Lecture 1 - Introduction

Question 1

Vision action cycle

Answer 1

• Vision for perception = features of objects such as colour, size, shape
• Vision for action = processing needed to guide movement e.g. catching a ball

Question 2

Sensory-motor system

Answer 2

• Senses shape and regulate movement
• Nerves = electrochemical signalling devices
• CNS regulates sensory systems
• Important part of cognition and influencing how you see world
• Senses shape and regulate movement
• Motor system changes you sense
• Innate loop

Question 3

Why understand vision and movement?

Answer 3

• All intentional interactions with environment done through movement
• All actions and behaviours start with sensation of stimulus and end with muscle movement
• These actions effect future perceptions producing a perception-action loop
• Understand of movement control gives understanding of the whole nervous system and cognitive process
• 1/3 cortex devoted to vision
• Experience world through perception filtered = alter way we sense world through altering receptions = need to have control over sensory apparatus

Question 4

What is special about human movement

Answer 4

Hands:

• Uniquely able to hold and manipulate objects
• Have strong opposable thumbs
• Have flexible and powerful grip
• Have evolved to become tool users
• Tool use has allowed us to be “general specialists’

Planning:

• Ability to resist to immediate reaction responses
• Able to plan ahead
• Use flexible rules

Question 5

Motor psychophysics

Answer 5

• Traditional sensory psychophysics = vary stimulus and record simple physiological response e.g. pupil dilation
• Motor psychophysics = keep stimulus simple and look for regular features of complex movement e.g. vary response parameters
• Planning choices = CNS much make decision in almost every movement

Question 6

Motor invariants

Answer 6

• Humans show highly stereotypes trajectories foe eye and arm movement
• E.g. path = sequence of positions of hand in space and velocity - time sequence along a path
• Some variability between pathways but all reach same end goal

Question 7

Neuronal processing

Answer 7

• Nemotade worm = 302 neurons so scientists can map all neurons and connection
• Humans = 100 billion neurons and 100 trillion synapse
• Too many to map out so have to use psychophysics to understand what broad groups of neurons are doing

Question 8

Synapse

Answer 8

• Pre-synaptic action potential increase membrane potential
• Influx of calcium
• Release of vesicle containing NT
• Bind to post-synaptic receptors
• Generation of PSP
• Single action potential unlikely to produce response in cell, usually need thousands of AP = exception is NMJ

Question 9

Neuromuscular junction (NMJ)

Answer 9

• Complex synapse between nerve and muscle
• Alpha motor neurons connect to muscles
• Axons that go from spinal cord to muscle fibres
• When alpha neurone fires = excited muscle fibres = muscle contracts = action
• One neurone connects to several fibres at once
• Single AP will cause muscle to contract
• Post-synaptic membrane = heavily folded = large SA = many receptors = when NT defuses across cleft = many PSR = muscle twitch
• Single AP will cause twitch

Question 10

Motor unit

Answer 10

• Motor unit = single motor neurons and all muscle fibres it activates
• To produce force = lots of AP in short time
• Fused tetanic contraction = AP arriving so frequently can no longer see twitches = see continuous line

Question 11

Different types of muscle fibres

Answer 11

Slow twitch fibres

• Type 1
• Small force
• Dont fatigue easily
• Long distance runner will have lots

Fast twitch fibres

• Type 2
• Strong amounts of force
• Cant maintain due to fatigue
• Sprinter would have lots

Muscle made up of combination = size principle = at lower forces recruit slow twitch fibres

Question 12

Can you record and measure nerve activity?

Answer 12

• Single neurones = rare in humans = can record peripheral nerves and occasionally during brain surgery
• Can easily record electrical discharge of single muscles through skin = EMG
• Can record electrical discharge or large populations of neurons through the scalp (EEG and MEG)
• Can detect some chemical signals - calcium, NT = with PET imaging or invasive methods

Question 13

Non-invasive methods of testing

Answer 13

• Electroencephalography (EEG)
• Magnetoencephalography (MEG)
• fMRI, PET, fNIRS

Question 14

Invasive methods of testing

Answer 14

• Microneurography

- Surgical patients