Methods and Neuroanatomy

Question 1

What is Parallel Processing

Answer 1

Assumes some or all processes involved in cognitive tasks occur at the same time.

eg; skilled typest can think a few letters ahead, whereas novice focuses on one letter at a time.

Question 2

Hierarchical organization

Answer 2

Memory viewed as a hierarchy with many component processes/systems

eg; explicit memory can be divided into episodic and semantic.

Question 3

Episodic Memory (explicit memory)

Answer 3

remembering an experience in life including time and place

Question 4

Semantic Memory (explicit memory)

Answer 4

Factual knowledge

Question 5

Context effects

Answer 5

prior knowledge or experience influences new knowledge.

Question 6

Cognitive Neuroscience

Answer 6

Study of all mental functions that are linked to neural processes and how those functions are organized in the brain to guide specific cognitive operations.

Question 7

Lesion-Deficit Approach

Answer 7

Damage to a particular brain region results in an inability to perform a given task. Brain region assumed to be involved in task function.

Question 8

Modularity

Answer 8

Isolated properties or modules that work independently as cognitive functions. Specialized processes.

Example; facial recognition may include semantic information which is separate than the perceptual component of the face.

Question 9

Brain Damage

Answer 9

May impair only a small fraction of the total number of modules (ideally it impairs only one)

Question 10

Encapsulated, automatic Perceptual Input Module

Answer 10

Unable to communicate with one another, and cannot be controlled by conceptual processes and unable to consciously reflect.

Question 11

Central, conceptual processes Unencapsulated, controlled

Answer 11

Open to other modules and conscious awareness, controlled

eg; conductor of an orchestra; combining information

governs a wide variety of cognitive functions (reasoning, attention)

Question 12

Lesion-Deficit Transparency

Answer 12

careful analysis of the pattern of intact and impaired performance will lead us to valid conclusions about the nature and function of the impaired module/modules.

difficult to infer on a single patient and a group to a particular region cause there may be other reasons why.

Question 13

Single Dissociation

Answer 13

Lesion to Region A causes a disruption in Function A but not in Function B

Inference; Region A mediates performance on task A but not task B

Does not rule out other interpretations.

Question 14

Double-Dissociation

Answer 14

Lesion to Region A causes a disruption in Function A but not in Function B, whereas lesion to Region B causes a disruption in Function B, but not in Function A.

Inference: Functions are independent because the viability of one cognitive function does not depend on the viability of other cognitive function.

Question 15

Diaschisis Effect

Answer 15

altered functioning in intact tissue that is functionally connected to a damaged region.

Module A is damaged and Module B cannot function properly without Module A

Question 16

K.C Case Study

Motorcycle accident:

Answer 16

bilateral hippocampal damage from head injury

preserved iq, perception, language, exeuctive function

preserved remote semantic memory

Impaired episodic memory for all times in his life.

Question 17

H.C Case Study

Answer 17

Impaired autobiographical episodic memory despite more selective hippocampal system volume loss.

Question 18

Structural MRI

Answer 18

Imaging individual slices of the brain that are close together which can be reconstructed in order to determine any structural abnormalities.

Question 19

CT Scan

Answer 19

Many x-rays of the brain to construct the brain

An attenuation of tissue encountered along the path of the x-rays.

Question 20

SPECT/PET Scan

Answer 20

Radiolabeled compounds injected in tracer amounts so that their proton emissions can be detected much like CT

Images made represent the accumulation of the labeled compound.

The compound may reflect blood flow, oxygen or glucose metabolism, or dopamine concentration.

Images often are shown with color scale.

Question 21

Structural Neuroimaging MRI

Answer 21

Hydrogen atoms make up 63% of the human body.

Hydrogen nuclei have an Nuclear Magnetic resonance signal.

Magnetic resonance imaging primarily images the NMR signal from the hydrogen nuclei

Large number of Slices acquired

Applying radio waves and turning them off to observe the energy emitted in the form of radio waves.

Question 22

Functional MRI (fMRI)

Answer 22

changes in neuronal activity are associated with local changes in physiological response.

Neural activity -> blood flow _> oxyhemoglobin -> MR signal.

Question 23

Functional MRI: BOLD Response

Answer 23

Blood oxygen level dependent.

Question 24

Functional MRI: BOLD Response

Answer 24

Blood oxygen level dependent.

Oxygen rich blood carried from the heart dimagnetic meaning it has magnetic properties

As blood passes through the capillary beds in the brain, oxygen is extracted and the blood loses its magnetic properties (para-magnetic)

BOLD RESPONSE:

The relative proportion of oxygenated blood to oxygenated blood increases in active brain regions.

Question 25

Talairach Coordinate System

Answer 25

Since individual brains are different shapes and sizes, how can we compare or average brains?

squish or stretch brain into shoebox and extract 3D coordinate (x,y,z) for each activation focus.

Advantages: Widespread system

allows averaging of fMRI data between subjects

allows researchers to compare activation foci

easy to us

disadvantages

based on the squished brain of an elderly woman (how representative is that)?

not appropriate for all brains activation foci can vary considerably. other landmarks like sulci may be more reliable.

Question 26

What are the advantages of neuroimaging vs. lesion methods

Answer 26

Neuroimaging

Advantages; healthy people
temporal resolution
able to view all regions involved in a task (who-brain analysis)

Disadvantages;

unable to determine if region necessary for a given task

interpretation of null results and “deactivation’s”

Question 27

Transcranial Magnetic Stimulation (TMS)

Answer 27

Doesn’t image neural activity

Modulates or disrupts neural activity

creates a reversible lesion or scrambles neural activity

How

coils placed on scalp create a magnetic field that induces an electrical field

this alters membrane potential of neurons causing them to fire randomly.

Causes muscle movement.

Question 28

Functional MRI: Subtraction Method

Answer 28

Example: Where are objects represented in the brain?

T1: View intact objects

T2: View Scrambled objects

T2-T1 = “object” areas

Possible factors added:

1) attentional salience (objects are more interesting than scrambled)
2) Memory (youve seen an apple before but problably not a scrambled apple )

Baseline

May be straightforward (vision studies often include fixation )

Sometimes baseline is less clear, especially during simple rest states