Topic 3 - Research Methods

Question 1

What do staining techniques tell you about?

Answer 1

Type / structure of cells in that area

Pathways and networking of cells

Question 2

3 stains

Answer 2

1. Axon stain
   - axons and dendrites
2. H & E stain
   - cell bodies
3. Golgi silver stain
   - entire neuron

Question 3

3 sectioning techniques

Answer 3

1. Spinalize
2. Decerebrate
3. Deafferent

Question 4

Spinalize sectioning technique

Answer 4

Cut SC just below brain stem

If fxn no longer works, it means it was happening in brain stem and above

Question 5

Decerebrate sectioning technique

Answer 5

Cut at top of brain stem

Separates higher order centers of the cerebral hemispheres from lower order structures of spinal cord and brain stem

If task no longer works, mean it was being completed by cerebral hemispheres

Cat could still walk bc cerebellum and brain stem was still in tact

Question 6

Deafferent sextioning technique

Answer 6

Cut all dorsal roots
- this removes source of somatosensory info

Ian watterman
- had to re learn how to walk and do many movements bc he had no somatosensory info

Question 7

2 types of structural brain imaging

Answer 7

1. Computerized tomography (CT)

2. Magnetic resonance imaging (MRI)

Question 8

Magnetic resonance imaging (MRI)

Answer 8

Magnetic field aligns rotation of specific molecules

Turn off mag feild causes disalignment/ degradation

Rate of degradation allows for you to know molecular composition

Composition allows to construct images

Provides images of intact & damaged structures

Question 9

PET & SPECT

Answer 9

INDIRECT AND INVASIVE

pump radioactive molecules (glucose) into blood

Highest concentration of energy released from molecules is in area of brain that is most active during a task

Measuring metabolic byproduce (indirect)

Question 10

fMRI

Answer 10

INDIRECT AND NON - INVASIVE

Works on BOLD principle
- blood oxygenation level dependant

Oxygenated blood produces a better MRI signal so active areas of the brain will take up more oxygenated blood and therefore produced stronger MRI sigal

Greatest signal is greatest activity

Question 11

EEG AND MEG

Answer 11

DIRECT AND NON-INVASIVE

record electrical or magentic activity of a large group of neurons

• wave analysis
• evoked potentials

MEG has better spatial location/resolution than EEG

Question 12

Wave analysis

Answer 12

Done with EEG or MEG

Longer period of time

Tracks frequency of oscillation shjch realtes to underlying neural activty (different frequencies when you’re awake vs asleep)

Question 13

Evoked potentials

Answer 13

Short term collection

Track transfer of information throughout brain on a millisecond basis (up to 1 sec)

Question 14

Which techniques have best spatial resolution?

Answer 14

MRI

CT

(Structural brain imaging techniques)

Question 15

Which techniques have the best temporal resolution?

Answer 15

EEG and MEG

Bc they’re direct, they don’t use a metabolic by product

Question 16

Single neuron recording

Answer 16

DIRECT AND INVASIVE

put a probe within neurons to directly record electrical activity

Highly selective
- even if you sample multiple neurons, you’re really only studying a low proportion within a region of the brain

Use rastor plots to show APs

Question 17

Difference between Transcranial Electrical Stimulation (TES) and Transcranial Magnetic Stimulation (TMS)

Answer 17

TES stimulates descending oyramidal neurons didectly (alpha motorneurons) and TMS synapses with a cortical interneuron first

Question 18

Peripheral Stimulation

Answer 18

Gives indication of integrity and excitability of the spinal circuit ans perioheral nerve

Question 19

TES

Answer 19

gives indication of integrity and excitability of contralaterak spinal motor pathway

Question 20

Cervicomeduary stimulation

Answer 20

Gives purest indication of integrity and excitability of spinal motor pathway bc the electrical current is applied to cervicomedullary jxn-> where brainstem ends and SC begins

• this is bc inhibition and excitation from cortex will not influence response in spinal motor pathway

Question 21

What has shorter latency, TES or CMS

Answer 21

CMS bc stimulus has less to travel bc with CMS stimulus is applied to cervicomedullary jxn rather than motor cortex

Question 22

TMS

Answer 22

Gives indication of integrity and excitability of entire contralateral corticospinal motor pathway

• remember corticospinal bc it activistes cortico interneurons whereas TES does not… TES directly activates pyramidsal nuerons

Question 23

Sexindary useful effects of TMS

Answer 23

1. Single pulse

Temporary brain lesion for 30-60 milliseconds
Increases neural noise which prevents area of the brain from performing purposeful activity

2. Repeitive TMS
   a. Low frequency (<1Hz) less than 1x/sec
   Decreases excitability (overall efect is inhibitory)
   b. High frequency (<5Hz) more than 5x/sec
   Increases excitability (oversll effect is excitatory)

Question 24

4 Stimulation Techniques

Answer 24

1. TES
2. CMS
3. TMS
4. Peripheral stimulation