Neural oscillations occur throughout the central nervous system and can be measured at different scales: microscopic (single neuron), mesoscopic (local groups of neurons), and macroscopic (between brain regions). At the microscopic level, neurons generate action potentials that form rhythmic spike trains. Groups of synchronized neurons give rise to local field potential oscillations. Interactions between brain areas also produce large-scale oscillations measured by EEG. Different neural oscillations have been linked to cognitive functions like perception and memory.

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8. Neural oscillations are observed throughout the central
nervous system and at all levels, e.g., spike trains, local field
potentials and large-scale oscillations which can be measured
by electroencephalography. In general, oscillations can be
characterized by their frequency, amplitude and phase. These
signal properties can be extracted from neural recordings
using time-frequency analysis. In large-scale oscillations,
amplitude changes are considered to result from changes in
synchronization within a neural ensemble, also referred to as
local synchronization. In addition to local synchronization,
oscillatory activity of distant neural structures (single neurons
or neural ensembles) can synchronize. Neural oscillations and
synchronization have been linked to many cognitive functions
such as information transfer, perception, motor control and
memory

9. Although neural oscillations in human brain activity are mostly
investigated using EEG recordings, they are also observed using
more invasive recording techniques such as single-unit
recordings. Neurons can generate rhythmic patterns of action
potentials or spikes. Some types of neurons have the tendency
to fire at particular frequencies, so-called resonators.[8] Bursting
is another form of rhythmic spiking. Spiking patterns are
considered fundamental for information coding in the brain.
Oscillatory activity can also be observed in the form of
subthreshold membrane potential oscillations (i.e. in the
absence of action potentials).[9] If numerous neurons spike in
synchrony, they can give rise to oscillations in local field
potentials (LFPs). Quantitative models can estimate the strength
of neural oscillations in recorded data

10. The functions of neural oscillations are wide ranging and vary for
different types of oscillatory activity. Examples are the
generation of rhythmic activity such as a heartbeat and the
neural binding of sensory features in perception, such as the
shape and color of an object. Neural oscillations also play an
important role in many neurological disorders, such as excessive
synchronization during seizure activity in epilepsy or tremor in
patients with Parkinson's disease. Oscillatory activity can also be
used to control external devices in brain-computer interfaces, in
which subjects can control an external device by changing the
amplitude of particular brain rhythmics.

11. Oscillatory activity is observed
throughout the central nervous system
at all levels of organization. Three
different levels have been widely
recognized: the micro-scale (activity of
a single neuron), the meso-scale
(activity of a local group of neurons)
and the macro-scale (activity of
different brain regions).

12. Neurons generate action potentials resulting
from changes in the electric membrane
potential. Neurons can generate multiple action
potentials in sequence forming so-called spike
trains. These spike trains are the basis for neural
coding and information transfer in the brain.
Spike trains can form all kinds of patterns, such
as rhythmic spiking and bursting, and often
display oscillatory activity
Microscopic(

13. Mesoscopic:
A group of neurons can also generate oscillatory activity. Through synaptic
interactions the firing patterns of different neurons may become
synchronized and the rhythmic changes in electric potential caused by their
action potentials will add up (constructive interference). That is, synchronized
firing patterns result in synchronised input into other cortical areas, which
gives rise to large-amplitude oscillations of the local field potential. These
large-scale oscillations can also be measured outside the scalp using
electroencephalography (EEG) and magnetoencephalography (MEG).

14. Macroscopic
Neural oscillation can also arise from interactions between
different brain areas. Time delays play an important role here.
Because all brain areas are bidirectionally coupled, these
connections between brain areas form feedback loops. Positive
feedback loops tends to cause oscillatory activity which
frequency is inversely related to the delay time. An example of
such a feedback loop is the connections between the thalamus
and cortex. This thalamocortical network is able to generate
oscillatory activity known as recurrent thalamo-cortical
resonance.[16] The thalamocortical network plays an important
role in the generation of alpha activity

15. IMPORTANT:
Neural synchronization can be modulated by task constraints,
such as attention, and is thought to play a role in feature
binding,[49] neuronal communication,[1] and motor coordination.[3]
Neuronal oscillations became a hot topic in neuroscience in the 1990s when
the studies of the visual system of the brain by Gray, Singer and others
appeared to support the neural binding hypothesis.[50] According to this
idea, synchronous oscillations in neuronal ensembles bind neurons
representing different features of an object. For example, when a person
looks at a tree, visual cortex neurons representing the tree trunk and those
representing the branches of the same tree would oscillate in synchrony to
form a single representation of the tree. This phenomenon is best seen in
local field potentials which reflect the synchronous activity of local groups of
neurons, but has also been shown in EEG and MEG recordings providing
increasing evidence for a close relation between synchronous oscillatory
activity and a variety of cognitive functions such as perceptual grouping

16. Neural oscillations are extensively linked to memory function, in particular
theta activity. Theta rhythms are very strong in rodent hippocampi and
entorhinal cortex during learning and memory retrieval, and are believed to
be vital to the induction of long-term potentiation, a potential cellular
mechanism of learning and memory. The coupling between theta and gamma
activity is thought to be vital for memory functions, including episodic
memory.[73][74] The tight coordination of spike timing of single neurons with
the local theta oscillations is linked to successful memory formation in
humans, as more stereotyped spiking predicts better memory

17. Alpha wave
Alpha waves are neural oscillations in the
frequency range of 8–13 Hz arising from
synchronous and coherent (in phase or
constructive) electrical activity of thalamic
pacemaker cells in humans. They are also called
Berger's wave in memory of the founder of EEG.

18. 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.

19. The second occurrence of alpha wave activity is during REM
sleep. As opposed to the awake form of alpha activity, this form
is located in a frontal-central location in the brain

20. Alpha wave intrusion occurs when alpha waves appear with non-REM sleep
when delta activity is expected. It is hypothesized to be associated with
fibromyalgia,[9] although the study may be inadequate due to a small
sampling size.
Despite this, alpha wave intrusion has not been significantly linked to any
major sleep disorder, including fibromyalgia, chronic fatigue syndrome, and
major depression. However, it is common in chronic fatigued patients, and
may amplify the effects of other sleep disorders

21. Binaural beats may influence functions of the brain in ways besides those
related to hearing. This phenomenon is called "frequency following
response". The concept is that if one receives a stimulus with a frequency in
the range of brain waves, the predominant brainwave frequency is said to be
likely to move towards the frequency of the stimulus (a process called
entrainment).[20] In addition, binaural beats have been credibly documented
to relate to both spatial perception and stereo auditory recognition, and,
according to the frequency following response, activation of various sites in
the brain

22. Perceived human hearing is limited to
the range of frequencies from 20 Hz to
20,000 Hz, but the frequencies of
human brain waves are below about
40 Hz. To account for this lack of
perception, binaural beat frequencies
are used. Beat frequencies of 40 Hz
have been produced in the brain with
binaural sound and measured
experimentally

23. When the perceived beat frequency corresponds to the delta, theta, alpha,
beta, or gamma range of brainwave frequencies, the brainwaves entrain to or
move towards the beat frequency.[29] For example, if a 315 Hz sine wave is
played into the right ear and a 325 Hz one into the left ear, the brain is
entrained towards the beat frequency 10 Hz, in the alpha range. Since alpha
range is associated with relaxation, this has a relaxing effect, or if in the theta
range, more alertness. An experiment with binaural sound stimulation using
beat frequencies in the beta range on some participants and the delta/theta
range on other participants found better vigilance performance and mood in
those on the awake alert state of beta-range stimulation

24. Binaural beat stimulation has been used fairly extensively in
attempts to induce a variety of states of consciousness, and
there has been some work done in regards to the effects of
these stimuli on relaxation, focus, attention, and states of
consciousness.[8] Studies have shown that with repeated
training to distinguish close frequency sounds that a plastic
reorganization of the brain occurs for the trained frequencies[32]
and is capable of asymmetric hemispheric balancing

26. Alpha-theta brainwave training has
also been used successfully for the
treatment of addictions

27. An uncontrolled pilot study of delta binaural beat technology
over 60 days has shown positive effects on self-reported
psychologic measures, especially anxiety. There was a significant
decrease in trait anxiety, an increase in quality of life, and a
decrease in insulin-like growth factor-1 and dopamine,[1] and it
has been successfully shown to decrease mild anxiety.[41] A
randomised, controlled study concluded that binaural beat audio
could lessen hospital acute pre-operative anxiety

28. Another claimed effect for sound-induced brain synchronization
is enhanced learning ability. It was proposed in the 1970s that
induced alpha brain waves enabled students to assimilate more
information with greater long-term retention.[43] In more recent
times has come more understanding of the role of theta brain
waves in behavioural learning.[44] The presence of theta
patterns in the brain has been associated with increased
receptivity for learning and decreased filtering by the left
hemisphere.[43][45][46] Based on the association between
theta activity (4–7 Hz) and working memory performance,
biofeedback training suggests that normal healthy individuals
can learn to increase a specific component of their EEG activity,
and that such enhanced activity may facilitate a working memory
task and to a lesser extent focused attention

29. Delta wave
A 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[1] (EEG) and are
usually associated with the deepest stages of
sleep (3 NREM), also known as slow-wave sleep
(SWS), and aid in characterizing the depth of sleep

30. Females have been shown to have more delta wave activity, and
this is true across most mammal species. This discrepancy does
not become apparent until early adulthood (in the 30's or 40's, in
humans), with men showing greater age-related reductions in
delta wave activity than their female counterparts.

31. Delta waves can arise either in the
thalamus or in the cortex. When
associated with the thalamus, they
likely arise in coordination with the
reticular formation

32. Delta activity stimulates the release of several hormones,
including growth hormone releasing hormone GHRH and
prolactin (PRL). GHRH is released from the hypothalamus, which
in turn stimulates release of growth hormone from the pituitary.
Like growth hormone, the secretion of prolactin - which is closely
related to growth hormone (GH) - is also regulated by the
pituitary. Thyroid stimulating hormone (TSH) activity is
decreased in response to delta-wave signaling

33. Theta rhythm
Cortical theta rhythms" are low-frequency
components of scalp EEG, usually recorded from
humans.
In human EEG studies, the term theta refers to
frequency components in the 4–7 Hz range,
regardless of their source. Cortical theta is observed
frequently in young children. In older children and
adults, it tends to appear during meditative, drowsy,
or sleeping states, but not during the deepest stages
of sleep. Several types of brain pathology can give
rise to abnormally strong or persistent cortical theta
waves.

34. mu wave
Mu waves, also known as mu rhythms, comb or
wicket rhythms, arciform rhythms, or sensorimotor
rhythms, are synchronized patterns of electrical
activity involving large numbers of neurons,
probably of the pyramidal type, in the part of the
brain that controls voluntary movement.[1] These
patterns as measured by electroencephalography
(EEG), magnetoencephalography (MEG), or
electrocorticography (ECoG) repeat at a frequency
of 8–13 Hz and are most prominent when the body
is physically at rest

35. The right fusiform gyrus, left inferior parietal lobule, right
anterior parietal cortex, and left inferior frontal gyrus are of
particular interest.[7][11][12] Some researchers believe that mu
wave suppression can be a consequence of mirror neuron
activity throughout the brain, and represents a higher-level
integrative processing of mirror neuron activity.[3] Tests in both
monkeys (using invasive measuring techniques) and humans
(using EEG and fMRI) have found that these mirror neurons not
only fire during basic motor tasks, but also have components
that deal with intention.[13] There is evidence of an important
role for mirror neurons in humans, and mu waves may represent
a high level coordination of those mirror neurons

36. Mu waves are thought to be indicative of an infant’s
developing ability to imitate. This is important because
the ability to imitate plays a vital role in the
development of motor skills, tool use, and
understanding causal information through social
interaction

37. recording of electrical activity over
the motor cortex.

38. Beta wave
Beta wave, or beta rhythm, is the term used to designate the
frequency range of human brain activity between 12 and 30 Hz (12
to 30 transitions or cycles per second). Beta waves are split into
three sections: Low Beta Waves (12.5-16 Hz, "Beta 1 power"); Beta
Waves (16.5–20 Hz, "Beta 2 power"); and High Beta Waves (20.528 Hz, "Beta 3 power").[1] Beta states are the states associated
with normal waking consciousness.

39. Low amplitude beta waves with multiple and varying frequencies are often associated
with active, busy, or anxious thinking and active concentration.[2]
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.[3] Bursts of beta activity are associated with a strengthening of sensory
feedback in static motor control and reduced when there is movement change.[4]
Beta activity is increased when movement has to be resisted or voluntarily
suppressed.[5] The artificial induction of increased beta waves over the motor cortex
by a form of electrical stimulation called Transcranial alternating-current stimulation
consistent with its link to isotonic contraction produces a slowing of motor
movements

40. Gamma wave
A gamma wave is a pattern of neural oscillation
in humans with a frequency between 25 and 100
Hz,[1] though 40 Hz is typical.[2]
According to a popular theory, gamma waves
may be implicated in creating the unity of
conscious perception (the binding problem)

41. Role in attentive focus
he proposed answer lies in a wave that, originating in the thalamus, sweeps
the brain from front to back, 40 times per second, drawing different neuronal
circuits into synch with the precept, and thereby bringing the precept into the
attentional foreground. If the thalamus is damaged even a little bit, this wave
stops, conscious awarenesses do not form, and the patient slips into profound
coma.

42. Thus the claim is that when all these neuronal clusters oscillate
together during these transient periods of synchronized firing,
they help bring up memories and associations from the visual
precept to other notions. This brings a distributed matrix of
cognitive processes together to generate a coherent, concerted
cognitive act, such as perception. This has led to theories that
gamma waves are associated with solving the binding problem

43. Delta wave – (0.1–4 Hz)
Theta wave – (4–8 Hz)
Mu wave – (8–13 Hz)
Beta wave – (13–30 Hz)
Gamma wave – (25–100 Hz)