1. The Brain

2. Lecture Overview Methods of Studying the Brain Structure of the Brain
Localization of Function
Brain Lateralization
Plasticity

3. Studying the Brain Study Brain Damage Recording the Brain
Animal Studies
Cases of Human Brain Damage
TMS
Recording the Brain
EEG
Neuroimaging
Using animals as subjects, researchers can examine the effects of brain damage by lesioning the animals brain

4. Researchers who study the effects of brain damage using animal subjects, lesion specific parts of the animals brain (make cuts or destroy small brain areas using an electrode), and examine deficits that occur after recovery
3.19 Brain lesioning All animal research strategies, including those aimed at creating a brain lesion, rely on a special apparatus that allows the precise measurement and placement of electrodes. 4

5. Brain Damage
In some animal studies, damage is produced in the laboratory.
But neuropsychologists often study naturally occurring cases of brain damage.
Transcranial magnetic stimulation (TMS):
Scientists can use TMS to study the effects of temporary brain damage.
Necessary????? 5

6. 3.21 Transcranial magnetic stimulation (TMS) At low intensities, TMS is used to stimulate specific brain regions. At higher intensities, TMS causes a temporary disruption. 6

7. Marcello Massimini/University of Wisconsin–Madison7

8. Recording the Brain Techniques are used to study the whole brain:
Electroencephalography
Uses sensitive electrodes on the scalp to measure voltages produced by brain activity
Neuroimaging
CT, MRI, fMRI, PET scans
Clinical observation of people or animals with brain damage or disease can lead to knowledge of how different areas of the brain causally contribute to specific functions.
Neuropsychology uses systematic experimentation to determine the effects of damage to a specific area of the brain, while transcranial magnetic stimulation allows researchers to temporarily disable a brain region and observe how this influences behavior and abilities. 8

9. AJ Photo/Photo Researchers
3.22 Recording brain waves The overall electricity of the brain can be measured via electrodes placed on the surface of the scalp. 9

10. Recording the Brain MRI and CT scans PET and fMRI scans
Study the brain’s anatomy—the size and location of individual structures
PET and fMRI scans
Reveal which brain locations are particularly active at any moment in time
Other techniques record from the whole brain; some, like electroencephalography (EEG), measure electrical activity; some, like computed axial tomography (CT scans) or magnetic resonance imaging (MRI), measure anatomical structure; and some, like positron emission tomography (PET) or functional MRI (fMRI), measure metabolic or blood-flow activity. Different methods have different advantages in spatial or temporal resolution. 10

11. (left) Custom Medical Stock Photo, (right) Neil Borden/Photo Researchers
3.23 Brain scans The CT scan (A) shows the brain of an 85-year-old woman. The MRI scan (B) shows the same brain in more detail. The dark regions are actually open spaces (called ventricles) within the brain, which are filled with fluid. The distinction between the brain’s white matter and gray matter is also visible. 11

12. The entire brain is active all the time, imaging shows increases in activity beyond a “baseline”

13. Recording the Brain
All these techniques make it clear that most activities rely on many brain sites.
Activities like reading or making decisions are supported by coordinated functioning of many different parts of brain.
An important point is that the entire brain is active all the time, and neuroimaging techniques show patterns of increases in activity beyond the constant “baseline” state.
If an area is said to be involved in a specific task, it is because that area becomes more active during the task.
To understand the relationship between the brain and behavior, researchers increasingly use several of these techniques together, combining their advantages to draw stronger inferences about brain function and causation. 13

14. Brain Anatomy

15. Brain Structure The very top of the spinal cord forms the brain stem.
It includes the medulla and the pons.
Just behind these is the cerebellum.
The midbrain is on top of the pons, and on top of them all is the forebrain.
Within the central nervous system (CNS), the brain can be divided into several large structures.
The brain stem, medulla, and pons control key life-sustaining functions, while the cerebellum is involved in movement and sensory integration.
The midbrain and thalamus relay and process sensory information and perform early regulatory functions. 15

16. 3.27 The brain stem The brain stem, consisting of the structures at the very top of the spinal cord, includes the pons and the medulla.
Medulla– respiration, blood circulation, maintaining balance
Pons– attentiveness, sleep and dreaming
Cerebellum– movement and integration of sensory information
Midbrain– direct information to the forebrain, pain, mood, motivation
Thalammus– relay station for forebrain 16

17. 3.29 The limbic system The limbic system is made up of a number of subcortical structures.
Hypothatlamus– control of motivated behaviors (eating, drinking, fightling, fleeing, mating)--- not actually part of the limbic system
Amygdala– emotions, (fear, anger)
Hippocampus– learning and memory 17

18. The Cortex The outer surface of forebrain is the cerebral cortex.
The cortex is a large, thin sheet of tissue crumpled inside the skull.
Some of the convolutions divide the brain into sections:
The frontal lobes, the parietal lobes, the occipital lobes, and the temporal lobes
The cerebral cortex, whose structures contribute to complex intelligent functions; the forebrain, located underneath the cortex, includes key structures involved in memory and emotion, like the hypothalamus, amygdala, and hippocampus.
The cortex is divided into the frontal, parietal, temporal, and occipital lobes. 18

19. (photo) Corbis
Central fissue divides frontal lobes from parietal lobes
Longitudinal fissure– separates right and left hemispheres
Lateral fissure
Here is the angular gyrus– which is implicated in language, mathematics, and cognition
3.28 The cortex of the cerebral hemispheres (A) Side-view diagram of the brain’s convolutions, fissures, and lobes. The cortex hides most of the brain’s other parts from view, although the cerebellum and brain stem are visible. (B) An actual human brain, shown from the side; the front of the head faces left. 19

20. Left and Right Hemispheres
The brain is symmetrical around the midline.
Most structures come in pairs:
One on the left side
One on the right side
The longitudinal fissure of the cerebral cortex divides the brain into the left and right hemispheres, which are more or less symmetrical. 20

21. Localization of Function
Different parts of the brain serve specialized functions
Sensory Information
Motor Control
Perception
Language
Planning and Social Cognition

22. Cerebral Cortex Some parts serve as projection areas:
The first receiving stations for information coming from the sense organs (e.g., somatosensory projection areas)
Departure points for signals going to the muscles (e.g., motor projection area)

23. Cerebral Cortex
Adjacent sites in the brains usually represent adjacent parts of the body.
Assignment of space is disproportionate:
Usually the parts of the body that are most sensitive to touch receive the most space (in somatosensory projection area).
Parts of the body that we can move with more precision receive the most space (in primary motor projection area)
In each area, a specific region of the cortex corresponds to a specific region of the body.
Both areas demonstrate contralateral control: the left hemisphere controls the right side of the body and receives sensory input from the right side of the body, and vice versa.
The somatosensory and motor areas devote the most cortical space to those parts of the body that require the most precision or sensitivity.
The visual cortex and auditory cortex are organized topographically; adjacent areas in the visual cortex represent adjacent areas in visual space, and the auditory cortex is organized by pitch. 23

24. 3.33 The primary motor and somatosensory projection areas The primary motor projection area is located at the rearmost edge of the frontal lobe, and each region within this projection area controls the motion of a specific body part, as illustrated on the top left. The primary somatosensory projection area, receiving information from the skin, is at the forward edge of the parietal lobe; each region within this area receives input from a specific body part. The primary projection areas for vision and hearing are located in the occipital and temporal lobes, respectively. These two areas are also organized systematically. For example, in the visual projection area, adjacent areas of the brain receive visual inputs that come from adjacent areas in visual space. 24

25. Courtesy of The Natural History Museum, London
3.34 The sensory homunculus An artist’s rendition of what a man would look like if his appearance were proportional to the area allotted by the somatosensory cortex to his various body parts. 25

26. Cerebral Cortex Most projection areas have contralateral organization:
Left hemisphere receives information from right side of body (sensory), or controls right side of body (motor)
Right hemisphere receives information from left side of body (sensory), or controls left side of body (motor)
One last brain damage study that illustrates lateralization

28. Cortical Damage
Much of what we know about the cortex comes from studying brain damage.
Damage at identifiable sites can produce:
Apraxias (disorders in action)
Agnosias (disorders in perception)
Aphasias (disorders of language)
Disorders of planning or social cognition
Apraxias, disturbances in organizing or initiating actions, result from some lesions to the frontal lobe.
Damage to the occipital-parietal region can result in agnosia, the inability to recognize objects, or (with some parietal and temporal damage) prosopagnosia, the inability to recognize faces.
Right hemisphere parietal damage can lead to neglect syndrome, a systematic neglect of the left side of the visual field.
Damage to Broca’s area leads to nonfluent aphasia, while damage to Wernicke’s area leads to fluent aphasia.
Damage to the prefrontal area (as in the case of Phineas Gage) leads to a loss of executive control, response inhibition, and decision making. 28

29. Apraxias
Difficulty in carrying out purposeful movements without the loss of muscle strength or coordination
Disconnection between primary and non-primary motor areas
Able to carry out each part of a complex movement, but disruption lies in coordination of the movements
Damage to the nonprimary motor association areas

30. Agnosias
Visual agnosia: disturbance in recognizing visual stimuli despite the ability to see and describe them
Prosopagnosia: inability to recognize faces (fusiform face area)
Neglect Syndrome: complete inattentiveness to stimuli on one side of the body
Akinetopsia: inability to perceive movement
“I see the world in snapshots – like frames of a move but most of the frames are missing”
Damage to the occipital-parietal region can result in agnosia, the inability to recognize objects, or (with some parietal and temporal damage) prosopagnosia, the inability to recognize faces.
Right hemisphere parietal damage can lead to neglect syndrome, a systematic neglect of the left side of the visual field. Damage to visual association cortex, or areas of the parietal lobe that receive information from the occipital lobe
-2nd link describes prosopagnosia,

31. Aphasias
Broca’s Aphasia: disturbance in speech production, caused by damage to Broca’s area
Agrammaticism
Anomia
Difficulty with articulation
Wernicke’s Aphasia: disturbance in speech comprehension, caused by damage to Wernicke’s area
Disruption in recognition of spoken words
Disruption in comprehension of the meaning of words
Inability to convert thought into words
Left hemisphere…there are others as well such as pure word deafness

32. Nature Reviews Neuroscience, 5 (October 2004): 812–819
3.36 Areas of the brain crucial for language (A) Many sites in the brain play a key role in the production and comprehension of language. In right-handed people, these sites are located in the left hemisphere, generally at the lower edge of the frontal lobe and the upper edge of the temporal lobe. Broca’s area, long thought to play a central role in speech production, is located near the areas that control speech muscles; Wernicke’s area, which plays a central role in our comprehension of speech, is near other areas that play a key part in audition. (B) This photo shows the brain of Broca’s actual patient, preserved from the nineteenth century. 32

33. (left) Wikimedia. com, (right) Damasio et al
(left) Wikimedia.com, (right) Damasio et al., “The Return of Phineas Gage,” Science, 264 (1994). Courtesy of Hanna Damasio
Profane, little deference (insubordinate, impatient, capricious, changing plans frequently
3.20 Phineas Gage (A) A photograph of Phineas Gage and the actual rod that passed through his brain. (B) A computer reconstruction showing the path of the rod. 33

34. Disorders of Planning and Social Cognition
Caused by damage to prefrontal area
Disrupts executive control– processes that allow us to direct our own cognitive activities
e.g., setting priorities, planning, strategizing, ignoring distractors
Case Studies of Brain Damage provides us with insight into the localization of functions within the brain…I have one more case study of brain damage to talk about, but whereas the previously mentioned studies concerned localization (specialization of specific areas of the brain), the following concerns specialization of the two hemispheres of the brain (lateralization)

35. Lateralization The left and right hemispheres are generally similar
However, the two hemispheres have specialized capacities
Left hemisphere: language
Right Hemisphere: visual and spatial tasks
The two halves of the brain work as an integrated whole
Communicate with each another through commissures
Split Brain Patients

36. 3.30 Corpus callosum In this drawing, the two halves of the brain are shown as if pulled apart, revealing the corpus callosum, one of the main bundles of fibers carrying information back and forth between the hemispheres. 36

37. Other Split Brain Experiments
3.31 The split-brain patient 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-hand side of the visual world.
Other Split Brain Experiments 37

38. Plasticity
The brain is plastic—subject to alteration in the way it functions, such as:
Changes in the brain’s overall architecture
The central nervous system can grow new neurons:
But appears unable to do so with cortical injury
This promotes stability in the brain’s connections but is an obstacle to recovery from brain damage.
On a larger scale, whole regions of the cortex can be reorganized with experience; for example, musicians who require sensitivity and skill in their fingers have more cortical area devoted to representing information about the fingers.
Similarly, individuals who are blind can show visual cortex activation to somatosensory tasks, suggesting that even specialized parts of the cortex can take on new roles.
Finally, evidence suggests that neurogenesis in response to learning continues throughout life, although the central nervous system does not appear to be able to grow new neurons to replace neurons damaged through injury.
Controversial research that induces stem cells to turn into healthy neurons, however, may lead to successful therapies for injuries and diseases of the nervous system. 38

39. Plasticity
Neurons are subject to alteration in the way they function, such as:
Changes in how much neurotransmitter a presynaptic neuron releases
Changes in neuron sensitivity to neurotransmitters
Creating new connections by growing new dendritic spines
- Important for learning 39