Cog5 lecppt chapter02


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  • In this chapter we lay a foundation regarding the brain and methods used to study the brain.
    We begin with an example of a bizarre syndrome that results from brain damage.
  • Patients are able to recognize family and friends but believe that these people are not who they appear to be, that they are imposters.
  • One hypothesis about Capgras syndrome is that it stems from two different facial recognition systems in the brain:
    A more cognitive system that underlies perceptual recognition is intact.
    However, a more emotional system that underlies the feeling of familiarity is disrupted.
  • To evaluate this hypothesis, we can also consider evidence from neuroimaging, methods that permit researchers to take high quality, three-dimensional images of the living brain. fMRI is used to detect areas of increased brain activity. MRI scans are used to view the structures of the brain.
  • The brain damage associated with Capgras syndrome involves the amygdala, an almond-shaped structure that is important for emotional processing.
  • Another damaged region is the right prefrontal cortex, a region at the front of the brain important for reasoning, planning and careful analysis. This area is also not active in patients with schizophrenia or in all humans during dreaming. Hence, lack of activity in this area is associated with illogical thinking. That is why patients with Capgrass see their loved ones as impostors. They have a strange feeling, a thought occurs, and they are unable to check the validity of this thought.
  • Some of the evidence comes from the psychology laboratory and confirms the suggestion that recognition of all stimuli (and not just faces) does involve two separate mechanisms—one that hinges on factual knowledge and one that’s more “emotional” and tied to the warm sense of familiarity (see Chapter 6).
  • Hypothesis testing in Capgras syndrome
    For instance, based on Capgras syndrome, researchers might then hypothesize that the amygdala is important for other aspects of emotional memory:
    Remembering emotional events in one’s life
    Making decisions that rest on emotional evaluations of the options
  • The simplest fact illustrated by Capgras syndrome is that different parts of the brain perform different jobs.
    Recognizing your father: recognition is based on factual information (one part of the brain), visual analysis (another part), matching memory with images in the world (a third area), and so on.
    Researchers began to realize this in the nineteenth century by studying the cognition and behavior of patients with lesions in the brain.
  • The human brain weighs between 3 and 4 pounds; it is roughly the size of a small melon. Yet this structure has been estimated to contain a trillion nerve cells (that’s 1012), each of which is connected to 10,000 or so others—for a total of roughly 10 million billion connections. The brain also contains a huge number of glial cells (and, by some estimates, the glia outnumber the nerve cells by roughly 10 to 1, so there are roughly 100 million billion of these).
  • Phineas Gage was one such famous patient. In 1848, an explosion during the construction of a railway sent a tamping iron through his frontal lobes. At first Gage appeared to be unharmed except for the hole in his head. However, it quickly became clear that the damage had a profound effect on him. This resulted in such strong cognitive and emotional changes that one person came to say that “Gage was no longer Gage.”
  • The study of people with brain lesions also helps us learn about the functions of these brain regions in healthy people.
  • The hindbrain sits directly atop the spinal cord.
    Controls rhythms of the heart and breathing
    Regulates levels of alertness
    Includes the cerebellum, which coordinates movements and balance, in addition to more recently discovered sensory and cognitive roles
  • The forebrain comprises most of the parts of the brain that are visible from the outer surface. It includes:
    The cortex, a thin convoluted sheet of tissue
    A variety of subcortical structures
  • The cortex is divided into the left and right cerebral hemispheres by the longitudinal fissure.
    Commissures, thick bundles of nerve fibers, connect the two hemispheres, the largest of which is the corpus callosum.
    The cortex is divided into anterior and posterior regions by the central fissure.
  • The thalamus acts as a relay station for nearly all the sensory information going to the cortex.
    The hypothalamus, a structure that plays a crucial role in controlling motivated behaviors such as eating, drinking, and sexual activity, lies beneath it.
    Surrounding the thalamus and hypothalamus is another set of interconnected structures that together form the limbic system (see Figure 2.4).
    ncluded here is the amygdala, and close by is the hippocampus, both located underneath the cortex in the temporal lobe (plurals: amygdalae and hippocampi).
    The hippocampus is involved in learning and memory, and the patient H.M., discussed in Chapter 1, developed his profound amnesia after surgeons removed these structures.
    The amygdala is involved in emotional processing, as we saw in the example with Capgrass syndrome, where lack of activity in this area was tied to a lack of emotional response to known people.
  • This is true of subcortical structures such as the hippocampus and also of cortical areas such as the temporal lobe.
    The corpus callosum and the anterior commissure connect the two halves of the brain, which work together
  • In some cases, though, there are medical reasons to sever the corpus callosum and some of the other commissures. (For many years, this surgery was a last resort for extreme cases of epilepsy.) The person is then said to be a “split brain patient”—still having both brain halves, but with communication between the halves severely limited. Research with these patients has taught us a great deal about the specialized function of the brain’s two hemispheres and has provided evidence, for example, that language capacities are generally lodged in the left hemisphere, while the right hemisphere seems crucial for a number of tasks involving spatial judgment (see Figure 2.5).
  • In this experiment, the patient is shown two pictures, one of a spoon and one of a fork. If asked what he sees, his response is controlled by the left hemisphere, which has seen only the fork (because it’s in the right visual field). If asked to pick up the object shown in the picture, however, the patient—reaching with his left hand—picks up the spoon. That happens because the left hand is controlled by the right hemisphere, and this hemisphere receives visual information from the left-handed side of the visual world.
  • The study of these cases generally falls within the domain of neuropsychology: the study of the brain’s structures and how they relate to brain function. Within neuropsychology, the specialty of clinical neuropsychology seeks (among other goals) to understand the functioning of intact, undamaged brains by careful scrutiny of cases involving brain damage.
    Lesions result from brain damage and have specific effects. Damage to the left side of the frontal lobe, for example, is likely to produce a disruption of language use; damage to the right side of the frontal lobe does not have this effect.
  • Recall that neuroimaging allows researchers to take high quality, three-dimensional images of the living brain.
    CT scans rely on X-rays and thus—in essence—provide a three-dimensional X-ray picture of the brain. For CT scans, the map tells us the shape, size, and position of structures within the brain.
    PET scans, in contrast, start by introducing a tracer substance such as glucose into the body; the molecules of this tracer have been tagged with a low dose of radioactivity, and the scan keeps track of this radioactivity, allowing us to tell which tissues are using more of the glucose (the body’s main fuel) and which are using less.
  • PET scans can measure how much glucose (the brain’s fuel) is being used at specific locations within the brain; this provides a measurement of each location’s activity level at a certain moment in time. In the figure, the brain is viewed from above, with the front of the head at the top and the back at the bottom. As the figure shows, visual processing involves increased activity in the occipital cortex.
  • Magnetic resonance imaging (MRI) relies on the magnetic properties of the atoms that make up the brain tissue, and it yields fabulously detailed pictures of the brain.
    The left panel shows a “slice” of the brain viewed from the top of the head (the front of the head is at the top of the image); clearly visible is the longitudinal fissure, which divides the left cerebral hemisphere from the right. The middle panel shows a slice of the brain viewed from the front; again, the separation of the two hemispheres is clearly visible, and so are some of the commissures linking the two brain halves. The right panel shows a slice of the brain viewed from the side; many of the structures in the limbic system (see Figure 2.4) are easily seen.
  • A closely related technique, functional magnetic resonance imaging (fMRI), measures the oxygen content in the blood flowing through each region of the brain; this turns out to be an accurate index of the level of neural activity in that region. In this way, fMRI scans provide an incredibly precise picture of the brain’s moment-by-moment activities.
  • Neurons vary communicate with each other via chemical signals called neurotransmitters. Once a neuron is “activated,” it releases the transmitter, and this chemical can then activate (or, in some cases, de-activate) other, immediately adjacent neurons. The adjacent neurons, in other words, “receive” this chemical signal, and they, in turn, can send the signal onward to still other neurons.
    It requires two types of communication. The first involves a chemical signal “between neurons” and “within the neuron,” which is an electrical pulse made possible by a flow of charged atoms (ions) in and out of the neuron (again, we will say more about this process later in the chapter). The amount of electrical current involved in this ion flow is minute, but, of course, many millions of neurons are active at the same time, and the current generated by all of them together is great enough to be detected by sensitive electrodes placed on the surface of the scalp. This is the basis for electroencephalography.
  • To record the brain’s electrical signals, researchers use a cap that is electrodes attached to it. The procedure is easy and entirely safe—it can even be used to measure brain signals in a young baby (A). In some procedures, researchers measure recurrent rhythms in the brain’s activity, including the rhythms that distinguish the stages of sleep (B). In other procedures, they measure the brain activity produced in response to a single event—such as the presentation of a well-defined stimulus (C).
  • Each imaging method has strengths and weaknesses. CT scans and MRI data tell us about the shape and size of brain structures, but they tell us nothing about the activity levels within these structures. PET scans and fMRI studies do tell us about brain activity, and they can locate the activity rather precisely (within a millimeter or two), but they are much less sensitive to when the activity took place. For example, fMRI data summarize the brain’s activity over a period of several seconds and cannot tell us when, within this time window, the activity took place. EEG data give us much more precise information about timing but are much weaker in telling us where the activity took place.
  • Using binocular rivalry, Tong and colleagues showed that the activation level in these two regions reflects what the person is conscious of, not just the presented visual stimuli.
  • Note that the regions indicated by fMRI studies are not always necessary for the task in question.
    Instead they may be only correlated with the task, in the way a speedometer is correlated with (but not needed for) the movement of a car.
    Another technique, known as transcranial magnetic stimulation (TMS), can be used to ask whether an area of the brain is necessary for the task.
  • Results from forming a mental picture reveals activity in very similar brain areas. This suggests that visualization and seeing things share a lot in common. The first column shows brain activity while a person is making judgments about simple pictures. The second column shows brain activity while the person is making the same sorts of judgments about “mental pictures,” visualized before the “mind’s eye.”
  • Primary projection areas are the arrival and departure points for information entering (sensory areas) and leaving (motor areas) the cortex. with the departure points known as the primary motor projection areas and the arrival points contained in regions known as the primary sensory projection areas.
    The rest of the cortex has traditionally been considered the association cortex.
  • The primary motor projection areas is located in the posterior frontal lobes.
    More cortical space is devoted to the regions of the body we move with the greatest precision.
  • The primary somatosensory projection area is located in the anterior parietal lobes.
    The primary auditory projection area is located in the superior temporal lobes.
    The primary visual projection area is located in the occipital lobes.
  • Cortical maps represent sensory or motor information in an orderly manner.
    Organization is by region of the body, region in space, or auditory frequency.
    Cortical space is assigned disproportionately.
    Greater sensory acuity or motor precision are associated with larger cortical representation.
  • The areas described so far—both motor and sensory—make up only a small part of the human cerebral cortex (roughly 25%). The remaining cortical areas are traditionally referred to as the association cortex, on the idea that these areas perform the task of associating simple ideas and sensations in order to form more complex thoughts and behaviors.
  • Neurological syndromes that reflect damage to regions of the association cortex include:
    Apraxia – problems with the initiation or organization of movement
    Agnosia – problems identifying familiar objects
    Aphasia – problems with language
    Neglect syndrome – problems in which half of the visual world is ignored
    Prefrontal damage – problems with planning and implementing strategies and inhibiting behaviors
  • The basic parts of a neuron are:
    Dendrites, which detect incoming signals
    The cell body, which contains the nucleus and cellular machinery
    The axon, which transmits signals to other neurons
  • The glia perform many functions: They help to guide the development of the nervous system in the fetus and young infant, support repairs if the nervous system is damaged, maintain and control the flow of nutrients to the neurons, and more. Specialized glial cells also provide a layer of electrical insulation surrounding parts of the neuron; this insulation dramatically increases the speed with which neurons can send their signals. Finally, some research suggests the glia may also constitute their own signaling system within the brain, separate from the information flow provided by the neurons
  • Communication between neurons is done via chemical signals.
    Neurotransmitters are chemicals released by one neuron to communicate with another neuron.
    The space between the two is called a synapse.
    Thus, the first neuron is called the presynaptic neuron and the second neuron is the postsynaptic neuron.
    The space between the neurons is called the synaptic gap; the bit of the neuron that releases the transmitter into this gap is called the presynaptic membrane, and the bit of the neuron on the other side of the gap, affected by the transmitters, is the postsynaptic membrane.
  • But if the ionic flows are large enough, they trigger a response in the postsynaptic cell. In formal terms, if the incoming signal reaches the postsynaptic cell’s threshold, then the cell fires; that is, it produces an action potential—a signal that moves down its axon, which in turn causes the release of neurotransmitters at the next synapse, potentially causing the next cell to fire.
    Second, note that the postsynaptic neuron’s initial response can vary in size; the incoming signal can cause a small ionic flow or a large one. Crucially, though, once these inputs reach the postsynaptic neuron’s firing threshold, there’s no variability in the response: Either a signal is sent down the axon or it is not; if the signal is sent, it is always of the same magnitude, a fact referred to as the all-or-none law.
  • Finally, let’s be clear about the central role of the synapse: Transmission across the synaptic gap does slow down the neuronal signal, but this is a tiny price to pay for the advantages created by this mode of signaling: Each neuron receives information from (i.e., has synapses with) many other neurons, and this allows the “receiving” neuron to integrate information from many sources. Among other benefits, this pattern of many neurons feeding into one makes it possible for a neuron to “compare” signals, and to adjust its functioning in light of information received from other sources. In addition, communication at the synapse is adjustable: The strength of a synaptic connection can be altered by experience, and this is almost certainly the biological basis for learning—the storage of new knowledge and new skills within the nervous system.
  • Vision is the modality through which much of our knowledge is acquired.
    Vision provides an excellent illustration of how the close study of the brain can proceed and what it can teach us.
  • The structure of the eye is designed to project a sharp image onto the retina, the light-sensitive tissue that lines the back of the eye.
    (A) Light enters the eye through the cornea, and the cornea and lens refract the light rays to produce a sharply focused image on the retina. The iris can open or close to control the amount of light that reaches the retina. (B) The retina is made up of three main layers: the rods and cones, which are the photoreceptors; the bipolar cells; and the ganglion cells, whose axons make up the optic nerve. Two other kinds of cells, horizontal cells and amacrine cells, allow for lateral (sideways) interaction. The retina also contains an anatomical oddity: the photoreceptors are at the very back, the bipolar cells are in between, and the ganglion cells are at the top. As a result, light has to pass through the other layers (they’re not opaque, so this is possible) to reach the rods and cones, whose stimulation starts the visual process.
  • Rods and cones stimulate bipolar cells, which in turn excite ganglion cells. The axons of ganglion cells converge to the optic nerve; this is the nerve tract that leaves the eyeball and carries information to various sites in the brain. This information travels to the thalamus called the lateral geniculate nucleus (LGN); from there, information is transmitted to the primary projection area for vision, in the occipital lobe.
  • Cells B and C receive the same input. Cell B, however, is inhibited by its neighbor on both sides (that is, is inhibited by Cells A and C). Cell C is inhibited by neighbors on only one side. (Cell D, one of C’s neighbors, is not being stimulated, and so is sending out no inhibition; therefore, Cell C receives inhibition from Cell B but not from Cell D.) As a result, Cell C will send a stronger signal to the brain, emphasizing the “edge” in the stimulus. By the same logic, Cells D and E receive the same input, but Cell D receives more inhibition. This cell will send a weaker signal to the brain, again emphasizing the edge of the dark gray patch. The spikes per second for each neuron are hypothetical figures.
  • Patterns of lateral inhibition between neighboring cells of the retina leads to edge enhancement.
  • A neuron’s firing rate, or frequency of action potentials, is recorded as various kinds of visual stimuli are presented to the subject. Investigators can manipulate what is being shown and then record how often the cell fires. This allows them to determine what stimulus characteristics influence the cell’s firing.
  • Using these methods, researchers map out the receptive field—the kinds of stimuli to which the neuron best responds—for various cells of the visual system.
    The receptive fields of the bipolar cells, ganglion cells, and cells in the lateral geniculate nucleus have a center-surround organization.
  • The receptive fields of the primary visual cortex (V1) are lines of particular orientations.
    These cells are sometimes called edge detectors.
  • Because of their different receptive fields, the neurons in area V1 are each specialized for a particular kind of analysis.
    This is an example of parallel processing, a system in which many different steps or kinds of analysis occur at the same time.
    The opposite of this is serial processing, in which steps are carried out one at a time.
  • Because of their different receptive fields, the neurons in area V1 are each specialized for a particular kind of analysis. This is an example of parallel processing, a system in which many different steps or kinds of analysis occur at the same time.
    The opposite of this is serial processing, in which steps are carried out one at a time. The advantage is that a complex process can be split up and worked on by different areas. Then these different processing streams can be quickly integrated. In parallel processing, one process does not have to wait for the other.
  • Another example of parallel processing is found earlier in the visual pathway in the ganglion cells, optic nerve, and LGN.
    Parvocellular cells have smaller receptive fields and tend to continue firing as long as the stimulus is present.
    Magnocellular cells have larger receptive fields and respond more strongly to changes in stimulation.
  • Parallel processing is also demonstrated by the higher visual pathways.
    From area V1, information is sent to many secondary cortical visual areas for further parallel processing.
  • These secondary visual areas lead to two major processing streams, the what system and the where system.
  • The what system:
    Is concerned with the identification of objects
    Involves an occipital-temporal pathway
    Damage to this system can result in visual agnosia (inability to recognize objects)
    The where system:
    Is concerned with determining the locations of objects and guiding our actions in response
    Involves an occipital-parietal pathway
    Damage to this system can result in problems with reaching for seen objects
  • With the great extent of parallel processing in the visual system, different aspects of a single object (e.g., shape, color, movement) are analyzed in different parts of the visual system.
    How the brain reunites these different features into a coherent, integrated perception of the objects in the visual scene is referred to as the binding problem.
  • Elements that help solve the binding problem:
    Spatial position—the visual areas processing features like shape, color, and motion each know the spatial position of the object.
    Neural synchrony—the visual areas processing features of the same object fire in a synchronous rhythm with each other.
  • Attention is also critical for the binding of visual features:
    When attention is overloaded, people will make conjunction errors—correctly detecting the features present on a visual display but making errors regarding how the features are bound together.
    For example, someone shown a blue “H” and a red “T” might report seeing a “red H” and a “blue T.”
  • Correct answer: a
    Feedback: It is not a recognition or memory problem. It involves binding emotion with a face.
  • Correct answer: c
    Feedback: Refer to Figure 2.1. The frontal lobe is in the front, occipital lobe in the back, and parietal and temporal lobes between the frontal and occipital. The parietal lobe is above the temporal.
  • Correct answer: c
    Feedback: They are present in both the left and right hemispheres.
  • Correct answer: d
    Feedback: TMS is used to temporarily stop neuronal firing. It does not measure anything.
  • Correct answer: a
    Feedback: These areas are later in the visual stream and hence depend on conscious visual processing.
  • Correct answer: a
    Feedback: Since it is sufficient. it causes a behavior when stimulated and prevents a behavior when disabled.
  • Correct answer: d
    Feedback: A lack of ability to move something has to do with apraxia. Aphasia has to do with language, neglect with attention and agnosia with object recognition.
  • Cog5 lecppt chapter02

    1. 1. © 2013 by W. W. Norton & Co., Inc. The Neural Basis for Cognition Chapter 2 Lecture Outline
    2. 2. Chapter 2: The Neural Basis for Cognition  Lecture Outline Capgras Syndrome: An Initial Example The Principal Structures of the Brain The Visual System
    3. 3. Chapter 2: The Neural Basis for Cognition  Brain-behavior functions Imaging of brain activity Impairment after damage
    4. 4. Capgras Syndrome: An Initial Example  Capgras syndrome  Recognize loved ones  But think they are impostors  May think they were kidnapped (or worse!)  May even see slight “defects”  情緒的解讀與認知發生衝突
    5. 5. Capgras Syndrome: An Initial Example  Capgras syndrome results from a conflict: Perceptual recognition is intact. But there is no emotion. Conflict Lack of familiarity
    6. 6. Capgras Syndrome: An Initial Example  Neuroimaging brain areas involved in Capgrass syndrome
    7. 7. Capgras Syndrome: An Initial Example  Amygdalar damage results in lack of emotional response
    8. 8. Capgras Syndrome: An Initial Example  Prefrontal cortex damage impairs reasoning  Illogical thoughts are not filtered out
    9. 9. Capgras Syndrome: An Initial Example  Factual and emotional knowledge are dissociated 9
    10. 10. Capgras Syndrome: An Initial Example  Cognitive psychology and cognitive neuroscience complement each other Amygdala linked to emotional processing in general
    11. 11. The Principal Structures of the Brain  One process is broken up by the brain and processed by different areas
    12. 12. The Principal Structures of the Brain 12
    13. 13. The Principal Structures of the Brain Gage’s skull A reconstruction of the lesion A portrait of Gage
    14. 14. The Principal Structures of the Brain  Loss of a function associated with normal processing
    15. 15. The Principal Structures of the Brain  Brain 15 Hindbrain Midbrain Forebrain
    16. 16. The Principal Structures of the Brain  Hindbrain. Atop the spinal cord Basic rhythms Alertness Cerebellum  Movements and balance  Sensory and cognitive roles
    17. 17. The Principal Structures of the Brain  The midbrain sits above the hindbrain  Coordinates movement, especially eye movement  Includes parts of the auditory pathways  Regulates the experience of pain
    18. 18. The Principal Structures of the Brain  The forebrain includes:  Cortex, convolutions  Subcortical structures 18
    19. 19. The Principal Structures of the Brain Axes Division Connection Left-right Longitudinal fissure Corpus callosum Anterior commisure Anterior-posterior Longitudinal fissure N/A Frontal-temporal Lateral Fissure
    20. 20. The Principal Structures of the Brain  Four cerebral lobes  Frontal lobe  Parietal lobe  Temporal lobe  Occipital lobe
    21. 21. The Principal Structures of the Brain  The subcortical parts of the forebrain include:  Thalamus  Hypothalamus  Limbic System  Amygdala  Hippocampus
    22. 22. Lateralization  Brain is roughly symmetrical Commissures connect hemispheres  Corpus callosum is the largest 22
    23. 23. Lateralization  Split brain patients Severing of the corpus callosum  Treatment of epilepsy  Limits right-left communication  23
    24. 24. The Principal Structures of the Brain  Cortical organization is contralateral The left side of the body or perceptual world has more representation on the right side of the brain, and vice versa
    25. 25. Lateralization 25 Left hemisphere produces language. Right hemisphere can only point. No language.
    26. 26. Neuropsychology  Neuropsychology Clinical neuropsychology Lesions 26
    27. 27. Data from Neuroimaging  Computerized axial tomography (CT)  X-rays   Positron emission tomography (PET)  Glucose   CT vs. PET
    28. 28. Data from Neuroimaging 28 Visual stimulation result in occipital lobe activity
    29. 29.  Magnetic resonance imaging (MRI) Data from Neuroimaging
    30. 30. Data from Neuroimaging  functional magnetic resonance imaging (fMRI)  30
    31. 31. Data from Neuroimaging  Electroencephalogram (EEG)  Buildup of chemical neurotransmitter  Firing of action potential in a neuron  Millions of neurons create an electrical field  31
    32. 32. Data from Neuroimaging  EEG cap with electrodes 32
    33. 33. Data from Neuroimaging  Every method has its limitations EEG is sensitive to time, not location fMRI detects location but is not time sensitive CT and MRI scans detect brain structures, not activity 33
    34. 34. Data from Neuroimaging  Combining techniques is more powerful EEG timing fMRI location 34
    35. 35. Data from Neuroimaging  The fusiform face area (FFA) is active when viewing faces  The parahippocampal place area (PPA) is active when viewing houses
    36. 36. The Principal Structures of the Brain  Increased activity only appears when person is consciously attending to one or the other
    37. 37. Data from Neuroimaging  Lesions to this area lead to face blindness 37
    38. 38. Data from Neuroimaging  The identified brain region may not be necessary  Activity may be correlated with task.  Transcranial magnetic stimulation (TMS) deactivates an area
    39. 39. Localization of Function  Specific brain areas have specific functions 39
    40. 40. The Cerebral Cortex Area Function Primary projection areas Sensory Input Motor Output Rest of cortex Association areas
    41. 41. The Cerebral Cortex  Primary motor projection areas Greater precision = more brain area Less precision = smaller brain area
    42. 42. The Cerebral Cortex  Primary projection areas of the cortex
    43. 43. The Cerebral Cortex  Orderly representation  Space proportional to acuity or precision  Contralateral representation
    44. 44. The Cerebral Cortex  Association Areas  Create associations between simple ideas and sensations 44
    45. 45. The Cerebral Cortex  Damage to association cortex results in problems with:  Apraxia – movement  Agnosia –identifying objects  Aphasia –language  Neglect syndrome – ignoring half the visual world  Prefrontal damage –planning, strategic thinking, inhibition
    46. 46. Brain Cells Detect incoming signals Nucleus and cellular machinery Transmits signals to other neurons
    47. 47. Brain Cells  Glia Guide development of nervous system Repairs damage Controls nutrient flow Electrical insulation speeds signal transmission 47
    48. 48. Presynaptic neuron Postsynaptic neuron Synapse Brain Cells
    49. 49. Brain Cells  Accumulation of neurotransmitter in postsynaptic cleft Will or will not trigger an action potential = all- or-none effect 49
    50. 50. Brain Cells  Synaptic transmission One neuron can receive information from many other neurons  Can compare many signals and adjust 50
    51. 51. The Visual System  Knowledge acquired through vision  Neural bases of vision well understood
    52. 52. The Visual System
    53. 53. The Visual System  Photoreceptors Rods Cones Lower sensitivity Higher sensitivity Lower acuity Higher acuity Color-blind Color-sensitive Periphery of the retina In the fovea
    54. 54. The Visual System 54 Rods are mostly in the periphery; cones mostly in the center
    55. 55. The Visual System  A series of neurons communicates information from the retina to the cortex In the eye:  Photoreceptors  Bipolar cells  Ganglion cells and the optic nerve In the thalamus:  Lateral geniculate nucleus (LGN) In the cortex:  V1, the primary visual projection area, or primary visual cortex, located in the occipital lobe
    56. 56. The Visual System  Cell C is more inhibited than cell B
    57. 57. The Visual System What we see is not what we perceive
    58. 58. The Visual System  Single-cell recording
    59. 59. The Visual System Stimulus in center leads to faster firing rates Stimulus in surrounding area leads to slower firing rates
    60. 60. The Visual System
    61. 61. The Visual System  Different neurons in area V1 are specialized, resulting in parallel processing, not serial processing.
    62. 62. The Visual System
    63. 63. The Visual System  Parallel processing in the visual pathway Parvocellular cells Magnocellular cells
    64. 64. The Visual System Object shape and identity Object location  Parallel processing in the visual system
    65. 65. The Visual System  The what and where system projected on the brain surface
    66. 66. The Visual System  The what system:  Identification of objects  Occipital-temporal pathway  Visual agnosia  The where system:  locations of objects and guiding our responses  Occipital-parietal pathway  Problems with reaching for seen objects
    67. 67. The Visual System Parallel processing splits up problem But we do not see the world as disjointed Binding problem
    68. 68. The Visual System  Elements that help solve the binding problem Spatial position Neural synchrony
    69. 69. The Visual System  Attention is also critical for the binding of visual features When attention is overloaded, people will make conjunction errors
    70. 70. The Visual System  Our account of vision requires both lower- level activities For example, what happens in individual neurons and the synaptic connections between them  And higher-level activities For example, the influence of attention on neural activity
    71. 71. Chapter 2 Questions
    72. 72. 1. A central problem in Capgras syndrome seems to be a difficulty with a) an emotional analysis of faces. b) matching faces that are in view to faces in memory. c) neither a nor b d) both a and b
    73. 73. 2. In the drawing at right, parts A, B, C, and D, are a) the frontal lobe, the occipital lobe, the parietal lobe, and the temporal lobe. b) the occipital lobe, the temporal lobe, the parietal lobe, and the frontal lobe. c) the parietal lobe, the frontal lobe, the temporal lobe, and the occipital lobe. d) the temporal lobe, the frontal lobe, the occipital lobe, and the parietal lobe.
    74. 74. 3. Many subcortical structures, such as the hippocampus and amygdala, come in groups of two. Why? a) Anatomy involves symmetry. b) There is a hindbrain and midbrain. c) It has to do with lateralization. d) none of the above
    75. 75. 4. Which of the following methodologies does not measure brain activity or structure? a) magnetic resonance imaging (MRI) b) computerized axial tomography (CT) c) positron emission tomography (PET) d) transcranial magnetic stimulation (TMS)
    76. 76. 5. In one study, investigators monitored activity levels in a brain area (the FFA) that seems particularly responsive to pictures of faces, and another area (the PPA), which seems particularly responsive to pictures of places. Their data showed that a) brain activity in these two regions depended on what the person was consciously perceiving and not just what the stimulus was. b) if a picture of a face was put in front of one eye and a picture of a different face was put in front of the other, then neither brain area would be highly activated. c) the activity of these areas could be predicted if one simply knew what stimulus was in front of the person’s eyes. d) high levels of activation were detected in the FFA even when pictures of houses were shown, illustrating the flexibility of brain function.
    77. 77. 6. If stimulating an area of the brain causes a behavior and disabling it with TMS prevents the behavior, then that area is _____ for that behavior. a) necessary and sufficient b) necessary but not sufficient c) sufficient but not necessary d) correlated with, but neither necessary nor sufficient
    78. 78. 7. Which of the following is the clinical term we use to describe a disturbance in the initiation or organization of voluntary action? a) aphasia b) neglect c) agnosia d) none of the above