People can measure scalp electric-voltage waves {electroencephalography}| (EEG).
cause
EEG wave voltages are sums of graded potentials in dendritic trees and their synapses [Creutzfeldt and Houchin, 1984] [Creutzfeldt, 1995] [Freeman, 1975] [Mountcastle, 1957] [Mountcastle, 1998] [Remond, 1984].
EEG potential changes are larger than neuron induced activity. Potential differences between cell bodies and neuron fibers influence EEG waves. Brain potential waves imply synchronized neuron activities, over distances more than two millimeters apart. Waves are coherent, not harmonic, across different cortical areas.
location
Electric waves appear in parietal lobe, then primary motor cortex and occipital lobe, and then prefrontal lobe.
amplitude
EEG wave voltages are 1 mV to 2 mV. To detect voltage change requires averaging hundreds of measurements to subtract noise. EEG can measure scalp potential differences less than 100 microvolts [Makeig et al., 2002].
correlations
Scalp evoked-potential changes in response to image, sound, or mental event [Galambos et al., 1981].
Anesthesia and responses to simple stimulus configurations can have prolonged brain potential synchronization. Brain-potential synchronization is less during awake states and complex situations.
Waves are large in tasks requiring activity integration across different cortical areas. Waves stop at perceptual-processing conclusion and motor-signaling beginning.
Waves do not carry information about stimuli nor relate to signals from individual neurons.
correlations: awake
Hippocampus has theta rhythm at 4 Hz to 10 Hz during active movement and alert immobility, synchronized between hemispheres and 8 mm along hippocampus longitudinal axis. Awake brain has synchrony, which increases with attention and preparation for motor acts. Brain potential synchronization is less when awake.
Other behaviors have local and bilaterally synchronous rhythm near 40 Hz.
200-Hz waves correlate with alert immobility.
A 12-millisecond phase shift goes from brain rostral to caudal pole, during alpha wave activity while awake.
Most waves during waking are in posterior cortex, lower than vertex.
correlations: sleep
EEG waves can differentiate seven sleep stages. Most waves during sleeping are in vertex and frontal lobe. Synchronous firing characterizes deep sleep and epilepsy.
Between waking and sleeping, brain wave change is abrupt in adults. Between waking and sleeping, brain wave change is slow in children.
correlations: slow-wave sleep
NREM sleep has low-frequency, high-amplitude waves. Non-REM-sleep phases 3 and 4 have low-frequency EEG waves {slow-wave sleep}.
correlations: REM sleep
Awake and REM sleep activation level has high-frequency, low-amplitude waves [Hobson, 1989] [Hobson, 1994] [Hobson, 1999] [Hobson, 1999] [Hobson, 2002] [Hobson et al., 1998].
correlations: other waves
EEG waves include bereitschaftspotential, contingent negative variation (CNV), and motor potential.
factors: age
EEG-wave localization, regularity, continuity, similarity from both hemispheres, synchrony from similar areas, and stability increase until age 35. Brain-wave amplitude decreases until age 35.
Biological Sciences>Zoology>Organ>Nerve>Brain>Electrical Activity
4-Zoology-Organ-Nerve-Brain-Electrical Activity
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Date Modified: 2022.0224