Supplementary motor area

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Supplementary motor area
Posterior Parietal Lobe.jpg
Some motor areas in the human cortex. The supplementary motor area is shown in pink.
Supplementary motor cortex.gif
3D visualization of the supplementary motor cortex in an average human brain
Anatomical terms of neuroanatomy

The supplementary motor area (SMA) is a part of the motor cortex of primates that contributes to the control of movement. It is located on the midline surface of the hemisphere just in front of (anterior to) the primary motor cortex leg representation. In monkeys the SMA contains a rough map of the body. In humans the body map is not apparent. Neurons in the SMA project directly to the spinal cord and may play a role in the direct control of movement. Possible functions attributed to the SMA include the postural stabilization of the body, the coordination of both sides of the body such as during bimanual action, the control of movements that are internally generated rather than triggered by sensory events, and the control of sequences of movements. All of these proposed functions remain hypotheses. The precise role or roles of the SMA is not yet known.

For the discovery of the SMA and its relationship to other motor cortical areas, see the main article on the motor cortex.


At least six areas are now recognized within the larger region once defined as the SMA. These subdivisions have been studied most extensively in the monkey brain. The most anterior portion is now commonly termed pre-SMA.[1][2][3] It has sparse or no connections to the spinal cord or the primary motor cortex and has extensive connectivity with prefrontal areas.[1][4][5][6][7]

The supplementary eye field (SEF) is a relatively anterior portion of the SMA that, when stimulated, evokes head and eye movements and perhaps movements of the limbs and torso.[8][9][10][11]

Dum and Strick[5] hypothesized on the basis of cytoarchitecture and connections to the spinal cord that the portion of SMA in the cingulate sulcus, on the medial part of the hemisphere, can be split into three separate areas, the cingulate motor areas. The functions of the cingulate motor areas have not yet been systematically studied, though may be involved in emotionally driven behaviours like the limbic laugh.

SMA proper in monkeys has now been confined to a region on the crown of the hemisphere and extending partly onto the medial wall, just anterior to the primary motor leg representation. SMA proper projects directly to the spinal cord and therefore is one of the primary output areas of the cortical motor system.[5][12][13][14][15][16]

Recently, Zhang et al.[17] investigated the functional subdivisions of the medial SFC on the basis of whole-brain connectivity characterized from a large resting-state fMRI data set. Other than replicating the boundaries between SMA and preSMA, the current results support a functional difference between the posterior and anterior pre-SMA. In contrast to the posterior pre-SMA, the anterior pre-SMA is connected with most of the prefrontal but not somatomotor areas. Overall, the SMA is strongly connected to the thalamus and epithalamus, the posterior pre-SMA to putamen, pallidum, and STN and anterior pre-SMA to the caudate nucleus, with the caudate showing significant hemispheric asymmetry.


Penfield and Welch[18] in 1951 first described SMA in the monkey brain and the human brain as a representation of the body on the medial wall of the hemisphere. Woolsey and colleagues[19] in 1952 confirmed SMA in the monkey brain, describing it as a rough somatotopic map with the legs in a posterior location and the face in an anterior location. The representations of different body parts were found to overlap extensively. Stimulation of many sites evoked bilateral movements and sometimes movements of all four limbs. This overlapping somatotopic map in SMA was confirmed by many others.[2][13][20][21][22]

Four main hypotheses have been proposed for the function of SMA: the control of postural stability during stance or walking,[18] coordinating temporal sequences of actions,[23][24][25][26][27][28][29][30] bimanual coordination,[31][32] and the initiation of internally generated as opposed to stimulus driven movement.[3][29][30][33] The data, however, tend not to support an exclusive role of SMA in any one of these functions. Indeed, SMA is demonstrably active during non-sequential, unimanual, and stimulus-cued movements.[34]

For human voluntary movement the role of the SMA has been elucidated: Its activity generates the early component of the Bereitschaftspotential (BP) or readiness potential BP1 or BPearly.[35] The role of the SMA was further substantiated by Cunnington et al. 2003,[36] showing that SMA proper and pre-SMA are active prior to volitional movement or action, as well as the cingulate motor area (CMA) and anterior mid-cingulate cortex (aMCC). Recently it has been shown by integrating simultaneously acquired EEG and fMRI that SMA and aMCC have strong reciprocal connections that act to sustain each other’s activity, and that this interaction is mediated during movement preparation according to the Bereitschaftspotential amplitude.[37]

SMA in the monkey brain may emphasize locomotion, especially complex locomotion such as climbing or leaping.[38][39][40] This suggestion was based on studies in which stimulation on a behaviorally relevant time scale evoked complex, full body movements that resembled climbing or leaping. This hypothesis is consistent with previous hypotheses, including the involvement of SMA in postural stabilization, in internally generated movements, in bimanual coordination, and in the planning of movement sequences, because all of these functions are heavily recruited in complex locomotion. The locomotion hypothesis is an example of interpreting the motor cortex in terms of the underlying behavioral repertoire from which abstract control functions emerge, an approach emphasized by Graziano and colleagues.[38]

Additional images[edit]


  1. ^ a b He, S.Q., Dum, R.P. and Strick, P.L (1995). "Topographic organization of corticospinal projections from the frontal lobe: motor areas on the medial surface of the hemisphere". J. Neurosci. 15 (5): 3284–3306. doi:10.1523/JNEUROSCI.15-05-03284.1995. PMC 6578253. PMID 7538558.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  2. ^ a b Luppino, G., Matelli, M., Camarda, R.M., Gallese, V. and Rizzolatti, G (1991). "Multiple representations of body movements in mesial area 6 and the adjacent cingulate cortex: an intracortical microstimulation study in the macaque monkey". J. Comp. Neurol. 311 (4): 463–482. doi:10.1002/cne.903110403. PMID 1757598. S2CID 25297539.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  3. ^ a b Matsuzaka, Y., Aizawa, H., and Tanji, J (1992). "A motor area rostrao to the supplementary motor area (presupplementary motor area) in the monkey: neuronal activity during a learned motor task". J. Neurophysiol. 68 (3): 653–662. doi:10.1152/jn.1992.68.3.653. PMID 1432040.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  4. ^ Bates, J.F. & Goldman-Rakic, P.S (1993). "Prefrontal connections of medial motor areas in the rhesus monkey". J. Comp. Neurol. 336 (2): 211–228. doi:10.1002/cne.903360205. PMID 7503997. S2CID 35838076.
  5. ^ a b c Dum, R.P. & Strick, P.L (1991). "The origin of corticospinal projections from the premotor areas in the frontal lobe". J. Neurosci. 11 (3): 667–689. doi:10.1523/JNEUROSCI.11-03-00667.1991. PMC 6575356. PMID 1705965.
  6. ^ Lu, M.T., Preston, J.B. and Strick, P.L (1994). "Interconnections between the prefrontal cortex and the premotor areas in the frontal lobe". J. Comp. Neurol. 341 (3): 375–392. doi:10.1002/cne.903410308. PMID 7515081. S2CID 13045173.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  7. ^ Luppino, G., Matelli, M., Camarda, R. and Rizzolatti, G (1993). "Corticocortical connections of area F3 (SMA-proper) and area F6 (pre-SMA) in the macaque monkey". J. Comp. Neurol. 338 (1): 114–140. doi:10.1002/cne.903380109. PMID 7507940. S2CID 6171579.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  8. ^ Chen, L.L. & Walton, M.M (2005). "Head movement evoked by electrical stimulation in the supplementary eye field of the rhesus monkey". J. Neurophysiol. 94 (6): 4502–4519. doi:10.1152/jn.00510.2005. PMID 16148273.
  9. ^ Russo, G.S. & Bruce, C.J (2000). "Supplementary eye field: representation of saccades and relationship between neural response fields and elicited eye movements". J. Neurophysiol. 84 (5): 2605–2621. doi:10.1152/jn.2000.84.5.2605. PMID 11068002. S2CID 16208146.
  10. ^ Schlag, J & Schlag-Rey, M (1987). "Evidence for a supplementary eye field". J. Neurophysiol. 57 (1): 179–200. doi:10.1152/jn.1987.57.1.179. PMID 3559671.
  11. ^ Tehovnik, E.J. & Lee, K (1993). "The dorsomedial frontal cortex of the rhesus monkey: topographic representation of saccades evoked by electrical stimulation". Exp. Brain Res. 96 (3): 430–442. doi:10.1007/bf00234111. PMID 8299745. S2CID 11322416.
  12. ^ Galea, M.P. & Darian-Smith, I (1994). "Multiple corticospinal neuron populations in the macaque monkey are specified by their unique cortical origins, spinal terminations, and connections". Cereb. Cortex. 4 (2): 166–194. doi:10.1093/cercor/4.2.166. PMID 8038567.
  13. ^ a b Macpherson, J., Marangoz, C., Miles, T.S. and Wiesendanger, M (1982). "Microstimulation of the supplementary motor area (SMA) in the awake monkey". Exp. Brain Res. 45 (3): 410–416. doi:10.1007/bf01208601. PMID 7067775. S2CID 10053006.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  14. ^ Murray, E.A. & Coulter, J.D (1981). "Organization of corticospinal neurons in the monkey". J. Comp. Neurol. 195 (2): 339–365. doi:10.1002/cne.901950212. PMID 7251930. S2CID 20215391.
  15. ^ Nudo, R.J. & Masterton, R.B (1990). "Descending pathways of the spinal cord, III: Sites of origin of the corticospinal tract". J. Comp. Neurol. 296 (4): 559–583. doi:10.1002/cne.902960405. PMID 2113540. S2CID 20563396.
  16. ^ Toyoshima, K & Sakai, H (1982). "Exact cortical extent of the origin of the corticospinal tract (CST) and the quantitative contribution to the CST in different cytoarchitectonic areas. A study with horseradish peroxidase in the monkey". J. Hirnforsch. 23 (3): 257–269. PMID 7130676.
  17. ^ Zhang, S., Ide, J.S., and Li, C.S. (2012). "Resting-State Functional Connectivity of the Medial Superior Frontal Cortex". Cereb. Cortex. 22 (1): 99–111. doi:10.1093/cercor/bhr088. PMC 3236794. PMID 21572088.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  18. ^ a b Penfield, W. & Welch, K (1951). "The supplementary motor area of the cerebral cortex: A clinical and experimental study". AMA Arch. Neurol. Psychiatry. 66 (3): 289–317. doi:10.1001/archneurpsyc.1951.02320090038004. PMID 14867993.
  19. ^ Woolsey, C.N., Settlage, P.H., Meyer, D.R., Sencer, W., Hamuy, T.P. and Travis, A.M. (1952). "Pattern of localization in precentral and "supplementary" motor areas and their relation to the concept of a premotor area". Association for Research in Nervous and Mental Disease. New York, NY: Raven Press. 30: 238–264.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  20. ^ Gould, H.J. III, Cusick, C.G., Pons, T.P. and Kaas, J.H (1996). "The relationship of corpus callosum connections to electrical stimulation maps of motor, supplementary motor, and the frontal eye fields in owl monkeys". J. Comp. Neurol. 247 (3): 297–325. doi:10.1002/cne.902470303. PMID 3722441. S2CID 21185898.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  21. ^ Muakkassa, K.F. & Strick, P.L (1979). "Frontal lobe inputs to primate motor cortex: evidence for four somatotopically organized 'premotor' areas". Brain Res. 177 (1): 176–182. doi:10.1016/0006-8993(79)90928-4. PMID 115545. S2CID 34047716.
  22. ^ Mitz, A.R. & Wise, S.P (1987). "The somatotopic organization of the supplementary motor area: intracortical microstimulation mapping". J. Neurosci. 7 (4): 1010–1021. doi:10.1523/JNEUROSCI.07-04-01010.1987. PMC 6568999. PMID 3572473.
  23. ^ Gaymard, B, Pierrot=Deseilligny, C. and Rivaud, S (1990). "Impairment of sequences of memory-guided saccades after supplementary motor area lesions". Annals of Neurology. 28 (5): 622–626. doi:10.1002/ana.410280504. PMID 2260848. S2CID 31214017.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  24. ^ Gerloff, C., Corwell, B., Chen, R., Hallett, M. and Cohen, L.G (1997). "Stimulation over the human supplementary motor area interferes with the organization of future elements in complex motor sequences". Brain. 120 (9): 1587–1602. doi:10.1093/brain/120.9.1587. PMID 9313642.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  25. ^ Jenkins, I.H., Brooks, D.J., Nixon, P.D., Frackowiak, R.S. and Passingham, R.E (1994). "Motor sequence learning: a study with positron emission tomography". J. Neurosci. 14 (6): 3775–3790. doi:10.1523/JNEUROSCI.14-06-03775.1994. PMC 6576955. PMID 8207487.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  26. ^ Lee, D. & Quessy, S (2003). "Activity in the supplementary motor area related to learning and performance during a sequential visuomotor task". J. Neurophysiol. 89 (2): 1039–1056. doi:10.1152/jn.00638.2002. PMID 12574479.
  27. ^ Mushiake, H., Inase, M. and Tanjii, J (1990). "Selective coding of motor sequence in the supplementary motor area of the monkey cerebral cortex". Exp. Brain Res. 82 (1): 208–210. doi:10.1007/bf00230853. PMID 2257906. S2CID 33522843.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  28. ^ Shima, K. & Tanji, J (1998). "Both supplementary and presupplementary motor areas are crucial for the temporal organization of multiple movements". J. Neurophysiol. 80 (6): 3247–3260. doi:10.1152/jn.1998.80.6.3247. PMID 9862919.
  29. ^ a b Roland, P.E., Larsen, B., Lassen, N.A. and Skinhoj, E (1980). "Supplementary motor area and other cortical areas in organization of voluntary movements in man". J. Neurophysiol. 43 (1): 118–136. doi:10.1152/jn.1980.43.1.118. PMID 7351547.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  30. ^ a b Roland, P.E., Skinhoj, E., Lassen, N.A. and Larsen, B. (1980). "Different cortical areas in man in organization of voluntary movements in extrapersonal space". J. Neurophysiol. 43 (1): 137–150. doi:10.1152/jn.1980.43.1.137. PMID 7351548.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  31. ^ Brinkman, C (1981). "Lesions in supplementary motor area interfere with a monkey's performance of a bimanual coordination task". Neurosci. Lett. 27 (3): 267–270. doi:10.1016/0304-3940(81)90441-9. PMID 7329632. S2CID 41060226.
  32. ^ Serrien, D.J., Strens, L.H., Oliveiero, A. and Brown, P (2002). "Repetitive transcranial magnetic stimulation of the supplementary motor area (SMA) degrades bimanual movement control in humans". Neurosci. Lett. 328 (2): 89–92. doi:10.1016/s0304-3940(02)00499-8. PMID 12133562. S2CID 35568770.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  33. ^ Halsband, U., Matsuzaka, Y. and Tanji, J. (1994). "Neuronal activity in the primate supplementary, pre-supplementary and premotor cortex during externally and internally instructed sequential movements". Neurosci. Res. 20 (2): 149–155. doi:10.1016/0168-0102(94)90032-9. PMID 7808697. S2CID 5930996.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  34. ^ Picard, N. & Strick, P.L (September 2003). "Activation of the supplementary motor area (SMA) during performance of visually guided movements". Cereb. Cortex. 13 (9): 977–986. doi:10.1093/cercor/13.9.977. PMID 12902397.
  35. ^ Deecke L, Kornhuber (1978). "supplementary" motor cortex in human voluntary finger movements". Brain Res. 159 (2): 473–476. doi:10.1016/0006-8993(78)90561-9. PMID 728816. S2CID 43904948.
  36. ^ Cunnington R, Windischberger C, Deecke L, Moser E (2003). "The preparation and readiness for voluntary movement: a high-field event-related fMRI study of the Bereitschafts-BOLD response". NeuroImage. 20 (1): 404–412. doi:10.1016/s1053-8119(03)00291-x. PMID 14527600. S2CID 13419573.
  37. ^ Nguyen VT, Breakspear M, Cunnington R (2014). "Reciprocal interactions of the SMA and cingulate cortex sustain pre-movement activity for voluntary actions". J Neurosci. 34 (49): 16397–16407. doi:10.1523/jneurosci.2571-14.2014. PMC 6608485. PMID 25471577.
  38. ^ a b Graziano, M.S.A. (2008). The Intelligent Movement Machine. Oxford, UK: Oxford University Press.
  39. ^ Graziano, M.S.A. and Aflalo, T.N. (2007). "Mapping behavioral repertoire onto the cortex". Neuron. 56 (2): 239–251. doi:10.1016/j.neuron.2007.09.013. PMID 17964243.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  40. ^ Graziano, M.S.A., Aflalo, T.N. and Cooke, D.F (2005). "Arm movements evoked by electrical stimulation in the motor cortex of monkeys". J. Neurophysiol. 94 (6): 4209–4223. doi:10.1152/jn.01303.2004. PMID 16120657.{{cite journal}}: CS1 maint: multiple names: authors list (link)

Further reading[edit]

  • Principles of Neural Science (2000), 4th ed., Kandel et al.
  • Debaere, F, Wenderoth, N, Sunaert, S, Van-Hecke, P, Swinnen, SP (Jul 2003). "Internal vs external generation of movements: differential neural pathways involved in bimanual coordination performed in the presence or absence of augmented visual feedback". NeuroImage. 19 (3): 764–76. doi:10.1016/s1053-8119(03)00148-4. PMID 12880805. S2CID 12977852.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  • Vorobiev; et al. (1998). "Parcellation of human mesial area 6: cytoarchitectonic evidence for three separate areas". Eur J Neurosci. 10 (6): 2199–203. doi:10.1046/j.1460-9568.1998.00236.x. PMID 9753106. S2CID 23787668.

External links[edit]