CPG organisation and pacemakers Flashcards
what does CPG stand for
central pattern generator
where is CPG locotion
throughout NS but mostly in spinal cord
what are CPGs
network of neurons which generate a range of rhythmic movements
what are 4 factors which determine CPG output
intrinsic properties
synaptic connectivity
properties of synapses
neuromodulation
what are intrinsic properties
individual neurons in network (ion channels and neurotransmitter expression) determine their output
what are two factors which are reflected by CPG rhythmicity
oscillating networks
endogenous bursters
what are oscillating networks
simple network of neurons which generate activity of time dependent processes exist to enhance or reduce activity of neurons
what do oscillating networks utilise?
the half centre hypothesis of inhibition
what is the main driver of half centre hypothesis
reciprocal inhibition and fatigue
what are endogenous bursters
pacemaker cells
capacity to burst spontaneously
what are the three stages of rhythmic pacemaker activity
initiation - depolarisation
maintenance
termination
what are the three channels involved in initiation of depolarising phase
hyperpolarisation activated inward current (h)
low voltage activated calcium currents (ILVA)
transient potassium current (Ia)
what is the main feature of a h channel
mixed cationic ions flow (k and na)
causes depolarisation if the membrane is depolarised
what is the main feature of ILVA channels
inactivating (transient) calcium currents activated at low voltages
how do we remove inactivation caused from ILVA channels
hyperpolarisation needed
