Brain stimulation

Question 1

What is Transcranial Electrical Stimulation?

Answer 1

Umbrella term for a series of methods that use a current source that passes through the scalp and seeing its effects

Question 2

What methods come under tES

Answer 2

Transcranial Direct Current Stimulation (tDCS)
Transcranial Alternating Current Stimulation (tACS)
Transcranial Random Noise Stimulation (tRNS)

Question 3

How do you know that the stimulation has worked?

Answer 3

Observe the behaviour

Question 4

How does TMS make muscles move?

Answer 4

By creating a quick sharp change in electric field to create action potentials

Question 5

What is the name for the muscle twitch created by TMS?

Answer 5

Motor Evoked Potential (MEP)

Question 6

What does MEP tell us about the brain?

Answer 6

How excitable the motor cortex is

Question 7

How is tES used with TMS?

Answer 7

It’s applied in between TMS to see if there’s a change in excitabillity

Question 8

How much of an increase in excitability was shown by nistche et al when applying TMS to 19 ptps?

Answer 8

1.3 size increase
Although this was only for anodal direct stim and decrease for cathodal

Question 9

Did the results of nitsche’s apply if the anode and cathode was in a different position?

Answer 9

No there was no significant effect

Question 10

What electrode was affected by the sodium and calcium blocker? what was the effect?

Answer 10

Anode - sodium abolished effect and calcium suppressed it

Question 11

What channel blocker affected the cathode?

Answer 11

DMO - NMDA inhibitor

Question 12

Why is MRS used alongside tDCS?

Answer 12

To give est. of excitatory and inhibitory neurotransmitter concentrations = GABA and glutamate

Question 13

What happened to the GABA and glutamate concentrations after stimulation shown by Stagg et al?

Answer 13

No change in glutamate but a decrease in GABA

Question 14

What do the results of Stagg et al tell us about how we get the increased MEP?

Answer 14

The excitatory we get is a result of a decrease in something that is inhibitory

Question 15

Why do you use a sham burst at the beginning and the end of the stimulation?

Answer 15

To modulate for any behaviour the ptp might have from knowing about the stimulation

Question 16

Why do we use tRNS?

Answer 16

To stop homeostasis - brain getting used to stimulation

Question 17

What two ways can tACS be used?

Answer 17

To entrain cortical rhythms so they become synched with the stimulation
To modulate - to create large bursts of oscillations and then do tasks during this

Question 18

What imaging technique is tACS used with?

Answer 18

MEG

Question 19

What is the limitation of used tACS with MEG

Answer 19

The alpha created by the stimuation and the two electrodes will drown out the signal taken from the MEG so hard to distinguish between them

Question 20

Had the use of tACS with MEG been successfully done before? how did they do it?

Answer 20

Yes, they did a SHAM paradigm and then the actual stimulation and compared
Got the same result as expected

Question 21

What is the limitation with tES

Answer 21

Limited outcome measures in humans
Unknown function of transfer from cellular to behaviour
Poorly mapped interindividual confounding factors