Chapter 2
Cognitive Neuroscience
Outline For Chapter 2 34
Supplemental Activities 37
A. In-Class Activities
1. A Working Neuron in the Classroom
2. Group Reaction Time and Neural Speed
3. Hemispheric Activity Interferes with Ability to Work a Counter
B. Promoting Discussion
1. Neurogenesis - Alcohol
2. Doogie Mice
CogLab Answers 44
Brain Asymmetry
Useful Websites 46
Test Bank 48
Outline for Chapter 2
I. FROM NEURON TO THE BRAIN: ORGANIZATION OF THE NERVOUS SYSTEM
A. Introduction
1. Mind Body Connection
2. Localization of Function
II. COGNITION IN THE BRAIN: CEREBRAL CORTEX AND OTHER STRUCTURES
A. Gross Anatomy of the Brain Forebrain, Midbrain, Hindbrain
1. Forebrain
a. Cerebral Cortex
b. Basil Ganglia
c. Limbic system
d. Septum
c. Amygdala
i. Maladaptive lack of fear
ii. Autism
d. Hippocampus
i. Korsakoff’s syndrome
ii. H.M.
f. Thalamus
i. Schizophrenia Link
g. Hypothalamus
i. Narcolepsy
2. Midbrain
a. Reticular activating system (RAS)
b. Brain stem
3. Hindbrain
a. Medulla oblongata
b. Pons
c. Cerebellum
B. Cerebral Cortex and Localization of Function
1. General Information
a. Cerebral cortex
b. Contralateral
c. Ipsilateral
d. Corpus callosum
e. Cerebral hemispheres
2. Hemispheric Specialization
a. Aphasia
b. Broca’s area
c. Wernicke’s area
d. Split-brain patients
i. Sperry’s Research
ii. Gazzaniga’s Research
e. Apraxia
3. Lobes of the Cerebral Hemispheres
a. Lobes
b. Frontal lobe
c. Parietal lobe
d. Temporal lobe
e. Occipital lobe
f. Projection areas
g. Primary motor cortex
h. Primary somatosensory cortex
4. Rostral, Ventral, Caudal and Dorsal brain regions
C. Neuronal Structure and Function
1. Neurons
a. Soma
b. Dendrites
c. Axon
i. myelin
ii. nodes of Ranvier
d. Terminal button
2. Synapse
3. Neurotransmitters
a. Three types of chemical substances involved in neurotransmission
i. Monoamine neurotransmitters
ii. Amino-acid neurotransmitters
iii. Neuropeptides
b. Acetylcholine
i. Deficit leads to Alzheimer’s
c. Dopamine
i. Too high linked with schizophrenia and lack of impulse control
ii. Too low linked with Parkinson’s disease
d. Serotonin
i. Too high linked with Anorexia
ii. Too low linked with aggression
4. Receptors and Drugs
a. Acute Toxicity
b. Chronic Toxicity
III. RESEARCH METHODS TO STUDY COGNITION IN THE BRAIN
A. Postmortem Studies
1. Phineas Gage
2. Brocas Tan
B. In Vivo Studies
1. Animal studies
a. Single-Cell Recordings
b. Lesioning to identify deficits
c. Neurochemicals to knock out functions
d. Genetic Manipulations
2. Electrical Recordings
a. Event-Related Potentials
b. Electroencephalograms (EEGs)
3. Static Imaging Techniques
a. Magnetic Resonance Imaging (MRI) Scan
4. Metabolic Imaging
a. Positron Emission Tomography (PET)
b. Functional Magnetic Resonance Imaging (fMRI)
c. Transcranial Magnetic Stimulation (TMS)
d. Magnetoencephalography (MEG)
5. Brain Disorders
a. Stroke
i. Vascular
ii. Ischemic stroke
iii. Hemorrhagic stroke
6. Brain Tumors
a. Neoplasms
7. Head Injuries
a. Closed-head injuries
b. Open-head injuries
IV. EXAMINING INTELLIGENCE AND BRAIN STRUCTURE
A. Brain size
B. Brain Architecture
1. Gender differences
C. Speed of Neuronal Conduction
D. Neuronal Efficiency
E. P-FIT Theory of Intelligence
V. REVISITING KEY THEMES
1. Biological versus Behavioral Methods
2. Nature versus Nurture
3. Applied versus Basic
Supplemental Activities
A. In-Class Activities
1. A Working Neuron in the Classroom
This demonstration gets students involved in understanding how neurons work. Several variants of this exercise exist (with and without the candy). Before the exercise, the instructor procures a bag of Hershey’s Kisses and also scatters index cards around the classroom. The kisses will represent neurotransmitters and the cards will stand for positive ions.
Assign five students who are willing to eat chocolate to come to the front of the class and act as dendrites (four students) and a cell body. Another five students are assigned to be the axon and they stand in a line. Two or three more students are the terminal fibers, clustered at the end of the axon. The terminal fibers are given Hershey’s Kisses but are instructed not to eat them. A second neuron can be formed in a similar manner if there are enough students in the class.
The instructor stands near the dendrites of the (first) neuron and tosses a handful of Hershey’s Kisses in the direction of the dendrites and cell body. This action represents the release of neurotransmitters into the synapse. The students who are acting the part of the dendrites and cell body eat the chocolate kisses and then begin to pick up the cards. When they have picked up three cards, the instructor advises them that they have reached the threshold. This demonstrates the “all-or-nothing” principle of an action potential. Now the first person forming the axon picks up a card, while the dendrites and cell body drop theirs. The second person forming the axon picks up a card as the first drops his or hers, etc. on down the line to the terminal fibers. The fibers then toss their chocolate kisses into the synapse. If a second neuron has been formed, the players repeat the process, if not, the instructor can take them, or the fibers can eat them (re-uptake.) The chocolate kisses can also be tossed to the other students in the class.
Variants of this exercise use different colored index cards, or Styrofoam peanuts instead of candy. The availability of chocolate kisses and “Hugs” with different colored wrappers also allows an instructor to demonstrate the action of agonist versus antagonist neurotransmitters and drugs. The dendrites can wrap their hands in tape to catch the kisses, cards, peanuts or whatever is being used. The axon can be “myelinated” using plastic wrap to demonstrate the insulating and transmission speeding qualities of the myelin sheath. (The message skips over the wrapped students, which saves time.)
This is a great exercise for getting the students involved and interested before introducing them to the fact-intensive and challenging biological psychology material, as well as demonstrating these concepts in a lively manner.
Written by Nancy Jo Melucci, Santa Monica College
2. Group Reaction Time and Neural Speed
Helmholtz devised a clever way to assess the speed of neural conduction. This same process can be demonstrated in class by having 10 students form a continuous chain by holding hands. At your signal, the first student tightens her grip on the hand of the second person in the chain. Upon feeling the pressure, the second person tightens his grip on the hand of the third, and so on. Have a volunteer start a stopwatch simultaneously with your signal, and stop timing when the 10th person raises her hand. Now have the students grip their neighbors’ shoulder and repeat the same procedure, again making note of the total time to finish the motion down the human chain. The results will show that the students performed the shoulder-squeezing task consistently faster than they performed the hand-squeezing task. The reason for the difference is that when the sensory input is received through the hand, it has to travel a greater distance—about two feet in the average-sized person—to reach the brain than when it is received through the shoulder. Thus, among the 10 people, the neural signal has to travel an additional 20 feet, and this is why it takes longer to reach the end of the chain (Rozin & Jonides, 1977).
Written by Nancy Jo Melucci, Santa Monica College
3. Hemispheric Activity Interferes With Ability to Work a Counter
Here is a classroom exercise that proves to be both very enjoyable and very informative about the functioning of the two sides of the brain. The only equipment you will need is a simple counter, the kind used at stadiums to count people as they pass through the gate.
Recruit a volunteer and have her sit in front of the class. She should hold the counter in her right hand, and when you say, “Go!” press it as fast as she can. Stop her after about 30 seconds and record the number of presses; this number will be your baseline level for the right hand. Reset the counter and repeat the procedure for the left hand to get a left hand baseline.
During the next phase of your experiment, the subject should again perform with the right and left hands but this time should do so while reciting a poem or speech (the Pledge of Allegiance works well). These two bits of data are your right and left “oral data.” In the next phase, the subject should perform with the right and left hands but this time should do so while humming a familiar tune. Encourage the students to hum and not to worry about the words. These two bits of data are your left and right “music data.”
The hypothesis in this experiment is that talking will interfere more with right-hand pressing, whereas humming will interfere more with left-hand pressing, due to the hemispheric specializations involved in these tasks.
Written by Nancy Jo Melucci, Santa Monica College
B. Promoting Discussion
1. Neurogenesis Alcohol
The Crews & Nixon (2003) article “Alcohol, Neural Stem Cells, and Adult Neurogenesis” discusses both genetic and environmental contribution on the process of neurogenesis. A “quick” definition of neurogenesis is the development of new cells in the brain. Previously it was thought that we are born with all of the neurons that we will ever have. Recent research suggests that certain parts of the brain do in fact “replace” or “grow” new neurons. Here are a few quotes from the Crews and Nixon (2003) article on this process:
Stem cells are cells that can divide indefinitely, renew themselves, and give rise to a variety of cell types. … Multipotent stem cells, including neural stem cells (NSCs), are more restricted in the types of cells they are capable of producing or becoming.
The discovery of NSCs and adult neurogenesis provides a new theoretical framework for understanding processes regulating brain plasticity.
Genetics influences the three main components of neurogenesis: NSC proliferation, cell survival, and cell differentiation into neurons and other types of brain cells.
We see neurogenesis in two areas of the brain:
1) Subventricular zone (SVZ) of the anterior lateral ventricles (this location is the origin for olfactory bulb neurons)
2) Dentate gyrus of the hippocampus (part of the brain that is involved with learning and memory) [neurogenesis for this part of the brain has been confirmed in rodents and in humans].
This is one of the main points Crew and Nixon make: “Interesting, genetics and specific environmental factors play an important role in regulating neurogenesis, and these same environmental factors … are key factors in the risk of developing alcoholism.”
Discussion Points:
• What are the different ways in which there is plasticity in the brain?
▪ Plasticity in the brain is due to a number of different factors. These can include neuronal growth (neurogenesis), changes in dendritic connections among neurons, and changes in chemicals bonds.
• In addition to alcohol, name other potential environmental factors that many influence neurogenesis.
• Researchers have been able to culture neural stem cells (NSCs) from a number of different regions in the brain. Ask students what are the implications for this. Two important points:
▪ The ability to do so, suggests that a variety of regions of the brain have the potential for neurogenesis.
▪ However, in most areas these cells are suppressed from dividing.
• What are the contributions of nature and nurture on neurogenesis?
▪ An enriched environment is a factor that tends to promote neurogenesis. Physical activity in particular seems to be helpful.
▪ Stress is an environmental factor that reduces neurogenesis.
▪ Alcohol decreases the proliferation of neural stem cells. However, the effect (at least in rats) is not seen until several weeks later.
▪ Serotonin is known to influence the neural stem cell proliferation in adults. Depression is associated with a decrease in the amount of serotonin released. The mechanism behind selective serotonin reuptake inhibitors (SSRIs) (an antidepressant), according to some researchers, is that is increases neurogenesis.
• Neurogenesis is seen in the hippocampus. What are the implications of neurogenesis in this particular region of the brain?
▪ The hippocampus in involved in learning and memory. Lack of neurogenesis in this particular part of the brain would have an impact on our ability to form new memories.
• What are the implications of the extent to which environmental stimuli can have an impact on cognitive functions?
▪ Alcohol can have an impact on brain functioning (physiological functioning that in turn can have an impact on psychological functioning)—this may potentially impact a number of different processes (e.g., perception, memory, attention, neuro-plasticity)
Written by Michael Bendele, Indiana University-Purdue University Fort Wayne
2. Doogie mice
This exercise could be used in a number of different chapters: the neuroscience chapter given the technique that is used to alter neurophysiology, the memory chapter given the change in ability to learn, or the chapter on intelligence when talking about the biological basis of intelligence. Another option would be to use the example throughout the semester for the various chapters as a means of unifying the content from a number of different perspectives.
Joe Tsien and colleagues altered a protein (N-methyl-D-aspartate [NMDA]) in mice that is involved with learning & memory. The NMDA Receptors are involved in strengthening the connection between two neurons that are activated at the same time. The altered protein in Doogie mice (named after the TV show Doogie Houser, MD) helped in terms of the NMDA receptor saying open twice the normal amount of time compared to normal mice. The additional time appears to help in terms of forming new memories. For the control condition, the Doogie mice and regular mice were allowed to explore an environment with two objects in it. Mice are naturally curious and spent time checking out both objects. For the experimental condition a few days later, one of the objects was replaced with a new object. Again, both sets of mice were allowed to explore the environment. The Doogie mice spent more of their time exploring the new object versus the regular mice, which spent about an equal amount of time exploring both objects. These results suggest that the Doogie mice remembered the old object while the regular mice did not. In general, the Doogie mice were able to remember information about 5 times longer than the regular mice.