Prac Week 1

Question 1

When was the first magnetic stimulator invented?

Answer 1

1980s

Question 2

Is TMS good to stimulate deep structures of the brain cortex?

Answer 2

NO.

Question 3

Can we stimulate muscles by stimulating the brain in TMS?

Answer 3

Yes.

Question 4

How do we make sure we do not stimulate the wrong are of the brain in TMS?

Answer 4

A low stimulation of the peripheral area. Eventually we hone in on the “motor hotspot” based on these reactions.

Question 5

What is a dual cortex approach in TMS?

Answer 5

Assessing the affect of stimulating two different cortex’s.

Question 6

How do we inhibit behaviour in TMS?

Answer 6

Stimulate the inhibitory neurons.

Question 7

If the smaller pulse does not result in an action potential in TMS, what does this tell us?

Answer 7

That we are activating an inhibitory neutron.

Question 8

What are three uses of TMS?

Answer 8

1. Assessment
2. Disruption
3. Modulation

Question 9

Define membrane or resting potentials:

Answer 9

Small electrical difference between inner and outer membrane surfaces

Question 10

What are nerve impulse or action potentials?

Answer 10

propagated changes across the membrane, unattenuated

Question 11

What are local or graded potentials (postsynaptic)?

Answer 11

Start at postsynaptic sites, passive spread and attenuated amplitude

Question 12

What are three types of electrical events?

Answer 12

1. Membrane or resting potentials
2. nerve impulse or action potentials
3. local or graded potentials (postsynaptic)

Question 13

A membrane is polarised. What does this mean?

Answer 13

That it carries a charge.

Question 14

What is the resting membrane potential largely determined by?

Answer 14

potassium equilibrium potential (we can determine this using the Nernst equation)

Question 15

What are two factors contributing to even distribution or ions (charged particles)?

Answer 15

1. random motion (particles tend to move down their concentration gradient)
2. electrostatic pressure (like charges repel, opposite charges attract)

Question 16

What are two factors contributing to uneven distribution of ions?

Answer 16

1. selective permeability (some ions pass through neuronal membrane more than others)
2. sodium-potassium pumps

Question 17

Is depolarisation up or down?

Answer 17

up (raising the membrane potential)

Question 18

Is hyperpolarisation up or down?

Answer 18

down (lowering the membrane potential)

Question 19

What is the electrical charge of the threshold of a neutron?

Answer 19

-65mv

Question 20

What are the 3 stages of an action potential in terms of an “ionic basis”?

Answer 20

1. depolarisation increases Na+ permeability
2. continues until inactivation of Na+ channels kick in (membrane to +40 mv)
3. This positive charge pushes K+ out, permeability to K+ increases -> resting potential

Question 21

What does myelin do to conduction?

Answer 21

Speeds it up

Question 22

What is sensitisation (in relation to the aplysia)?

Answer 22

sensitisation is where touching of the siphon is paired with a strong electrical stimulus to the animals tail, eliciting a strong withdrawal of the gill) This can last days or weeks

Question 23

What does short-term sensitisation involve?

Answer 23

changes in only the synaptic transmission

Question 24

What does long-term sensitisation require to change aswell as synaptic transmission

Answer 24

Changes in gene expression.

Question 25

In the phantom limb case, why is it that he feels his fingers when his face is touched? And how is this an example of neural plasticity?

Answer 25

Because the sensory cortex is organised into categories of body parts, when one section is not receiving any sensory information (the arm), the sensory neurons which are next to that body part (the face) are invaded with information.