The Brain, Motor Control and Senses

Question 1

Lobes of the Brain

Answer 1

Frontal
Parietal
Occipital
Temporal

Question 2

Regions of the Brain

Answer 2

Cerebrum
Diencephalon
Brainstem
Cerebellum

Question 3

• Cerebrum consists of right & left hemispheres
• Central core - diencephalon
• Cerebral hemispheres consist of cerebral cortex
• Cerebral cortex is outer shell of grey matter
• Inner part of cerebral cortex is layer of white matter
• Within grey matter are subcortical nuclei (important for movement/posture)

Answer 3

Forebrain

Question 4

• Each cortex connected by bundle of nerve fibres - corpus callosum
• Ridges - gyri
• Grooves - sulci
• Integrating area:
  
  • Basic afferent information processed
  • Control over systems that govern movement
• Cells:
  
  • Pyramidal
  • Non-pyramidal

Answer 4

Cerebrum

Question 5

Diencephalon contains and is responsible for:

Answer 5

• Thalamus - arousal, movement, attention

- Hypothalamus - neural and endocrine

Question 6

• Important centre for coordinating movements & controlling posture & balance
• Receives info from muscles, joints, eyes, skin, ears & parts of brain controlling movement
• Implicated in some forms of learning

Answer 6

Cerebellum

Question 7

• All nerve fibres that relay signals between forebrain, cerebellum and spinal cord pass through.
• Contains reticular formation:
  
  • Motor functions
  • CV, respiratory, swallowing
  • Sleep, attention, eye movement
• Receives and integrates input from all regions of CNS

Answer 7

Brainstem

Question 8

• Membranes that line the structures
• Add additional support and protection:
  * Dura mater
  * Arachnoid mater
  * Pia mater
• Function:
  * Cover & protect CNS
  * Protect blood vessels
  * Contain cerebrospinal fluid
  * Form partitions in skull

Answer 8

Meninges

Question 9

What is the Blood Brain Barrier?

Answer 9

Protective mechanism that helps maintain a stable environment for the brain.

Question 10

Motor Control Hierarchy

Answer 10

• General intention at highest level of hierarchy
• Info relayed to middle level structures
• Receive afferent information from receptors on muscle, tendon, joints, skin, etc.

Question 11

• Accompanied by a conscious awareness

- Attention directed toward purpose

Answer 11

Voluntary movement

Question 12

• Unconscious

- Automatic

Answer 12

Involuntary movement

Question 13

Sensory Receptors

Answer 13

• Mechanoreceptors
• Thermoreceptors
• Photoreceptors
• Chemoreceptors
• Nociceptors

Question 14

• Compromise 90% of spinal neurons
• Integrate information from higher centres and peripheral receptors
• Crucial for coordinating repetitive, rhythmical movements
• Can be turned on or off

Answer 14

Interneurons

Question 15

Withdrawal reflex

Answer 15

1 - Stimulus
2 - Pain detected by nociceptor and signal sent to CNS
3 - Extensor muscle relaxes due to inhibitory synapse
4 - Flexor muscle contracts due to excitatory muscle
5 - Stand up on other leg
6 - Signal sent to brain

Question 16

Stretch Reflex - Knee Jerk

Answer 16

1 - Tap
2 - Tendon pushed in
3 - Thigh muscle stretched
4 - Muscle spindle activated
5 - AP afferent neuron
6 - Excitatory synapse
7 - Thigh contracts
8 - Knee jerks

Question 17

Decreased levels of attention - EEG

Answer 17

Alpha rhythm

Question 18

Increased levels of attention - EEG

Answer 18

Beta rhythm

Question 19

Peripheral endings of afferent nerve fibers wrapped around modified muscle fibers. What does it monitor?

Answer 19

Muscle Spindle. Monitors muscle length and rate of change in length.

Question 20

Endings of afferent nerve fibers that wrap around collagen bundles in tendons. What does it monitor?

Answer 20

Golgi Tendon Organ. Tension.

Question 21

What does tension depend on?

Answer 21

• Muscle length
• Load on the muscle
• Fatigue

Question 22

• Transduction process involving opening/closing of ion channels
• Ion flux results in a change in membrane potential
• Current flows to a region where there are voltage-gated channels

Answer 22

Receptor potential

Question 23

Conversion of a stimulus into a signal that conveys the relevant information

Answer 23

Primary sensory coding

Question 24

Important characteristics for primary sensory coding

Answer 24

• Type of energy it represents
• Intensity
• Location of body it affects

Question 25

The area that when stimulated, leads to activity in a particular afferent neuron

Answer 25

Receptive field

Question 26

Stimulus location of vision, hearing and smell

Answer 26

Interpreted as outside the body

Question 27

Stimulus location coded for by…

Answer 27

Site of stimulated receptor and pathways of APs

Question 28

Factors that affect stimulus location:

Answer 28

• Size of receptive field
• Density of sensory units
• Overlap between receptive fields

Question 29

A neuron responds most vigorously when…

Answer 29

Stimulus is in middle of receptive field

Question 30

What happens when strength of stimulus increases?

Answer 30

Receptors on adjacent branches of an afferent neuron are activated, resulting in summation

Question 31

• Enables localisation of a stimulus site for some sensory systems
• Information from afferent neurons whose receptors are at the edge of a stimulus is strongly inhibited
• Enhances the contrast between the centre and periphery of stimulated region

Answer 31

Lateral inhibition