The EEG is about declared in agreement of (1) adroit action and (2) transients. The adroit action is disconnected into bands by frequency. To some degree, these abundance bands are a amount of classification (i.e., any adroit action amid 6–12 Hz can be declared as "alpha"), but these designations arose because adroit action aural a assertive abundance ambit was acclaimed to accept a assertive administration over the attic or a assertive biological significance. Abundance bands are usually extracted application ashen methods (for instance Welch) as implemented for instance in advisedly accessible EEG software such as EEGLAB.
Most of the bookish arresting empiric in the attic EEG avalanche in the ambit of 1–20 Hz (activity beneath or aloft this ambit is acceptable to be artifactual, beneath accepted analytic recording techniques).
edit Comparison table
Comparison of EEG bands Blazon Frequency (Hz) Location Normally Pathologically
Delta up to 4 frontally in adults, posteriorly in children; top amplitude after-effects
adults apathetic beachcomber sleep
in babies
Has been begin during some connected absorption tasks16
subcortical lesions
broadcast lesions
metabolic encephalopathy hydrocephalus
abysmal midline lesions
Theta 4 – 8 Found in locations not accompanying to assignment at duke
adolescent children
blackout or activation in earlier accouchement and adults
idling
Associated with inhibition of elicited responses (has been begin to fasten in situations area a being is actively aggravating to repress a acknowledgment or action).16
focal subcortical lesions
metabolic encephalopathy
abysmal midline disorders
some instances of hydrocephalus
Alpha 8 – 13 posterior regions of head, both sides, college in amplitude on ascendant side. Central sites (c3-c4) at blow
relaxed/reflecting
closing the eyes
Aswell associated with inhibition control, acutely with the purpose of timing inhibitory action in altered locations beyond the brain.
coma
Beta >13 – 30 both sides, balanced distribution, a lot of axiomatic frontally; low amplitude after-effects
alert/working
active, alive or afraid thinking, alive concentration
benzodiazepines
Gamma 30 – 100+ Somatosensory case
Displays during cross-modal acoustic processing (perception that combines two altered senses, such as complete and sight)1718
Aswell is apparent during abbreviate appellation anamnesis analogous of accustomed objects, sounds, or accurate sensations
A abatement in gamma bandage action may be associated with cerebral decline, abnormally if accompanying the theta band; however, this has not been accurate for use as a analytic analytic altitude yet
Mu 8 – 13 Sensorimotor case
Shows blow accompaniment motor neurons.19
Mu abolishment could announce that motor mirror neurons are working. Deficits in Mu suppression, and appropriately in mirror neurons, ability play a role in autism.20
It should be acclaimed that while these are the universally accustomed ranges, they are not accurate definitions of the ambit of brain-waves. While advisers tend to chase these guidelines, abounding advisers use their own specific boundaries depending on the ambit they accept to focus on. Additionally, some advisers ascertain the bands application decimal ethics rather than rounding to accomplished numbers (for example, one researcher may ascertain the lower Beta bandage absolute as 12.1, while accession may use the amount 13), while still others sometimes bisect the bands into sub-bands. Generally, this is alone done for the account of analysis.
edit Beachcomber patterns
delta waves.
Basin is the abundance ambit up to 4 Hz. It tends to be the accomplished in amplitude and the slowest waves. It is apparent commonly in adults in apathetic beachcomber sleep. It is aswell apparent commonly in babies. It may action focally with subcortical lesions and in accepted administration with broadcast lesions, metabolic encephalopathy hydrocephalus or abysmal midline lesions. It is usually a lot of arresting frontally in adults (e.g. FIRDA - Aboveboard Intermittent Adroit Delta) and posteriorly in accouchement (e.g. OIRDA - Occipital Intermittent Adroit Delta).
theta waves.
Theta is the abundance ambit from 4 Hz to 7 Hz. Theta is apparent commonly in adolescent children. It may be apparent in blackout or activation in earlier accouchement and adults; it can aswell be apparent in meditation.21 Excess theta for age represents aberrant activity. It can be apparent as a focal agitation in focal subcortical lesions; it can be apparent in ambiguous administration in broadcast ataxia or metabolic encephalopathy or abysmal midline disorders or some instances of hydrocephalus. On the adverse this ambit has been associated with letters of relaxed, meditative, and artistic states.
alpha waves.
Alpha is the abundance ambit from 8 Hz to 12 Hz. Hans Berger alleged the aboriginal adroit EEG action he saw as the "alpha wave". This was the "posterior basal rhythm" (also alleged the "posterior ascendant rhythm" or the "posterior alpha rhythm"), apparent in the after regions of the arch on both sides, college in amplitude on the ascendant side. It emerges with closing of the eyes and with relaxation, and attenuates with eye aperture or brainy exertion. The after basal accent is in fact slower than 8 Hz in adolescent accouchement (therefore technically in the theta range).
sensorimotor accent aka mu rhythm.
In accession to the after basal rhythm, there are added accustomed alpha rhythms such as the mu accent (alpha action in the contralateral acoustic and motor cortical areas that emerges if the easily and accoutrements are idle; and the "third rhythm" (alpha action in the banausic or aboveboard lobes).2223 Alpha can be abnormal; for example, an EEG that has broadcast alpha occurring in blackout and is not acknowledging to alien stimuli is referred to as "alpha coma".
beta waves.
Beta is the abundance ambit from 12 Hz to about 30 Hz. It is apparent usually on both abandon in balanced administration and is a lot of axiomatic frontally. Beta action is carefully affiliated to motor behavior and is about attenuated during alive movements.24 Low amplitude beta with assorted and capricious frequencies is about associated with active, alive or afraid cerebration and alive concentration. Adroit beta with a ascendant set of frequencies is associated with assorted pathologies and biologic effects, abnormally benzodiazepines. It may be absent or bargain in areas of cortical damage. It is the ascendant accent in patients who are active or afraid or who accept their eyes open.
gamma waves.
Gamma is the abundance ambit about 30–100 Hz. Gamma rhythms are anticipation to represent bounden of altered populations of neurons calm into a arrangement for the purpose of accustomed out a assertive cerebral or motor function.2
Mu ranges 8–13 Hz., and partly overlaps with added frequencies. It reflects the ancillary battlefront of motor neurons in blow state. Mu abolishment is anticipation to reflect motor mirror neuron systems, because if an action is observed, the arrangement extinguishes, possibly because of the accustomed neuronal arrangement and the mirror neuron arrangement "go out of sync", and baffle with anniversary other.20
"Ultra-slow" or "near-DC" (Direct current) action is recorded application DC amplifiers in some analysis contexts. It is not about recorded in a analytic ambience because the arresting at these frequencies is affected to a amount of artifacts.
Some appearance of the EEG are brief rather than rhythmic. Spikes and aciculate after-effects may represent access action or interictal action in individuals with attack or a predisposition against epilepsy. Added brief appearance are normal: acme after-effects and beddy-bye spindles are apparent in accustomed sleep.
Note that there are types of action that are statistically uncommon, but not associated with dysfunction or disease. These are about referred to as "normal variants." The mu accent is an archetype of a accustomed variant.
The accustomed Electroencephalography (EEG) varies by age. The neonatal EEG is absolutely altered from the developed EEG. The EEG in adolescence about has slower abundance oscillations than the developed EEG.
The accustomed EEG aswell varies depending on state. The EEG is acclimated forth with added abstracts (EOG, EMG) to ascertain beddy-bye stages in polysomnography. Stage I beddy-bye (equivalent to blackout in some systems) appears on the EEG as drop-out of the after basal rhythm. There can be an access in theta frequencies. Santamaria and Chiappa cataloged a amount of the array of patterns associated with drowsiness. Stage II beddy-bye is characterized by beddy-bye spindles—transient runs of adroit action in the 12–14 Hz ambit (sometimes referred to as the "sigma" band) that accept a frontal-central maximum. A lot of of the action in Stage II is in the 3–6 Hz range. Stage III and IV beddy-bye are authentic by the attendance of basin frequencies and are about referred to collectively as "slow-wave sleep." Stages I-IV comprise non-REM (or "NREM") sleep. The EEG in REM (rapid eye movement) beddy-bye appears somewhat agnate to the alive EEG.
EEG beneath accepted anesthesia depends on the blazon of analgesic employed. With halogenated anesthetics, such as halothane or intravenous agents, such as propofol, a accelerated (alpha or low beta), nonreactive EEG arrangement is apparent over a lot of of the scalp, abnormally anteriorly; in some earlier analogue this was accepted as a WAR (widespread antecedent rapid) pattern, assorted with a WAIS (widespread slow) arrangement associated with top doses of opiates. Analgesic furnishings on EEG signals are alpha to be accepted at the akin of biologic accomplishments on altered kinds of synapses and the circuits that acquiesce synchronized neuronal action (see: http://www.stanford.edu/group/maciverlab/).
Most of the bookish arresting empiric in the attic EEG avalanche in the ambit of 1–20 Hz (activity beneath or aloft this ambit is acceptable to be artifactual, beneath accepted analytic recording techniques).
edit Comparison table
Comparison of EEG bands Blazon Frequency (Hz) Location Normally Pathologically
Delta up to 4 frontally in adults, posteriorly in children; top amplitude after-effects
adults apathetic beachcomber sleep
in babies
Has been begin during some connected absorption tasks16
subcortical lesions
broadcast lesions
metabolic encephalopathy hydrocephalus
abysmal midline lesions
Theta 4 – 8 Found in locations not accompanying to assignment at duke
adolescent children
blackout or activation in earlier accouchement and adults
idling
Associated with inhibition of elicited responses (has been begin to fasten in situations area a being is actively aggravating to repress a acknowledgment or action).16
focal subcortical lesions
metabolic encephalopathy
abysmal midline disorders
some instances of hydrocephalus
Alpha 8 – 13 posterior regions of head, both sides, college in amplitude on ascendant side. Central sites (c3-c4) at blow
relaxed/reflecting
closing the eyes
Aswell associated with inhibition control, acutely with the purpose of timing inhibitory action in altered locations beyond the brain.
coma
Beta >13 – 30 both sides, balanced distribution, a lot of axiomatic frontally; low amplitude after-effects
alert/working
active, alive or afraid thinking, alive concentration
benzodiazepines
Gamma 30 – 100+ Somatosensory case
Displays during cross-modal acoustic processing (perception that combines two altered senses, such as complete and sight)1718
Aswell is apparent during abbreviate appellation anamnesis analogous of accustomed objects, sounds, or accurate sensations
A abatement in gamma bandage action may be associated with cerebral decline, abnormally if accompanying the theta band; however, this has not been accurate for use as a analytic analytic altitude yet
Mu 8 – 13 Sensorimotor case
Shows blow accompaniment motor neurons.19
Mu abolishment could announce that motor mirror neurons are working. Deficits in Mu suppression, and appropriately in mirror neurons, ability play a role in autism.20
It should be acclaimed that while these are the universally accustomed ranges, they are not accurate definitions of the ambit of brain-waves. While advisers tend to chase these guidelines, abounding advisers use their own specific boundaries depending on the ambit they accept to focus on. Additionally, some advisers ascertain the bands application decimal ethics rather than rounding to accomplished numbers (for example, one researcher may ascertain the lower Beta bandage absolute as 12.1, while accession may use the amount 13), while still others sometimes bisect the bands into sub-bands. Generally, this is alone done for the account of analysis.
edit Beachcomber patterns
delta waves.
Basin is the abundance ambit up to 4 Hz. It tends to be the accomplished in amplitude and the slowest waves. It is apparent commonly in adults in apathetic beachcomber sleep. It is aswell apparent commonly in babies. It may action focally with subcortical lesions and in accepted administration with broadcast lesions, metabolic encephalopathy hydrocephalus or abysmal midline lesions. It is usually a lot of arresting frontally in adults (e.g. FIRDA - Aboveboard Intermittent Adroit Delta) and posteriorly in accouchement (e.g. OIRDA - Occipital Intermittent Adroit Delta).
theta waves.
Theta is the abundance ambit from 4 Hz to 7 Hz. Theta is apparent commonly in adolescent children. It may be apparent in blackout or activation in earlier accouchement and adults; it can aswell be apparent in meditation.21 Excess theta for age represents aberrant activity. It can be apparent as a focal agitation in focal subcortical lesions; it can be apparent in ambiguous administration in broadcast ataxia or metabolic encephalopathy or abysmal midline disorders or some instances of hydrocephalus. On the adverse this ambit has been associated with letters of relaxed, meditative, and artistic states.
alpha waves.
Alpha is the abundance ambit from 8 Hz to 12 Hz. Hans Berger alleged the aboriginal adroit EEG action he saw as the "alpha wave". This was the "posterior basal rhythm" (also alleged the "posterior ascendant rhythm" or the "posterior alpha rhythm"), apparent in the after regions of the arch on both sides, college in amplitude on the ascendant side. It emerges with closing of the eyes and with relaxation, and attenuates with eye aperture or brainy exertion. The after basal accent is in fact slower than 8 Hz in adolescent accouchement (therefore technically in the theta range).
sensorimotor accent aka mu rhythm.
In accession to the after basal rhythm, there are added accustomed alpha rhythms such as the mu accent (alpha action in the contralateral acoustic and motor cortical areas that emerges if the easily and accoutrements are idle; and the "third rhythm" (alpha action in the banausic or aboveboard lobes).2223 Alpha can be abnormal; for example, an EEG that has broadcast alpha occurring in blackout and is not acknowledging to alien stimuli is referred to as "alpha coma".
beta waves.
Beta is the abundance ambit from 12 Hz to about 30 Hz. It is apparent usually on both abandon in balanced administration and is a lot of axiomatic frontally. Beta action is carefully affiliated to motor behavior and is about attenuated during alive movements.24 Low amplitude beta with assorted and capricious frequencies is about associated with active, alive or afraid cerebration and alive concentration. Adroit beta with a ascendant set of frequencies is associated with assorted pathologies and biologic effects, abnormally benzodiazepines. It may be absent or bargain in areas of cortical damage. It is the ascendant accent in patients who are active or afraid or who accept their eyes open.
gamma waves.
Gamma is the abundance ambit about 30–100 Hz. Gamma rhythms are anticipation to represent bounden of altered populations of neurons calm into a arrangement for the purpose of accustomed out a assertive cerebral or motor function.2
Mu ranges 8–13 Hz., and partly overlaps with added frequencies. It reflects the ancillary battlefront of motor neurons in blow state. Mu abolishment is anticipation to reflect motor mirror neuron systems, because if an action is observed, the arrangement extinguishes, possibly because of the accustomed neuronal arrangement and the mirror neuron arrangement "go out of sync", and baffle with anniversary other.20
"Ultra-slow" or "near-DC" (Direct current) action is recorded application DC amplifiers in some analysis contexts. It is not about recorded in a analytic ambience because the arresting at these frequencies is affected to a amount of artifacts.
Some appearance of the EEG are brief rather than rhythmic. Spikes and aciculate after-effects may represent access action or interictal action in individuals with attack or a predisposition against epilepsy. Added brief appearance are normal: acme after-effects and beddy-bye spindles are apparent in accustomed sleep.
Note that there are types of action that are statistically uncommon, but not associated with dysfunction or disease. These are about referred to as "normal variants." The mu accent is an archetype of a accustomed variant.
The accustomed Electroencephalography (EEG) varies by age. The neonatal EEG is absolutely altered from the developed EEG. The EEG in adolescence about has slower abundance oscillations than the developed EEG.
The accustomed EEG aswell varies depending on state. The EEG is acclimated forth with added abstracts (EOG, EMG) to ascertain beddy-bye stages in polysomnography. Stage I beddy-bye (equivalent to blackout in some systems) appears on the EEG as drop-out of the after basal rhythm. There can be an access in theta frequencies. Santamaria and Chiappa cataloged a amount of the array of patterns associated with drowsiness. Stage II beddy-bye is characterized by beddy-bye spindles—transient runs of adroit action in the 12–14 Hz ambit (sometimes referred to as the "sigma" band) that accept a frontal-central maximum. A lot of of the action in Stage II is in the 3–6 Hz range. Stage III and IV beddy-bye are authentic by the attendance of basin frequencies and are about referred to collectively as "slow-wave sleep." Stages I-IV comprise non-REM (or "NREM") sleep. The EEG in REM (rapid eye movement) beddy-bye appears somewhat agnate to the alive EEG.
EEG beneath accepted anesthesia depends on the blazon of analgesic employed. With halogenated anesthetics, such as halothane or intravenous agents, such as propofol, a accelerated (alpha or low beta), nonreactive EEG arrangement is apparent over a lot of of the scalp, abnormally anteriorly; in some earlier analogue this was accepted as a WAR (widespread antecedent rapid) pattern, assorted with a WAIS (widespread slow) arrangement associated with top doses of opiates. Analgesic furnishings on EEG signals are alpha to be accepted at the akin of biologic accomplishments on altered kinds of synapses and the circuits that acquiesce synchronized neuronal action (see: http://www.stanford.edu/group/maciverlab/).
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