Basal Nuclei: Movement And Disorders Flashcards
(94 cards)
1
Q
Where do voluntary movement signals originate
A
Cerebral cortex
2
Q
Where are the voluntary movements that originate in the cortex fine tuned
A
They are fine tuned and made smooth and pieces by basal nuclei
3
Q
What are the basal nuclei involved in
A
- motor activities
- sensorimotor integration and cognitive functions: learning and mastering of new , complex movements (dancing, skiing, swimming)
- Affects (pleasure) which helps us “remember it”
4
Q
Pyramidal
A
Pathway mediated by corticospinal neurons
5
Q
Extrapyramidal
A
Basal nuclei, cerebellum, or descending brainstem pathways
6
Q
The dorsal basal nuclei
A
Caudate nucleus Putamen Globes pallidus Subthalamic nucleus Substantial nigra
7
Q
What is considered to be the striatum of the dorsal basal nuclei
A
Caudate nucleus
Putamen
8
Q
What is considered to be the lenticular nucleus of the dorsal basal nuclei
A
Putamen
Globus pallidus
9
Q
What separates the dorsal and ventral basal nuclei
A
Anterior commisure
10
Q
What are the ventral basal nuclei involved with
A
Emotional cortex, pleasure for successful movements
11
Q
What are the components of the ventral basal nuclei
A
- nucleus accumbens: a continuation of the lenticular nucleus
- substantia innominata: a continuation of the pallidum
- nucleus basalis of Meynert
- olfactory tubercle
12
Q
What is the ventral region of the basal nuclei involved with
A
Potions of the amygdala and ventral tegmental area
13
Q
What does the neostriatum (striatum) consist of
A
The caudate nucleus
The putamen
14
Q
What is the putamen functionally tightly connected with
A
The caudate nucleus
15
Q
What is the caudate nucleus and the putamen separated by
A
The internal capsule
16
Q
What is the ventral striatum composed of
A
Nucleus accumbens
17
Q
What is the pallidal complex composed of
A
Globus pallidus and the ventral pallidum
18
Q
Anatomy of the globus pallidus
A
Has a medial and lateral part divided by medullary lamina
19
Q
Anatomy of the ventral pallidum
A
Synonymous with the substantia innominata
20
Q
The main input TO the pallidum
A
Is from the striatal complex (putamen)
21
Q
The main output FROM the pallidum is
A
To the thalamus
22
Q
How do the pallidothalamic fibers exit the globus pallidus
A
As two bundles: the ansa lenticularis and the lenticular fasciculus
23
Q
What are the two divisions of the substantia nigra
A
- a cell dense portion called the paras compacta
- reticulated portion called the pars reticulata
24
Q
Major afferents to the nigra complex
A
Striatal (putamen)
Pallidal complexes
25
What does the substantia nigra do
Helps other basal nuclei work in concert
26
Substantia nigra-pars compacta
Contains melanin containing neurons, whose dark color gives the name "black substance"
27
Neurons in the pars compacta of the substantia nigra
Use dopamine and project primarily to the neostriatum (putamen and caudate nucleus) as nigostriatal fibers
28
What kind of NT does substantia nigra use
Dopamine
29
Function of the dopamine released form the substantia nigra
May excite or inhibit striatal neurons depending on the type of receptor on the postysynaptic membrane
30
What is the pars reticulata of the substantia nigra formed by
Loose aggregations of GABAergic neurons that are indistinguishable from those of the medial pallidum
31
Neurons of the pars reticulata of the substantia nigra
Have axons with an extensive system of collaterals; consequently they may project to inhibit one or mroe target structure (neostriatum or thalamus)
32
What part of the substantia nigra have a high rate of discharge and tonically inhibit their targets
Pars reticulata
33
Lens shaped cell group that makes up the largest part of the ventral thalamus
Subthalamic nucleus
34
How does the subthalamic nucleus sit in comparison to the substantia nigra
It is rostral to the substantia nigra
35
What does the subthalamic nucleus receive projections from
- the lateral pallidal division
- cerebral cortex
- nigral complex
36
What connections are an essential part of the indirect pathway underlying basal nuclear function
The subthalamic nucleus projecting to both pallidal divisions and to the substantia nigra
37
Formed from the axons of the neurons in the globus pallidus internal (GPi) and go to the thalamus
Ansa lenticularis
| Lenticular fasciculus
38
What are the main bridges from the pallidus to the thalamus
Ansa lenticularis
| Lenticular fasciculus
39
Fibers of the ansa lenticularis and the lenticular fasciculus join together to form the _________ which enters the thalamus
Thalamic fasciculus
40
What do the fibers of the thalamic fasciculus terminate in
The ventral anterior and ventral lateral nuclei of the thalamus
41
The _______ is a principal efferent nucleus of the basal nuclei
Medial division of the pallidal complex
42
The _______ carries fibers of the indirect pathway from the external segment of the globus pallidus to the subthalamic nucleus and from the subthalamic nucleus to the internal segment of the globus pallidus
Subthalamic fasciculus
43
Blood supply to the basal nuclei
The blood supply of the striatum and globus pallidus is mainly from the lenticulostriate branches of the MCA
There are some possible variations
- medial GP is often supplied by the anterior choroidal artery
- the caudate head and anterior portions of the lentiform nucleus are often supplied by the recurrence artery of Heubner
44
What is the gerenalized pathway of the basal nuclei
Cortex-putamen-GPe + GPi-thalamus-cortex
45
What does the basal nuclei loop constant do
Monitors movements surrender happening. They are multiple and parallel. Function simultaneously for multiple movements at same time
46
D1 receptors
Dopamine receptor type 1
| -activates the neuron if expressed
47
D2 receptors
Dopamine type II receptors
| -deactivates the neuron if expressed
48
Information flow through the basal nuclei is separated into _______ distinct ______ circuits
Multiple and parallel
49
Where do the basal nuclei circuits originate from
Functionally distinct regions of the cerebral cortex, pass through distinct regions of each basal nuclear component, affect different areas of the thalamus, and return to functionally distinct cortical regions
50
All the basal nuclei circuits can be divided into _____ and ______ pathways that have OPPOSING actions on the activity of motor nuclei of the thalamus and thalamocortical projections
Direct and indirect
51
What pathway facilitates thalamic activity
Direct pathways
52
What pathways inhibits the flow for thalamic activity
Indirect pathway
53
What do the direct and indirect pathways create
A balance in the inhibitory outflow of the basal nuclei
54
What NT has a major role in both direct and indirect pathways
Dopamine
55
The main input to the basal nuclei comes from the _______ to the striatum
Cerebral cortex
56
The ________ is the most important input nucleus of the striatum for motor control pathways
Putamen
57
Most cortical inputs to the striatum are excitatory and use _________ as the NT
Glutamate
58
The main outputs from the basal nuclei are from the
Internal segment of the globus pallidus
59
Output pathways of the internal segment of the globus pallidus
Inhibitory and use the NT GABA
60
What are the main output pathways of the internal globus pallidus to
Ventral lateral and ventral anterior nuclei of the thalamus via the thalamic fasciculus
61
Motor loop (direct pathway) at rest
Neurons of the internal segment of the globus pallidus and of the substantia nigra pars reticulata that project to the thalamus have high rates of spontaneous activity and tonically inhibit the thalamic neurons
62
What tonically inhibits the thalamic neurons
Neurons of the internal segment of the globus pallidus and of the substantia nigra pars reticulata
63
During the motor loop (direct pathway) when there is cortical activity and voluntary movement is intended
The Cortex sends as an excitatory, glutamatergic signal to the putamen
64
What activated the putamen in the direct pathway?
Cortex
65
What do signals from the putamen do
Inhibit neurons in the internal segment of the globus pallidus and in the substantia nigra pars reticulata (GABA)
66
When the putamen is activated, what does it in turn do in the direct pathway
Deactivates Gpi and substantia nigra
67
In the direct pathway, when the putamen deactivates the Gpi and the substantia nigra what happens
This stops the inhibitory inputs to thalamocortical neurons and the thalamus is disinhibition, net effect is excitation of the cerebral cortex
68
What is the net effect of the direct pathway
Excitation of the cerebral cortex
69
Which pathway is inhibitory, direct or indirect
Indirect
70
The indirect pathway at rest
The pallido-subthalamic fibers (GABA) have high spontaneous firing rates and tonically inhibit subthalamic neurons
71
In the indirect pathway what happens when the pallido-subthalamic,ic fibers get inhibited
It is done by the neostriatum that releases the subthalamic cells from their tonically inhibited state.
72
What do the striatopallidal neurons involved in the indirect pathway contain
GABA and enkephalin
73
In the indirect pathway, what do the subthalamic neurons do
They have spontaneous activity that activates the internal globus pallidum
74
In the indirect pathway, what does the activation of the internal globus pallidum by the subthalamic neurons do
Increases the firing rate of glutamatergic subthalamopallidal fibers to the medial pallidal segment
75
In the indirect pathway, what does increasing the firing rate of glutamatergic subthaalmopallidal fibers to the medial pallidal segment do
The firing rate of the inhibitory pallidothalamic fiber is increased, with a resultant decrease in the activity of thalamocortical neurons
76
What is the net effect of the indirect pathway
To decrease activity of the thalamus and consequently to decrease activity of the cerebral cortex
77
Where does the motor loop originate
In the supplementary motor, primary motor, and promoter cortices
78
Where do the corticostriatal projections in the motor loop terminate in
Putamen
79
In the motor loop, where do efferent from the putamen go
Terminate in the internal segment of the GPi and substantia nigra pars reticulata
80
In the motor loop, where does the GPi project to
The ventral lateral nucleus of the thalamus. These areas project back to the supplementary, premotor, and motor cortices
81
What does the basal nuclear pathway for the motor loop affect
Both cortical motor and brainstem motor centers
82
What sends signals to the putamen during movements to determine whether or not to inhibit or excite
Substantia nigra
| -can be excitatory or inhibitory depending on the type if the receptors for dopamine
83
This receives most of the inputs form the motor and somatosensory areas of cortex and projects by way of the globus pallidus and thalamus to the motor, premotor, and supplementary motor areas. Thus it is involved in the motor functions of the basal ganglia
Putamen
84
What is involved in the motor functions of the basal ganglia
Putamen
85
This receives most of tis inputs form association areas of cortex and projects by way of GPi-SNr and the thalamus mostly to prefrontal areas. Thus it is involved more predominantly in cognitive functions and less directly movements
Caudate nucleus
86
What basal ganglia is more involved with cognitive functions and less directly in movement
Caudate nucleus
87
This indicate its probable role in the initiation of drive-related behaviors
The limb ic connections of the ventral striatum
88
This allows us to learn new complex movements
Caudate nucleus
89
What basal ganglia is most involved with the executive loop
Caudate nucleus
90
What are executive functions
Cognitive mechanisms that allow the individual to optimize function when multiple tasks need to be performed at the same time
91
What basal ganglia is not really involved in the executive loop
Putamen
92
What is the pathway of the executive loop
Prefrontal cortex--caudate nucleus---GPi, SNr--VA/MD
93
Motivational loop
- pleasure helps remember movement
- this loop includes lateral orbitofrontal cortex, anterior cingulate cortex, medial prefrontal cortex, amygdala, and hippocampus
- these project to the caudate nucleus and the ventral striatum (VS)
- then to the GPi, nucleus accumbens, and others
- then to VA, DM of the thalamus
94
Visuomotor loop
Similar to cognitive loop
| -FEF--Caudate nucleus---GPi+SNr--VA/MD---FEF
