Week 1: neural intro

Week 1: neural intro

1. understanding brains control of movement = movement centered view of brain. the reason the brain does anything, is it interact with the environment.

   • all our interactions with the environment are through movement

2. hands = unique ability to hold and manipulate objects.

   • specialised animals = woodpecker spongy skull to hit wood. Humans = general specialists as we can manipulate tools to specialise in a variety to tasks.
   • planning: crows bend stick for reward, humans can resists immediate reward for later and greater gain

3. psychological aspects of movement: sensory = lose sense, lose movement. feedback based system on sensations. Learning and memory (riding a bike). Action perception (observing and applying to own system)

   • Learning systems: CORTEX- relationships BASAL GANGLIA = reward and reinforcement. CEREBELLUM = learning through error
     • motor planning: Extrinsic task goals - hand path - hand trajectory - joint kinematics - muscle activation - neural commands
       • planning choices: duration, path, muscle activity, velocity, joint angles, neural firing pattern
   • motor psychophysics = keep the stimulus the same and vary the responses. analyse the complex responses. The CNS must make a decision in every movement, planning choices.

4. motor invariants = very stereotyped behaviour. choosing our movements on a rule to be consistent

   • movements to minimise the cost: MINIMUM JERK = smooth movement MINIMUM TORQUE = stable level of force MINIMUM VARIANCE = high consistency
     • purpose of CNS = to move, produce adaptable and complex movement. Sea squirt digests CNS when found a place to rest.

5. action potential: resting potential > Excitation > Threshold > stereotyped response > Opening channels > sodium or potassium

   • sodium = fast permeability, Potassium = slow change of permeability

6. neuromuscular junction = special type of synapse. ALPHA MOTOR NEURONS can innervate different muscle fibres

   • when an alpha motor neuron fires it causes a twitch/ contraction of the muscle.
     • motor unit = motor neuron and all the fibres it innervates. motor unit pool = multiple motor units = stronger connections
       • fused tetanic connections = using and contracting all possible muscle fibres, strongest response. Unfused teanic contraction = not all at full potential
   • TYPE 1 - slow twitch fibres = little force for long time TYPE 2 - fast twitch fibres = lot of force for short time
     • can be adapted e.g. weight lifters and distance runners

7. Measuring nerve activity: EEG/MEG = electrical signals from scalp, EMG = through skin.

   • EMG= electromyography. invasive into muscle, can record individual activity
   • can correlate single cell activity to behaviour, plotted on Raster plots
     • raster plots show individual trials of each action potential in response to a stimulus. An average of all trials shown in a histogram underneath

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