Sensorimotor rhythm
Encyclopedia
Description
The Sensory Motor Rhythm (SMR) is brain wave rhythm. It is an oscillatory idle rhythm of synchronized electromagnetic brain activity. It appears in spindles in recordings of EEGEEG
EEG commonly refers to electroencephalography, a measurement of the electrical activity of the brain.EEG may also refer to:* Emperor Entertainment Group, a Hong Kong-based entertainment company...
, MEG
Magnetoencephalography
Magnetoencephalography is a technique for mapping brain activity by recording magnetic fields produced by electrical currents occurring naturally in the brain, using arrays of SQUIDs...
, and ECoG over the sensorimotor cortex
Motor cortex
Motor cortex is a term that describes regions of the cerebral cortex involved in the planning, control, and execution of voluntary motor functions.-Anatomy of the motor cortex :The motor cortex can be divided into four main parts:...
. For most individuals, the frequency of the SMR is in the range of 8 to 12 Hz. The feline SMR has been noted as being analogous to the human mu rhythm
Mu rhythm
Mu rhythm is a kind of brain wave rhythm measured using Electroencephalography that has a maximal amplitude of somatosensory cortices at rest. It is also called arciform rhythm because of the shape of the waveforms.-Description:...
.
Meaning
The meaning of SMR is not fully understood. Phenomenologically, a person is producing a stronger SMR amplitude when the corresponding sensory-motor areas are idle, e.g. during states of immobility. SMR typically decrease in amplitude when the corresponding sensory or motorMotor system
The motor system is the part of the central nervous system that is involved with movement. It consists of the pyramidal and extrapyramidal system....
areas are activated, e.g. during motor tasks and even during motor imagery.
Conceptually, SMR is sometimes mixed up with alpha waves
Alpha wave
Alpha waves are neural oscillations in the frequency range of 8–12 Hz arising from synchronous and coherent electrical activity of thalamic pacemaker cells in humans...
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 as it is usually superimposed by the stronger occipital alpha waves.
Neurofeedback
NeurofeedbackNeurofeedback
Neurofeedback , also called neurotherapy, neurobiofeedback or EEG biofeedback is a type of biofeedback that uses realtime displays of electroencephalography or functional magnetic resonance imaging to illustrate brain activity, often with a goal of controlling central nervous system activity...
training can be used to gain control over the SMR activity. Neurofeedback practitioners believe—and have produced experimental evidence to back up their claims - that this feedback enables the subject to learn the regulation of their own SMR.
People with learning difficulties
Learning difficulties
Learning difficulties may refer to:*The conditions known in North America as learning disabilities, which are called "specific learning difficulties" in the United Kingdom...
, ADHD, epilepsy
Epilepsy
Epilepsy is a common chronic neurological disorder characterized by seizures. These seizures are transient signs and/or symptoms of abnormal, excessive or hypersynchronous neuronal activity in the brain.About 50 million people worldwide have epilepsy, and nearly two out of every three new cases...
, and autism
Autism
Autism is a disorder of neural development characterized by impaired social interaction and communication, and by restricted and repetitive behavior. These signs all begin before a child is three years old. Autism affects information processing in the brain by altering how nerve cells and their...
may benefit from an increase in SMR activity via neurofeedback
Neurofeedback
Neurofeedback , also called neurotherapy, neurobiofeedback or EEG biofeedback is a type of biofeedback that uses realtime displays of electroencephalography or functional magnetic resonance imaging to illustrate brain activity, often with a goal of controlling central nervous system activity...
.
In the field of Brain-Computer Interfaces (BCI)
Brain-computer interface
A brain–computer interface , sometimes called a direct neural interface or a brain–machine interface , is a direct communication pathway between the brain and an external device...
, the deliberate modification of the SMR amplitude during motor imagery can be used to control external applications .
Specific brain waves
- Delta waveDelta waveA delta wave is a high amplitude brain wave with a frequency of oscillation between 0–4 hertz. Delta waves, like other brain waves, are recorded with an electroencephalogram and are usually associated with the deepest stages of sleep , also known as slow-wave sleep , and aid in characterizing the...
– (0.1–4 Hz) - Theta wave – (4–7 Hz)
- Alpha waveAlpha waveAlpha waves are neural oscillations in the frequency range of 8–12 Hz arising from synchronous and coherent electrical activity of thalamic pacemaker cells in humans...
– (8–12 Hz) - Mu waveMu waveMu waves, also known as the comb or wicket rhythm, are electromagnetic oscillations in the frequency range of 8–13 Hz and appear in bursts of at 9 – 11 Hz. Mu wave patterns arise from synchronous and coherent electrical activity of large groups of neurons in the human brain...
– (8–13 Hz) - Beta waveBeta waveBeta wave, or beta rhythm, is the term used to designate the frequency range of human brain activity between 12 and 30 Hz . Beta waves are split into three sections: High Beta Waves ; Beta Waves ; and Low Beta Waves...
– (12–30 Hz) - Gamma waveGamma waveA gamma wave is a pattern of neural oscillation in humans with a frequency between 25 to 100 Hz, though 40 Hz is prototypical.According to a popular theory, gamma waves may be implicated in creating the unity of conscious perception...
– (25–100 Hz)