Key concepts

Question 1

current

Answer 1

I
the rate of flow of electrons-inverse (positive flow)
amperes
flow of charge It=Q

Question 2

voltage

Answer 2

V
volts
energy required to move charge through an electrical field

Question 3

resistance

Answer 3

R
Ohms
inverse to current
resists flow of current

Question 4

capacitance

Answer 4

C
farads (F)
conductive materials with insulator between charge builds on either side
charges up until charge= that of battery

Question 5

Ohms law

Answer 5

V=IR

Question 6

R circuit

Answer 6

resistor, battery circuit

Question 7

resistors in series

Answer 7

Req= R1 + R2 + R3

Question 8

Batteries in series

Answer 8

sum of batteries in same direction

Question 9

resistors in parallel

Answer 9

1/Req= 1/R1 +1/R2 + 1/R3

Question 10

Kirschoff’s current law

Answer 10

sum of all currents at a node is zero

Question 11

Kirschoff’s voltage law

Answer 11

around loop net change in voltage is zero

Question 12

RC-circuit

Answer 12

resistor capacitor circuits

Question 13

capacitor equation

Answer 13

Q=CV

Question 14

which varies with time and which is constant?
Q=CV

Answer 14

Q and V vary
C is a contant

Question 15

relationship between I, C and V?

Answer 15

I(t) = C dV/dt

Question 16

voltage across battery

Answer 16

fixed with time

Question 17

voltage across capacitor and resistor

Answer 17

varies as a function of time

Question 18

LIF model

Answer 18

description of neuronal behaviour
2 components: leaky-integrator and firing threshold
leaky integrator- the neuron is modelled on RC circuit. Capacitor=membrane and resistor= ion channels
Tm dV/dt= -(Vm-Vrest)+ R*I(t)
basically saying that time constant (CmRm) and rate of change of membrane with respect to time = leak + input
balance between bleak and input determines dynamics
firing threshold- the neuron fires an AP when membrane potential reaches a threshold value then resets

Question 19

if LIF neuron with 0Vm and no Iinj has initial V(0). What is membrane potential after time 2T

Answer 19

Vm=V(0) e ^-t/tau
t=2T
Vm=V(0) e^-2= 0.135 volts

Question 20

LIF model firing rates

Answer 20

the rate at which the neuron generates APs in response to incoming stimuli- number of spikes generated per period of time (Hz/s). influenced by dynamics of membrane potential and threshold

Question 21

LIF input current

Answer 21

external stimuli/synaptic inputs received by neuron over time - effect firing behaviour

Question 22

F-I curves LIF model

Answer 22

the firing rate as a function of input- LIF model gives a linear relationship- which isn’t real due to refractory period

Question 23

refractroy period

Answer 23

after-hyperpolarisation
where neuron is less responsive to additional inputs

Question 24

LIF synaptic input

Answer 24

input from other neurons
excitatory and inhibitory
spatial summation- input from several neurons summates
temporal summation- input over time summates
synaptic weight- strength of connection

Question 25

Euler Method

Answer 25

Numerical solution to membrane Vm(t) updates the membrane potential at each time step, updating formula at each
V(t+change in t)= Vm(t) + dVm/dt change in time

gives underlying principle as to how ODE is solved

Question 26

basic principles governing ion flux across the membrane and how it affects Vm

Answer 26

ion channels allow ion flow across membrane
concentration gradient and electrical gradient need to balance (electrochemical gradient)
Nernst equation calculates equiblibrium potential for individual ion species
Es= RT/zF ln ([S]o/[S]i)
R=8.314 j/mol
T= Celsius + 273/15 kelvin
z= charge
F= 96,485

Question 27

resting potential

Answer 27

membrane potential when not actively receiving or transmitting current- negative around -60mV. maintained by selective permeability of ions, especially K+ and Na+/K+ pumps (3 Na+ out for 2 K+ in)

Question 28

reversal potential

Answer 28

AKA equilibrium potential
the membrane potential at which a specific ion’s net flow=0
K+~-90mV
Na+~+60
Cl-~-75
K+ has most effect on resting Vm

Question 29

IF Vm doesn’t equal reversal potential, the net current depends on

Answer 29

conc. gradient for s
membrane permeability for s
membrane potential Vm

Question 30

goldman-hodgkin-katz equation

Answer 30

takes concentration gradient and permeability for several ion to work out Vm

Vm= RT/F ln Pk[K]o/Pk[K]i+ PNa[Na]o/PNa[Na]i+Pcl[Cl]i/PCl[Cl]o

Question 31

conductance for an ions species- gs

Answer 31

the ability of a membrane to support current of s through a particular ion channel

Question 32

relationship between g and r

Answer 32

g=1/r

Question 33

ohms law for current of particular ion

Answer 33

Is=gs(Es-Vm)