Motor Learning and Neurological Syndromes Flashcards
Which cortical area is involved with voluntary movement?
The Primary Motor Cortex
Voluntary movement follows a monosynaptic pathway from
the cortex through an upper motor neuron, which synapses in anterior horn of the spinal cord
the lower motor neuron then synapses at the muscle
Primary Motor Cortex: Which Broddmann area?
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Parasaggital Meningioma:
slow brain tumours, very little symptoms or notice symptoms because the tumour grows slowly
causes upper motor neuron symptoms due to pressure on the bones
Upper Motor Neuron Disorders; Signs:
- weakness
- spasticity
- brisk reflexes
- babinski’s sign:
- normal flexion
- extension and flaring
upper motor neurons come from the cortex, through spinal cord
Upper or lower motor neuron disease?
insert slide
upper motor neuron symptoms:
some flexor muscle movement
stronger extensors
increased tone
brisk reflexes
maintain posture due to spasticity
Lower Motor Neuron Disease: Signs:
- weakness
- wasting of muscles
- fasciculations
- reduction in tone
- reduced reflexes
anterior horn cell to muscle cell
Hierarchy of Control (3):
Strategy Level:
- goal of movement
- association areas of neocortex, basal
ganglia
Tactics Level:
- sequence of muscle contractions to
accurately achieve goal
- motor cortex, cerebellum
Execution Level:
- activation of motor and interneuron
pools to generate movement and
corrections
- brainstem, spinal cord
How Do We Start Planning a Movement?
Higher Cortical Regions
- perceptual mechanisms generate a
sensory representation of external
world and individual - posterior parietal cortex
- cognitive processes decide on course of
action - frontal lobes
- motor plan relayed to action systems to
implement - primary motor cortex
Posterior Parietal Cortex: Brodmann Area:
- area 5
- area 7
Premotor Area: Brodmann Number:
area 6
Movement: Role of the Posterior Parietal Cortex:
- input from the spinothalamic
tract/dorsal columns via the thalamus - input from visual afferents
- localises body in space
- integrates sensory and visual
information - passes on information to the premotor
area
Movement: Posterior Parietal Cortex: Damage:
- damage leads to neglect
- problem with mental image
- able to perceive but not attend to
information - eg. drawing clock but all numbers are
squashed on one side
Movement: Role of the Premotor Area:
Lateral Premotor Cortex (PMC):
- input from the posterior parietal
cortex and cerebellum
- output via descending spinal tracts
- important in movements requiring
visual guidance
Medial Supplementary Motor Area:
- input from basal ganglia and the
posterior parietal complex
- output to the primary motor
cortex/spinal cord
- involved in co-ordinating more
complex voluntary movement
Premotor Area:
Lateral Premotor Cortex (PMC):
- input from the posterior parietal
cortex and cerebellum
- output via descending spinal tracts
- important in movements requiring
visual guidance
Medial Supplementary Motor Area:
- input from basal ganglia and the
posterior parietal complex
- output to the primary motor
cortex/spinal cord
- involved in co-ordinating more
complex voluntary movement
- involved in the intention to move
Apraxia:
- inability to carry out skilled movements
in the absence of paralysis
Ideational Apraxia:
unable to put together higher sequences to perform action eg show me how to brush your hair
Ideomotor Apraxia:
unable to use tool
eg. show me show to use these scissors
Utilisation Behaviour:
lesion in the prefrontal cortex/ supplementory motor area
Motor Control of Movement:
motor regions feed in to basal ganglia and cerebellum
cerebellum into brainstem then spinal cord
then to sensory receptors
Basagl Ganglia/Nuclei:
comprises of the striatum:
- caudate nucleu, putamen, nucleus
accumbens
comprises of the globus pallidus (external
and internal which extends to midbrain as a reticular part of substantia nigra)
subthalamic nucleus
pigmented compact part of substantia nigra
Basal Ganglia: Movement:
- segregated into circuits to control
movement - circuits begin in the motor cortex
- cross basal ganglia
- return to cortex
- don’t initiate movement but involved in
control
Basal Ganglia: Motor Loops:
- direct pathway promotes activity
- indirect pathway promotes inhibition
Both the direct and indirect pathways of basal ganglia motor loops receive excitatory cortical inputs which are ——ergic
glutamatergic
Both the direct and indirect pathways of basal ganglia motor loops receive modulatory ——ergic input from the
- dopaminergic
- substantia nigra
Pathways within basal ganglia are —-ergic
GABAergic
inhibitory
Output from the basal ganglia and thalamus is tonically active but affected by
the direct and indirect motor loop pathways
Basal Ganglia: Motor Loops: Direct Pathway:
- messages from the sensorimotor cortex
stimulate the putamen and caudate
nucleus - stimulates inhibitory neurons to the
globus pallidus - the inhibitory neurons REDUCE
inhibition to the thalamus - net result is increase in activity from the
thalamus to the supplementary motor
area and back to the motor cortex - results in promotion of activity
Basal Ganglia: Motor Loops: Indirect Pathway:
- pathway activated by the supplementary
cortex - message from putamen/caudate
nucleus to globus pallidus externa is
inhibitory - message then reduces inhibitory input
to the subthalamic nucleus - this increase stimulation to the globus
pallidus interna - increases the inhibitory signal to the
thalamus therefore reducing the output
to the supplementary motor area - promotes inactivity
What is the main role of the motor loops of the basal ganglia?
to reinforce the chosen motor action
to inhibit unwanted action
Loss of inhibition from basal ganglia leads to
involuntary movements
hyperkinetic disease
eg: huntington’s disease
The cerebellum is connected to the brainstem by
the inferior and middle peduncles which are mainly afferents
the superior peduncle which is mainly efferent
All input into the cerebellum is excitatory or inhibitory?
excitatory
Cerebellar: Efferents:
- efferents from the cerebellar cortex are
from purkinje cells - inhibitory (GABA)
- project to the cerebellar nuclei
- efferents from cerebellar nuclei are
excitatory
Feedback pathway between the motor cortex and the cerebellum:
- afferents from the cerebral motor
cortex synapse in the pons with
afferents into the cerebellum - these afferents synapse with fibers in
the dentate nucleus in the cerebellum
and are excitatory - afferents to the cerebellar cortex also
stimulate purkinje fibers which inhibit
the dentate nucleus - dentate nucleus feeds back to the
cerebral cortex via the thalamus - influences motor output from the
primary motor cortex
Pathway between the Vestibular Nuclei, Cerebellum and Spinal Cord:
- balance information from the vestibular
apparatus sends afferents to the
cerebellum - efferents from the fastigial nucleus
synapse with the vestibulospinal tracts
Relationship of Reticular Nuclei and Spinal Tractss:
- afferents from pontine and medullary
reticular formations - efferents to spinal cord via reticulospinal
tracts - facilitates the extension of limbs
Tectospinal Pathway:
- originates in the superior colliculus in
the midbrain - input from visual cortex
- helps create a visual map to coordinate
eye movements and head control
descending pathway
The rubrospinal pathway activates
flexor muscles in the arms
Midline cerebellar lesions
affect trunk and axial muscles
wide based gait seen (gait ataxia)
Hemisphere cerebellar lesions cause
unilateral deficits
function on same side as lesion
nystagmus
intention tremor
