The Basal Ganglia Flashcards
What is the basic function of the basal ganglia?
To modulate thalamo-cortical activity
Where does the basal ganglia receive input from?
the cerebral cortex
Where are basal ganglia outputs directed?
to the thalamus
The basal ganglia processes executive commands for the initiation and suppression of what?
- Initiation of appropriate movement
- Suppression of inappropriate movement
What are the 5 nuclei that are included in the basal ganglia?
- Caudate
- Putamen
- Globus pallidus
- Subthalamic nucleus
- Substantia nigra
Which of the nuclei are located in the cerebrum?
The caudate, putamen, and globus pallidus
Where is the subthalamic nucleus located?
Within the diencephalon
Where is the substantia nigra located?
Within the midbrain
The globus pallidus and putamen together form what?
The lentiform nucleus
The caudate and putamen together form what?
The striatum
What is the junction between the caudate and putamen called?
The ventral striatum
What is the nucleus accumbens?
part of ventral striatum
What 2 structures are the 2 output nuclei of the basal ganglia system?
The substantia nigra reticularis and the globus pallidus internus
What does dopamine from the substantia nigra to the striatum adjust?
Signals to the output nuclei, so the output nuclei provide the appropriate level of inhibition to their target nuclei.
What does output of the basal ganglia motor circuit regulate?
Muscle contraction, muscle force, multijoint movements, and the sequence of movements
What does the basal ganglia motor circuit include?
- cerebral cortex motor areas
- putamen
- subthalamic nucleus
- globus pallidus internus
- motor areas of the thalamus
Do the basal ganglia have direct output to LMNs?
No
What are the 3 routes in which motor control exerted by the basal ganglia is transmitted to the LMNs? What does stimulation of each signal?
1) Via thalamus and then to UMN tracts to muscles for voluntary movements
2) Via the pedunculopontine nucleus (PPN) to reticulospinal tracts to regulate contraction of postural and girdle muscles
3) Via midbrain locomotor region to reticulospinal tracts to elicit rhythmical lower limb movements similar to walking or running
What structure receives input from the premotor and motor cortex?
the putamen
What 2 structures processes information within the basal ganglia circuit?
The subthalamic nucleus and the substantia nigra compacta
What structure sends output to motor areas of the cerebral cortex, PPN, and the midbrain locomotor region?
globus pallidus internus
What are the 4 additional basal ganglia–thalamic loops that the basal ganglia are a critical part of?
- Oculomotor
- Executive
- Behavioral flexibility and control
- Limbic
What do all 5 loops (motor, oculomotor, executive, behavioral flexibility and control, and limbic) contribute to?
The prediction of future events, selecting desired behaviors, preventing undesired behaviors, motor learning, shifting attention, and spatial working memory
What does the oculomotor loop do?
Make decisions about eye movements and spatial attention
Where does the oculomotor loop run?
Parallel to the motor loop
What is the function of the executive loop?
Participates in goal-directed behavior, including evaluating information for making perceptual decisions, planning, and choosing actions in context
Where is the executive loop located?
In the head of the caudate and the globus pallidus
Basal ganglia movement disorders range from ___kinetic (too little movement) to ___kinetic (excessive movement).
hypokinetic
hyperkinetic
Movement disorders are due to dysfunction in what parts of the basal ganglia?
- ganglia-thalamocortical motor circuit
- pedunculopontine nucleus (PPN)
- midbrain locomotor region (MLR)
Excessive inhibition of the motor thalamus, PPN, and MLR results in what?
hypokinetic disorders
Inadequate inhibition of the motor thalamus, PPN, and MLR results in what?
hyperkinetic disorders
What is the most common basal ganglia disorder?
Parkinson’s Disease
Parkinson’s Disease is a ____kinetic disorder
hypokinetic
What are the 3 subtypes of Parkinson’s disease and what is the prevalence of each?
- Akinetic or rigid (50%)
- Tremor dominant (40%)
- Mixed (10%)
Parkinson’s Disease is due to what?
Death of dopaminergic neurons, which leads to an insufficient level of dopamine
Decreased dopamine from the substania nigra compacta is the primary change leading to excessive activity of what structure?
The globus pallidus internus
What 3 things does the globus pallidus internus inhibit?
- motor thalamus
- midbrain locomotor region
- pedunculopontine nucleus
Inhibition of the motor thalamus causes what?
Decreased activity of cerebral cortex motor areas to the lateral group of UMNs which results in less activity of the lateral group of UMNs, impairing voluntary movement
Inhibition of the midbrain locomotor region causes what?
Decreased signals from the reticular formation to spinal stepping pattern generators which results in a loss of automatic gait
Inhibition of the pedunculopontine nucleus causes what?
Disinhibition of the reticulospinal tracts, activating LMNs which causes rigidity of postural and girdle muscles
What are the 4 motor symptoms of Parkinson’s Disease?
- Akinesia/bradykinesia/hypokinesia
- Rigidity
- Resting tremor
- Postural instability
What are the 5 non-motor symptoms of Parkinson’s Disease?
- Depression
- Psychosis
- PD dementia
- Autonomic dysfunction
- Fatigue
What is the Unified PD Rating Scale (UPDRS)?
a clinical tool used to evaluate the course of Parkinson’s
Describe the 4 parts of the UPDRS
- Part I: Non-motor aspects of experiences of daily living
- Part II: self-evaluation of the motor aspects of activities of daily life including speech, swallowing, handwriting, dressing, hygiene, turning in bed etc.
- Part III: clinician-scored monitored motor examination including rigidity, tremor, hand movements, gait, and posture
- Part IV: Motor complications such as dyskinesia
What 3 treatment techniques are used to treat Parkinson’s Disease?
- drugs
- invasive procedures
- PT and OT
What types of drugs are administered in Parkinson’s Disease patients?
Drugs that replace dopamine such as L-dopa
What limits the effectiveness of L-dopa?
Side effects and the progression of the disease with involvement of other cells and neurotransmitters
What do invasive procedures to treat Parkinson’s Disease consist of?
deep-brain stimulation (DBS), neuronal transplantation, and destructive surgery
How do PT and OT improve mobility and functional status in individuals with Parkinson’s disease?
Intense resistance training produces muscle hypertrophy and functional gains which can reduce symptoms associated with:
- Balance problems - Gait dysfunction - Muscle weakness - Lack of coordination - Mobility disability - Rigidity
What are the red flags that indicate a different diagnosis other than Parkinson’s Disease?
- Early postural instability
- Rapid progression
- Respiratory dysfunction
- Abnormal postures
- Uncontrollable and inappropriate laughter or crying
- Signs of cerebellar, corticospinal, voluntary gaze dysfunction
What is the collective name for primary neuro-degenerative diseases that cause signs similar to PD?
Parkinson-Plus Syndromes
What does the term primary neurodegenerative disease indicate?
that the cause of the Parkinson-plus syndrome is idiopathic or genetic
What do Parkinson-Plus Syndromes include?
- progressive supranuclear palsy
- dementia with Lewy bodies
- multiple system atrophy
What is the most common cause of death in people with Parkinson-Plus Syndrome?
pneumonia
What is progressive supranuclear palsy characterized by?
- early onset of gait instability with a tendency to fall backward
- axial rigidity
- freezing of gait
- depression, psychosis
- rage attacks
- supranuclear gaze palsy
What does dementia with Lewy bodies cause?
- early, generalized cognitive decline
- visual hallucinations
- Parkinsonism
What is multiple system atrophy characterized by?
- akinesia/rigidity
- cerebellar signs
- autonomic dysfunction
- corticospinal tract dysfunction
What is Parkinsonism?
A disorder that mimics Parkinson’s disease, but the cause is known to be toxic, infectious, or traumatic.
What is Parkinsonism often a side effect of?
drugs that treat psychosis or digestive problems
What are the signs of Parkinsonism?
- subacute, bilateral onset with rapid progression
- early postural tremor
- involuntary movements of the face and mouth
What are 4 types of hyperkinetic disorders?
- Huntington’s disease
- Dystonia
- Tourette’s disorder
- Some types of cerebral palsy
What are the signs of Huntington’s disease?
chorea and dementia
What does Huntington’s disease cause?
Degeneration in many areas of the brain, most prominently in the striatum and cerebral cortex
What are dystonias?
Genetic, usually nonprogressive, movement disorders characterized by involuntary sustained muscle contractions, causing abnormal posture, twisting, and repetitive movements.
When do dystonias increase?
during activity and emotional stress
Do dystonias ever vanish?
Yes, completely during sleep
What is frequently associated with dystonia?
tremors
What does Tourette’s disorder cause?
vocal and motor tics
What types of things exacerbate tics associated with Tourette’s disorder?
Stress, emotional excitement, and fatigue
What is choreoathetosis?
A type of cerebral palsy that includes abrupt, jerky movements and slow, writhing, purposeless movements.
What is choreoathetoid cerebral palsy associated with?
Lesions involving both the basal ganglia and ventrolateral thalamus