Week 2

Question 1

The scientific method as a tool

Answer 1

observation, hypothesis, prediction, experimental test

Question 2

Cognitive neuropsychology

Answer 2

the study of of mental activities and information-processing problems. They seek to identify the internal processing that underlies observable behavior.

Question 3

The cognitive approach

Answer 3

1. information processing depends on mental representations
2. These mental representations undergo internal transformations

Question 4

Mental representations

Answer 4

The letter matching task by Posner shows that even with simple stimuli the mind can derive multiple
representations.

Participants respond fastest to the physical-identity condition, next
fastest to the phonetic-identity condition, and slowest to the same-category condition, especially when the
two letters are both consonants.

Posner’s task

Question 5

Internal Transformations

Answer 5

Mental representations undergo transformations in the mind. However, information processing is not a simple sequential
process (sensation-perception-memory-action). Memory and attention may alter the way things are
perceived.
Sternberg’s task

Question 6

Sternberg’s Task

Answer 6

participant must engage in four primary mental operations:

1. Encoding: the participant must identify the visible target
2. Comparing: the participant must compare the mental representation of the target with the
   representations of the items in memory
3. Deciding: the participant must decide whether the target matches one of the memorized items
4. Responding: the participant must respond appropriately for the decision made in Step 3

Question 7

Word superiority effect

Answer 7

refers to the fact that participants are most accurate in identifying the target letter
when the stimulus is a word and parallel processing facilitates the performance.

Question 8

Sternberg’s basic question

Answer 8

A highly efficient
system might simultaneously compare a representation of the target with all of the items in the memory set.
Or, the recognition process might be able to handle only a limited amount of information at any point in time.
Sternberg realized that the reaction time data could distinguish between these two alternatives. If the
comparison process can be simultaneous for all items, a parallel process, then the reaction time should be
independent of the number of items in the memory set. But if the comparison process operates in a
sequential, or serial, manner, then reaction time should slow down as the memory set becomes larger.

Question 9

Cerebrovascular accidents (strokes)

Answer 9

sudden disruption of the blood flow to the brain. The most frequent cause is occlusion of a blood passage in the brain.

Question 10

Atherosclerosis

Answer 10

A collection of fatty tissue tissue in the arteries create embolus, tissue that breaks free and travels through the arteries to the brain and
blocks the blood flow in brain areas.

Question 11

Ischemia

Answer 11

is the inadequate blood supply to the brain, due to shock, low
blood pressure or excess bleeding This can create infractions, meaning dead tissue due to the inadequate
blood supply (no oxygen/nutrients).

Question 12

Neoplasm (tumor)

Answer 12

is a mass of tissue that grows abnormally and has no physiological function. Brain tumors in glial cells are common.

Question 13

traumatic brain injury (TBI).

Answer 13

The consequence is edema (swelling) around the lesion. The limited
space in the skull, due to the edema, causes an increase in the intracranial pressure, in turn reducing the
perfusion pressure and flow of blood throughout the brain, resulting in ischemia and, in some cases, the
emergence of secondary lesions.

Question 14

Epilepsy

Answer 14

An excessive and abnormally patterned activity in the brain. The cardinal
symptom is a seizure, a transient loss of consciousness. An EEG (electroencephalography) can confirm seizure activity.

Question 15

Single dissociation

Answer 15

When a lesion to brain area X impairs the ability of a patient to do task A but not task B, then we can say that brain area X and task A are associated, whereas brain area X and task B are dissociated.

Example: damage to Broca’s area in the left hemisphere impairs a person’s ability to speak fluently, but it does not impair comprehension.

Question 16

Double Dissociation

Answer 16

when damage to area X impairs the ability to do task A but not task B, and damage to area Y impairs the ability to do task B but not task A. The two areas have complementary processing. It
identifies whether two cognitive functions are independent of each other. It can be also used for comparisons
between groups.

Example: related to the Broca’s area example, damage to Wernicke’s area impairs comprehension but not the
ability to speak fluently

Question 17

A knockout procedure

Answer 17

Manipulating a specific gene (or set of genes) such that it does not express
itself. They can then study the knockout strains to explore the consequences of this change.

Question 18

Deep brain stimulation (invasive)

Answer 18

An invasive procedure in which electrodes are implanted in specific
brain regions to modulate neuronal activity (used in Parkinson’s
patients; coma, PTSD). Produces dramatic and sustained improvements in
the motor function of patients, even though the progression of the
disease is not stopped.

Question 19

Optogenetics (invasive)

Answer 19

To modulate neuronal activity. Provides a reliable switch to activate neurons using viral transduction.
Scientists inserted the ChR-2 gene into the part of the mouse’s brain
that contains the motor neurons controlling its whiskers.

Question 20

TRANSCRANIAL MAGNETIC STIMULATION (TMS) - Non-invasive.

Answer 20

Produces a focal stimulation of the human brain noninvasively. TMS pulses at various intensities, timings (single, repetitive, continuous), and frequencies.

Online: while participant performs a task
Offline: no task performance

• Repetitive TMS: bursts of TMS pulses
  over several minutes.
• Continuous TMS: very-high-frequency
  stimulation for 40 seconds (decreases
  activity in the area for 45-60 minutes)

Question 21

TMS virtual lesions

Answer 21

Produces only a relatively brief alteration in neural activity and allowing comparisons between stimulated
and unstimulated conditions in the same individual.

Question 22

TRANSCRANIAL DIRECT CURRENT STIMULATION (TDCS)- non-invasive

Answer 22

A brain stimulation procedure that delivers a constant, low current to the brain via electrodes placed on the
scalp. A current is sent between an anode and a cathode. The neurons under the anode become depolarized,
they achieve an elevated state of excitability, making them more likely to initiate an action potential when a
stimulus or movement occurs.

Question 23

TRANSCRANIAL ALTERNATING CURRENT STIMULATION (TACS) - non-invasive

Answer 23

Is a newer procedure in which the electrical current oscillates rather than remaining constant as in tDCS. The
experimenter controls the rate of tACS oscillation, providing another tool to modulate brain function. The
direction and the duration of the tACS-induced effects can vary with the frequency, intensity and phase of the
stimulation.

Question 24

LIMITATIONS AND NEW DIRECTIONS IN NON-INVASIVE BRAIN STIMULATION

Answer 24

• tDCS, tACS, and to a lesser extent TMS all have poor spatial resolution
• Results from studies are inconsistent (variables in strength of electrical field and individuals)

Question 25

TRANSCRANIAL STATIC MAGNETIC STIMULATION (TSMS) AND TRANSCRANIAL FOCUSED
ULTRASOUND (TFUS): non-invasive

Answer 25

tFUS has improved spatial resolution, able to target deeper structures. It uses low-intensity, low-frequency
ultrasound signals. This signal increases the activity of voltage-gated sodium and calcium channels, thus
triggering action potentials. tSMS uses strong magnetic fields (like TMS) perturb electrical activity, temporarily altering cortical function.

Question 26

CT or CAT, computerized tomography

Answer 26

the first method to offer an in vivo look at the human brain. This method was actually an extension of X-rays.

Question 27

MRI

Answer 27

MRI exploits the magnetic properties of atoms that make up organic tissue.
The distribution of water throughout the brain largely determines the hydrogen proton distribution, enabling
MRI to clearly distinguish the brain’s gray matter, white matter, and ventricles.

MRI scans provide a much clearer image of the brain than is possible with CT scans. The reason for the
improvement is that the density of protons is much greater in gray matter than in white matter.

Question 28

diffusion tensor imaging (DTI).

Answer 28

A variant of the traditional MRI. This is used to study the anatomical
structures of the axon tracts that form the brain’s white matter, this method offers information about
anatomical connectivity between regions. DTI is performed with an MRI scanner that measures the density
and the motion of these water molecules and, taking into account the known diffusion characteristics of
water, determines the boundaries that restrict water movement throughout the brain.
-Isotropic: free water
diffusion occurs equally in all directions.
-anisotropy: is greatest in axons because the myelin sheath creates a nearly pure lipid (fat) boundary.

Question 29

Single-cell neurophysiology in animals

Answer 29

An electrode is inserted through a surgical opening in the skull into the cortex/deep structures. This
technique is difficult, and penetrating the membrane frequently damages the cell.
By measuring the action potentials produced by individual neurons in living animals, researchers could begin
to uncover how the brain responds to sensory information, produces movement and changes with learning.

The primary goal is to
determine which experimental manipulations produce a
consistent change in the response rate of an isolated cell.

Question 30

Multiunit recording

Answer 30

a new technique developed to enable the recording of many neurons simultaneously, since the function of an area can be better understood by identifying correlations in the firing patterns of
groups of neurons rather than in each individual neuron.

Question 31

INVASIVE NEUROPHYSIOLOGY IN HUMANS

Answer 31

Surgeons may insert intracranial electrodes to localize an abnormality before its surgical resection (epilepsy).
e.g. Electrocorticography (ECoG)

Question 32

Electrocorticography (ECoG)

Answer 32

a diffuse invasive neurophysiological method in which a grid or strip of
electrodes is placed directly on the surface of the brain to record activity of a population of neurons for a
sustained amount of time. They enable the surgical team to monitor brain activity in order to identify the
location and frequency of abnormal brain activity, such as seizures. seizures. In a second procedure, they remove the
electrodes and perform the corrective surgery. Researchers can stimulate the brain with the electrodes, using
them to localize and map cortical and subcortical neurological functions such as motor or language function.
The time-varying record of the signals from the electrodes is an electrocorticogram.

Question 33

NONINVASIVE ELECTRICAL RECORDING OF NEURAL ACTIVITY

Answer 33

EEG, ERP, MEG

Question 34

ELECTROENCEPHALOGRAPHY (EEG)

Answer 34

The electrical potential produced by a single neuron is minute; it would be impossible to detect that signal
from an electrode placed on the scalp. When populations of neurons are active, they generate a much larger
composite of electrical signal. You can measure those with noninvasively by using electrodes placed on the
scalp, because normal EEG patterns are consistent among individuals, we can detect abnormalities in brain function from EEG recordings.

Question 35

MAGNETOENCEPHALOGRAPHY (MEG)

Answer 35

MEG is a technique that measures the magnetic fields produced by the brain’s electrical activity that is parallel to the surface of the skull. The spatial resolution can be superior because there is
minimal distortion of magnetic signals by organic tissue such as the brain or skull. The MEG traces over a series of trials to obtain event-related signals, called event-related fields (ERF).

It is much easier to localize the source of a MEG signal as compared to an EEG signal.

MEG’s major limitation is that the system is expensive

Question 36

Neuroimaging techniques

Answer 36

PET, fMRI. They do not directly measure neural events. When a brain area is active, increasing the blood flow to that region provides it with more oxygen and glucose at the expense of other parts of the brain. PET and fMRI can detect this change in blood flow, known as hemodynamic response.

Question 37

POSITRON EMISSION TOMOGRAPHY (PET)

Answer 37

PET uses radioactive-labeled compounds to measure local variants in the cerebral blood flow (correlate with mental
activity). A radioactive tracer is injected into the bloodstream, which is distributed in the brain.

condition. The results are
reported as a change in regional cerebral blood flow (rCBF) between the control and experimental conditions.

A new tool for diagnosing Alzheimer’s.

Question 38

FUNCTIONAL MAGNETIC RESONANCE IMAGING (FMRI)

Answer 38

The fMRI detectors measure the ratio of oxygenated to deoxygenated hemoglobin; this value is referred to as
the blood oxygen level–dependent (BOLD) effect. As a region of the brain becomes active, the amount of blood
directed to that area increases and the neural tissue is unable to absorb all the oxygen. fMRI measures the time course of blood flow that occurs slowly, unlike the neural events that happen in milliseconds. Much less expensive than PET

Question 39

multivoxel pattern analysis (MVPA)

Answer 39

a pattern classification algorithm in which the researcher identifies the distributed patterns of neural activity consistently present for a particular event, task, stimulus.

Question 40

MAGNETIC RESONANCE SPECTROSCOPY (MRS)

Answer 40

A method used to obtain
information about chemical composition of tissues. From the MRS data, researchers can estimate the
concentration of different neurochemicals in one brain area or the same neurotransmitter in multiple areas.