Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Semester 3 > basal ganglia > Flashcards

basal ganglia Flashcards

1
Q

which part of the midbrain degenerates in parkinsons

A

substantia nigra
the compact part = pars compacta

this part becomes a bit paler in patients

(medial to the pars reticulata)

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

why dark pigmentation of substantia nigra

A

accumulation or neuromelanin = by product of dopamine synthesis and degradation

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

5 main types of dopamine receptors

A

D1- like = D1 and D5receptors
- depolarised (excited) by dopamine

D2-like = D2,3,4
- hyper polarised (inhibited) by dopamine

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

what makes up the basal ganglia

A

corpus striatum = caudate and lentiform nuclei

(lentiform = putamen + external/internal segments of globus pallidus)

substantia nigra

sub thalamic nucleus

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

is the thalamus part of the basal ganglia

A

no but projects do from it do pass via the internal capsule

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

3 parts of internal capsule

A

anterior limb - between caudate nucleus and lentiform

genu - at the bend/apex of lentiform nucleus

posterior limb - between thalamus and lentiform

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

coronal section rules in term of different parts of the internal capsule

A

if you see the:

thalamus = posterior limb

no thalamus = anterior limb

genu is only seen in a single coronal slice at level of the interventricular foramen of Monro

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

what does the posterior limb of the internal capsule include

A

coritcalspinal tract

immediately behind it = ascending sensory pathways (dorsal column/spinothalmic)

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

what type of axons are within internal capsule (3)

A

descending motor projections from motor/premotor of cerebral cortex

ascending sensory projection from thalamus

afferent/efferent connections of basal ganglia

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

striatum

A

caudate nucleus + ONLY putamen part of lentiform

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

afferent and efferent part of basal ganglia

A

afferent = striatum (caudate nucleus/putamen)

efferent = pallidum INTERNAL part

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

where do projections from the basal ganglia go (the efferent)

A

to the thalamus then back to the cortex

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

where is substantia nigra located

A

midbrain (cerebral peduncle)

crus cerebri in front of it
tegmentum behind it

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

the simplified basal ganglia loop

A

frontal lobe—>striatum—>pallidum—>thalamus—->frontal lobe

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

the 3 different loops

A

cognitive - from PREFRONTAL CORTEX enter via caudate nucleus

motor - from MOTOR/PREMOTOR FRONTAL CORTEX enter via putamen

limbic - enter via ventral striatum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

limbic loop

A

arises from limbic lobe, hippocampus and amygdala

has to do with emotion, behaviour and reward-based learning

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

dopamine supply for the 3 loops

A

(dopamine regulates the basal ganglia loops)

cognitive and motor = from substantia nigra

limbic = ventral tegmental area

of midbrain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

treatment of parkinson

difficult to initiate movement

A

replacement of dopamine

  • stimulate D1/D2 receptors
  • replacemnt of dopamine (eg. oral levodopa = precursor)

we want to increase direct pathway and decrease the indirect pathway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

indirect and direct pathway

A

basal ganglia output(internal palidum) to thalamus = inhibitory
(therefore supressing unwanted movement/thoughts)

direct = switches off the inhibitory (brake)

(direct disinhibits to facilitate movement)

indirect = reinforces the inhibitory

(indirect inhibits activity by reinforcing basal ganglia inhibitory output)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

role of dopamine between indirect and direct pathways

A

dopamine disinhibits the thalamus

promotes direct pathway

but excessive dopamine–> dyskinesias (involuntary movement)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

indirect pathway route

A

from striatum(caudate+putamen) –>external palidum–>sub thalamic nucleus—to inhibit–> internal palidum (inhibiting the brake)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what projects to the ventral striatum

A

orbitomedial prefrontal cortex
anterior cingulate cortex
(emotion/behaviour/decision making)

hippocampus (spatial and temporal context about behaviour)

amygdala

23
Q

what kind of receptors are found in ventral striatum

A

opiates and cannabinoids
therefore addiction is linked

can lead to dopamine dysregulation syndrome

24
Q

relationship of caudate and lentiform nucleus in ventral striatum

and what nucleus is found

A

only part where they are fused

the anterior limb runs superior to them

nucleus accumbens = lower part of the fused caudate+putamen `(ventral striatum)

25
Q

what condition do you get with loss of neurones in the striatum

A

huntington’s

loss of GABAergic inhibitory (low Ach)

26
Q

Parkinson’s clinical features

A

lack of dopaminergic inhibition–> overactivity of GABAergic inhibitory neurones inhibiting the thalamus

(neurodegenerative disorder)
= hypokinesia (inability to initiate movement - lack of movement)

TRAPS
Tremor (resting)
Rigidity 
Akinesia 
Postural instability
Shuffling gait w/ short steps
27
Q

Huntington’s clinical features

A

(inherited disorder)

= hyperkinesia (jerky involuntary movements

28
Q

cause of parkinsons

A

MPTP able to get in via DA transporters–> gets metabolised by MAO-b –> MPP++ (extremely neuro-toxic)—> neurones death

29
Q

treatment for parkinsons

can’t cure but delayed

A

dopamine agonists

  • ropinirole, pramipexole, bromocriptine
  • cant cross BBB

L-dopa (precursor)

  • can cross BBB
  • given with decarboxylase inhibitor that cannot pass the BBB so its not decarboxylate outside brain

MAOb inhibitor : selegiline

COMT inhibitor: entacapone
(slows down elimination of l-dopa)

antimuscarinics (benzatropine) for tremor

surgery/deep brain stimulation -only if its serious

30
Q

What clinical condition is caused by infarction of the subthalamic nucleus

A

Hemiballismus (wild, involuntary flailing movements on one side of body)

31
Q

Does the subthalamic nucleus excite or inhibit the internal pallidum

A

It excites the pallidum (pallidum = break; subthalamus = foot on pedal)

32
Q

what part of the ventricular system separates the 2 thalami

+ what is this called (makes this part of ventricle a donut shape)

A

third ventricle

thalamic interconnexus

33
Q

Which type of memory or learning might the basal ganglia be involved with?

A

motor learning

implicit (=non-declarative) memory and the subtype is procedural memory

34
Q

what does the rabbit represent on a coronal section of the posterior part of basal ganglia

what is the tail part and what is above the head (csf fluid)

A

the anterior part of hippocampus (pes)

tail = tail of caudate nucleus

above the head = inferior horn of the lateral ventricle

35
Q

which part of brain do you see the caudate nucleus appear twice on a coronal slice

A

posterior
the head of caudate and the tail

because caudate nucleus is c shaped

36
Q

Why might a person with Parkinson’s disease find it easier to run from a burning building than to rise from an armchair or turn over in bed? What is this phenomenon called?

A

paradoxical kinesis

Parts of the limbic lobe and basal ganglia that are less affected in Parkinson’s disease (amygdala, ventral striatum) enable movement under emotionally-charged circumstances

37
Q

Which part of the internal capsule separates the caudate and lentiform nuclei?

A

anterior limb

38
Q

Why do psychiatrists often see patients with symptoms that mimic parkinson’s?

A

Extrapyramidal side-effects of antipsychotic medication (dopamine antagonists

39
Q

chorea

A

involuntary movements (Huntington’s)

40
Q

mode/pattern of inheritance for huntingtons

A

autosomal dominant

41
Q

foramen of monro

A

interventricular foramen connecting lateral ventricles to third ventricle

42
Q

what flexure gives the rhomboid fossa its shape

A

pontine flexure

43
Q

Where is cerebrospinal fluid reabsorbed into the venous system?

A

Dural venous sinuses (in particular, the superior saggital sinus)

44
Q

What is idiopathic intracranial hypertension?

A

Raised intracranial pressure, often in young overweight females; threatens vision – Unknown cause

45
Q

Which basal ganglia nucleus (part of the diencephalon) is the best target for deep brain stimulation in the surgical management of refractory Parkinson’s disease?

A

Subthalamic nucleus (STN) – especially the motor part which is dorsolateral.

46
Q

The electrode is placed in the dorsolateral (motor) part of subthalamic nucleus; what side effects might occur if it were placed in the ventromedial part?

A

ventromedial part is “limbic” in function and stimulation here causes psychiatric side-effects such as unpredictable mood changes: e.g. acute depression, with suicidal ideation or euphoria/mania with spontaneous hilarity and attacks of laughter.

47
Q

Do the primary motor cortex projections contribute to the ‘open’ or ‘closed’ part of the voluntary motor control loop?

A

Open loop. The main closed loop part is from the SMA (supplementary motor area) into the putamen, through the pallidum and back to the SMA (hence ‘closed’). The open loop components start in the primary motor cortex, primary sensory cortex, and elsewhere, but loop back to the SMA.

48
Q

What are the clinical features of the SMA syndrome?

+Infarction in which major cerebral arterial territory might lead to this syndrome?

A

Reduced spontaneous movements and difficulty initiating voluntary actions affecting the side of the body opposite to the lesion (cf. Parkinson’s disease). The features may mimic a stroke or hemiplegia, BUT the limb is not in fact paralysed as demonstrated by normal movement in certain semiautomatic (less “voluntary”) actions like walking.

Anterior cerebral artery

49
Q

Fibres of which special sense do not reach the cortex via the thalamus?

A

Olfactory

olfactory bulb projects directly to the primary olfactory cortex in the medial temporal lobe and amygdala). Olfactory cortex is a more primitive type of three-layered (paleo)cortex, in contrast to six-layered neortex

50
Q

What is the arrangement of the blood supply to the thalamus?

A

Receive central perforating vessels from the posterior cerebral/posterior communicating arteries

51
Q

what separates the thalamus into anterior, lateral and medial regions

A

Y-shaped internal medullary lamina

52
Q

what does the ventral part of the thalamus receive

A

ascending sensory projections

53
Q

How might a thalamic stroke cause contralateral (a) hemi-anaesthesia or (b) hemianopia?

A

Damage to the (a) ventral posterior [VP] nucleus of the thalamus which projects to the primary somatosensory cortex in the postcentral gyrus of the parietal lobe via the posterior limb of the internal capsule or (b) the lateral geniculate nucleus [LGN] of the thalamus which projects to the primary visual cortex in the banks of the calcarine sulcus in the occipital lobe.

54
Q

what gland is in the roof of the 3rd ventricle

A

pineal

Semester 3 (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions