Chapter 2 - Cognitive Neuroscience

Question 1

Cognitive Neuroscience

Answer 1

• the study of the physiological basis of cognition

- involved an understanding of both the nervous system and the individual units that compromise that system

Question 2

Levels of Analysis

Answer 2

• we study things in several different ways, with each approach contributing its own dimensions to our understanding
• we do not examine topics of interest from a single perspective, but rather we look at them from multiple angles and different points of view
• Each “viewpoint” can add small amounts of information which, when considered together leads to greater understanding

Question 3

Nerve Nets and the Neuron Doctrine

Answer 3

• early concept of interconnected neurons creating a nerve net, similar to a highway network
• streets are connected without stop signs
• this allows for almost nonstop, continuous communication of signals throughout the network
• contradicted by the neuron doctrine
• Ramon Y Cajal
• individual nerve cells transmit signals, and are not continuously linked with other cells

Question 4

-Cell body

Answer 4

is the metabolic center of the neuron

Question 5

-Neurons:

Answer 5

cells specialized to receive and transmit electrical signal to other neurons

Question 6

-Axons:

Answer 6

tube filled with fluid that transmits electrical signal to other neurons

Question 7

-Dendrites:

Answer 7

multiple branches reaching from the cell body, which receives information from other neurons

-sensory receptors: specialized to respond to information received from the senses

Question 8

How Neurons Communicate

-Action potential

Answer 8

• neuron receives signal from environment
• information travels down the axon of that neuron to the dendrite of another neuron
• Measuring action potentials
• microelectrodes pick up electrical signal
• places near axon
• size is not measure; it remains consistent
• low intensity stimulus: slow firing
• high intensity stimulus: fast firing

Question 9

-Synapse:

Answer 9

space between axon of one neuron and dendrite or cell body of another

-when the action potential reaches the end of the axon, synaptic vesicles open and release chemical neurotransmitters

Question 10

-Neurotransmitters,

Answer 10

chemicals that affect the electrical signal of the receiving neuron, cross the synapse and bind the receiving dendrites

Question 11

-receptors

Answer 11

are like brain neurons in that they have an axon, but they have specialized receptors that pick-up information from the environment

Question 12

-nerve impulse

Answer 12

transmitted down the axon

Question 13

-excitatory:

Answer 13

increases chance neuron will fire

Question 14

-inhibitory:

Answer 14

decreases chance neuron will fire

Question 15

Principle of Neural Representation

-Definition of the mind:

Answer 15

• a system that creates representations of the world, so we can act on it to achieve goals
• principle of neural representation
• everything a person experiences are based on representations in the person’s nervous system

Question 16

Feature Detectors

-Hubel and Wiesel (1960s) research with visual stimuli in cats

Answer 16

• Feature Detectors
• neurons that respond best to a specific stimulus
• Experience-dependent plasticity
• the structure of the brain changes with experience
• Kittens exposed to vertical-only stimuli over time could only perceive verticals in normal stimuli
• demonstrated that perception is determined by neurons that fire to specific qualities of a stimulus

Question 17

Hierarchical Processing

Answer 17

• when we perceive different objects, we do so in a specific order that moves from lower to higher areas of the brain
• the ascension from lower to higher areas of the brain corresponds to perceiving objects that range from lower (simple) to higher levels of complexity

Question 18

Sensory Coding

-Specificity Coding:

Answer 18

representation of a stimulus by firing of specifically tuned neurons specialized to respond only to a specific stimulus

Question 19

-Population Coding:

Answer 19

Representation of a stimulus by the pattern of firing of a large number of neurons

Question 20

Sparse Coding:

Answer 20

representation of stimulus by a pattern of firing of only a small group of neurons, with the majority or neurons remaining silent

Question 21

Localization of Function

Answer 21

• specific functions served by specific areas of the brain
• cognitive functioning declines in specific ways when certain areas of the brain are damaged
• Cerebral cortex (3mm thick layer covering the brain) contains mechanisms responsible for most cognitive functions
• other functions are served in the subcortical areas that are located below the cortex

Question 22

Language

Answer 22

• Language production is impaired by damage to Broca’s area (Broca’s aphasia)
• frontal lobe
• frontal lobe
• Language comprehension is impaired by damage to Wernicke’s area (Wernicke’s Aphasia)
• Temporal Lobe

Question 23

-primary receiving area for the senses

Answer 23

• Occipital lobe: vision
• Parietal Lobe: touch, temperature and smell
• Temporal lobe: hearing, taste and smell
• Coordination of information received from all other sense
• Frontal lobe

Question 24

-prosopagnosia

Answer 24

inability to recognize faces, also due to damage to the temporal lobe

Question 25

Double Dissociation

Answer 25

• When damage to one part of the brain causes function A to be absent while function B is present, and damage to another area causes function B to be absent while function A is present
• allows us to identify functions that are controlled by different parts of the brain

Question 26

Organization: Brain Imaging

-Positron Emission Tomography (PET)

Answer 26

• Blood flow increases in areas of the brain activated by cognitive task
• Radioactive tracer is injected into a person’s bloodstream
• Measure signal from tracer at each location of the brain
• Higher signals indicate higher levels of brain activity

Question 27

Method: Brain Imaging

Answer 27

• Subtraction technique measures brain activity before and during stimulation presentation
• Difference between activation determines what areas of the brain are active during manipulation

Question 28

Localization Demonstrated by Brain Imaging

Answer 28

• Functional Magnetic Resonance Imaging (fMRI)
• measure neural activity by identifying highly oxygenated hemoglobin molecules
• Activity recorded in voxels (3D pixels)
• red and yellow in the scans show increase in brain activity, while blue and green show decreases

Question 29

Method: Event-Related Potential (ERP)

Answer 29

• Neuron “firing” is an electrical event
• Measure electrical activity on the scalp and make inferences about underlying brain activity
• Averages over large number of trials to calculate ERSs
• Advantage: continuous and rapid measurements
• Disadvantage: does not give precise location

Question 30

Localization Demonstrated by Brain Imaging

Answer 30

• Fusiform Face Area (FFA) responds specifically to faces
• damage to this area causes prosopagnosia (inability to recognize faces)
• Para-hippocampal place area (PPA) responds specifically to places (indoor/outdoor scenes)
• Extrastriate body area (EBA) responds specifically to pictures of bodies and parts of bodies

Question 31

Distributed Representation in the Brain

Answer 31

• central principle of cognition
• most of our experience is multidimensional - that is even simple experiences involve combination of different qualities
• in addition to localization of function, specific functions are processed by many different areas of the brain
• May seem to contradict the notion of localization of function, but the concepts are complementary
• the fact that looking at a face activates many areas of the brain is called distributed representation

Question 32

Neural Networks

Answer 32

• interconnected areas of the brain that communicate with each other
• Connectome: structural description of the network of elements and connections forming the human brain

Question 33

Structural and Functional Connectivity

-Structural Connectivity:

Answer 33

• the brain’s “wiring system” created by axons that connect brain areas
• as unique to individuals as fingerprints
• track-weighted imaging (TWI) is based on detection of how water diffuses along the length of nerve fibers

Question 34

-Functional Connectivity:

Answer 34

• how groups of neurons within the connectome function in relation to types of cognition
• determined by the amount of correlated neural activity in two brain areas

Question 35

Resting-State Functional Connectivity

Answer 35

• use tasks related fMRI to determine a brain location associated with carrying out a specific task. For example, movement of the finger causes an fMRI response at the location marked Motor (L) in Figure 2.25a. This location is called seed location
• Measure the resting-state fMRI at the seed location. The resting state fMRI of the seed location shown in the figure, is called a time series response because it indicates how the response changes over time
• measure the resting rate fMRI at another location, which is called the test location. The response at the test location Somatosensory, which is in an area of the brain responsible for sensing touch, shows in the figure below
• Calculate the correlation between the seed and test location responses

Question 36

Dynamics of Cognition and Default Mode Network

-Dynamics of cognition

Answer 36

-the flow and activity within and across the brain’s function networks change based on conditions

Question 37

-Default mode network:

Answer 37

• mode of brain functions that occurs when it is at rest (activation at rest is higher than at tasks) e.g. mind wandering is higher than when you engage I the class
• one of the brain’s largest networks

Question 38

Coglab: Brain Asymmetry

Answer 38

This experiment uses a technique devised by Levy, Heller, Banich, & Burton (1983) (also see Rueckert, 2005) for demonstrating differences between the hemispheres of a normal subject’s brain. The stimuli involve chimeric faces. A chimeric face is made by taking two different faces, dividing them in half, and combining the left side of one face with the right side of the other face to make a combined, chimeric, face.

Prediction: A right-handed observer will choose the chimeric face with the younger half on the left in terms of the viewpoint of the subject. Left-handed people will not show as strong differences in choose the chimeric face.