Ch. 2

Question 1

Explain what cognitive neuroscience is and what its study can teach us.

Answer 1

the study of the physiological basis of cognition.

Question 2

Describe how information is transmitted from one place to another in the nervous system.

Question 3

Describe how items in the environment, such as faces and places, are represented in the brain.

Question 4

Explain neural networks and their role in cognition.

Question 5

Describe the default mode network and how it differs from other neural networks.

Question 6

levels of analysis

Answer 6

Is our rationale behind studying the physiology of the mind.

It refers to the idea that a topic can be studied in many different ways, with each approach contributing its own dimension to our understanding.

(1)
operating a computer,

(2)
describing the components of a computer, and

(3)
learning how vital computer components function—provides more information about how computers work than could be gained by simply using a computer.

Just as we can study what is happening inside a computer at different levels, we can study the physiology of cognition at levels ranging from the whole brain, to structures within the brain, to chemicals that create electrical signals within these structures.

Question 7

neurons

Answer 7

Cell that is specialized to receive and transmit information in the nervous system

Question 8

nerve net

Answer 8

A network of continuously interconnected nerve fibers (as contrasted with neural networks, in which fibers are connected by synapses).

Spanish physiologist Ramon y Cajal (1852–1934) First, he used the Golgi stain, which stained only some of the cells in a slice of brain tissue.

Second, he decided to study tissue from the brains of newborn animals because the density of cells in the newborn brain is small compared with the density in the adult brain.

made it possible for Cajal to clearly observe that the nerve net was not continuous but rather interconnected individual units

Question 9

neuron doctrine

Answer 9

The idea that individual cells called neurons transmit signals in the nervous system, and that these cells are not continuous with other cells as proposed by nerve net theory.

From Spanish physiologist Ramon y Cajal (1852–1934)

Question 10

basic parts of a neuron

Answer 10

cell body: is the metabolic center of the neuron; it contains mechanisms to keep the cell alive.

dendrites: Structures that branch out from the cell body to receive electrical signals from other neurons.

Axons: Part of the neuron that transmits signals from the cell body to the synapse at the end of the axon. also called nerve fibers )

Question 11

Cajal also came to some other conclusions about neurons:

1

2

3

Answer 11

There is a small gap between the end of a neuron’s axon and the dendrites or cell body of another neuron. This gap is called a synapse.

Neurons are not connected indiscriminately to other neurons but form connections only to specific neurons. This forms groups of interconnected neurons, which together form neural circuits .

In addition to neurons in the brain, some neurons are specialized to pick up information from the environment, such as the neurons in the eye, ear, and skin. These neurons, called receptors are similar to brain neurons in that they have an axon, but they have specialized receptors that receive information from the environment.

Question 12

resting potential

Answer 12

Difference in charge between the inside and outside of a nerve fiber when the fiber is at rest (no other electrical signals are present).

neuron has a charge that is 70 mV more negative than the outside

Edgar Adrian was able to record electrical signals from single sensory neurons, an achievement for which he too was awarded the Nobel Prize in Physiology or Medicine in 1932

Question 13

action potential

Answer 13

Propagated electrical potential responsible for transmitting neural information and for communication between neurons. Action potentials typically travel down a neuron’s axon.

Question 14

nerve impulse

Answer 14

An electrical response that is propagated down the length of an axon (nerve fiber). Also called an Action potential.

each action potential travels all the way down the axon without changing its height or shape. This property makes action potentials ideal for sending signals over a distance because it means that once an action potential is started at one end of an axon, the signal will still be the same size when it reaches the other end.

Question 15

neurotransmitters

Answer 15

Chemical that is released at the synapse in response to incoming action potentials.

These chemicals make it possible for the signal to be transmitted across the gap that separates the end of the axon from the dendrite or cell body of another neuron

Question 16

how these signals contribute to the mind

Answer 16

Adrian studied the relation between nerve firing and sensory experience by measuring how the firing of a neuron from a receptor in the skin changed as he applied more pressure to the skin. He found the shape and height of the action potential remained the same as he increased the pressure, but the rate of nerve firing—that is, the number of action potentials that traveled down the axon per second—increased.

Adrian drew a connection between nerve firing and experience. He describes this connection in his book The Basis of Sensation (1928) by stating that if nerve impulses “are crowded closely together the sensation is intense, if they are separated by long intervals the sensation is correspondingly feeble”.

electrical signals are representing the intensity of the stimulus

Question 17

The connection between nerve firing and experience

Answer 17

electrical signals are representing the intensity of the stimulus.

Thus, the rate of neural firing is related to the intensity of stimulation, which, in turn, is related to the magnitude of an experience, such as feeling pressure on the skin or experiencing the brightness of a light. Thus, the firing rate is consistent with the quantity of a stimulus.

Question 18

how is the quality of experience represented in neural firing?

Answer 18

For the senses, quality across the senses refers to the different experiences associated with each of the senses—perceiving light for vision, sound for hearing, smells for olfaction, and so on.

We can also ask about quality within a particular sense, such as for vision: color, movement, an object’s shape, or the identity of a person’s face.

The short answer to this question is that different qualities of stimuli, and also different aspects of experience, activate different neurons and different brain regions.

Question 19

principle of neural representation

Answer 19

Everything a person experiences is based on representations in the person’s nervous system.

Adrian’s research marked the beginning of research on neural representation.

Question 20

1960s, researchers began focusing on recording from single neurons in the primary visual receiving region, the place where signals from the eye first reach the cortex.

Answer 20

(a)
Early work on neural representation and cognition focused on recording from single neurons in the visual cortex, where signals first arrive at the cortex.

(b)
Researchers then began to explore other places in the brain and found that visual stimulation causes activity that is distributed across many regions of the cortex.

(c)
Recent work has focused on examining how these distributed regions are connected by neural networks and how activity flows in these networks.

Question 21

As research progressed, researchers began recording from neurons in regions outside the primary visual region and discovered two key facts:

Answer 21

(1)
Many neurons at higher levels of the visual system fire to complex stimuli like geometrical patterns and faces; and

(2)
a specific stimulus causes neural firing that is distributed across many regions of the cortex

Question 22

neural networks

Answer 22

As it became clear that understanding neural representation involves casting a wide net across the brain, many researchers began considering the way different regions are connected to one another.

The idea of neural signals transmitted between many destinations in an interconnected brain has led to today’s conception of the brain as containing a vast highway system that can be described in terms of “neural networks”

Question 23

how can nerve impulses stand for different qualities?

Answer 23

Blakemore and Cooper’s experiment is important because it is an early demonstration of experience-dependent plasticity.

The environment in which our brain develops can literally change the physical organization of the brain.

These findings have an important message regarding neural representation: When a kitten’s cortex contained mainly vertically sensitive neurons, the kitten perceived only vertical contours, and a similar result occurred for horizontal contours.

This result supports the idea that perception is determined by neurons that fire to specific qualities of a stimulus (orientation, in this case).

Question 24

feature detectors

Answer 24

1960s, Hubel and Wiesel

Neurons that respond to specific visual features, such as orientation, size, or the more complex features that make up environmental stimuli.

Question 25

experience-dependent plasticity

Answer 25

A mechanism that causes an organism’s neurons to develop so they respond best to the type of stimulation to which the organism has been exposed.

Question 26

If we understand that neurons in the visual system fire to specific types of stimuli…

Answer 26

If we understand that neurons in the visual system fire to specific types of stimuli, we can consider the way that specific objects stimulate neural activity. For example, each of the thousands of neurons that fire when we look at a tree do so in response to different features of the tree. Some neurons fire to the vertically oriented trunk, others to the variously oriented branches, and some to more complex combinations of miscellaneous features. The idea that a tree is represented by the combined response of many feature detectors is similar to building objects by combining building blocks like Legos. Visual processing begins in the visual cortex, and our experience of vision depends on signals that are sent from the visual cortex to other regions of the brain.

Question 27

How are complex stimuli represented by the firing of neurons in the brain?

Question 28

hierarchical processing

Answer 28

Processing that occurs in a progression from lower to higher areas of the brain. What is happening is that neurons in the visual cortex that respond to relatively simple stimuli send their axons to higher levels of the visual system, where signals from many neurons combine and interact; neurons at this higher level, which respond to more complex stimuli such as geometrical objects, then send signals to even higher regions, combining and interacting further and creating neurons that respond to even more complex stimuli such as faces.

Question 29

sensory code

Answer 29

How neural firing represents various characteristics of the environment.

Question 30

the problem of sensory coding

Answer 30

The problem of determining the neural representation for the senses.

Question 31

specificity coding

Answer 31

The representation of a specific stimulus by the firing of neurons that respond only to that stimulus. An example would be the signaling of a person’s face by the firing of a neuron that responds only to that person’s face. Although the idea of specificity coding is straightforward, it is unlikely to be correct. Even though there are neurons that respond to faces, these neurons usually respond to several different faces. There are just too many different faces and other objects (and colors, tastes, smells, and sounds) in the world to have a separate neuron dedicated to each object.

Question 32

Population coding

Answer 32

is the representation of a particular object by the pattern of firing of a large number of neurons. An advantage of population coding is that a large number of stimuli can be represented because large groups of neurons can create a huge number of different patterns. There is good evidence for population coding in the senses and for other cognitive functions as well. However, some functions only require a small number of neurons.

Question 33

Sparse coding

Answer 33

occurs when a particular object is represented by a pattern of firing of only a small group of neurons. Notice that a particular neuron can respond to more than one stimulus.

Question 34

Memories are also represented by the firing of neurons, but

Answer 34

there is a difference between the representation of perceptions and the representation of memories. The neural firing associated with experiencing a perception is associated with what is happening while a stimulus is physically present. The neural firing associated with memory is associated with information about the past that has been stored in various locations in the brain. We know less about the actual form of the stored information for memory, but it is likely that the basic principles of population and sparse coding also operate for memory, with specific memories being represented by particular patterns of stored information that result in a particular pattern of nerve firing when we experience the memory.

Question 35

localization of function

Answer 35

Location of specific functions in specific areas of the brain. For example, areas have been identified that are specialized to process information involved in the perception of movement, form, speech, and different aspects of memory. Early evidence for localization of function came from neuropsychology —the study of the behavior of people whose brains have been damaged by traumatic injury.

Question 36

cortical equipotentiality

Answer 36

In the early 1800s, an accepted theory of brain function was cortical equipotentiality , the idea that the brain operated as an indivisible whole as opposed to consisting of specialized regions.

Question 37

Broca’s area

Answer 37

An area in the frontal lobe associated with the production of language. Damage to this area causes Broca’s aphasia. A condition associated with damage to Broca’s area, in the frontal lobe, characterized by labored ungrammatical speech and difficulty in understanding some types of sentences. speech was slow and labored and often had jumbled sentence structure. production of language

Question 38

Wernicke’s area

Answer 38

Area in the temporal lobe associated with understanding language. Damage to this area causes Wernicke’s aphasia. A condition, caused by damage to Wernicke’s area, that is characterized by difficulty in understanding language, and fluent, grammatically correct, but incoherent speech. patients produced speech that was fluent and grammatically correct but tended to be incoherent. not only produce meaningless speech but are unable to understand other people’s speech. Their primary problem is their inability to match words with their meanings, with the defining characteristic of Wernicke’s aphasia being the absence of typical grammar. comprehension of language

Question 39

prosopagnosia

Answer 39

an inability to recognize faces. For some with prosopagnosia, people can tell that a face is a face, but they cannot recognize whose face it is—even for people they know well such as friends and family members.

Question 40

One of the goals of the neuropsychology research we have been describing is to determine whether a particular region of the brain is specialized to serve a particular cognitive function.

Answer 40

use caution when determining the function of specific brain regions. Some brain regions can have many functions. Also, some functions (like vision or memory) require coordination between many different brain regions. It is important to note, however, that just because a brain region accomplishes one task (face perception) but not another (recognizing other objects) does not mean that region only serves a single function. _{If an alien race with no knowledge of humans were to arrive on Earth, they may wonder what humans are and what purpose they serve. Let’s say they conduct an experiment. If they dump water on a human, the human will likely respond by screaming or running away. The alien may infer that humans are water detectors. Yes, humans can detect water being dumped on our heads, but we can do so much more! So too can regions of the brain.}

Question 41

double dissociation

Answer 41

A situation in which a single dissociation can be demonstrated in one person and the opposite type of single dissociation can be demonstrated in another person (i.e., Person 1: function A is present, function B is damaged; Person 2: function A is damaged, function B is present). The importance of demonstrating a double dissociation is that it enables us to conclude that functions A and B are served by different mechanisms, which operate independently of one another.

Question 42

Electroencephalography (EEG)

Answer 42

A non-invasive neuroimaging method used to record electrical activity of the brain that involves placing electrodes on the scalp to detect and measure the electrical signals produced by neurons. first used on humans in the 1920s However, this technology has poor spatial resolution, meaning EEG cannot precisely locate from where in the brain the activity originates. EEG can measure with some accuracy general locations across the cortex, but it typically cannot measure activity in deeper brain regions.

Question 43

Magnetoencephalography (MEG)

Answer 43

A non-invasive neuroimaging technique that measures the magnetic fields produced by neural activity in the brain. These magnetic fields are generated by electrical currents in neurons. first used in the 1960s Similar to EEG, this technology has very good temporal resolution. However, MEG tends to have better spatial resolution than EEG.

Question 44

Near-Infrared Spectroscopy (NIRS)

Answer 44

A non-invasive imaging technique that uses near-infrared light to measure changes in blood oxygenation and blood volume in the brain. NIRS can infer the levels of oxygenated and deoxygenated hemoglobin in the brain by producing near-infrared light and detecting the light that is reflected. first used on humans in the 1970s

Question 45

Transcranial Magnetic Stimulation (TMS)

Answer 45

A non-invasive procedure that uses magnetic fields to stimulate nerve cells in the brain. A TMS device generates a magnetic pulse that induces an electrical current in specific areas of the brain, which can temporarily disrupt localized brain activity. developed in the 1980s In other words, the magnetic field can interrupt and effectively stop brain processes in a given region for a short amount of time.

Question 46

Diffusion Tensor Imaging (DTI)

Answer 46

A specialized type of magnetic resonance imaging (MRI) that focuses on measuring the diffusion of water molecules in human (or other animal) tissue, particularly in white matter tracts of the brain. This technique allows for the visualization and mapping of the brain’s structural connectivity by revealing the pathways of white matter fibers. developed in the 1980s and 1990s

Question 47

Functional magnetic resonance imaging (fMRI)

Answer 47

A brain imaging technique that measures how blood flow changes in response to cognitive activity. takes advantage of the fact that neural activity causes the brain to bring in more oxygen, which binds to hemoglobin molecules in the blood. This added oxygen increases the magnetic properties of the hemoglobin, so when a magnetic field is presented to the brain, these more highly oxygenated hemoglobin molecules respond more strongly to the magnetic field and cause an increase in the fMRI signal. Activity is recorded in voxels , which are small, cube-shaped regions of the brain about 2 or 3 mm on a side. Voxels are not brain structures but are simply small units of analysis created by the fMRI scanner. Increases or decreases in brain activity associated with cognitive activity are indicated by colors, with specific colors indicating the amount of activation.

Question 48

fusiform face area (FFA)

Answer 48

An area in the temporal lobe that contains many neurons that respond selectively to faces. is part of the fusiform gyrus , is located on the underside of the temporal lobe Damage to this brain region can result in prosopagnosia

Question 49

Alex Huth and coworkers (2012) conducted an fMRI experiment using stimuli similar to what we observe in the environment, by having participants view film clips.

Answer 49

four scenes and the categories (labels) associated with them. By determining how each voxel responded to each scene and then analyzing his results using a complex statistical procedure, Huth was able to determine which voxels responded to each category of stimuli. For example, one voxel responded well when streets, buildings, roads, interiors, and vehicles were present. Objects and actions similar to each other are located near each other in the brain. The reason there are two regions for humans and two for animals is that each region represents different features related to humans or animals. For example, the region labeled “Humans” at the bottom of the brain (which is actually on the underside of the brain) corresponds to the fusiform face area which responds to all aspects of faces. The region labeled “Humans” higher on the brain responds specifically to facial expressions. The regions labeled “Talking” correspond to Broca’s and Wernicke’s areas. present an interesting paradox. On one hand, the results confirm the earlier research that identified specific regions of the brain responsible for the perception of specific types of stimuli like faces, places, and bodies. On the other hand, these new results reveal a map that stretches over a large region of the cortex.

Question 50

multidimensional

Answer 50

The multidimensional nature of cognition refers to the fact that even simple experiences involve combinations of different qualities.

Question 51

Looking at a Face

Answer 51

In addition to identifying an object as a face (“that’s a face”) (1) emotional aspects (“they are smiling, so they are probably happy,” “looking at that face makes me happy”); (2) where someone is looking (“that person is looking at me”); (3) how parts of the face move (“I can understand the instructor better by watching their lips move”); (4) how attractive a face is (“that person has a handsome face”); and (5) whether the face is familiar (“I remember that person from somewhere”).

Question 52

distributed representation

Answer 52

The fact that looking at a face activates many regions of the brain is called distributed representation. Occurs when a specific cognition activates many areas of the brain.

Question 53

Remembering

Answer 53

short-term memories last only about 10 to 15 seconds unless repeated over and over. long-term memories last much longer, including things you did a few minutes ago, last week, or even as a child. Episodic memories are memories for events in a person’s life, like remembering what you did yesterday. Semantic memories are memories for facts, like knowing that the capital of California is Sacramento.

Question 54

Neural Network principles

Answer 54

Groups of neurons or structures that are connected together. 1.There are complex structural pathways called networks that form the brain’s information highway. 2. Within these structural pathways there are functional pathways that serve different functions. 3. These networks operate dynamically, mirroring the dynamic nature of cognition. 4. There is a resting state of brain activity, so parts of the brain are active all the time, even when there is no cognitive activity.

Question 55

Structural connectivity

Answer 55

The physical connections between different brain regions, established through neural pathways. It is the brain’s “wiring diagram” created by nerve axons that connect different brain regions. Pictures of the brain’s pathways obtained by these techniques have led to the coining of the term connectome to indicate the “structural description of the network of elements and connections forming the human brain” or more simply, the “wiring diagram” of neurons in the brain. (A map of the brain that details the complex network of neurons and their connections.) maps of structural connectivity of the brain have been likened to “fingerprints” that are different for every person, so it could be argued that the brain’s wiring makes us who we are. Measured using track weighted imaging. A technique for determining connectivity in the brain that is based on detection of how water diffuses along the length of nerve fibers.

Question 56

Functional Connectivity

Answer 56

The extent to which the neural activity in separate brain areas is correlated with each other. If the responses of two brain regions are correlated with each other, this means that they are likely to be functionally connected. One method of determining whether the responding of two regions is correlated is based on resting-state fMRI —the fMRI response measured while a person is at rest (that is, not performing a cognitive task). can also be measured by task-related fMRI It is important to note that saying two regions are functionally connected does not necessarily mean that they directly communicate by neural pathways. regions with high structural connectivity often show a high level of functional connectivity.

Question 57

default mode network (DMN)

Answer 57

Network of structures that are active when a person is not involved in specific tasks. discovery of this network begins with a paper by Gordon Shulman and coworkers (1997), who noted a few earlier fMRI studies in which the presentation of a task caused a decrease in activity in some regions of the brain, and stopping the task caused an increase in activity in the same regions. When the DMN is active, people’s minds tend to wander

Question 58

Progress in understanding the physiology of cognition has depended on

Answer 58

advances in technology. This is demonstrated by considering the connection between technology and answering three basic questions: The Representation Question, The Organization Question, and The Communication Question. The Representation Question: “How are cognitions represented by neural firing?” The Organization Question: “How are cognitions localized in different regions of the brain?” The Communication Question: “How are different regions of the brain connected and how do they communicate?”