12. Motor III - the Basal Ganglia and Motor Association Cortex Flashcards
key regions for HIGHER MOTOR CONTROL are the CEREBELLUM, BASAL GANGLIA and MOTOR ASSOCIATION CORTICES.
what is the role of the CEREBELLUM
PRECISION OF ACTION
what is the role of the BASAL GANGLIA
to AMPLIFY MOVEMENT
- controls the AMOUNT of movement
what is BRADYKINESIA
TOO LITTLE (or too slow) MOVEMENT
- fault at BASAL GANGLIA
what is DYSKINESIA
TOO MUCH MOVEMENT
- fault at BASAL GANGLIA
what is the role of the MOTOR ASSOCIATION CORTICES
SELECT THE CORRECT ACTION (PRAXIS)
LOSS of FUNCTION of CEREBELLUM:
ATAXIA
LOSS of FUNCTION of BASAL GANGLIA:
BRADYKINESIA or DYSKINESIE
LOSS of FUNCTION of BASAL GANGLIA:
BRADYKINESIA or DYSKINESIA
LOSS of FUNCTION of MOTOR ASSOCIATION CORTICES
APRAXIA
WHERE is the BASAL GANGLIE
in the CENTRE of the FOREBRAIN (deep part)
- ANTERIOR to THALAMUS
BASAL GANGLIA are …. MATTER STRUCTURES
GREY MATTER STRUCTURES
/ a group of NUCLEI
BASAL GANGLIA GREY MATTER is traversed by WHITE matter creating a STRIPY APPEARANCE known as:
CORPUS STRIATUM
parts of the CORPUS STRIATUM of the BG:
- NEOSTRIATUM : CAUDATE (nucleus) & PUTAMEN
- GLOBUS PALLIDUS (external and internal)
BASAL GANGLIA also includes two other parts besides the Corpus Striatum that are not part of the basal ganglia proper (located outside):
- SUBTHALAMIC NUCLEUS (lower Diencephalon)
- SUBSTANTIA NIGRA (Midbrain)
where is the SUBTHALAMIC NUCLEUS
in the LOWER DIENCEPHALON
(area between brainstem and cerebrum)
where is the SUBSTANTIA NIGRA
MIDBRAIN
SUBSTANTIA NIGRA (PARS COMPACTA) consists of BLACK STAINING CELLS. why do they get this black colour
BY-PRODUCT of SYNTHESISING their main neurotransmitter : DOPAMINE
DOPAMINE is produced in the SUBSTANTIA NIGRA of the BASAL GANGLIA. what does it do?
ENAHNCE MOVEMENT / ACTVITY in BASAL GANGLIA of BRAIN
- have MODULATING EFFECTS (adjust amplification of movement)
- has role in brains REWARD CENTRE (feeling of reward)
LACK OF DOPAMINE (due to loss of dopaminergic cells in Substantia Nigra) results in what disease
PARKINSON’S DISEASE
- with SLOWING of MOVEMENT (BRADYKINESIA) and TREMOR
DOPAMINE is what type of NEUROTRANSMITTER
AMINE
HUNTINGTON’S DISEASE is caused by what
ATROPHY / DEGENERATION OF CORPUS STRIATUM
- causing EXCESSIVE MOVEMENT (DYSKINESIA)
- LOSS of INHIBITORY EFFECTS on the THALAMUS and CORTEX
Dance-like Dyskinesia in HD is called CHOREA
INHIBITORY OUTPUT to the THALAMUS comes from which part of the BASAL GANGLIA
GLOBUS PALLIDUS INTERNAL
there are both DIRECT and INDIRECT PATHWAYS of the BASAL GANGLIA.
which pathway has a STIMULATORY / EXCITATORY EFFECT on the THALAMUS -> CORTEX
DIRECT PATHWAY
SUBSTANTIA NIGRA
-> NEOSTRIATUM
-> GLOBUS PALLIDUS INTERNAL
-> THALAMUS -> CORTEX
(as two negatives make a positive, so two inhibitory effects create excitatory effect)
INDIRECT PATHWAY of BASAL GANGLIA has GLOBUS PALLIDUS EXTERNAL after the STRIATUM and before the GLOBUS PALLIDUS INTERNAL so 3 negatives make a … effect
INHIBITORY
NIGROSTRIATAL PATHWAY starts from the SUBSTANTIA NIGRA to the STRIATUM.
which RECEPTORS does DOPAMINE act on for the DIRECT PATHWAY, POSITIVE NEUROMODULATORY EFFECT
D1 RECEPTORS
DOPAMINE on D2 RECEPTORS of STRIATUM activate what effect
INHIBITORY NEUROMODULATORY EFFECTS
- INDIRECT PATHWAY
(striatum -> globus pallidus external -> globus pallidus internal)
SUBSTANTIA NIGRA of the MIDBRAIN has two parts
- main functional part: PARS COMPACTA
with DOPAMINERGIC CELLS (tight together) - PARS RETICULIS - basic part, network of cells
DAMAGE to the SUBTHALAMIC NUCLEUS in the DIENCEPHALON causes..
BALLISMUS
THALAMUS is the station for what
SENSORY RELAY STATION
&
RELAY STATION of MOTOR FEEDBACK from Cerebellum and Basal Ganglia
NEOSTRIATUM consists of 3 functional parts
(1 is small and less important)
- PUTAMEN : MOTOR PROCESSING
- CAUDATE : PLANNING MOVEMENT & BEHAVIOUR
- NUCLEUS ACCUMBENS : EMOTIONAL OUTPUT
what causes PARKINSON’S DISEASE
LACK OF DOPAMINE from SUBSTANTIA NIGRA
ATROPHY of … causes HUNTINGTON’S
CORPUS STRIATUM of the Basal Ganglia
which part of the NEOSTRIATUM is involved in MOTOR PROCESSING
PUTAMEN
what are the MOTOR ASSOCIATION CORTICES:
- PRIMARY MOTOR CORTEX (BA 4)
- PREMOTOR CORTEX (BA 6)
- SUPPLEMENTARY MOTOR CORTEX (BA 6)
where is the PRIMARY MOTOR CORTEX (which brodmann’s area)
BA 4
where are the PREMOTOR CORTEX and SUPPLEMENTARY MOTOR CORTEX (both premotor cortices)
BA 6
Premotor cortex: MEDIAL
Supplementary motor cortex: LATERAL
which is the DIFFERENCE between the PRIMARY MOTOR CORTEX (BA 4) and PREMOTOR CORTICES (BA 6)
PREMOTOR CORTICES (BA 6)
require much STRONGER STIMULI (small stimulus won’t generate movement)
and the triggered movements are MORE COMPLEX
BA 4 only needs a small stimulus and movements are less complex
medial parts of BA 6 seem to be crucial in..
Lateral parts of BA 6 seem to be crucial in..
- Medial: IMAGINED, SELF-INITIATED MOVEMENTS
- Lateral: Movements undertaken in relation to a sensory cue ie light at a particular position
when is a MIRROR NEURON Active
both when making / planning the movement and when WATCHING THE MOVEMENT (someone doing the movement)
MOTOR ASSOCIATION CORTICES are for PRAXIS.
what does PRAXIS refer to
range of higher motor functions which involve SELECTION of the CORRECT MOVEMENT
Deficiency: APRAXIA / DYSPRAXIA
where are the MOTOR ASSOCIATION CORTICES
CORTEX OF FOREBRAIN
