Subcortical nuclei (VI) Flashcards

1
Q

Cover the labels and identify each of the structures here. Where is the inderpedincular fossa? https://quizlet.com/gb/274895161/session-5-coronal-section-diagram/

https://quizlet.com/gb/595698327/coronal-section-of-the-brain-diagram/

A

https://quizlet.com/gb/274895161/session-5-coronal-section-diagram/

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

whats the central core

A

all the collection of nuclei deep deep in the white matter of the brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what parts of the lateral ventricles can you see on a coronal section?

A

you can see the bodies and maybe atrium(s) of the lateral ventricles and the temporal horns going into the temporal lobes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

If we divide the brain into: forebrain and brainstem, what two regions do we have in the forebrain? Show the areas on a saggital section.

Which foramen can we see here, at what is it for?

A
  • telencephalon (cerebrum(al hemisphreres))
  • diencephalon: thalamus, hypothalamus, hypothalamic sulcus (/subthalamus), epithalamus (pineal gland)
  • foramen monro: connect the paired lateral ventricles with the third ventricle at the midline of the brain. As channels, they allow cerebrospinal fluid (CSF) produced in the lateral ventricles to reach the third ventricle and then the rest of the brain’s ventricular system.
  • Location: on a sagittal section, you would find the foramina of Monro in the midline of the brain, at the level where the lateral ventricles connect with the third ventricle, JUST IN FRONT OF THE THALAMUS
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What part of the internal capsule runs laterally to the thalamus? show it on an axial section

A

the posterior limb. This is long.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What important structure forms the wall of the third ventricle?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

which tracts go through the Internal capsule? give examples,
and which part do the descending tracts go down?

A

thalamo-cortical, cortico-thalamic and decending tracts

  • posterior limb
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

which parts of the thalamus are the medial and geniculate bodies at?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what actually is the thalamus?

A

a collection of nuclei, its a relay structure
It is above the midbrain or mesencephalon, allowing for nerve fiber connections to the cerebral cortex in all directions — each thalamus connects to the other via the interthalamic adhesion, but th

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

optic radiations go from where to where?

A

Axons go from the lateral geniculate nucleus, as “thalamic radiations”to the V1 in the occipital lobe.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Do the descending pathways go through the thalamus? What about the ascending pathways?

A

While the descending motor pathways bypass (ignore) the thalamus, the ascending sensory pathways do involve the thalamus as a relay station for sensory information on its way to the cerebral cortex. The thalamus plays a crucial role in filtering and routing sensory signals to the appropriate areas of the brain for further processing and perception

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Which layer of the cortex does the corticothalamic projections go up to, and from where do they come back down?

A

Cortical areas receive thalamo-cortical projections in L4 and send back L6 cortico-thalamic projections !

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

where do the corticospinal tract upper motor neurons originate? i.e., where are their cell bodies?

A

The cell bodies of these upper motor neurons are primarily located in the fifth layer of the cerebral cortex, known as the internal pyramidal layer or layer V. This layer is also referred to as the “pyramidal layer” because it contains large pyramidal-shaped neurons, including the Betz cells, which are particularly prominent in motor areas of the cortex.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

does the thalamus just relay sensory info?

A

No! its also a site where sensory inputs can be modulated!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

does the thalamus relay ALL sensory info? What about motor info?

A
  • No, it relays all but not olfaction!!!
  • the thalamus does relay motor control from the cerebellum and the basal ganglia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

LGN and MGN of the thalamus have functions in what?

A

LGN: visual info
MGN: auditory info

17
Q

4 functions of thalamus?

A
  1. Sensory gating: relay and filtering of all specific sensory information (but smell!)
  2. Motor gating: relay and filtering of motor control from the cerebellum and the basal ganglia
  3. Cognition, autonomous and emotion: association nuclei
    connecting association and limbic areas
  4. Arousal: regulation of sleep, arousal, awareness
18
Q

What are the 7 basal ganglia?

A

those in the telencephalon:
* caudate nucleus
* Putamen
* Nucleus Accumbens
* External Globus Pallidus (Gpe)
* Internal Globus Pallidus (Gpi)

those in diencephalon
Subthalamic nucleus

those in mesencephalon
Substancia Nigra

19
Q

what is Dyskinesia and what are the two types?

A
  • movement disorders in basal ganglia diseases.
  • 1) hypokinetic disorders e.g., parkinsons disease (bradykinesia, rigidity, tremor, postural instability)
  • 2) hyperkinetic disorders e.g., huntington’s disease (involuntary jerking - “chorea”)
20
Q

what is the “striatum”? Why striatum?

A

*Caudate nucleus - curling around, encircling the lenticulate nucleus (putamen + globus pallidus)
*Putamen
*Nucleus Accumbens (ventral striatum)

“striatum” is derived from the Latin word “striae,” which means “stripes” or “streaks,”

the caudate and putamen are separated from one another by a white matter tract called the internal capsule, but there are many strands of grey matter that cross the internal capsule, giving the structure a striped appearance.

21
Q

the caudate and putamen are separated by what?

A

internal capsule, with axons

22
Q

what’s the paler area deeper inside the putamen?

A

the globus pallidus - that’s why its called “pallidus” because its paler than the putamen

23
Q

caudate has what shape?

A

c-shaped, encircles the lenticulate nucleus!

24
Q

where is the NAcc?

A

It’s the NOSE Of the striatum!!!! frontal, a bit downwards
positioned at the frontal interface between the caudate nucleus and the putamen.

25
Q

Two parts of the substancia nigra?

A

fropm up to down:
pars compacta
pars reticulata

26
Q

overall function of the basal ganglia?

A

Modulation of movements by selecting and initiating motor plans

27
Q

Where does input to the basal ganglia come from and output from the BG go?

What are the main intrinsic pathways of the BG itself?

A
  • input from cortex –> BG
    *output from BG –> thalamic relay (he Ventral Lateral Complex and the Ventral Anterior Complex. The VL complex and the ventral anterior (VA) complex)–> motor associated areas
  • 2 pathways of BG: direct & indirect
28
Q

which parts of the thalamus deal with motor relays from the BG
?

A

Ventral Lateral Complex (VLC) and the Ventral Anterior Complex (VAC).

29
Q

direct pathway model?

A

In both direct and indirect pathways, the cortex excites the striatum (caudate, putamen NAcc). And the internal globus pallidus always inhibits the thalamus from sending excitatory impulses back to the cerebral cortex. Because the thalamus sending excitatory impulses to the cortex will instigate movement.

In the direct (DISINBITION) pathway - two – make a +:
* cortex excites striatum
* that causes striatum to send inhibitory impulses to globus pallidus internal.
* the GPi,which usually inhibits the thalamus, is inhibited itself! therfeore its is disinhibited
* so the GPI which usually stops thalamus from sending excitation to the motor cortex, is disinhibited
* and the thalamus is excited, sending excitatory impulses to the motor cortex –> PROMOTES MOVEMENT.

https://www.youtube.com/watch?v=qHp0SCnX3Jc

30
Q

Indirect pathway model?

A

Remember: In both direct and indirect pathways, the cortex excites the striatum (caudate, putamen NAcc). And the**GPi always (GABAergic) inhibits the thalamus from sending excitatory impulses back to the cerebral cortex. ** Because the thalamus sending excitatory impulses to the cortex will instigate movement.

  • INDIRECT PATHWAY (via STN):
  • cortex sends excitatory signals to striatum
  • striatum inibits the globus pallidus like in the direct pathway, but it inhibits the GPe (globus pallidus external)
  • the GPe has inhibitory projections to the STN - subthalamic nucleus, which promotes GPi’s inhibition of the thalamus. –> ENHANCED INHIBITION –> LESS MOVEMENT
31
Q

Where does act dopamine in the direct/indirect pathway circuits?

A

Dopamine comes from the substancia nigra pars compacta.
It basically works to enhance the roles the parts already have.

Direct pathway: Dopamine, when present, binds to dopamine receptors in the striatum and enhances the excitatory signals from the cortex, further promoting the disinhibition of the GPi/SNr. This disinhibition ultimately allows for increased activation of the thalamus and, subsequently, facilitates motor movement.

Indirect pathway: In the indirect pathway, dopamine acts to inhibit movement. Dopamine, in this case, suppresses the inhibitory influence that the GPe has on the striatum. Ultimately, this decreased activation of the GPi/SNr inhibits the thalamus, resulting in the suppression of movement

32
Q

What happens in parkinsons and huntingtons diseases?

A

Parkinson’s:
* death/degeneration of dopamine neurons of the substantia nigra –> affects the direct pathway in that there is less disinhibition of the thalamus. –> **MORE THALAMUS INHIBITION. **The thalamus, which is the unlocking key to movement. –> Hypokinesia

Huntington’s:

degeneration of the striatum --> affects the indirect pathway from the start, which works to inhibit movement through the **subthalamic nucleus **exciting the GPi to inhibit the thalamus more. –> DECREASED THALAMIC INHIBITION –> Hyperkinesia

33
Q

Are movement regulations the only functions of the basal ganglia?

A

we also have the Associative loop
and Limbic loop

34
Q

whats the ventral striatum and where can you find it?

A

nucleus accumbens. nose of the caudate nucleus & putamen. Can find it near the anterior perforated substance just to the side of the optic chiasm, looking from the below.

35
Q

whats the ventral striatum and where can you find it?

A

nucleus accumbens. nose of the caudate nucleus & putamen. BUT YOU CAN FIND IT IN THE BASAL FOREBRAIN Can find it near the anterior perforated substance just to the side of the optic chiasm, looking from the below.

36
Q

function of dorsal striatum vs the function of ventral striatum?

A
  • dorsal striatum: movement motor function, executive function…
  • ventral striatum : reward-related. its part of the mesolimbic and mesocortical pathways with VTA, dopaminergic
37
Q

how to find the ventral tegmental area?.

A

section of midbrain - you can see the crus cerebri. Going inside, you see the substantia nigra - the VTA are the inward noses of the SN.