1. Studying the Brain, the Old Brain, and the Limbic System
AP Psychology
Mr Tulper 2013

2. How do we study the brain?
There are many methods.
lesion: tissue destruction. A brain lesion is a naturally or experimentally caused destruction of brain tissue.
Scientists and doctors can selectively lesion small areas of normal or defective brain cells, leaving the surrounding brain unharmed.

3. Clinical Observation
The oldest method of studying the brain-mind connection, by observing the effects of specific brain diseases and injuries.
There are records of thousands of brain-injured patients across the country.
These stories provide clues to our own brains’ inner workings.

4. Manipulating the Brain
Scientists can electrically, chemically, or magnetically stimulate various parts of the brain and note effects.
They also surgically lesion specific brain areas in animals.
Video: Transcranial Magnetic Stimulation

5. Recording the brain’s electrical activity
Scientists can stick a tiny microelectrode into a single neuron to measure its activity.

6. Recording the brain’s electrical activity
electroencephalogram (EEG): an amplified recording of the waves of electrical activity that sweep across the brain’s surface. These waves are measured by electrodes placed on the scalp.
Repeated study of the read-out can help researchers filter out brain activity and find the electrical wave caused by the specific stimulus.

7. Neuroimaging Techniques
Ways to observe the brain in a living person.

8. PET Scan
PET (positron emission tomorgraphy) scan: a visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task.
Active neurons hog the glucose (the brain’s chemical fuel), and the PET scan tracks where in the brain the radioactive glucose goes.
Researchers can have participants think about certain topics or do activities to see where the glucose goes (thereby showing what part of the brain is active during that activity).

9. PET Scan

10. MRI
MRI (magnetic resonance imaging): a technique that uses magnetic fields and radio waves to produce computer-generated images that distinguish among different types of soft tissue; allows us to see structures within the brain.
Putting one’s head into a strong magnetic field aligns the spinning atoms.
A pulse of a radio wave disorients the atoms briefly.
When the atoms return to their normal spin, they release signals that give us a detailed image of the body.
Video: MRI

11. fMRI
fMRI (functional magnetic resonance imaging): a technique for revealing blood flow and, therefore, brain activity by comparing successive MRI scans. MRI scans show brain anatomy; fMRI scans show brain functions.
Researchers compare images taken less than a second apart, they can see which parts of the brain “light up” with increased blood flow.

12. fMRI
fMRI (functional magnetic resonance imaging): a technique for revealing blood flow and, therefore, brain activity by comparing successive MRI scans. MRI scans show brain anatomy; fMRI scans show brain functions.
Researchers compare images taken less than a second apart, they can see which parts of the brain “light up” with increased blood flow.
Video: fMRI

13. Older Brain Structures
The brain makes up 1/45th of a person’s body weight.
There are newer structures that help animals think in more complex ways
There are also older structures that have not changed much over many, many years.

14. The Brainstem
The brainstem: The oldest part and central core of the brain, beginning where the spinal cord swells as it enters the skull; the brainstem is responsible for automatic survival functions.

15. The Brainstem
medulla: the base of the brainstem; controls heartbeat and breathing.
pons: right above the medulla, it helps coordinate movement
The brainstem is a crossover point, where most nerves to and from each side of the brain connect with the body’s opposite side.

16. Reticular Formation
reticular formation: a nerve network in the brainstem that plays an important role in controlling arousal.
finger-shaped network of neurons that extends from the spinal cord right up to the thalamus.
filters incoming stimuli and relates important information to other areas of the brain.

17. Reticular Formation

18. Thalamus
thalamus: the brain’s sensory switchboard, located on top of the brainstem; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla.
receives information from all the senses except smell.

19. Cerebellum
Cerebellum: the “little brain” attached to the rear of the brainstem
Its functions include processing sensory input and coordinating movement output and balance.
It also enables one type of nonverbal learning and memory.
Helps us judge time, modulate our emotions, and discriminate sounds and textures.
Coordinates voluntary movement.

20. Cerebellum

21. Older Brain Structures
***Most of these older brain functions occur without any conscious effort

22. DO NOW:
What are three ways scientists can study the brain?

23. The Limbic System
A doughnut-shaped system of neural structures at the border of the brainstem and cerebral hemispheres.
Associated with emotions such as fear and aggression, and drives such as those for food.
Includes the hippocampus, amygdala, and hypothalamus.

24. Amygdala
Amygdala: two lima bean-sized neural clusters that are components of the limbic system and are linked to emotion.
Associated with both rage and fear
BUT, other areas of the brain are involved as well, not just the amygdala.
Research has shown that lesioning the amygdala in violent monkeys has transformed them into peaceful creatures.
However, people with the same damage may have been calmer, but lost other forms of functioning as well.

25. Amygdala

26. Hypothalamus
Hypothalamus: a neural structure lying below the thalamus.
It directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system via the pituitary gland, and is linked to emotion.
It both monitors blood chemistry and takes orders from other parts of the brain.
Is a “reward center” in the brain.

27. Hypothalamus

28. Hypothalamus
May be related to “reward deficiency syndrome” – a genetically disposed deficiency in the natural brain systems for pleasure and well-being that leads people to crave whatever provides that missing pleasure or relieves negative feelings.

29. The Cerebral Cortex
The intricate fabric of interconnected neural cells that covers the cerebral hemispheres; the body’s ultimate control and information-processing center.
Like the bark of a tree, this is the brain’s outer layer.

30. The Cerebral Cortex
Adaptability increases as the cerebral cortex expands and genetic controls relax.
Larger cortex = increased capabilities for learning and thinking
What makes humans different from animals is the complex functions of our brain’s cerebral cortex.

31. Structure of the Cortex
80% of the brain’s weight comes from the left and right cerebral hemispheres.
They are filled with mostly axon connections between the surface and its other regions.
The cortex contains around 20 to 23 billion nerve cells.

32. Structure of the Cortex
The wrinkled surface greatly increases the overall surface area of the brain, and therefore increases its complexity.
Lower mammals have smoother cortexes, and therefore simpler brains.

33. Glial Cells
Cells in the nervous system that support, nourish, and protect neurons.
a.k.a “glue cells”
They guide neural connections, provide nutrients and insulating myelin, and mop up ions and neurotransmitters.
They may play a role in learning and thinking by “talking” to neurons.
Fun fact: Einstein’s brain didn’t have larger or more than normal amount of neurons, but it did have a larger concentration of glial cells.

34. Lobes of the Brain
Divided by prominent fissures, or folds, in the brain.
Frontal lobes: start at the front of your brain and go over the top of it, behind your forehead.
Parietal lobes: at the top and to the rear of the head.

35. Lobes of the Brain Occipital lobes: the back of your head.
Temporal lobes: on the sides of your head, just above your ears.
Each lobe does specific functions, and many functions are completed with the interaction of several lobes.

36. Functions of the Cortex
Where do certain functions take place in the cortex?
It is hard to say where complex activities take place (most likely in several areas), but scientists have localized some simple functions.

37. Motor Functions
Motor Cortex: an area at the rear of the frontal lobes that controls voluntary movements.
Researchers have found that when they stimulate specific parts of the motor cortex in the left or right hemispheres, specific body parts moved on the opposite side of the body.

38. Mapping the Motor Cortex
Otfrid Foerster and Wilder Penfield both individually researched the motor cortex in patients who were awake during the procedure.
This did not cause any pain because there are no sensory receptors in the brain.
They stimulated different cortical areas and noted that different parts of the motor cortex caused different body parts to move.

39. Mapping the Motor Cortex
They created a map of the motor cortex, according to the body parts it controls.
The amount of cortex devoted to a body part is not proportional to that part’s size. Instead, the brain devotes more tissue to sensitive areas and to areas requiring precise control.
E.g. the fingers have more cortex devoted to them than the arm.

40. Neural Prosthetics
Research has been done on monkeys to determine whether our knowledge of the motor cortex could give movement to someone lacking mobility.
They implanted electrodes into the monkeys brains and recorded activity (e.g. moving a joystick on a computer or reaching for a specific spot on a computer screen).
Then, the neural activity was recorded and programmed into a computer.

41. Neural Prosthetics
When the monkey thought about the movement, the computer could now make the cursor move in response to the monkey’s thoughts.
The first human trial was approved by the US Food and Drug Administration in 2004 for a 25-year-old paralyzed man.
They implanted a small (aspirin-sized) chip in his head on his cortex that records activity.
He can now mentally control a television, draw shapes on a computer screen, and play video games with only his thoughts to control them.

42. Sensory Functions
Sensory cortex: the area at the front of the parietal lobes that registers and processes body touch and movement sensations.
Runs parallel to the motor cortex and just behind it.
It is the part of the cortex that receives the incoming messages.

43. Sensory Functions
If you stimulate a point on this cortex, people may report feeling like they’re being touched somewhere else on the body.
Again, more sensitive areas have more cortex devoted to them.
We also receive visual information in our occipital lobes at the very back of our brains.
Sound is processed in the auditory areas of our temporal lobes.

44. Association Areas
Three-fourths of our cortex is dedicated to our association areas.
Areas of the cerebral cortex that are not involved in primary motor or sensory functions.
They are involved in higher mental functions, such as learning, remembering, thinking, and speaking.

45. Association Areas
We cannot specify the functions of association areas because stimulating these parts of the cortex does not produce an observable response.
Association areas in our frontal lobes help us judge, plan, and process new memories.
Frontal lobe damage can also affect personality, removing inhibitions.
Take the case of Phineas Gage: his mental abilities and memories were intact after his accident, but his personality completely changed.