UNIT THREE- motor behaviour

Q1: What are the three jobs required for voluntary movement?

A1: Translate intention to perform a movement into motor control signals. Transmit motor control signals from brain to muscles. Monitor sensory information generated by movement.

Q2: What is efference?

A2: Motor control signals sent from the brain to the muscles.

Q3: Through which pathways do efference signals travel?

A3: Descending motor tracts (e.g.

Q4: What type of body organization does the motor system primarily follow?

A4: Contralateral (left brain controls right body; right brain controls left body).

Q5: Where do motor signals cross over?

A5: At the medulla.

Q6: What does the motor system need to do?

A6: Simultaneously contract and relax muscles. Convey accurately timed commands to multiple muscles. Set up and control body posture.

Q7: What is afference?

A7: All sensory information reaching the brain.

Q8: What is re-afference vs ex-afference?

A8: Re-afference: sensory info from one’s own body. Ex-afference: sensory info from the environment.

Q9: Through which pathways do afference signals travel?

A9: Ascending sensory tracts.

Q10: What type of body organization does the sensory system follow?

A10: Primarily contralateral.

Q11: What does exteroception provide?

A11: Sensory info about events in the environment (e.g.

Q12: What does proprioception provide?

A12: Sensory info about the location and movement of the body.

Proprioceptors

Q13: What do muscle spindles detect?

A13: Muscle length and muscle velocity.

Q14: What do Golgi tendon organs detect?

A14: Muscle force.

Q15: What do joint receptors detect?

A15: Joint position.

Q16: What does the vestibular apparatus detect?

A16: Head linear and angular acceleration; orientation (which way is up).

Q17: Where does unconscious proprioceptive processing occur?

A17: At lower levels of the CNS.

Q18: Where does conscious proprioceptive processing (perception) occur?

A18: At higher levels of the CNS.

Q19: Who was Ian Waterman and what was his condition?

A19: Known as “the man who lost his body”; he lost proprioception (sensory info) but retained motor nerves.

Q20: What compensatory strategy did Ian use?

A20: Used vision to guide his movements.

Q21: What was the advantage and disadvantage of this strategy?

A21: Advantage: Vision could guide movement. Disadvantage: Lost automaticity normally provided by proprioception.

Q22: What is the function of the frontal lobe?

A22: Motor control.

Q23: What is the function of the parietal lobe?

A23: Somatosensory processing.

Q24: What is the function of the occipital lobe?

A24: Vision.

Q25: What is the function of the temporal lobe?

A25: Auditory processing.

Q26: What is the function of the thalamus?

A26: Gateway to the cerebral cortex.

Q27: What is the function of the brainstem?

A27: Carries ascending sensory and descending motor tracts.

Q28: What is the function of the spinal cord?

A28: Carries motor and sensory info to/from the periphery.

Q29: What separates the frontal and parietal lobes?

A29: The central sulcus.

Q30: Which cortex lies on the frontal side of the central sulcus?

A30: Primary motor cortex.

Q31: Which cortex lies on the parietal side of the central sulcus?

A31: Primary somatosensory cortex.

Q32: What is the descending motor pathway sequence?

A32: Cerebral cortex (motor) → thalamus → brainstem → spinal cord → muscles → movement.

Q33: What is the ascending sensory pathway sequence?

A33: Movement → proprioceptors → spinal cord → brainstem → thalamus → cerebral cortex (somatosensory).

Somatotopic Organization

Q34: What is somatotopic organization?

A34: A specific location on the cortex corresponds to a specific body region (for both motor and sensory).

Q35: Is somatotopic representation fixed?

A35: No

Q36: What is feedback information in motor control?

A36: Info from sensory receptors returned to a reference of correctness for comparison with the desired state.

Q37: What are the advantages of feedback?

A37: Redundant systems—if one source fails

Q38: What are the disadvantages of feedback?

A38: Sensory conflict—may rely on the wrong source.

Q39: What is feedforward information?

A39: Info sent ahead of time to prepare the system for events.

Q40: Example of feedforward?

A40: In a reaction-time task (hear tone

Q41: What characterizes open-loop control?

A41:Pre-programmed instructions sent to effector. No feedback or error detection. Used for very rapid/discrete skills.

Q42: What characterizes closed-loop control?

A42:Uses feedback

Q43: What is efference copy?

A43: Duplicate of motor commands sent to the reference of correctness to compare desired vs actual state.

Q44: What brain structure acts as the reference of correctness?

A44: The cerebellum.