The sensorimotor rhythm (SMR) is a brain wave. It is an oscillatory idle rhythm of synchronized electric brain activity. It appears in spindles in recordings of EEG, MEG, and ECoG over the

sensorimotor cortex The motor cortex is the region of the cerebral cortex involved in the planning, motor control, control, and execution of voluntary movements. The motor cortex is an area of the frontal lobe located in the posterior precentral gyrus immediately ...

. For most individuals, the frequency of the SMR is in the range of 7 to 11 Hz.

Meaning

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 or motor areas are activated, e.g. during motor tasks and even during motor imagery. Conceptually, SMR is sometimes mixed up with

alpha wave Alpha waves, or the alpha rhythm, are neural oscillations in the frequency range of 8–12 Hz likely originating from the synchronous and coherent ( in phase or constructive) neocortical neuronal electrical activity possibly involving thala ...

s 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 human mu rhythm.

Relevance in research

Neurofeedback

Neurofeedback Neurofeedback is a form of biofeedback that uses electrical potentials in the brain to reinforce desired brain states through operant conditioning. This process is non-invasive neurotherapy and typically collects brain activity data using elect ...

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 with learning difficulties,

ADHD Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterised by symptoms of inattention, hyperactivity, impulsivity, and emotional dysregulation that are excessive and pervasive, impairing in multiple ...

epilepsy Epilepsy is a group of Non-communicable disease, non-communicable Neurological disorder, neurological disorders characterized by a tendency for recurrent, unprovoked Seizure, seizures. A seizure is a sudden burst of abnormal electrical activit ...

, and

autism Autism, also known as autism spectrum disorder (ASD), is a neurodevelopmental disorder characterized by differences or difficulties in social communication and interaction, a preference for predictability and routine, sensory processing d ...

may benefit from an increase in SMR activity via

neurofeedback Neurofeedback is a form of biofeedback that uses electrical potentials in the brain to reinforce desired brain states through operant conditioning. This process is non-invasive neurotherapy and typically collects brain activity data using elect ...

. Furthermore, in the sport domain, SMR neurofeedback training has been found to be useful to enhance the golf putting performance. In the field of Brain–Computer Interfaces (BCI), the deliberate modification of the SMR amplitude during motor imagery can be used to control external applications.Andrea Kübler and Klaus-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

Meaning

Relevance in research

Neurofeedback

See also

Brain waves

References

Further reading