basal ganglia Flashcards
components of basal ganglia
- caudate
- putamen
- globus pallidus: internus and externus
- subthalamic nucleus
- substantia nigra: pars reticulata and pars compacta
striatum
- caudate
- putamen
lenticular nucleus
- putamen
- globus pallidus
dorsal basal nuclei
cuadate
putamen
globus pallidus
ventral striatum
nucleus accumbens
olfactory tubercle
ventral pallidum
substantia
innominata
striatal complex
caudate
putamen
nucleus accumbens
olfactory tubercle
pallidal complex
globus pallidus
substantia
innominata
input nuclei
caudate
putamen
nucleus accumbens
output nuclei
globus pallidus - internal segment
ventral pallidum - output part
substantia nigra pars reticulata
intrinsic nuclei
globus pallidus -external segment ventral pallidum - intrinsic part subthalamic nucleus substantia nigra pars compacta ventral tegmental area
direct pathway
cortex –glutamate–> putamen –GABA, SP–I GPi SNr – GABA –I thalamus –glutamate –> cortical motor areas
indirect pathway
cortex –glutamate –> putamen –GABA, Enk–I GPe –GABA –I STN –glutamate –> GPi, SNr –GABA–I Thalamus –glutamate –> cortical motor areas
skeletomotor loop
cerebral cortex: somatic sensory, primary motor, premotor, supplementary motor –> putamen –> GPi, SNr –> thalamic nuclei (ventral anterior, ventral lateral) –> cerebral cortex
-role in the control of facial, limb, and trunk musculature
oculomotor loop
posterior parietal prefrontal: frontal eye field, supplementary eye field –> caudate (body) –> SNr, GPi –> ventral anterior and medial dorsal thalamic nuclei –>
-role in control of saccadic eye movements
associative loop
posterior parietal, middle and inferior temporal lobe: prefrontal, premotor –> caudate (head) –> SNr, GPi –> ventral anterior, medial dorsal thalamic nuclei –>
-role in cognition and executive behavioral functions
limbic loop
medial and lateral temporal lobes, hippocampal formation: anterior cingulate gyrus, orbitofrontal cortex –> ventral striatum –> ventral pallidum, GPi and SNr –> medial dorsal and ventral anterior thalamic nuclei
-participates in the motivational regulation of behavior and in emotions
Parkinson disease
- rapid, progressive
- age
- what may cause (general)
- progressive disorder
- age 60
- environmental toxins
- substantia nigra pars compacta doesn’t release enough dopamine onto basal ganglia
Parkinson disease
- type of disease
- symptoms
- hypokinetic disorder
- resting tremor 4-5 Hz pill rolling
- rigidity
- bradykinesia or hypokinesia
- may affect walking, speech, and facial expression
- akinesis
- visuoperceptive impairments
- cogwheel rigidity = resting tremor + rigidity
- postural instability and dementia
Parkinson disease
-treatment
- drugs to increase dopamine levels
- drugs to prevent dopamine breakdown
- surgery to transplant fetal tissue
- removal of globus pallidus to slow tremors
Hypokinetic disorder
-symptoms
- mask-like facial expression
- pill-rolling tremor
- flexion of trunk
- slow, shuffling feet movement
bradykinesia
slow movement
hypokinesia
decreasing ROM
hypokinetic disorder
occur when there is too little direct pathway effect and too much indirect pathway effect
akinesis
delay in initiation or starting movements
cogwheel rigidity
resting tremor AND rigidity
causes of hypokinetic or parkinsonian syndrome
- idiopathic Parkinson disease
- Encephalitis lethargica
- head trauma - dementia pugilistica
- MPTP - designer drug
- CO and manganese poisoning
- drug induced - neuroleptics (dopamine blocking)
- Wilson disease - hepatolenticular degeneration
- rigidity plus other deficits in multiple neurodegenerative diseases
Huntington’s disease
- type
- age
- cause
- progressive
- 45 years
- AD hereditary disorder
- degeneration of neurons in the striatum (caudate and putamen) and cerebral cortex resulting in decreased GABA
Huntington’s disease
-symptoms
- involuntary jerky, rapid movements and dementia
- increased or decreased muscle tone
- unsteady gait
- slurred speech
- irregular breathing
- trouble maintaining tongue protrusion
Huntington’s disease
-treatment
Tetrabenazine (serotonin antagonist)
hyperkinetic disoder characteristics
- twitching movements of head
- grimacing movements in face, lips, and tongue
- gesticulating movements in distal parts of upper limbs
- jerking movements in distal parts of lower limbs
causes of hyperkinetic disorders
- Huntington disease: loss of medium-sized spiny stellate neurons (GABA neurons of indirect pathway)
- Sydenham chorea (rheumatic chorea)
- drug induced
- lupus erythematous
- thyrotoxicosis (grave’s disease)
- part of other neurodegenerative diseases
chorea
spontaneous, rapid, jerky, arrhythmic involuntary movements which are purposeless or “fragments of motor programs”
athetosis
inability to sustain the body part in one position. movements are writhering or snake-like. often seen with chorea, hence the term choreoathetosis.
ballismus
flailing, flinging movmeent of the whole extremity seen in lesions of the contralateral subthalamic nucleus
dystonia
persistence or fixing of the posture at the extreme of an athetoid movement of either the extremities or trunk
