<s>
Brainwave	B-Algorithm
entrainment	I-Algorithm
,	O
also	O
referred	O
to	O
as	O
brainwave	B-Algorithm
synchronization	I-Algorithm
or	O
neural	O
entrainment	O
,	O
refers	O
to	O
the	O
observation	O
that	O
brainwaves	B-Algorithm
(	O
large-scale	O
electrical	O
oscillations	B-Algorithm
in	O
the	O
brain	O
)	O
will	O
naturally	O
synchronize	O
to	O
the	O
rhythm	O
of	O
periodic	O
external	O
stimuli	O
,	O
such	O
as	O
flickering	O
lights	O
,	O
speech	O
,	O
music	O
,	O
or	O
tactile	O
stimuli	O
.	O
</s>
<s>
As	O
different	O
conscious	O
states	O
can	O
be	O
associated	O
with	O
different	O
dominant	O
brainwave	B-Algorithm
frequencies	O
,	O
it	O
is	O
hypothesized	O
that	O
brainwave	B-Algorithm
entrainment	I-Algorithm
might	O
induce	O
a	O
desired	O
state	O
.	O
</s>
<s>
Neural	B-Algorithm
oscillations	I-Algorithm
are	O
rhythmic	O
or	O
repetitive	O
electrochemical	O
activity	O
in	O
the	O
brain	O
and	O
central	O
nervous	O
system	O
.	O
</s>
<s>
Such	O
oscillations	B-Algorithm
can	O
be	O
characterized	O
by	O
their	O
frequency	O
,	O
amplitude	B-Application
and	O
phase	O
.	O
</s>
<s>
The	O
activity	O
of	O
neurons	O
generate	O
electric	O
currents	O
;	O
and	O
the	O
synchronous	O
action	O
of	O
neural	O
ensembles	O
in	O
the	O
cerebral	O
cortex	O
,	O
comprising	O
large	O
numbers	O
of	O
neurons	O
,	O
produce	O
macroscopic	O
oscillations	B-Algorithm
.	O
</s>
<s>
These	O
phenomena	O
can	O
be	O
monitored	O
and	O
graphically	O
documented	O
by	O
an	O
electroencephalogram	B-Application
(	O
EEG	B-Application
)	O
.	O
</s>
<s>
The	O
electroencephalographic	B-Application
representations	O
of	O
those	O
oscillations	B-Algorithm
are	O
typically	O
denoted	O
by	O
the	O
term	O
'	O
brainwaves	B-Algorithm
 '	O
in	O
common	O
parlance	O
.	O
</s>
<s>
The	O
technique	O
of	O
recording	O
neural	B-Algorithm
electrical	I-Algorithm
activity	I-Algorithm
within	O
the	O
brain	O
from	O
electrochemical	O
readings	O
taken	O
from	O
the	O
scalp	O
originated	O
with	O
the	O
experiments	O
of	O
Richard	O
Caton	O
in	O
1875	O
,	O
whose	O
findings	O
were	O
developed	O
into	O
electroencephalography	B-Application
(	O
EEG	B-Application
)	O
by	O
Hans	O
Berger	O
in	O
the	O
late	O
1920s	O
.	O
</s>
<s>
The	O
functional	O
role	O
of	O
neural	B-Algorithm
oscillations	I-Algorithm
is	O
still	O
not	O
fully	O
understood	O
;	O
however	O
they	O
have	O
been	O
shown	O
to	O
correlate	O
with	O
emotional	O
responses	O
,	O
motor	O
control	O
,	O
and	O
a	O
number	O
of	O
cognitive	O
functions	O
including	O
information	O
transfer	O
,	O
perception	O
,	O
and	O
memory	O
.	O
</s>
<s>
Specifically	O
,	O
neural	B-Algorithm
oscillations	I-Algorithm
,	O
in	O
particular	O
theta	B-Algorithm
activity	O
,	O
are	O
extensively	O
linked	O
to	O
memory	O
function	O
,	O
and	O
coupling	O
between	O
theta	B-Algorithm
and	O
gamma	B-Algorithm
activity	O
is	O
considered	O
to	O
be	O
vital	O
for	O
memory	O
functions	O
,	O
including	O
episodic	O
memory	O
.	O
</s>
<s>
The	O
theory	O
explains	O
the	O
way	O
that	O
two	O
or	O
more	O
independent	O
,	O
autonomous	O
oscillators	B-Algorithm
with	O
differing	O
rhythms	O
or	O
frequencies	O
,	O
when	O
situated	O
in	O
proximity	O
where	O
they	O
can	O
interact	O
for	O
long	O
enough	O
,	O
influence	O
each	O
other	O
mutually	O
,	O
to	O
a	O
degree	O
dependent	O
on	O
coupling	O
force	O
.	O
</s>
<s>
Examples	O
include	O
the	O
mechanical	O
entrainment	O
or	O
cyclic	O
synchronization	O
of	O
two	O
electric	O
clothes	O
dryers	O
placed	O
in	O
close	O
proximity	O
,	O
and	O
the	O
biological	O
entrainment	O
evident	O
in	O
the	O
synchronized	O
illumination	O
of	O
fireflies	B-Device
.	O
</s>
<s>
Brainwaves	B-Algorithm
,	O
or	O
neural	B-Algorithm
oscillations	I-Algorithm
,	O
share	O
the	O
fundamental	O
constituents	O
with	O
acoustic	O
and	O
optical	O
waves	O
,	O
including	O
frequency	O
,	O
amplitude	B-Application
and	O
periodicity	O
.	O
</s>
<s>
Brainwave	B-Algorithm
entrainment	I-Algorithm
is	O
a	O
colloquialism	O
for	O
'	O
neural	O
entrainment	O
 '	O
,	O
which	O
is	O
a	O
term	O
used	O
to	O
denote	O
the	O
way	O
in	O
which	O
the	O
aggregate	O
frequency	O
of	O
oscillations	B-Algorithm
produced	O
by	O
the	O
synchronous	O
electrical	O
activity	O
in	O
ensembles	O
of	O
cortical	O
neurons	O
can	O
adjust	O
to	O
synchronize	O
with	O
the	O
periodic	O
vibration	O
of	O
external	O
stimuli	O
,	O
such	O
as	O
a	O
sustained	O
acoustic	O
frequency	O
perceived	O
as	O
pitch	O
,	O
a	O
regularly	O
repeating	O
pattern	O
of	O
intermittent	O
sounds	O
,	O
perceived	O
as	O
rhythm	O
,	O
or	O
of	O
a	O
regularly	O
rhythmically	O
intermittent	O
flashing	O
light	O
.	O
</s>
