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Questions and Answers
What is primarily involved in the conversion of mental images of intended actions into motor execution?
What is primarily involved in the conversion of mental images of intended actions into motor execution?
- Subthalamic nucleus
- Cerebellum
- Left parietal hub (correct)
- Right occipital cortex
Which region of the brain has shown activity in response to recognizing actions associated with object use?
Which region of the brain has shown activity in response to recognizing actions associated with object use?
- Lateral geniculate nucleus
- Anterior cingulate cortex
- Inferior parietal lobule (correct)
- Entorhinal cortex
What term describes the learned skilled movements that are essential for effective praxis?
What term describes the learned skilled movements that are essential for effective praxis?
- Cognitive action maps
- Visuokinesthetic motor engrams (correct)
- Motor schemas
- Praxis patterns
Which function does action semantics primarily serve in the context of tool use?
Which function does action semantics primarily serve in the context of tool use?
Which area of the brain is involved in the translation of movement formulas into motor programs?
Which area of the brain is involved in the translation of movement formulas into motor programs?
In addition to movement formulas, what other elements are considered crucial in models of praxis?
In addition to movement formulas, what other elements are considered crucial in models of praxis?
What is the role of the left parietal sub-regions in the context of motor control?
What is the role of the left parietal sub-regions in the context of motor control?
Which of the following modalities can activate spatiotemporal movement formulas?
Which of the following modalities can activate spatiotemporal movement formulas?
What is the primary function of the SMA in the context of movement?
What is the primary function of the SMA in the context of movement?
Which brain area is primarily associated with the sequencing of multiple arm and hand movements?
Which brain area is primarily associated with the sequencing of multiple arm and hand movements?
What pathway does the brain use to convey motor programs for ipsilateral movements?
What pathway does the brain use to convey motor programs for ipsilateral movements?
Which area of the brain shows more activity during action imagery compared to the right hemisphere?
Which area of the brain shows more activity during action imagery compared to the right hemisphere?
Which of the following brain regions is associated with proximal limb control representations?
Which of the following brain regions is associated with proximal limb control representations?
Which factors contribute to the occurrence of apraxia according to this model?
Which factors contribute to the occurrence of apraxia according to this model?
What role do both parietal regions play in upper-extremity movements?
What role do both parietal regions play in upper-extremity movements?
When are the right parietal regions more active compared to the left during gestural tasks?
When are the right parietal regions more active compared to the left during gestural tasks?
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Study Notes
Models of Apraxia
- Most models of praxis include a left parietal hub with connections to anterior motor areas.
- This hub plays a central role in learning and converting mental images of intended action into motor execution.
- Spatiotemporal movement formulas, also known as praxicons or visuokinesthetic motor engrams, are necessary for learned skilled movements.
Spatiotemporal Movement Formulas
- These formulas can be activated by multiple input modalities, including visual, verbal-auditory, and tactile.
- Cells in the inferior parietal lobule fire selectively in response to hand movements, visually presented information about object size and shape, or the actual manipulation of objects.
- Functional neuroimaging studies show activity in this region in response to recognition of actions associated with object or tool use (transitive actions).
Left Parietal Region
- This region appears to contain action semantics and conceptual systems such as tool action, tool–object association information, and general principles of tool use.
- Action semantics specify knowledge of tool action (e.g. turning, pounding) and the knowledge of which tool or object to use for a task.
Motor Programs
- The premotor region, specifically the supplementary motor area (SMA), translates movement formulas into motor programs.
- The SMA receives projections from parietal neurons and projects axons to motor neurons in the primary motor cortex.
- Motor programs are then sent to activate the motor neurons, resulting in movement of the contralateral extremity in the prescribed spatial trajectory and timing.
Additional Regions Involved in Praxis
- Prefrontal cortex: participates in sequencing multiple arm, hand, and finger movements.
- Right hemisphere: involved in apraxia, especially in distal limb control areas.
- Basal ganglia (putamen and globus pallidus), thalamus, and their white-matter connections: also play a role in apraxia.
Bilateral Control and Imitation
- Bilateral inferior frontal gyri are associated with proximal limb control representations for both limbs.
- Distal limb control areas are generally left-lateralized for both limbs.
- Both parietal regions participate in the integration of visual information and upper-extremity movement, and in performing nonpurposeful movements.
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