sensorimotor integration

Question 1

why do we have brains

Answer 1

animals have evolved brains to generate meaningful movemnet [behaviour]

Question 2

the minimal unit of sensorimotor integration the monosynaptic stretch reflexes

how is the sensory info used to generate behaviours

Answer 2

1. Stretch of the mechanoreceptors in the muscle increase firing rate of the afferent sensory neuron.
2. Increased neurotransmitter release activates the motor neuron.
3. Contraction of biceps muscle.

Question 3

behaviour in an ever-changing world?

what is the role of the brain in sensorimotor integration?

Answer 3

Meaningful behaviour requires sensorimotor integration.

• Selecting an appropriate behaviour will depend on:
  
  • Context
  • Internal state
  • Stage in life
  • Prior experience (memory)
  • Current sensory information

Question 4

1. seeing the tennis ball

how does the brain and muscle generate the behaviour? [tennis]

Answer 4

• Cones in the fovea detect the light reflecting from the tennis ball.
• Photoreceptors transduce the light stimulation into neural activity.
• Ganglion cells, convey visual information to the brain.

Question 5

2.tracking the tennis ball: saccased and visual attention - visual attention and saccades

Answer 5

• The content of a subject’s visual attention can be traced from the course of that person’s saccades.
• Neurons in the posterior parietal cortex fire more vigorously when the visual stimulus are the target of saccades.
• Lesions on the posterior parietal region cause attentional deficits in humans (e.g.,spatial neglect).

Kandel et al., 5th Ed.

Question 6

2.tracking the tennis ball: saccased and visual attention - eye saccades

Answer 6

the saccade system keeps the image of the ball in the fovea, where vision is more accurate
- Superior colliculus performs visuomotorintegration.
- This region forms a map of potential eye movement. Each neuron within the map fires before the eyes move to the corresponding location in that map.
- Movement-related neurons: fire before saccades to specific locations.
- Visual-fixation neurons: fire after the saccade, inhibiting movements away from the target.

Question 7

eye saccades

Tracking the tennis ball: saccades and visual attention

Answer 7

the caudate nucleus inhibit the tonic inhibition of the substantial nigra pars reticulata [disinhibition], which allows the superior colliculus neurons to fire and produce a saccade

Question 8

two pathways in the integration of visual information

Tracking the tennis ball: saccades and visual attention

Answer 8

1. geniculostriate pathway
2. tectopulvinar pathway

Question 9

geniculostriate pathway

Tracking the tennis ball: saccades and visual attention

Answer 9

• perception of motion and depth by the dorsal visual stream [how]
• perception of contrasts, contour and colour by the ventral visual pathway [what]

Question 10

tectopulvinar pathway

Tracking the tennis ball: saccades and visual attention

Answer 10

perception of the court by the pulvinar pathway [where]

Question 11

trajectory projection: integration of information over time

Tracking the tennis ball: saccades and visual attention

Answer 11

• The prior information about where the ball is likely to bounce is from experience(memory).
• Sensorial integration produce a likelihood of where the ball will bounce.
• Using both the prior and the likelihood the brain estimates the bounce and produce behaviour.

Question 12

movement control by basal ganglia

action!!

Answer 12

• Oculomotor loop controlling eyemovement and tracking of the tennis ball.
• Skeletomotor loop control voluntary movements.

Question 13

basal ganglia are involved in :

action!!

Answer 13

• action selection (as seen for the saccades before)
• Initiation and terminating actions.
• Relating actions with consequences.

Question 14

reaching and hitting the ball

action!!

Answer 14

• The “motor homunculus” maps the areas of the motor cortex responsible for moving each part of the body.
• Specific sections of the motor cortex will be active at different stages on the approach, racquet swing and ball hitting.

Question 15

muscle contraction: neuromuscular junction

action!!

Answer 15

Acetylcholine release by the motor neuron axon terminal will contract fibers in the target muscle

Question 16

what is the waitress task

Answer 16

1. Hold a heavy book with your right hand horizontally in front of your chest (as a waitress holds a full tray).
2. Your task is to keep your right hand still.
3. Trial 1: lift the book with your left hand. Did your right hand move?
4. Trial 2: ask your friend to lift the book from your hand. What happened to your right hand?