Action selection in health science Flashcards
what is computational neuroscience
mathematical modelling of core features of cells, circuits, and neural networks
how is computational neuroscience used
to develop predictions and test hypotheses
how is animal movement described as action sequences
hierarchial
serially organised (reactions occur together and converge)
what does the central complex contain
protocerebral bridge (pb)
fan shaped body (fb)
ellipsoid body (ep)
noduli (no)
how is EB neuron firing measured
picrotoxin (triggers inhibitory GABAergic neurons)
sum of net output = increased firing rate
what core features of neurons can be mathematically modelled
potassium current
leakage current
membrane potential
gates
sodium current
what does an action potential resemble
sine wave (idealised)/rotating phasor
what is an action potential
membrane potential/time
what is circular frequency equal to
angular velocity (w)
period defines frequency
w = 2pi/T
what is frequency
number of cycles per second (Hz)
1/T
what does many APs mean
many quasi-periodic rotating phasors
many sine waves (resembles neural activities within a circuit)
what is the fourier transform
idealised sine waves integrate
which domains are involved
time domain s(t) is converted into a frequency domain s(w)
role of the sinusoidal functions
defines circuit/neural activity
types of neural activity
periodic
aperiodic
neural activity is often aperiodic
what happens to rotating behaviour
coalesce in the centre
each 360 turn in the phase space = burst of a neuron
what is the attractor
trajectory/point in a phase space to which the system will converge from a set of initial coordinates
features of neural circuits
-non linear systems may have one or more attractor
-operate near instability for rapid response
-dynamic systems
lorenz attractor
open, non-equilibrium systems are dynamic, non-linear phase transitions of attractor states
types of attractors
-periodic
-quasi periodic
-chaos
what is action selection
coordinates motor actions and their organisation into action sequences by facilitating appropriate motor programmes while inhibiting competing ones
(right thing at the right time)
BG direct pathway
(D1)
striatum
–> GPi/Snr
–> Thalamus
BG indirect pathway
(D2)
striatum
–> GPe
–> STN
–> GPi/Snr
–> thalamus
what forms the striatum
caudate nucleus + putamen
channelrhodopsin and optogenetics experiment
Kravitz et al., 2010
D1 laser on:
mouse running, direct pathway facilitates movement
D2 laser on:
Indirect pathway inhibits unwanted movement
how is action selection coordinated by the direct and indirect pathway
both pathways activated at the same time
different from accelerator and break model
examples of impaired action selection
-dyskinesia
-motor neuron disease
-PD
-FTD (fronto-temporal dementia - unwanted behaviour)
BG dysfunction pathological manifestations
motor abnormalities
impaired memory formation
attention deficits
affective disorders
sleep disturbances
PD
loss of DA neurons in substantia nigra pars compacta
causes tremor, rigidity, bradykinesia and sleep disturbances (non-motor symptom)
what is parkinsonism
induced oscillations resonate across BG networks with focal entrainment of STN, GPe and SNr
regions involved in action selection
vertebrate basal ganglia
arthopod central complex
central complex direct pathway
(D1)
pb/fb
mEB
gall
dEB/LAL
LAL
what are EB ring neurons involved in
feature detection
role of EB layers and hemisphere divisions
reciprocal inhibtion of networks
selection and switching in EB
R-neuron circuitry mediate salience detection by winner take all functionality, selection of only one active module/wedge. It allows selection between activity states
(strongest signal wins)
maintenance in EB
lateral inhibition can maintain selected activity after input changes
parkinsonism in drosophila
loss of DA-EB-LAL pathway
is conserved
how is action selection achieved
competing activity of direct and indirect pathway in BG
neural activity of EB ring neurons
