Notes for Unit 3B: The Brain, p. 66ff
Updated notes for 20ll
(goes with Ch. 2 for 2007 book)
Tools of Discovery, pp. 68-70
How do scientists study the brain’s connections to behavior and mind?
Lesion tissue destruction; a brain lesion is a naturally or experimentally caused destruction of brain tissue
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
PET (positron emission tomography) Scan is a visual display of brain activity that detects a radioactive form of glucose while the brain performs a given task.
MRI (magnetic resonance imaging) uses magnetic fields and radio waves to produce computer-generated images that distinguish among different types of brain tissue. Top images show ventricular enlargement in a schizophrenic patient. Bottom image shows brain regions when a participants lies.
fMRI Functional Magnetic Resonance Imaging. Goes beyond taking a picture of the brain Shows video of the brain in action as the brain thinks and responds to the environment.
Computed Tomograph Scan: a series of x-ray photographs taken from different angles and combined by computer into a composite representation of a slice through the body. Also called CT scan.
Older Brain, pp. 69
What are the functions of lower level brain structures?
The Brainstem is the oldest part of the brain, beginning where the spinal cord swells and enters the skull. It is responsible for automatic survival functions.
The Medulla [muh-DUL-uh] is the base of the brainstem that controls heartbeat and breathing.
Reticular Formation is a nerve network in the brainstem that plays an important role in controlling arousal. May play a role in dreaming: the activation synthesis theory of McCarley and Hobson.
The Thalamus: the brain’s sensory switchboard, located on top of the brainstem. It directs messages to the sensory areas (visual, auditory, etc) in the cortex and transmits replies to the cerebellum and medulla.
Cerebellum: The “little brain” attached to the rear of the brainstem. It helps coordinate voluntary movements and balance.
The Limbic System is a doughnut-shaped system of neural structures at the border of the brainstem and cerebrum, associated with emotions such as fear, aggression and drives for food and sex. It includes the hippocampus, amygdala, and hypothalamus.
Parts of the Limbic System:
H.A.H.!:
Hypothalamus
Amygdala
Hippocampus
Hippocampus: memory. An elephant never forgets (which is sorta like a hippo).
The Amygdala consists of two almond-shaped neural clusters linked to the emotions of fear and anger.
Amygdala- aggression and fear. “I once dated Amy G. Dala. We broke up because she was always angry and afraid of everything.”
The Hypothalamus lies below (hypo) the thalamus. It directs several maintenance activities like eating, drinking, body temperature, and control of emotions. It helps govern the endocrine system via the pituitary gland. This was identified by Olds and Milner as the pleasure center in the brain
Cerebral Cortex, pp. 74-
What functions are served by the various cerebral cortex regions?
The intricate fabric of interconnected neural cells that covers the cerebral hemispheres. It is the body’s ultimate control and information processing center.
Each brain hemisphere is divided into four lobe(eight total, one in each hemisphere) that are separated by prominent fissures. These lobes are the frontal lobe (forehead), parietal lobe (top to rear head), occipital lobe (back head) and temporal lobe (side of head).
Parietal lobe: Awareness of where your feet and hands are (proprioception); controls touch and other senses; if you scratch the top of your head you’re at this lobe.
Frontal lobe: Deciding your driving destination and how you will get there; conscious control of voluntary movement; controls judgment.
Temporal lobe: Interpreting auditory information about traffic; balance (vestibular sense); near the ears.
Occipital lobe: Interpreting visual information from the instrument panel and traffic; if you get hit on the back of the head, you may see stars; this lobe is located there.
Gyri are the grooves in the brain’s surface; sulci are the humps between the grooves.
The Motor Cortex is the area at the rear of the frontal lobes that control voluntary movements.
Mapping the motor cortex. Foerster and Penfield mapped the cortex by stimulating wide awake patients.
The Sensory Cortex (parietal cortex) receives information from skin surface and sense organs.
Fig. 3B.13 shows the sensory homunculus, the amount and location of the brain devoted to each sense. Largely developed by Wilder Penfield.
p. 76-77: Neural prosthetics can be used to help paralyzed humans control aspects of their environment.
Association Areas, 78
Areas of the cerebral cortex that are not involved in primary motor or sensory functions
involved in higher mental functions such as learning, remembering, thinking, and speaking
Phineas Gage: Injured in an 1848 accident when a steel pipe passed through his head, his personality changed; the frontal cortex, where judgment occurs, was disconnected from his emotion center in the limbic system.
What areas of the brain are involved in language processing? Page 80
Broca’s area ( speaking); People suffering from damage to this area may show a condition called Broca's aphasia where they are unable to understand or create grammatically complex sentences; their speech will contain almost nothing but content words.
Wernicke’s area (understanding). Wernicke’s area: an area in the posterior temporal lobe of the left hemisphere of the brain involved in the recognition of spoken words.
In processing language the brain divides mental functions into subfunctions: speaking, perceiving, thinking, and remembering.
The brain’s plasticity: To what extent can a damaged brain reorganize itself? 82
Plasticity refers to the brain’s ability to modify itself after some type of injury or illness.
Easier the younger you are
The blind can learn to see using their hearing: see vid clip in Brain Games.
Constraint induced therapy is used for those needing to retrain a bad hand or leg.
Neurogenesis: growing new neurons (may occur with shock therapy for the depressed).
Our Divided Brain, pp. 83-91
What do split brains reveal about the functions of our two hemispheres?
Corpus Callosum: largest bundle of neural fibers; connects the two brain hemispheres; carries messages between the hemispheres
With the corpus callosum severed, objects presented in the right visual field can be named. Objects in the left visual field cannot.
In his Nobel Prize winning work, Roger Sperry separated the corpus callosum, the area of the brain used to transfer signals between the right and left hemispheres, to treat epileptics. One of the first was a Korean War veteran.
Through his study of patients with hemispheric disconnection, which he cointed "split brains," Michael Gazzaniga, a young grad student of Sperry’s, has discovered that the two sides of the brain interpret and organize information differently. The left hemisphere is the interpreter, constructing theories to explain our behavior.
Our brain is divided into two hemispheres.
The left hemisphere processes reading, writing, speaking, mathematics, and comprehension skills. Even deaf people process language in the left hem. In the 1960s, it was termed as the dominant brain.
The right hemisphere perceives objects easily, understands simple requests, understands emotions, recognizes faces, and is more engaged with quick responses. The rt. Hem. orchestrates our sense of self.
A number of brain scan studies show normal individuals engage their right brain when completing a perceptual task and their left brain when carrying out a linguistic task.
COMPLEX ACTIVITIES SEEM TO EMERGE FROM THE ACTIVITIES OF BOTH HEMISPHERES WORKING TOGETHER; A PROCESS CALLED INTEGRATION
Brain organization and handedness, page 88
How does handedness relate to brain organization?
Most right handers process speech in the left hemisphere as do 70% of lefties.
Is handedness inherited? Yes. Archival and historic studies, as well as modern medical studies, show that the right hand is preferred. This suggests genes and/or prenatal factors influence handedness.
The brain and consciousness, page 89
What is the dual processing being revealed by today’s cognitive neuroscience?
Consciousness: our awareness of self and environment
Cognitive neuroscience: how changes in the brain relate to cognitive activities
Computers run on serial processing; human brains on parallel processing. As a result humans can tackle several mental tasks at once, while computers do things one a time.
Dual processing: our mental activity often operates on two levels: conscious and unconscious.
The two track mind: (Goodale and Milner)
Visual perception track: mental furniture allowing us to think about the world
Visual action track: guides moment to moment thought
Conflicts between the two create illusions in your mind. (hollow face illusion on page 90)
Some neural activity precedes consciousness. (Libert experiment on page 91)
Sigmund Freud was correct about the importance of unconscious processing though not necessarily about what he unconscious contains (the id).
KNOW THE KEY TERMS ON PAGE 92
TRY the practice questions on pp. 92-93