Methods in Brain Research 2

Question 1

What is neuropsychology?

Answer 1

Examines the effect of the brain lesions on behaviour and mental functions under the assumption that if the lesion of the brain region X impairs function Y, Y must be dependent on the integrity of X.

Brain lesions occurr after strokes, accidents, tumors, cerebral hypoxia, etc.
The study of the effects of brain lesions on behaviour started in mid-1800
Lesions in specific parts of the brain induce deficits in specific cognitive functions, changes in personality or behaviour

Discovered prosopagnasia.

Question 2

Define prosopagnosia.

Answer 2

Deficit in identifying faces after lesions of face-selective brain regions.

Question 3

What are the pros of neuropsychology?

Answer 3

It provides causal information -
The deficit of function Y has emerged AFTER the lesion of
brain region X, therefore Y must depend on X visa versa.

Question 4

What are the cons neuropsychology?

Answer 4

Difficult to find patients
Patients generally have lesions in more than one part of the brain and their cognitive deficit is not specific (difficult to establish a clear brain-function correlation).

Question 5

What is EEG?

Answer 5

Involves the recording of electrical brain activity (post-synaptic potential) from large pools of neurons through electrodes placed on the scalp according to a specific arrangment.

Question 6

What are the conditions required for effective recording of electrical brain activity in EEG?

Answer 6

• Large numbers– large populations of neurons need to be activated in the same fashion.
• Synchrony- activation of different neurons must be very close in time.
• Orientation – the orientation of the active neurons needs to be the same.

Question 7

Outline the process for EEG.

Answer 7

• Biological signals to digital signals
• The signal will be digitized and amplified so a computer can capture and record it. The raw EEG data is the electrical activity recorded from the beginning until the end of a test. It contains signals and noise (artifacts, blinks, muscles).
• Raw EEG “cut” into many segments, time-locked these segments to the onset of specific event, and analyze the signal within the segment as a function of experimental conditions (positive vs. negative vs. neutral).

Question 8

What are the ways EEG signal segments analyzed?

Answer 8

1) brain oscillations: information in the frequency domain
2) event related potentials (ERPs): information in the time domain

Question 9

What is brain oscillation?

Answer 9

• Signals extracted from the EEG that
  are evoked by mental or physiological
  state
• Extracting signals from specific range
  of frequencies of EEG
• Affords scientist to study a specific
  mental or physiological state during a
  short period of time
• Represent specific cortical activities

Question 10

What are event-related brain potentials?

Answer 10

Signals that are evoked by an event and cognitive process
* By averaging across all signals evoked by a specific experimental condition
* ERP components have a specific latency and polarity (positive, negative) with well-defined functional significance
*functional significance = components are
associated with a specific mental processes

Question 11

What are the pros of ERPs?

Answer 11

• Precision in when
• Portable (but not always)

Question 12

What are the cons of ERPs?

Answer 12

• Bad precision in where
• Easily affected by artifacts/movements