Chapter 16 Basal Ganglia Flashcards
basal ganglia function
goal-directed behavior, social behavior, and emotions, in addition to motor control
turn off motor programs that interfere with desired movements
striatum
cuadate and putamen
lentiform nucleus
globus pallidus and putamen
Prosaccades
fast eye movements to direct attention toward an object
saccade: rapid eye movement
pro: towards an object
antisaccades
fast movements away from an object
result of more complex interactions and require inhibition of prosaccade reflex
Oculomotor Circuit
makes decisions about spatial attention and eye movements
determining whether to use fast eye movements to direct attention toward an object
body of caudate
Motor Circuit
regulates skeletal muscle contraction, muscle force, multijoint movements, and sequencing of movements
includes: cerebral cortex motor areas, substantia nigra compacta, putamen, EPG, IPG, subthalamic nucleus and motor thalamus
disinhibition
occurs when another neuron inhibits the inhibitory neuron, allowing increasing activity in the target neuron
There is no direct communication between
Basal Ganglia and LMN
Cerebellum and LMN
Stop, Go, and No-Go Pathways
all happen at the same time
normal movement requires all 3 of them
Stop Pathway (Hyperdirect)
suppression of voluntary movement (stop drinking)
powerful inhibition of motor thalamus
Fastest Pathway
Cerebral Cortex → excites STN → STN excites IGP → IGP inhibits motor thalamus
Go Pathway (Direct)
facilitates specific movements (reach for cookie)
Substantia Nigra D1 → Putamen → inhibits IGP → IGP inhibits motor thalamus → motor thalamus excites motor areas of cortex
No-Go Pathway (Indirect)
suppression of unwanted movements (do not abduct shoulder)
Substantia Nigra D2 → Putamen → inhibit EGP → EGP inhibits STN →STN excites IGP → IGP inhibits motor thalamus
Neurotransmitters of the 3 pathways
Glutamate is excitatory
GABA is inhibitory
(Acetylcholine is excitatory)
Substantia Nigra supplies motor circuit with
Dopamine
D1 is excitatory (excites inhibitory neurons in Go)
D2 is inhibitory (inhibits neurons from putamen)
Voluntary muscle activity via
IGP →Motor Thalamus uses Glu to corticospinal tracts
Postural and girdle muscle activity via
IGP →Pedunculopontine Nucleus (PPN) uses GABA via reticulospinal tracts
Walking via
IGP →Midbrain locomotor region (MLR) uses ACh via reticulospinal tracts
Hypokinetic Disorders
too little movement
Parkinson’s
Secondary Parkinson’s
Hyperkinetic Disorder
excessive movement
Huntington’s
Dystonia
Tourette’s
Dyskinetic CP
Parkinson’s Disease
most common
affects voluntary and automatic movements
affecting upper body with rigidity and/or resting tremor
2 types: Postural Instability Gait Difficulty PIGD
and Tremor Dominant (akinetic/rigid type)
can shift from one to another
Postural Instability Gait Difficulty PIGD
Rigidity of trunk, freezing of gait FOG, resting tremor/action tremor, dementia, orthostatic hypotension, constipation, festinating gait (body leans forward and takes very small steps), falling is big risk, retropulsion (pushing back on chair when standing up leads to falling), akinesia/hypokinesia/bradykinesia
Akinesia
the absence of movement
Hypokinesia
loss of automatic movements, including facial expression and normal arm swing during walking
Bradykinesia
slowness of movement
Rigidity
increased resistance to movement in both flexor and extensor muscles
Cogwheel rigidity
rigidity experienced by people with Parkinson’s
move joint passively through its range, the motion catches and releases as if the joint contained a cogwheel and lever
Freezing of gait (FOG)
movement abruptly stops due to visual block
doorway or chair
Resting Tremor
involuntary, rhythmic shaking movements of the limbs produced by contractions of antagonist muscles
4-6 tremors per second
Action Tremor
involuntary, rhythmic shaking during voluntary movement
due to cerebellar dysfunction or parkinson’s
faster, 5-8 tremors per second
Parkinson’s dementia
social impairment, emotional/motivation impairment, and autonomic dysfunction.
deterioration of intellectual function
interferes with ability to plan, maintain goal direction, and make decisions
Apathy
loss of interest, emotion, and motivation
Pathology in Parkinson’s
death of DA-producing cells in the substantia nigra compacta and GABA producing cells in the PPN
Treatments for Parkinson’s
drug therapy that replaces DA with Ldopa
OT, PT, moderate-high intensity cardio
Invasive procedures : deep brain stimulation, destructive surgery (Thalamotomy and Pallidotomy), neuronal transplant
LSVT BIG
Secondary Parkinsonism
symptoms that mimic Parkinsons
origin is due to trauma, toxic, infections, drugs
lesions of lentiform nucleus
Chronic Traumatic Encephalopathy
type of secondary parkinsonism
Parkinson-like signs, disordered thinking, depression, memory loss, dysfunction of goal-directed behavior, and disinhibition
requires history of head trauma
Huntington’s Disease
chorea/athetosis and dementia, progressive
fatal hereditary disease, excess number of repeats affecting 3 DNA building blocks in Huntington gene, results in protein with excess number of glutamine units
move frequently and forcefully in sleep
goal directed and emotions affected with apathy and depression
no treatments
Chorea
involuntary jerky rapid movements
athetosis
slow, squirming, purposeless movements
Dystonia
involuntary sustained muscle contractions that cause abnormal postures or twisting and/or repetitive movements + tremor
increases during activity and emotional stress, goes away with sleep
genetic and nonprogressive
Focal Dystonia
most common type, limited to one part of the body
ex. spasmodic torticollis
Torticollis
involuntary, asymmetric contraction of neck muscles causing abnormal position of the head
Generalized dystonia
causes involuntary twisting postures of the limbs and trunk
begins with inversion and plantarflexion of the foot while walking
often progressive
Tourette’s Disorder
causes vocal and motor tics
abrupt, repetitive, stereotyped movements
stress, emotional excitement, and fatigue exacerbate tics
Dyskinetic CP
muscle tone and posture are abnormal and involuntary movements occur
Dystonia causes abnormal posture
involuntary movements are choreoathetosis
