Neurophysiology Flashcards
What are the 4 controls of the Nervous System?
- Control of internal environment
- Voluntary control of movement
- Programming of spinal cord reflexes
- Assimilation of experiences necessary for memory and learning
Define
degrees of freedom:
Motor equivalence:
How many degrees of freedom does the shoulder have?
- the number of parameters of the system that may vary independently(simple terms: how many things can change - making a complex thing relatively simple and easier to control)
- the ability to carry out a task in a different way by gain the same outcome, e.g.: writing with a pencil in between your teeth and have the same handwriting. This is done by freezing degrees of freedom
○ Shoulder has 3 degrees of freedom: movement up, down and twist
Why do we freeze the DF when learning a new skill?
- To reduce the number of possibilities for movement
- Increase control
- This reduces the likelihood of the performance method affecting the person reaching the skill goal, which simplifies the control.
- Not a clear understanding to whether this is the correct method to use when learning a skill
Define the Humoral mechanism:
when the bulk flow of liquids in an animal is through convection and diffusion
○ A difference of potentials is made by the movement of Cl- and Na+ to the other sides of the membrane(tiny fraction not balanced)
What are Bernstein’s stages of motor learning?
- Stage 1: Freezing the degrees of freedom
–> goal: minimise variability(e.g.: freezing the shoulder for a gun shot)
○ Coupling the body parts reduces the number of options of how to move
○ Not optimal technique, only happens early in skill acquisition - Stage 2: Releasing and reorganising
–> goal: minimise variability of the pistol tip
–> skilled: increase variability of individual joint motions
○ increased degrees of freedom than the start amount - Stage 3: Exploiting mechanical properties (e.g.: golf swing, effective skills make good use of mechanical properties)
not applicable to all joints + the joint range of motion is not 0 at the beginning of learning - Values of 1 & -1 show a coupling or dependency between joints
- 1 = joints move in phase
- -1 = joints move out of phase
- 0 = joint independence
- Task type and task objectives, can influence the freezing of degrees of freedom. The coordination pattern made depends on the task constraints
Define:
Motor program
Motor program - “an abstract representation, that when initiated results in the production of a coordinated movement sequence”(Schmidt)
What are the levels to the Nervous System?
What direction are nerve impulses sent through the:
- afferent
- efferent
CNS –> Peripheral NS
Peripheral NS to both (afferent/sensory & efferent/motor)
efferent to both (somatic/skeletal & autonomic/involuntary)
Afferent - sensory info towards the NS
Efferent - takes info to effectors
Neuron:
What is contained in the soma?
What is the dendrites role?
What is the role of myelin?
What is the axon hillock dense in?
What is a group of axons called?
What are Schwann cells?
- mitochondria
- initiate the activation of new neurons
- speeds up the action potential movement
- sodium channels
- neural tracts/nerves
- contain large amounts of lipid protein substance called myelin innervating skeletal muscle
Describe an action potential:
How does it work?
What is a transmembrane potential?
The change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell
* when the depolarisation of the neuron membrane reaches a “threshold” value an AP is formed
- Transmembrane potential is the difference between the outside and inside of the membrane
What are the factors crucial for the propagation of an action potential?
- Inactivation of sodium channels just after an action potential, leading to the absolute refractory period within the membrane
- Different densities of sodium channels at different sections of the membrane
- The action potential can only move in one direction, after exciting site 1 - 2 cannot re-excite site 1
- The thicker the fibres the higher the velocity of the action potential
What is the resting potential of the neuron?
What is a Rheobase?
- -70mV - the higher conductance of Cl- ions as compared to the conductance of K+/Na+
- Rheobase - the strength a stimulus must be, even with an increase in duration an action potential cannot be stimulated
How is the resting potential determined?
- The permeability of the membrane to different ions
- The difference in concentrations between the intracellular and extracellular ions
How is the threshold stimulated?
- Rapid rush of sodium when gate opens is the action potential
- The depolarisation are known as excitatory post-synaptic potentials(EPSPs), which is reached by temporal/spatial summation
Identify the 3 parts in synaptic transmission:
- Presynaptic membrane - transmits information coded by a sequence of action potentials
- Postsynaptic membrane - the cell receiving information
- Synaptic cleft - the gap between the pre and post synaptic neurons
What are the 2 groups of synapses?
- Obligatory - action potential on the presynaptic membrane that always gives rise to an action potential on the postsynaptic membrane e.g.: neural cells and muscle cells
- Non-obligatory - an action potential on the presynaptic membrane that is typically unable to induce and action potential on the postsynaptic membrane
