Basal ganglia

<p>Also Habits.</p>

<p>

Jul 5, 2010 1:45 PM &nbsp;ANATOMY of BASAL GAQNGLIA...

Look at pix in nodes below.</p>

<p>

Basal Ganglia seem to be more and more implicated in <b>learning and memory</b>.

see eg &nbsp;Mark Gluck's wonderful talk at Google Tech Talks.

and also to <b>motor control</b>.</p>

<p>

<b>LENTIFORM NUCLEUS</b> refers to BOTH the&nbsp;

GLOBUS PALLIDUS (GP) and the PUTAMEN (P)

<b>Putamen means &nbsp;falls off in pruning</b>.. &nbsp;it is oval &nbsp;(the term also refers to <b>the stone of fruit </b>like

a peach pit... which it resembles). &nbsp;</p>

<p>

The putamen is lateral to the globus pallidus which is medial.

Both together are the LENTIFORM NUCLEUS. &nbsp;(Note: however, the article on&nbsp;

Globus Pallidus in Wiki which claims that the globus pallidus is NOT globe shaped

and furthermore that the lentiform nucleus UNDULY links the GP with the putamen, which

is really part of the dorsal striatum &nbsp;(ie the putamen/ caudate complex). &nbsp;Pallidus means

pale &nbsp;(ie pale globe, &nbsp;it looks yellowish compared to the Putamen).

Taken together, the GP and the Putamen DO look like a lens.</p>

<p>

from medial to lateral, it is &nbsp;GPinternal, &nbsp;GPexternal, Putamen (biggest, roundest part of lens)

(GPint is the smallest narrowest part of the cone)</p>

<p>

The Thalamus is &nbsp;interior to it. &nbsp;and behind it/ posterior to it</p>

<p>

The internal capsule goes out btwn the Putamen

and the CAUDATE.</p>

<p>

The Caudate (which means TAIL) is really big and long &nbsp;(head is the front part and emerges in a long tail that terminates at the amygdala at its posterior end. Reminds me of the testicle and Vas deferens.</p>

<p>

Substantia Nigra is in the midbrain!! &nbsp;It is huge. &nbsp;It is BLACK because of the

melanin that builds up there as we age. &nbsp;The melanin is thot to be a byproduct of the

production of monoamines like dopamine. &nbsp;Its efferents go to the putamen. That is the

NIGROSTRIATAL pathway... &nbsp;v important &nbsp;dopaminergic pathway that modulates

the Striatum.</p>

<p>

The last piece of the Basal Ganglia is the STN... the subthalamic nucleus &nbsp;(below the thalamus).

See the nice circuit diagram in the node below.</p>

<p>

<b>STRIATUM refers to the Caudate and Putamen </b>considered together. &nbsp;They get a huge input from

the Cortex that is appar. modulated by the dopaminergic input from the substantia nigra via

the <b>Nigrostriatal</b> pathway.</p>

<p>

<b>The basal ganglia have a limbic sector </b>whose components are assigned distinct names: the <b>nucleus accumbens (NA)</b>, ventral pallidum, and<b> ventral tegmental area (VTA). The VTA provides dopamine to the nucleus accumbens (ventral striatum) in the same way that the substantia nigra provides dopamine to the dorsal striatum. The VTA→NA dopaminergic projection has attracted a great deal of attention</b>, because there is much evidence that it plays a central role in <b>reward learning</b>. A number of highly addictive drugs, including cocaine, amphetamines, and nicotine, are thought to work by increasing the efficacy of the VTA→NA dopamine signal. There is also evidence implicating overactivity of the VTA dopaminergic projection in schizophrenia.</p>

<p>

Summary: &nbsp;the motivational piece seems to be only in the Nucleus Accumbens and ventral tegmental area in the limbic part of the BG. &nbsp;The VTA &nbsp;provides a dopaminergic projection to the Nuc Accumbens.</p>