Unit 3: Study Questions

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Describe the structure and functions of the glia cells and neurons. (pp. 86-87)

Describe the various parts of the neuron, and explain their functions. (pp. 87-88)

What is a neural impulse? Describe what happens when a neuron is stimulated. Describe how sodium and potassium ions contribute to the neural impulse. (pp. 88-89)

Describe the “battery-like” features of a neuron at rest. Define the resting potential of a neuron. How many millivolts is the resting potential in most neurons? (p. 88)

Comment: For centuries, philosophers have regarded humans as a combination of flesh and spirit, but during the last 100 years, we have come to know more and more about the biology of the nervous system, which indicates that it is a kind of machine. In this case, for example, you can see that neural firing, which is the basis of our thoughts and behaviour, has its basis in the positive and negative charges of electrical energy.

Define the action potential of a neuron. (p. 88)

What is the absolute refractory period? (p. 88)

Describe the all-or-none law of the neural impulse. Explain how neurons convey information about the strength or intensity of a stimulus. (p. 89)

Figure 3.1 Neuronal Inhibition and Excitation

Adapted from F. B. Goldstein (19960. Sensation and perception (4th ed) (p. 12). Pacific Grove, CA: Brooks/Cole.

Comment: There is sometimes confusion about the all-or-none nature of neural impulses. Some students believe that “all” is an excitatory message and that “none” is the lack of an excitatory message, which yields inhibition. This is not true. A neuron can send an excitatory message, an inhibitory message, or no message at all. Also, there is often confusion about the resting potential of a neuron. This term does not indicate that neurons merely “sit there” doing nothing until stimulated to fire. In fact, a neuron at rest has a slow constant rate of firing that is interpreted by the nervous system as no response. The inhibition and excitation of a neuron is represented in Figure 3.1. In this figure, drawing c represents the spontaneous firing level of a neuron (equal amounts of excitation and inhibition are received). As more excitatory postsynaptic potentials occur (drawings a and b), the electrical current builds up, and the cell fires an action potential. The brain is able to interpret this excitatory message because the spontaneous level of firing of the neuron has been exceeded. On the other hand, the build-up of inhibitory postsynaptic potentials (drawings d and e) results in inhibition and makes it more difficult for the cell to fire. The brain interprets this as inhibitory because the firing rate of the neuron is slower than its spontaneous level.

What is a synapse? Explain how neural impulses travel at the synapses. (pp. 89-90)

Describe a synaptic cleft. Define presynaptic neuron and postsynaptic neuron. (p. 89)

Define neurotransmitter and synaptic vesicle. (p. 89)

What are the postsynaptic potentials? Do they follow the all-or-none law? Explain. (p. 90)

What are excitatory and inhibitory postsynaptic potentials? Describe the process of re-uptake that occurs at the synapses. (p. 90)

Describe the process in which the neuron integrates signals that arrive at the synapses. Explain the sense in which our activities are due to patterns of neural activity. (pp. 90-91)

Describe the process by which neural networks are formed. What is synaptic pruning? (pp. 90-92)

How many neurotransmitters are there? Explain how neurotransmitters function and how they bind to receptor sites. (p. 92)

Describe the properties and functions of acetylcholine. (pp. 92-93)

Define agonist and antagonist. (p. 93)

Define and describe the monoamines. Explain how they are related to behaviour. (pp. 93-94)

Define GABA, glycine, and glutamate. Describe their roles in the nervous system. (p. 94)

What is morphine? How does it influence the nervous system? What are endorphins, and how are they related to morphine? (p. 94)

Comment: As discussed in this section, endorphins are the neurotransmitter produced by exercise, which are responsible for the pleasant feeling people have after they engage in physical activity. There are likely individual differences in the amount of endorphins produced, so some people savour the experience of strenuous physical activity, whereas others seem to feel only unpleasant pain.

Describe the organization of the nervous system. Define and describe the central (CNS) and peripheral nervous systems. (p. 95)

Specify and describe the two parts of the peripheral nervous system. (pp. 95-97)

Define and describe the somatic nervous system. (p. 96)

What are afferent nerve fibres? What are efferent nerve fibres? Explain their functions. (p. 96)

Define and describe the autonomic nervous system (ANS). (pp. 96-97)

What is the fight-or-flight response? Which nervous system is involved in this response? (pp. 96-97)

Identify and define the two branches of the autonomic nervous system. (p. 97)

Describe the biology of the central nervous system. What are the meninges? What is cerebrospinal fluid (CSF)? What are its functions? What are ventricles? (pp. 97-98)

What is the spinal cord? What does it do? (pp. 97-98)

Describe the physical characteristics of the brain. (p. 98)

What is an electroencephalograph (EEG)? How is it used to study how brain functions? (pp. 98-99)

Describe how lesioning and electrical stimulation of the brain (ESB) are used to investigate brain function. Describe how Wilder Penfield studied and mapped brain functions. (pp. 99-101)

Describe and differentiate among the new brain-imaging methods (TMS, CT, PET, MRI, and fMRI scans). (pp. 101-105)

Describe the procedure and results in the study entitled “Searching for the Self in the Brain.” (p. 103)

Describe the hindbrain and midbrain components and their functions. (pp. 105-107)

What is the forebrain? Describe the structure and functions of the thalamus, the hypothalamus, and the limbic system as components of the forebrain. (pp. 107-109)

Describe Olds’s research in brain self-stimulation. (pp. 108-109)

Describe the structure of the cerebrum and the functions of the four lobes in the cerebral cortex. (pp. 109-110)

Explain the allocation of areas in the primary motor cortex to different types of body movements. (pp. 109-110)

Describe the structure and function of the corpus callosum. (p. 109)

Explain the concept of brain plasticity. What is neurogenesis? Describe how our knowledge of this feature of the brain has changed over time. Describe the lines of research that support the notion of brain plasticity. What are stem cells, and what potential applications does stem-cell research have for altering brain functions? (pp. 110-112)

Comment: It was once thought that the key to understanding relationships between the brain and behaviour was to pinpoint how particular areas of the brain were related to particular behaviours. This view has been validated in part by work in which specific brain functions, such as the coordination of movements, are localized in particular brain structures. However, work in the plasticity of the brain has shown that much of the brain's structures are changing and adaptive, with new neural circuitry growing according to what we learn in our interactions with the environment. Brain plasticity also has important implications for education. Children are not necessarily fated by brain physiology to attain a particular level of intelligence or proficiency at various tasks. Instead, the ability of the brain to adapt at the neural level means that through practice and learning, our capabilities can expand in a way that is not rigidly constrained by brain structures.

Comment: Although Weiten and McCann suggest that the brain is to a large extent hard-wired, considerable evidence suggests that it is malleable. The brain maps presented in the text are only approximations, even though they seem to show precise locations for certain functions and abilities. The brain is adaptable to a degree, and some structures can take over for other structures, if necessary. This adaptability is usually referred to as plasticity. An example of plasticity can be found in the study of infants who have undergone hemispherectomies (removal of an entire hemisphere). In many cases, these children show little speech disturbance even when the left hemisphere is removed. This plasticity appears to decline with age. It is also either less evident or non-existent when the centres of the brain that protect life itself—the basic survival reflexes—are implicated.

What are Broca’s and Wernicke’s areas of the brain? In what side of the brain, and in what lobes of the brain, are each located? For what functions are they responsible? (pp. 112-113)

What is split-brain surgery? Why is this type of surgery sometimes performed? Explain the “crisscrossed” ways in which visual information, auditory information, and motor information are routed to and from the two hemispheres. (pp. 113-114)

Describe how the split-brain experiments supported the notion that language is based in the left hemisphere and that the right hemisphere is responsible for different types of tasks. For what types of tasks is the right hemisphere thought to be specialized? Can hemispheric specialization be studied in neurologically intact individuals? What are perceptual asymmetries, and what have they revealed about hemispheric specialization? (pp. 113-116)

What is the endocrine system? What are hormones, and how do they differ from neurotransmitters? Describe the endocrine system and its components and functions, including the role of the pituitary gland. What is oxytocin and what are its suspected effects? What forebrain area controls much of the endocrine system, and how? (pp. 116-118)

What is the field of behavioural genetics? (p. 118)

What are chromosomes and genes? Explain how they operate and how they are involved in genetic transmission. (pp. 118-119)

What are dominant and recessive genes? Under what conditions are each of these expressed in the phenotype? Explain. (p. 119)

Comment: Weiten and McCann state that “a dominant gene is one that is expressed when paired genes are different” (p. 119). A dominant gene is also expressed in the phenotype if it is paired with another dominant gene.

Define genotype and phenotype. Distinguish between the two and be able to provide and recognize original examples of each. (p. 120)

Explain polygenic inheritance. (p. 120)

Define family studies, and explain how they have aided our understanding of the heritability of schizophrenia. (pp. 120-121)

Describe how the study of identical and fraternal twins can be used to investigate the influence of heredity on behaviour. (pp. 121-122)

What is genetic mapping? What implications does genetic mapping have for advancing the study of heredity? (pp. 122-123)

Explain how heredity and environmental factors interact. (p. 123-124)

What is evolutionary psychology? (p. 124)

Describe how Darwin came to his conclusions about evolutionary processes. Define natural selection and fitness. Explain why Darwin’s conclusions were controversial. (pp. 124-125)

Describe the refinements that have been made to evolutionary theory after Darwin made his contributions. Define genetic drift, mutations, gene flow, adaptations, and inclusive fitness. How does the notion of inclusive fitness explain the practice of self-sacrifice? (pp. 125-126)

Can behaviours be considered as adaptive traits? Explain. Give examples of "stotting" by Thomson’s gazelles as an adaptive behavioural trait. (pp. 126-127)

Do the right and left brains give people two minds in one? Explain. (pp. 128-130)

Does each half of the brain have its own specialized mode of thinking? Explain. (pp. 128-130)

Are some people right-brained while others are left-brained? Explain. (pp. 128-130)

Should schools be reformed so that students obtain better exercise for the right side of the brain? Give reasons for your answer. (pp. 129-130)

What is an overextrapolation? Discuss, with reference to the concept of critical periods and education. Be able to provide and recognize original examples of overextrapolation. (pp. 131-132)