<s>
Phase	B-Algorithm
precession	I-Algorithm
is	O
a	O
neurophysiological	O
process	O
in	O
which	O
the	O
time	O
of	O
firing	O
of	O
action	B-Algorithm
potentials	I-Algorithm
by	O
individual	O
neurons	O
occurs	O
progressively	O
earlier	O
in	O
relation	O
to	O
the	O
phase	O
of	O
the	O
local	B-Algorithm
field	I-Algorithm
potential	I-Algorithm
oscillation	B-Algorithm
with	O
each	O
successive	O
cycle	O
.	O
</s>
<s>
In	O
place	O
cells	O
,	O
a	O
type	O
of	O
neuron	O
found	O
in	O
the	O
hippocampal	O
region	O
of	O
the	O
brain	O
,	O
phase	B-Algorithm
precession	I-Algorithm
is	O
believed	O
to	O
play	O
a	O
major	O
role	O
in	O
the	O
neural	O
coding	O
of	O
information	O
.	O
</s>
<s>
John	O
O'Keefe	O
,	O
who	O
later	O
shared	O
the	O
2014	O
Nobel	O
Prize	O
in	O
Physiology	O
or	O
Medicine	O
for	O
his	O
discovery	O
that	O
place	O
cells	O
help	O
form	O
a	O
"	O
map	O
"	O
of	O
the	O
body	O
's	O
position	O
in	O
space	O
,	O
co-discovered	O
phase	B-Algorithm
precession	I-Algorithm
with	O
Michael	O
Recce	O
in	O
1993	O
.	O
</s>
<s>
As	O
a	O
rat	O
moves	O
along	O
a	O
path	O
,	O
individual	O
place	O
cells	O
fire	O
action	B-Algorithm
potentials	I-Algorithm
at	O
an	O
increased	O
rate	O
at	O
particular	O
positions	O
along	O
the	O
path	O
,	O
termed	O
"	O
place	O
fields	O
"	O
.	O
</s>
<s>
Each	O
place	O
cell	O
's	O
maximum	O
firing	O
ratewith	O
action	B-Algorithm
potentials	I-Algorithm
occurring	O
in	O
rapid	O
burstsoccurs	O
at	O
the	O
position	O
encoded	O
by	O
that	O
cell	O
;	O
and	O
that	O
cell	O
fires	O
only	O
occasionally	O
when	O
the	O
animal	O
is	O
at	O
other	O
locations	O
.	O
</s>
<s>
Although	O
simple	O
rate	O
coding	O
(	O
the	O
coding	O
of	O
information	O
based	O
on	O
whether	O
neurons	O
fire	O
more	O
rapidly	O
or	O
more	O
slowly	O
)	O
resulting	O
from	O
these	O
changes	O
in	O
firing	O
rates	O
may	O
account	O
for	O
some	O
of	O
the	O
neural	O
coding	O
of	O
position	O
,	O
there	O
is	O
also	O
a	O
prominent	O
role	O
for	O
the	O
timing	O
of	O
the	O
action	B-Algorithm
potentials	I-Algorithm
of	O
a	O
single	O
place	O
cell	O
,	O
relative	O
to	O
the	O
firing	O
of	O
nearby	O
cells	O
in	O
the	O
local	O
population	O
.	O
</s>
<s>
These	O
oscillations	O
are	O
measurable	O
in	O
local	B-Algorithm
field	I-Algorithm
potentials	I-Algorithm
and	O
electroencephalography	B-Application
(	O
EEG	B-Application
)	O
.	O
</s>
<s>
In	O
the	O
CA1	O
region	O
of	O
the	O
hippocampus	O
,	O
where	O
the	O
place	O
cells	O
are	O
located	O
,	O
these	O
firing	O
patterns	O
give	O
rise	O
to	O
theta	B-Algorithm
waves	I-Algorithm
.	O
</s>
<s>
In	O
1993	O
,	O
O'Keefe	O
and	O
Recce	O
discovered	O
a	O
relationship	O
between	O
the	O
theta	B-Algorithm
wave	I-Algorithm
and	O
the	O
firing	O
patterns	O
of	O
individual	O
place	O
cells	O
.	O
</s>
<s>
Although	O
the	O
occasional	O
action	B-Algorithm
potentials	I-Algorithm
of	O
cells	O
when	O
rats	O
were	O
outside	O
of	O
the	O
place	O
fields	O
occurred	O
in	O
phase	O
with	O
(	O
at	O
the	O
peaks	O
of	O
)	O
the	O
theta	B-Algorithm
waves	I-Algorithm
,	O
the	O
bursts	B-Algorithm
of	O
more	O
rapid	O
spikes	B-Algorithm
elicited	O
when	O
the	O
rats	O
reached	O
the	O
place	O
fields	O
were	O
out	O
of	O
synchrony	O
with	O
the	O
oscillation	B-Algorithm
.	O
</s>
<s>
As	O
a	O
rat	O
approached	O
the	O
place	O
field	O
,	O
the	O
corresponding	O
place	O
cell	O
would	O
fire	O
slightly	O
in	O
advance	O
of	O
the	O
theta	B-Algorithm
wave	I-Algorithm
peak	O
.	O
</s>
<s>
As	O
the	O
rat	O
moved	O
closer	O
and	O
closer	O
,	O
each	O
successive	O
action	B-Algorithm
potential	I-Algorithm
occurred	O
earlier	O
and	O
earlier	O
within	O
the	O
wave	O
cycle	O
.	O
</s>
<s>
Then	O
,	O
as	O
the	O
rat	O
continued	O
to	O
move	O
on	O
past	O
the	O
place	O
field	O
and	O
the	O
cell	O
firing	O
slowed	O
,	O
the	O
action	B-Algorithm
potentials	I-Algorithm
continued	O
to	O
occur	O
progressively	O
earlier	O
relative	O
to	O
the	O
theta	B-Algorithm
wave	I-Algorithm
,	O
until	O
they	O
again	O
became	O
synchronous	O
with	O
the	O
wave	O
,	O
aligned	O
now	O
with	O
one	O
wave	O
peak	O
earlier	O
than	O
before	O
.	O
</s>
<s>
O'Keefe	O
and	O
Recce	O
termed	O
this	O
advancement	O
relative	O
to	O
the	O
wave	O
phase	O
"	O
phase	B-Algorithm
precession	I-Algorithm
"	O
.	O
</s>
<s>
Subsequent	O
studies	O
showed	O
that	O
each	O
time	O
a	O
rat	O
entered	O
a	O
completely	O
different	O
area	O
and	O
the	O
place	O
fields	O
would	O
be	O
remapped	O
,	O
place	O
cells	O
would	O
again	O
become	O
phase-locked	O
to	O
the	O
theta	B-Algorithm
rhythm	I-Algorithm
.	O
</s>
<s>
It	O
is	O
now	O
widely	O
accepted	O
that	O
the	O
anti-phase	O
cell	O
firing	O
that	O
results	O
from	O
phase	B-Algorithm
precession	I-Algorithm
is	O
an	O
important	O
component	O
of	O
information	O
coding	O
about	O
place	O
.	O
</s>
<s>
There	O
have	O
been	O
conflicting	O
theories	O
of	O
how	O
neurons	O
in	O
and	O
around	O
the	O
hippocampus	O
give	O
rise	O
to	O
theta	B-Algorithm
waves	I-Algorithm
and	O
consequently	O
give	O
rise	O
to	O
phase	B-Algorithm
precession	I-Algorithm
.	O
</s>
<s>
As	O
these	O
mechanisms	O
became	O
better	O
understood	O
,	O
the	O
existence	O
of	O
phase	B-Algorithm
precession	I-Algorithm
was	O
increasingly	O
accepted	O
by	O
researchers	O
.	O
</s>
<s>
This	O
,	O
in	O
turn	O
,	O
gave	O
rise	O
to	O
the	O
question	O
of	O
whether	O
phase	B-Algorithm
precession	I-Algorithm
could	O
be	O
observed	O
in	O
any	O
other	O
regions	O
of	O
the	O
brain	O
,	O
with	O
other	O
kinds	O
of	O
cell	B-General_Concept
circuits	I-General_Concept
,	O
or	O
whether	O
phase	B-Algorithm
precession	I-Algorithm
was	O
a	O
peculiar	O
property	O
of	O
hippocampal	O
tissue	O
.	O
</s>
<s>
The	O
finding	O
that	O
theta	B-Algorithm
wave	I-Algorithm
phase	B-Algorithm
precession	I-Algorithm
is	O
also	O
a	O
property	O
of	O
grid	O
cells	O
in	O
the	O
entorhinal	O
cortex	O
demonstrated	O
that	O
the	O
phenomenon	O
exists	O
in	O
other	O
parts	O
of	O
the	O
brain	O
that	O
also	O
mediate	O
information	O
about	O
movement	O
.	O
</s>
<s>
Theta	B-Algorithm
wave	I-Algorithm
phase	B-Algorithm
precession	I-Algorithm
in	O
the	O
hippocampus	O
also	O
plays	O
a	O
role	O
in	O
some	O
brain	O
functions	O
that	O
are	O
unrelated	O
to	O
spatial	O
location	O
.	O
</s>
<s>
When	O
rats	O
were	O
trained	O
to	O
jump	O
up	O
to	O
the	O
rim	O
of	O
a	O
box	O
,	O
place	O
cells	O
displayed	O
phase	B-Algorithm
precession	I-Algorithm
much	O
as	O
they	O
do	O
during	O
movement	O
along	O
a	O
path	O
,	O
but	O
a	O
subset	O
of	O
the	O
place	O
cells	O
showed	O
phase	B-Algorithm
precession	I-Algorithm
that	O
was	O
related	O
to	O
initiating	O
the	O
jump	O
,	O
independently	O
of	O
spatial	O
location	O
,	O
and	O
not	O
related	O
to	O
the	O
position	O
during	O
the	O
jump	O
.	O
</s>
<s>
Phase	B-Algorithm
precession	I-Algorithm
in	O
the	O
entorhinal	O
cortex	O
has	O
been	O
hypothesized	O
to	O
arise	O
from	O
an	O
attractor	O
network	O
process	O
,	O
so	O
that	O
two	O
sequential	O
neural	O
representations	O
within	O
a	O
single	O
cycle	O
of	O
the	O
theta	O
oscillation	B-Algorithm
can	O
be	O
temporally	O
linked	O
to	O
each	O
other	O
downstream	O
in	O
the	O
hippocampus	O
,	O
as	O
episodic	O
memories	O
.	O
</s>
