It's always a delay. Okay. Back with the basal
ganglia. So last time we talked about the go
area and the no -go area. Okay. Action and inaction.
And these are operating simultaneously. Non -stop
action here through these five sub -cortical
areas. Okay. Just remember the input areas or
the cadet. Remember this is the midline here.
Okay. So this is one hemisphere and this is the
other. so ipsilateral, contralateral okay so
the cadet the cadet nucleus is here and the putamen
here these are the inputs area receiving inputs
from basically the cortex a lot of excitation
here okay then the relay stations in purple globus
pallidus external globus pallidus external subthalamic
nucleus, which is basically an assistant for
the thalamus. The thalamus is a workhorse. And
then the output areas in blue. Globus pallidus
internal. Remember the Globus pallidus kind of
makes a triangle. And the substantia nigra pars
reticulata. This is GABA. Substantia nigra pars
compacta. is dopamine, both excitatory, D1, dopamine,
and inhibitory, D2, dopamine. Parascompacta is
a modulator. It intensifies. It amplifies the
signals. Wherever the living organism is experiencing
this dopamine intensifies it. Pay attention to
this. This is valuable. This is rewarding. This
is worth doing again. Or this is bad. Avoid this.
Type of thing. So we talked about habits, right?
We talked about this we extracted a specific
cell out of here and highlighted it here and
then we zoomed in and extracted a specific spine
from the dentrite right here and a good way of
thinking about this I want to cover this now
is Let's just say the most severe case of the
basal ganglia being hijacked being hijacked by
habits and learning and so forth is OCD. OCD
is heavily involved with the basal ganglia. So
the spine right here, okay, remember we talked
about morphology and how these bigger connections.
When you think about morphology is you have a
synaptic connection here but they will grow in
size. So it's grown. It's almost doubled in size
right here. Okay, and the bigger one the bigger
connections will have preference and We can think
about OCD like this OCD is I need to draw this
out here OCD is corticosteroidal thalamom or
thalamic Sometimes it's thalamocortical corticosteroidal
striato thalamom cortical or sometimes it's just
cortico striato thalamic but this is a loop remember
we talked about okay remember the beds of ganglia
is right through here we got the thalamus the
cadet nucleus here butamen putamen right these
are subcortical areas with OCD you might have
a lot of connections let's just say right through
here the sensory motor because a lot of habits
will live here we like to shift our things to
here for the habits this is the primary input
area to the cadet and the pertainment not the
only one but let's just say this cell right here
from the pertainment is receiving an axon and
this spine is receiving an axon from a cell right
here and sending down to the containment, okay?
The instructions from this cell can't execute
the motor function. So that's why the basal ganglia
is recruited. Remember, all of our actions or
movements are orchestrated through the basal
ganglia, except for the reflexes. So this information
coming down, each synapsis, each synaptic connection
is building a little summary. and then it's overall
building a story. All of these connections are
coming together. All of these inputs, these neural
correlates are coming together to form a story
that's very specific to the living organism.
So this cell here that's sending an axon down
is just carrying information. It cannot execute
the function, the motor movement, the action.
But this cell right here is saying flip the light
switch. Flip the light switch flip the light
switch flip the light switch. It can't flip the
light switch So it has to recruit the basal ganglia
here. So let's just say a specific cell here
in the containment let's just say it's this one
and Let's just say this spine Specifically is
the one that receives the information to flip
the light switch flip the light switch so this
connection This spine from this cell will say,
OK, I can flip the light switch. It doesn't know
any better. It's just responding to the information
coming down. So it executes the light switch.
It will orchestrate this light switch. And it's
all happening within these five subcortical regions.
The no ghost side will suppress any other alternative
function, action, movement. And this go -side
flips the light switch and then turns it back
on probably or off whatever the sequence is for
the OCD to have satisfaction. Flip the light
switch again. Flip the light switch. Flip the
light switch. This is all happening in the basal
ganglia and this connection saying flip the light
switch is strong in OCD. So this input area that
is happening right here from this cell will say,
okay, I need to flip the light switch. It doesn't
know any better. It doesn't care. These things
are dumb. It has no value. Value is coming outside
of that. Things like this dopamine, yeah, it
helps carry value and the ACC and so forth, which
is here, you know, there's There's various functions
here that are providing intact or inputs as well
Context just say okay, that's valuable. Let's
do that But with OCD there's this hijacked that
cortical striatal thalamic loop So this is a
good way of thinking about how powerful the basal
ganglia are and these five subcortical areas
here these input areas They don't care They're
just going to respond. This is how the brain
in the central nervous system works. We just
respond. We don't like to think about things.