modulation of movement by the basal ganglia

Question 1

what is called the pyramidal pathway

Answer 1

executor pathway

Question 2

in the extrapyramidal pathways what accessory pathways are the signals relayed thru

Answer 2

singals are relayed thru multiple pathways involving basal ganglia, cerebellum, brainstem nuclei

Question 3

what is the function of basal ganglia, cerebellum, reticulospinal and vestibulospinal tracts, corticorubrospinal system

Answer 3

-basal ganglia: complex motor actions
-cerebellum: mvt coordination -reticulospinal and vestibulospinal tracts: antigravity and equilibrium
-corticorubrospinal system: fine motor control

Question 4

basal ganglia consists of what 5 nuclei

Answer 4

Caudate
Putamen
Globus Pallidus
Substantia Nigra
Subthalamus

Question 5

basal ganglia influences mvt by reg the activity of the umn circuits

Answer 5

-reg m. cnt
-F initiation and termination of mvt
-reg multi-jnt mvt
-Control movement sequencing,
-Oculomotor control (e.g. saccadic eye movement),
-Motor habit learning

Question 6

what complex patterns of motor activity does the basal ganglia control

Answer 6

Writing,
Using scissors,
Throwing balls,
Shoveling dirt,
Some aspects of vocalization (speech),

Question 7

what is the input zone

Answer 7

striatum: caudate, putamen

Question 8

input zone receive and process mvt related signals from

Answer 8

Cerebral cortex,
Substantia nigra pars compacta (dopaminergic neurons).

Question 9

what are the main neurons of the caudate and putamen

Answer 9

medium spiny neurons (inhibitory, GABA)

Question 10

the axons from medium spiny neurons contact neurons of:

Answer 10

Globus pallidus (External
& Internal),
Substantia nigra pars reticulata (not SN pars compacta).

Question 11

describe the output zone pathway (GP, VL/VM, motor cortex)

Answer 11

Neurons of the of internal segment of globus pallidus (inhibitory) –> Ventral anterior and ventral lateral complex nuclei of the thalamus (excitatory) –> Motor cortex on the frontal cortex (upper motor neurons)

Question 12

describe output zone (SNPR and sup colliculus)

Answer 12

Neurones of the Substantia nigra pars reticulata (inhibitory) –> Superior colliculus (excitatory) that command head and eye movements

Question 13

Efferent cells of globus pallidus internal and substantia nigra pars reticulata are ______

Answer 13

inhibitory

Question 14

They have high levels of spontaneous activity
that prevent unwanted movement by ______ ______ cells in the
thalamus and superior colliculus.

Answer 14

tonically inhibiting

Question 15

at resting state, describe the chain of n. cells arranged in a disinhibitory circuit

Answer 15

At resting state: Striatum
neuron (A) is silent, no
inhibition on Globus pallidus
neuron (B). Globus pallidus
neuron (B) is tonically inhibiting VA/VL thalamus neuron (C). No excitation of the motor neuron (D)

Question 16

at initiation of voluntary (intended) movement, describe the chain of n. cells arranged in a disinhibitory circuit

Answer 16

Striatum neuron (A) is transiently excited by cortical inputs. Globus pallidus neuron (B) is transiently inhibited. The VA/VL thalamus neuron (C) is disinhibited (released from inhibition), so excitatory input can excite it. The upper motor neuron (D) is excited.

Question 17

what does the direct pathway serve

Answer 17

serves to release the thalamic neurons from tonic inhibition practiced by the globus pallidus to facilitate the initiation of voluntary (intended) movement

Question 18

what does the indirect pathway serve

Answer 18

serves to increase the level of tonic inhibition of the thalamic neurons in order to prevent unwanted movement

Question 19

what pathway is seen as a brake

Answer 19

indirect pathway

Question 20

what pathway is seen as a accelerator

Answer 20

direct pathway

Question 21

what is the principle functions of basal ganglia in motor control in the direct pathway

Answer 21

facilitates the initiation of motor programs that express movement (i.e., promotes voluntary movement in targeted muscles)

Question 22

what is the principle functions of basal ganglia in motor control in the indirect pathway

Answer 22

facilitates the suppression of competing or non-synergistic motor programs (i.e., inhibits movement in other muscles that do not contribute to overall wanted movement).

Question 23

what is the result of both pathways

Answer 23

smooth and coordinated movements

Question 24

what diseases do dysfunctions in the 2 pathways explain

Answer 24

parkinson’s and huntingdon’s

Question 25

why is the basal ganglia ideally placed

Answer 25

to provide contextual info to movement production

Question 26

the basal ganglia serves to program movement but also to do what

Answer 26

cognitive and emotional operations