Prac Week 1 Flashcards
When was the first magnetic stimulator invented?
1980s
Is TMS good to stimulate deep structures of the brain cortex?
NO.
Can we stimulate muscles by stimulating the brain in TMS?
Yes.
How do we make sure we do not stimulate the wrong are of the brain in TMS?
A low stimulation of the peripheral area. Eventually we hone in on the “motor hotspot” based on these reactions.
What is a dual cortex approach in TMS?
Assessing the affect of stimulating two different cortex’s.
How do we inhibit behaviour in TMS?
Stimulate the inhibitory neurons.
If the smaller pulse does not result in an action potential in TMS, what does this tell us?
That we are activating an inhibitory neutron.
What are three uses of TMS?
- Assessment
- Disruption
- Modulation
Define membrane or resting potentials:
Small electrical difference between inner and outer membrane surfaces
What are nerve impulse or action potentials?
propagated changes across the membrane, unattenuated
What are local or graded potentials (postsynaptic)?
Start at postsynaptic sites, passive spread and attenuated amplitude
What are three types of electrical events?
- Membrane or resting potentials
- nerve impulse or action potentials
- local or graded potentials (postsynaptic)
A membrane is polarised. What does this mean?
That it carries a charge.
What is the resting membrane potential largely determined by?
potassium equilibrium potential (we can determine this using the Nernst equation)
What are two factors contributing to even distribution or ions (charged particles)?
- random motion (particles tend to move down their concentration gradient)
- electrostatic pressure (like charges repel, opposite charges attract)
What are two factors contributing to uneven distribution of ions?
- selective permeability (some ions pass through neuronal membrane more than others)
- sodium-potassium pumps
Is depolarisation up or down?
up (raising the membrane potential)
Is hyperpolarisation up or down?
down (lowering the membrane potential)
What is the electrical charge of the threshold of a neutron?
-65mv
What are the 3 stages of an action potential in terms of an “ionic basis”?
- depolarisation increases Na+ permeability
- continues until inactivation of Na+ channels kick in (membrane to +40 mv)
- This positive charge pushes K+ out, permeability to K+ increases -> resting potential
What does myelin do to conduction?
Speeds it up
What is sensitisation (in relation to the aplysia)?
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
What does short-term sensitisation involve?
changes in only the synaptic transmission
What does long-term sensitisation require to change aswell as synaptic transmission
Changes in gene expression.
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?
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.
