Lec 21 Flashcards
what two pathways control voluntary movement.
what is this circuit called?
Direct path and indirect path
Basal ganglia motor circuit
what is the word for when a negative signal in GPI acts on another negative signal
Disinhibition
explain both paths of the basal ganglia motor circuit and what effect the substantia nigra pars reticulata has on each
Direct - gas
Cortex + striatum - GPi - thalamus + cortex (then send command)
- substantia nigra pars reticulata supplies positive signal to this path (promote movement)
Indirect- brake
cortex + striatum - subthalamic nucleus + GPI - thalamus + cortex (then sends command)
- sub nig have negative effect on this path
how does dopamine affect movement regarding the direct and indirect paths
the cortex excites both pathways (press gas and brake)
when striatum receive dop, it lessens the inhibition, and hits the accelerator. It helps you move.
Possible functions of the basal ganglia (3)
affect contralateral movements
go signal for intentional movement
predictive control over movement
- adjust tone e.g.
Describe how Parkinson’s disease affects the Basal ganglia motor circuit
what point notice affects?
PD is the degeneration of the dopaminergic neurons in the Substantia Nigra pars compacta.
Therefore you get brake and gas at same time from cortex and not a lot of regulation from sub nig
notice after lose >85% of substantia nigra
EXTRA FACTS:
- 40-70 y/o
- start unilateral then can progress
- progressive dis
- cause unknown
difference between the Substantia Nigra pars reticulata and compacta
reticulata less dens than compacta
compacta appears black, contains dopaminergic nuclei
difference bet park dis and park like symptoms
park dis is the disease.
Parkinson-like symptoms are similar but have another known cause
Hallmark symptoms of parkinsons dis (4)
Bradykinesia - slow and small movements
Resting tremor
Rigidity - stiffness caused by increased tone (cog-wheel rigidity)
Postural instability
Bradykinesia
slow and small movements . symp of PD
additional sympts of PD (dont try too hard on this)
- stooped posture
- expressionless face
- microphagia (small hand writing)
- difficulty turning
- shuffling gait
- stiff arms when walk (not swing)
- freezing
Describe the Hoehn and Yahr scale
assesses PD symptoms
I-IV where…
I - unilateral symptoms
II - bilateral sympt, no postural instability
III - Bilat + postural instability
IV - considerably impaired walking or balance
V - wheelchair-bound or need assistance to walk
