L7 - techniques - electrophysiology and functional imaging

Question 1

intracellular electrophysiology used to study….

Answer 1

electrical activity in single cells

Question 2

extracellular electrophysiology used to study…

Answer 2

electrical activity from groups of cells in one anatomical location

Question 3

functional Ca2+ imaging used to study…

Answer 3

electrical activity from groups of cells in a larger anatomical area

Question 4

electrophysiology

Answer 4

measures electrical activity (membrane potential) in biological tissue

Question 5

membrane potential

Answer 5

potential difference between an electrode inside a cell and an electrode outside a cell

Question 6

intracellular component is ….. charged compared to extracellular

Answer 6

negatively

Question 7

what causes difference in intra/extra-cellular charges

Answer 7

difference in K+ concentration

Question 8

K+ is more concentrated….

Answer 8

inside cell

Question 9

K+ leak channels

Answer 9

allow K+ to flow freely across membrane and leave cell

therfore inside is more -ve

Question 10

what creates equilibrium

Answer 10

chemical and electrical gradients in opposing directions

Question 11

3 different methods of preparation for measuring neuronal electrical changes

Answer 11

1. dissociated neuronal culture
2. acute brain slices
3. whole animal

Question 12

dissociated neuronal culture

Answer 12

take neurons from embryo and dissociate into parts

plate on cover slips so they grow into networks

Question 13

action potentials require cells to have….

Answer 13

negative resting membrane potential

Question 14

example of wide diversity in shapes of action potentials

Answer 14

purkinje neuron AP very tall steep thin

dopamine neuron more like a hump

Question 15

features of hippocampal CA1 pyramidal neurons

Answer 15

glutamatergic

longer AP

Question 16

features of O-LM interneuronsq

Answer 16

GABAergic

shorter AP

Question 17

what are phase plane plots for

Answer 17

give information on max rate of rise and max rate of fall of action potential
and AP peak

Question 18

calculations of rate of rise/fall

Answer 18

dv/dt

Question 19

what determines the peak of the AP

Answer 19

Na+/K+ currents

Question 20

how do you measure ionic currents

Answer 20

using voltage clamps

Question 21

what mediates ionic currents

Answer 21

channels

Question 22

single channel recordings open/close …

Answer 22

stochastically

Question 23

V1/2 activation

Answer 23

size of current against test potential

Question 24

expressing a-subunit with B-subunit causes….

x2

Answer 24

• shift in voltage dependance of Na+ currents

- a-subunits form pore for Na+ channel

Question 25

rebound event

Answer 25

cell is pushed back towards resting membrane potential

Question 26

AHP

Answer 26

after-hyperpolarisation

Question 27

large AHP

Answer 27

high frequency firing

Question 28

3 states of channels

Answer 28

resting activated inactivated

Question 29

channel in resting state

Answer 29

closed ability to open -ve potential

Question 30

channel in activated state

Answer 30

open depolarised inward current

Question 31

channel in closed state

Answer 31

unable to open | recovering from activation

Question 32

why can interneurons fire more quickly

Answer 32

they recover more quickly

Question 33

recovery time from activation requires .... | x2

Answer 33

time | -ve membrane potential

Question 34

when does high frequency burst firing occur

Answer 34

if after-depolarising hump is big enough it will reach threshold potential another AP can be initiated

Question 35

Kv3 subtypes expressed by interneurons

Answer 35

produce large post-spike AHP | this allows fast repolarisation and quick recovery

Question 36

are firing patterns fixed?

Answer 36

no

Question 37

what modulates firing patterns

Answer 37

``` membrane potential developmental stage disease - channelopathies pharmacological agents synaptic actiivty intrinsic activity - affected by neurotransmitters ```

Question 38

EPSP

Answer 38

excitatory post synaptic potential