Motor systems: the higher level

Question 1

what set of subcortical nuclei make up the basal ganglia?

Answer 1

the striatum, the subthalamic nucleus, the SN and the amygdala

Question 2

what are the components of the striatum of the basal ganglia?

Answer 2

the putamen and caudate nucleus

Question 3

information is drawn from all areas of the cortex to the basal ganglia via the

Answer 3

striatum

Question 4

the striatum feeds information from the cortex to the

Answer 4

globus pallidus and substantia nigra

Question 5

the globus pallidus is

Answer 5

an output target of the (striatum of the) basal ganglia

Question 6

information from the globus pallidus and SN feed into which nucleus?

Answer 6

the ventroanterior nucleus of the thalamus

Question 7

information that has gone through the BG to the VA nucleus of the thalamus then feeds back into the

Answer 7

cortex

Question 8

the information loop involving the cortex, BG and thalamus can be described as

Answer 8

reentrant as it then goes round again

Question 9

what is the supplementary area concerned with?

Answer 9

movement planning and selection of motor programs

Question 10

the fact that info is drawn from all areas of the cortex to the BG allow the BG to select programs according to all

Answer 10

sensory areas an behavioural needs

Question 11

what are the 2 functions of the BG?

Answer 11

1. selection of motor programs

2. appropriate scaling of programs and hence of muscular output

Question 12

what are the 2 major classes of BG disorder?

Answer 12

Akinesia (because of failure to select motor program) and dyskinesia (because of inappropriate scaling/selection of programs)

Question 13

akinesia is

Answer 13

decreased movement and rigidity, also referred to as parkinsonism

Question 14

dyskinesia is

Answer 14

involuntary movement

Question 15

what are the 5 main symptoms of parkinsonism

Answer 15

1. shuffling/festinating gait
2. tremor (increases with agitation)
3. rigidity (due to increased muscular hypertonus)
4. Akinesia
5. bradykinesia

Question 16

in parkinsons akinesia is seen especially in the

Answer 16

face, so is associated with an expresssionless face with reduced blinking

Question 17

bradykinesia is

Answer 17

slowness of movement and inappropriate scaling of movements

Question 18

inappropriate scaling of movements in parkinsons results in

Answer 18

the need for repeated agonist and antagonist activity to achieve simple movements, where normally a simple ag.–>antag.–>ag. (triphasic emg pattern) is used

Question 19

the 5 parts of the BG involved in motor control are the

Answer 19

1. putamen
2. caudate nucleus
3. globus pallidus
4. subthalamic nucleus
5. SN

Question 20

the caudate nucleus and putamen are anatomically similar and so can be distinguished by

Answer 20

the fact that they are separated by the internal capsule

Question 21

the globus pallidus can be separated into the

Answer 21

1. GPe (external/lateral part)

2. GPi (internal/medial part)

Question 22

the SN can be divided into 2 parts:

Answer 22

1. SNpc (pars compacta)

2. SNpr (pars reticulata)

Question 23

which of the 2 parts of the SN is darker?

Answer 23

the SNpc

Question 24

what are the 2 afferent projections into the striatum?

Answer 24

corticostriatal projection and thalamic projection

Question 25

the corticostriatal projection is organised

Answer 25

topographically (diff. areas of cortex project into diff. areas of striatum)

Question 26

projections from cortex to striatum come from which parts of the cortx?

Answer 26

all of them including ex visual, limbic, etc

Question 27

examples of the functions of the caudate nucleus:

Answer 27

eye movements and cognitive function

Question 28

examples of functions of the putamen:

Answer 28

general motor function and limbic function

Question 29

which parts of the putamen are associated with limbic function?

Answer 29

the most ventral parts

Question 30

where do fibres of the corticospinal tract terminate?

Answer 30

on distal parts of medium sized cells with spiny dendrites

Question 31

which cells make up 98% of striatal neurones?

Answer 31

the medium sized cells with spiny dendrites that the corticospinal fibres terminate on

Question 32

what is the NT used between the fibres of the corticostriatal projection and the dendrites on to which they terminate, and where do the latter receive input from?

Answer 32

glutamate, cortex and striatum

Question 33

which thalamic nuclei project into the basal ganglia?

Answer 33

intralaminar

Question 34

what is the thalamic projection of particular interest in motor control?

Answer 34

motor cortex to thalamic centromedian nucleus to putamen

Question 35

spiny neurones of the striatum project either to the :

Answer 35

globus pallidus or SNpr

Question 36

striatopallidal pathway=

Answer 36

striatum to globus pallidus

Question 37

striatonigral pathway=

Answer 37

striatum to SNpr

Question 38

how are the striatopallidal and striatonigral pathways organised?

Answer 38

topographically, so functional organisation is maintained in GP and SN

Question 39

the GPe inhibits the

Answer 39

subthalamic nucleus

Question 40

the GPi inhibits the

Answer 40

thalamus (ventrolateral and centromedial nuclei of)

Question 41

GPi inhibition of thalamus occurs in direct or indirect?

Answer 41

both

Question 42

GPe inhibition of STN occurs in direct or indirect?

Answer 42

indirect only

Question 43

the NT of striatum to GPi (in direct) is

Answer 43

GABA and substance P (inhib)

Question 44

the NT of striatum to GPe (in indirect) is

Answer 44

GABA and ekephalin (inhib)

Question 45

is the direct route excited by DA?

Answer 45

yes

Question 46

is the indirect route excited or inhib by DA?

Answer 46

inhib

Question 47

what is the effect of deplettion of DA on the routes through BG?

Answer 47

removes 1 excitatory from direct and removes 1 inhib from indirect

Question 48

whats the difference between direct and indirect routes of BG?

Answer 48

indirect has 1 more inhibitory neuron

Question 49

what does excitation of striatal neurones lead to?

Answer 49

inhibition of pallidal targets, and therefore disinhibition of thalamic targets, and therefore net excitation of cortex

Question 50

what does the thalamocortical projection allow the BG to do?

Answer 50

activate motor areas of the cerebral cortex