<s>
In	O
neuroanatomy	O
,	O
a	O
neural	B-General_Concept
pathway	I-General_Concept
is	O
the	O
connection	O
formed	O
by	O
axons	B-Algorithm
that	O
project	O
from	O
neurons	O
to	O
make	O
synapses	B-Application
onto	O
neurons	O
in	O
another	O
location	O
,	O
to	O
enable	O
neurotransmission	O
(	O
the	O
sending	O
of	O
a	O
signal	O
from	O
one	O
region	O
of	O
the	O
nervous	O
system	O
to	O
another	O
)	O
.	O
</s>
<s>
Neurons	O
are	O
connected	O
by	O
a	O
single	O
axon	B-Algorithm
,	O
or	O
by	O
a	O
bundle	O
of	O
axons	B-Algorithm
known	O
as	O
a	O
nerve	O
tract	O
,	O
or	O
fasciculus	O
.	O
</s>
<s>
Shorter	O
neural	B-General_Concept
pathways	I-General_Concept
are	O
found	O
within	O
grey	O
matter	O
in	O
the	O
brain	O
,	O
whereas	O
longer	O
projections	O
,	O
made	O
up	O
of	O
myelinated	O
axons	B-Algorithm
,	O
constitute	O
white	O
matter	O
.	O
</s>
<s>
In	O
the	O
hippocampus	O
there	O
are	O
neural	B-General_Concept
pathways	I-General_Concept
involved	O
in	O
its	O
circuitry	O
including	O
the	O
perforant	O
pathway	O
,	O
that	O
provides	O
a	O
connectional	O
route	O
from	O
the	O
entorhinal	O
cortex	O
to	O
all	O
fields	O
of	O
the	O
hippocampal	O
formation	O
,	O
including	O
the	O
dentate	O
gyrus	O
,	O
all	O
CA	O
fields	O
(	O
including	O
CA1	O
)	O
,	O
and	O
the	O
subiculum	O
.	O
</s>
<s>
Ascending	O
sensory	B-Architecture
tracts	O
in	O
the	O
dorsal	O
column	O
–	O
medial	O
lemniscus	O
pathway	O
(	O
DCML	O
)	O
carry	O
information	O
from	O
the	O
periphery	O
to	O
the	O
cortex	O
of	O
the	O
brain	O
.	O
</s>
<s>
The	O
first	O
named	O
pathways	O
are	O
evident	O
to	O
the	O
naked	O
eye	O
even	O
in	O
a	O
poorly	O
preserved	O
brain	O
,	O
and	O
were	O
named	O
by	O
the	O
great	O
anatomists	O
of	O
the	O
Renaissance	B-Application
using	O
cadaver	O
material	O
.	O
</s>
<s>
This	O
naming	O
can	O
extend	O
to	O
include	O
any	O
number	O
of	O
structures	O
in	O
a	O
pathway	O
,	O
such	O
that	O
the	O
cerebellorubrothalamocortical	O
pathway	O
originates	O
in	O
the	O
cerebellum	O
,	O
synapses	B-Application
in	O
the	O
red	O
nucleus	O
(	O
"	O
ruber	O
"	O
in	O
Latin	O
)	O
,	O
on	O
to	O
the	O
thalamus	O
,	O
and	O
finally	O
terminating	O
in	O
the	O
cerebral	O
cortex	O
.	O
</s>
<s>
Note	O
that	O
the	O
"	O
old	O
"	O
name	O
was	O
primarily	O
descriptive	O
,	O
evoking	O
the	O
pyramids	O
of	O
antiquity	O
,	O
from	O
the	O
appearance	O
of	O
this	O
neural	B-General_Concept
pathway	I-General_Concept
in	O
the	O
medulla	O
oblongata	O
.	O
</s>
<s>
The	O
axon	B-Algorithm
of	O
a	O
nerve	O
cell	O
is	O
,	O
in	O
general	O
,	O
responsible	O
for	O
transmitting	O
information	O
over	O
a	O
relatively	O
long	O
distance	O
.	O
</s>
<s>
Therefore	O
,	O
most	O
neural	B-General_Concept
pathways	I-General_Concept
are	O
made	O
up	O
of	O
axons	B-Algorithm
.	O
</s>
<s>
If	O
the	O
axons	B-Algorithm
have	O
myelin	O
sheaths	O
,	O
then	O
the	O
pathway	O
appears	O
bright	O
white	O
because	O
myelin	O
is	O
primarily	O
lipid	O
.	O
</s>
<s>
If	O
most	O
or	O
all	O
of	O
the	O
axons	B-Algorithm
lack	O
myelin	O
sheaths	O
(	O
i.e.	O
,	O
are	O
unmyelinated	O
)	O
,	O
then	O
the	O
pathway	O
will	O
appear	O
a	O
darker	O
beige	O
color	O
,	O
which	O
is	O
generally	O
called	O
grey	O
.	O
</s>
<s>
For	O
example	O
,	O
motor	O
neurons	O
,	O
which	O
travel	O
from	O
the	O
spinal	O
cord	O
to	O
the	O
muscle	O
,	O
can	O
have	O
axons	B-Algorithm
up	O
to	O
a	O
meter	O
in	O
length	O
in	O
humans	O
.	O
</s>
<s>
The	O
longest	O
axon	B-Algorithm
in	O
the	O
human	O
body	O
belongs	O
to	O
the	O
Sciatic	O
Nerve	O
and	O
runs	O
from	O
the	O
great	O
toe	O
to	O
the	O
base	O
of	O
the	O
spinal	O
cord	O
.	O
</s>
<s>
These	O
are	O
archetypal	O
examples	O
of	O
neural	B-General_Concept
pathways	I-General_Concept
.	O
</s>
<s>
Neural	B-General_Concept
pathways	I-General_Concept
in	O
the	O
basal	O
ganglia	O
in	O
the	O
cortico-basal	O
ganglia-thalamo-cortical	O
loop	O
,	O
are	O
seen	O
as	O
controlling	O
different	O
aspects	O
of	O
behaviour	O
.	O
</s>
<s>
It	O
has	O
been	O
proposed	O
that	O
the	O
dopamine	O
system	O
of	O
pathways	O
is	O
the	O
overall	O
organiser	O
of	O
the	O
neural	B-General_Concept
pathways	I-General_Concept
that	O
are	O
seen	O
to	O
be	O
parallels	O
of	O
the	O
dopamine	O
pathways	O
.	O
</s>
<s>
Dopamine	O
is	O
provided	O
both	O
tonically	O
and	O
phasically	O
in	O
response	O
to	O
the	O
needs	O
of	O
the	O
neural	B-General_Concept
pathways	I-General_Concept
.	O
</s>
