PA 10. motor brain Flashcards
key motor function of primary motor cortex
execution
key motor function of `premotor cortex
preparation of actions
key motor function of prefrontal cortex
higher level of planning
key motor function of parietal cortex
sensory-motor links
Hemiplegia
paralysis of one side
Hemiparesis
weakness of one side
M1- connections
Input from supplementary
motor area, premotor
area and primary
somatosensory area
Output to spinal cord –
control of muscles
Lateral Premotor Cortex responsible for
externally generated actions (taping to music)
Supplementary Motor Area – (medial PC) responsible for
internally generated actions e.g. well learnt
sequences
SMA in sequence learning
responsible only for most complex sequences
Prefrontal - Higher level responsible for
- Attention to action – when difficult or
learning - Longer term goals and intentions
- Not specific to action, e.g. generating
random numbers
Prefrontal Lesions
Can produce:
- Perseveration – repeat same action when
no longer relevant - Utilisation behaviour – act on irrelevant
(or inappropriate) object in environment - Disinhibition e.g. antisaccade task
- Frontal apraxia – not able to follow steps
in routine tasks (e.g. making tea)
Antisaccades
- Required to look in
opposite direction to
the target - Must inhibit (prepotent) tendency to
look at target
Normal and Shallice model
Contention scheduling – selects appropriate
schema
Supervisory attentional System (SAS) –
required for novel/less automatic actions
Explaining action errors
PRESERVATION
Utilisation beahviour
- Perseveration – unable to change
schemas when no longer appropriate - Utilisation behaviour – schemas activated
by environment without SAS suppressing
them
(cf. Cognitive failures questionnaire)
Damage to the parietal
cortex can lead to apraxia:
Inability to perform skilled
purposeful movement
Ideomotor Apraxia
idea and execution disconnected – retain
knowledge of action
* Can recognise action performed by another
* Fail in pantomiming action (e.g. body part as
tool)
* Can perform sequence but not components
Cerebellar patients
Can lead to
- Action tremor
- Dysmetria – over and undershooting of
movements - Deficits in:
– coordinating across joints
– Motor learning
– Timing
Parkinson’s disease symptom
- 1 in 1000, 1 in 100 over 65
1. Bradykinesia – slow movement
2. Tremor (resting)
3. Rigidity
Shuffling
Death of dopaminergic cells in substantia nigra
pars compacta - Internal/external – more problems with
internally generated movements - Complex movements – bimanual,
sequences - Cognitive effects – attention shifting,
everyday cognitive failures
