Oscillatory idle rhythm of synchronized electric brain activity
SMR waves
Thesensorimotor rhythm (SMR) is abrain wave. It is an oscillatory idle rhythm of synchronized electric brain activity. It appears in spindles in recordings ofEEG,MEG, andECoG over thesensorimotor cortex. For most individuals, the frequency of the SMR is in the range of 7 to 11 Hz.[1]
The meaning of SMR is not fully understood. Phenomenologically, a person is producing a stronger SMR amplitude when the corresponding sensorimotor areas are idle, e.g. during states of immobility. SMR typically decreases in amplitude when the corresponding sensory ormotor areas are activated, e.g. during motor tasks and even during motor imagery.[2]
Conceptually, SMR is sometimes mixed up withalpha waves of occipital origin, the strongest source of neural signals in the EEG. One reason might be, that without appropriate spatial filtering the SMR is very difficult to detect because it is usually flooded by the stronger occipital alpha waves. The feline SMR has been noted as being analogous to the humanmu rhythm.[3]
Neurofeedback training can be used to gain control over the SMR activity. Neurofeedback practitioners believe that this feedback enables the subject to learn the regulation of their own SMR.People withlearning difficulties,[4]ADHD,[5]epilepsy,[6] andautism[7] may benefit from an increase in SMR activity vianeurofeedback.In the field ofBrain–Computer Interfaces (BCI), the deliberate modification of the SMR amplitude during motor imagery can be used to control external applications.[8]
^Ernst Niedermeyer, Fernando Lopes da Silva Electroencephalography. Basic principles, Clinical Applications and Related Fields. 3rd edition, Williams & Wilkins Baltimore 1993
^Tansey MA (February 1984). "EEG sensorimotor rhythm biofeedback training: some effects on the neurologic precursors of learning disabilities".Int J Psychophysiol.1 (2):163–77.doi:10.1016/0167-8760(84)90036-9.PMID6542077.
^Vernon, David; Tobias Egner; Nick Cooper; Theresa Compton; Claire Neilands; Amna Sheri; John Gruzelier (January 2003). "The effect of training distinct neurofeedback protocols on aspects of cognitive performance".International Journal of Psychophysiology.47 (1):75–85.doi:10.1016/S0167-8760(02)00091-0.PMID12543448.
^Egner, Tobias; M Barry Sterman (February 2006). "Neurofeedback treatment of epilepsy: from basic rationale to practical application".Expert Review of Neurotherapeutics.6 (2):247–257.doi:10.1586/14737175.6.2.247.PMID16466304.S2CID38841067.
^Andrea Kübler andKlaus-Robert Müller. An introduction to brain computer interfacing. In Guido Dornhege, Jose del R. Millán, Thilo Hinterberger, Dennis McFarland, and Klaus-Robert Müller, editors, Toward Brain–Computer Interfacing, pages 1-25. MIT press, Cambridge, MA, 2007
Robbins, Jim (2000).A Symphony in the Brain. Atlantic Monthly Press.ISBN978-0-87113-807-1.
Sterman, M. B.; Wyrwicka, W. (1967). "EEG correlates of sleep: Evidence for separate forebrain substrates".Brain Research.6 (1):143–163.doi:10.1016/0006-8993(67)90186-2.PMID6052533.
Wyrwicka, W.; Sterman, M. B. (1968). "Instrumental conditioning of sensorimotor cortex eeg spindles in the waking cat".Physiology and Behavior.3 (5):703–707.doi:10.1016/0031-9384(68)90139-X.
