iwamoto Y, Sasaki S, Suzuki I (1990) Input-output organization of reticulospinal neurones, with special reference to connections with dorsal neck motoneurons in the cat. Exp Brain Res 80:260–276
Iwatsubo T, Kuzuhara S, Kanemitsu A, Shimada H, Toyokura Y (1990) Corticospinal projections to the motor nuclei of the brainstem and spinal cord in humans. Neurology 40:309–312
Keizer K, Kuypers HGJM (1984) Distribution of corticospinal neurons with collaterals to lower brain stem reticular formation. Exp Brain Res 54:107–120
Kuypers HGJM (1958) Corticobulbar connections to the pons and lower brain-stem in man. An anatomical study. Brain 81:364–388
Merton PA, Morton HB (1980) Stimulation of cerebral cortex in the intact human subjects. Nature 285:277
Priori A, Berardelli A, Inghilleri M, Cruccu G, Zaccagnini M, Manfredi M (1991) Electrical and magnetic stimulation of the accessory nerve at the base of the skull. Muscle Nerve 477–478
Rossini PM, Di Stefano E, Stanzione P (1985) Nerve impulse propagation along central and peripheral fast conducting motor and sensory pathways in man. EEG Clin Neurophysiol 60:320–334
Rothwell JC, Thompson PD, Day DL, Dick JPR, Kachi T, Cowan JMA, Marsden CD (1987) Motor cortex stimulation in intact man. I. Brain 110:1173–1190
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Berardelli, A., Priori, A., Inghilleri, M. et al. Corticobulbar and corticospinal projections to neck muscle motoneurons in man. Exp Brain Res 87, 402–406 (1991). https://doi.org/10.1007/BF00231857
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DOI: https://doi.org/10.1007/BF00231857