31-05-2012, 12:39 PM
Alpha wave intrusion
[attachment=23666]
Alpha waves are electromagnetic oscillations in the frequency range of 8–12 Hz arising from synchronous and coherent (in phase / constructive) electrical activity of thalamic pacemaker cells. They are also called Berger's wave in memory of the founder of EEG.
Alpha waves are one type of brain waves detected either by electroencephalography (EEG) or magnetoencephalography (MEG) and predominantly originate from the occipital lobe during wakeful relaxation with closed eyes. Alpha waves are reduced with open eyes and drowsiness and sleep. They are thought to represent the activity of the visual cortex in an idle state. Occipital alpha waves during periods of eyes closed are the strongest EEG brain signals. They usually can be detected with the naked eye.
An alpha-like variant called mu (μ) can be found over the motor cortex (central scalp) that is reduced with movement, or the intention to move. Alpha waves do not start to appear until three years of age.[1]
Alpha wave intrusion
If alpha waves intrusion occurs when alpha waves appear with non REM sleep when delta activity is expected. It is hypothesized to be associated with fibromyalgia[2], although the study was too small to be conclusive.
A delta wave is a high amplitude brain wave with a frequency of 1–4 hertz which can be recorded with an electroencephalogram[1] (EEG) and is usually associated with slow-wave sleep (SWS).
Delta wave activity occurs most frequently during stage N3 slow-wave sleep, accounting for 20% or more of the EEG record during this stage.[2] These waves are believed to originate in the thalamus in coordination with the reticular formation.[3]
Function
Low amplitude beta waves with multiple and varying frequencies are often associated with active, busy, or anxious thinking and active concentration.
Over the motor cortex beta waves are associated with the muscle contractions that happen in isotonic movements and are suppressed prior to and during movement changes.[1] Bursts of beta activity are associated with a strengthening of sensory feedback in static motor control and reduced when there is movement change.[2] Beta activity is increased when movement has to be resisted or voluntarily suppressed.[3] The artificial induction of increased beta waves over the motor cortex by a variety of Transcranial magnetic stimulation called Transcranial alternating-current stimulation consistent with its link to isotonic contraction produces a slowing of motor movements.[4]
[edit]
Pathology
Rhythmic beta with a dominant set of frequencies is associated with various pathologies and drug effects. For instance, beta activity can be accentuated by sedative-hypnotic drugs such as benzodiazepines or barbiturates.[citation needed] It can also be absent or reduced in a patient with cortical damage. Exaggerated beta activity is found in Parkinson’s disease and this links to their motor slowing.[5]
[attachment=23666]
Alpha waves are electromagnetic oscillations in the frequency range of 8–12 Hz arising from synchronous and coherent (in phase / constructive) electrical activity of thalamic pacemaker cells. They are also called Berger's wave in memory of the founder of EEG.
Alpha waves are one type of brain waves detected either by electroencephalography (EEG) or magnetoencephalography (MEG) and predominantly originate from the occipital lobe during wakeful relaxation with closed eyes. Alpha waves are reduced with open eyes and drowsiness and sleep. They are thought to represent the activity of the visual cortex in an idle state. Occipital alpha waves during periods of eyes closed are the strongest EEG brain signals. They usually can be detected with the naked eye.
An alpha-like variant called mu (μ) can be found over the motor cortex (central scalp) that is reduced with movement, or the intention to move. Alpha waves do not start to appear until three years of age.[1]
Alpha wave intrusion
If alpha waves intrusion occurs when alpha waves appear with non REM sleep when delta activity is expected. It is hypothesized to be associated with fibromyalgia[2], although the study was too small to be conclusive.
A delta wave is a high amplitude brain wave with a frequency of 1–4 hertz which can be recorded with an electroencephalogram[1] (EEG) and is usually associated with slow-wave sleep (SWS).
Delta wave activity occurs most frequently during stage N3 slow-wave sleep, accounting for 20% or more of the EEG record during this stage.[2] These waves are believed to originate in the thalamus in coordination with the reticular formation.[3]
Function
Low amplitude beta waves with multiple and varying frequencies are often associated with active, busy, or anxious thinking and active concentration.
Over the motor cortex beta waves are associated with the muscle contractions that happen in isotonic movements and are suppressed prior to and during movement changes.[1] Bursts of beta activity are associated with a strengthening of sensory feedback in static motor control and reduced when there is movement change.[2] Beta activity is increased when movement has to be resisted or voluntarily suppressed.[3] The artificial induction of increased beta waves over the motor cortex by a variety of Transcranial magnetic stimulation called Transcranial alternating-current stimulation consistent with its link to isotonic contraction produces a slowing of motor movements.[4]
[edit]
Pathology
Rhythmic beta with a dominant set of frequencies is associated with various pathologies and drug effects. For instance, beta activity can be accentuated by sedative-hypnotic drugs such as benzodiazepines or barbiturates.[citation needed] It can also be absent or reduced in a patient with cortical damage. Exaggerated beta activity is found in Parkinson’s disease and this links to their motor slowing.[5]