5) Methods 1 (TMS)

Question 1

What are Cytoarchitectonics?

Answer 1

An anatomical method based on segmenting the brain according to its appearance under a microscope

Question 2

What do Cytoarchitectonics do?

Answer 2

Looks at differences between layers, not cell type

Question 3

What affects how the cortisol tissue appears in the microscope?

Answer 3

Staining

Question 4

What 3 things do cytoarchitectonic features of the brain correspond with?

Answer 4

Main function
Output from the brain for motor cortex
Input to the brain for somatosensory cortex

Question 5

What are the 2 features of the motor cortex according to cytoarchitectonic’s?

Answer 5

Thin layer 4 (input)
Wide layer 5 (output)

Question 6

What are the 2 features of the somatosensory cortex according to cytoarchitectonic’s?

Answer 6

Wide layer 4 (input)
Thin layer 5 (output)

Question 7

What does the Primary cortical area suggest?

Answer 7

Simplified view that these areas are directly connected to the periphery and other cortical areas are not

Question 8

What 2 advantages does Transcranial magnetic stimulation (TMS) have?

Answer 8

Millisecond temporal resolution
Can resolve within cortical maps

Question 9

What is a disadvantage of TMS?

Answer 9

Can only be applied to a single location at any point in time

Question 10

What does TMS allow for when studying the brain cortex?

Answer 10

Non-invasive, painless and safe stimulation

Question 11

What are 3 key features of TMS methods?

Answer 11

-Studies behaviour during experimentally controlled ‘virtual’ brain lesions (fully reversible)
-Chronometry (time measurement) in brain activation
-Functional connectivity

Question 12

What is the process of TMS outside the brain?

Answer 12

-A circular coil (stimulator) is placed above the scalp
-A brief pulse of electrical current is fed through the coil
-A magnetic field arises with flux lines perpendicular to the plane of the coil

Question 13

What happens with TMS inside the brain?

Answer 13

-The magnetic field induces an electric field of direction perpendicular to the magnetic field

-This electrical field leads to neuronal excitation in brain tissue

Question 14

What does the TMS activate in the motor cortex?

Answer 14

Corticospinal neurons

Question 15

What is found in relaxed target muscles?

Answer 15

Motor evoked potentials start from 20ms post TMS

Question 16

What is typically found in a contracted target muscle?

Answer 16

A silent period of 150ms after TMS to motor cortex

Question 17

What was shown in TMS stimulation of the occipital cortex?

Answer 17

Inhibitory effects can occur as ppts reported suppression of motion perception

Question 18

What occurs in auditory cortex stimulation?

Answer 18

Interpretation of results is challenging as the TMS stimulus is accompanied by a loud coil click

Question 19

What 3 ways are effects of TMS potentially measured?

Answer 19

-As peripheral responses
-Impaired/altered perception
-Improved/impaired task performance

Question 20

What is an example of cross modal plasticity?

Answer 20

Reading braille as it activates a blind person’s occipital cortex

Question 21

What did Cohen et al (1997) find out about occipital cortex activation in blind ppts?

Answer 21

The occipital cortex is essential to early blind ppts but not to sighted ppts performance, so indicates cortical plasticity.

Question 22

What are 3 further advantages of using TMS as a method?

Answer 22

-Repeated studies in same subject
-Short duration reduces risk of plasticity
-Studies double dissociations

Question 23

What are double dissociations?

Answer 23

Stimulate or temporarily disrupt different cortical regions during one task, one region during different tasks

Question 24

What are 3 further disadvantages of using TMS?

Answer 24

-Only cortical areas accessible
-Need sham stimulation due to loud coil click
-Auditory cortex stimulation is problematic