Biology & Behavior

1. Biology & Behavior Unit 2

2. Biology and Behavior • Huntingon’s disease is a deadly genetic disorder that affects the brain • After psychologist Lenore Wexler’s mother died of Huntington’s, she changed her research from the clinical to the biological area and eventually discovered the genetic marker for the disease • She decided not to take the test that may have identified her as having the gene (would you take the test?) • To know what makes us who we are, we need to understand the physiological processes and genetic underpinnings of our thoughts, feelings, and behavior

4. What Are the Basic Brain Structures and Their Functions? • Identify the basic structures of the brain and their primary functions.

6. The Cerebellum Is Essential for Movement • Cerebellum (little brain): extremely important for proper motor function, learning, and motor memory • Damage to its different parts produces different effects: • Damage to lobes on either side causes a loss of limb coordination • Damage to the nodes at the very bottom causes balance problems • Cerebellum is activated when a person experiences a painful stimulus or observes a loved one receiving that stimulus, which means the cerebellum may be involved in the experience of empathy

8. Subcortical Structures Control Emotions and Appetitive Behaviors • The forebrain consists of the two cerebral hemispheres, right and left • The most noticeable feature of the forebrain is the convoluted surface of the cerebral cortex • Subcortical structures that lie below the cerebral cortex include: Hypothalamus, thalamus, hippocampus, amygdala, and basal ganglia • Some of these structures belong to the limbic system, whichcontrols appetitive behaviors and emotion

10. Hypothalamus • The hypothalamus is the brain’s master regulatory structure • Affects the functions of many internal organs, regulating body temperature, body rhythms, blood pressure, and blood glucose levels • Also involved in many motivated behaviors, including thirst, hunger, aggression, and lust

11. Thalamus • The thalamus is the gateway to the cortex • Excepting smell, it receives all incoming sensory information, organizes it, and relays it to the cortex • During sleep, the thalamus partially shuts the gate on incoming sensations while the brain rests

12. Hippocampus and Amygdala • The hippocampus (Greek, “sea horse”) plays an important role in the storage of new memories • Recently shown to grow larger with increased use; may be involved in how we remember the arrangements of both places and objects in space • Maguire and colleagues (2003) found that one region of the hippocampus in London taxi drivers’ brains was much larger than in most other London drivers’ brains • The amygdala(Latin, “almond”) serves a vital role in our learning to associate things in the world with negative and positive emotional responses

13. The Basal Ganglia • Basal ganglia:crucial for planning and producing movement • Damage to the basal ganglia can produce tremors and rigidity, uncontrollable jerky movements, and can impair the learning of movements and habits • Contains the nucleus accumbens, which is important for experiencing reward and motivating behavior

14. The Cerebral Cortex Underlies Complex Mental Activity • Cerebral cortex (Latin, “bark”): the outer layer of the cerebral hemispheres • It is the site of all thoughts, detailed perceptions, and complex behaviors • Each cerebral hemisphere has four “lobes”: Occipital, parietal, temporal, frontal • Corpus callosum: a bridge of axons connecting the hemispheres and permitting information to flow between them

18. The Prefrontal Cortex in Close-Up • Phineas Gage: His accident led to major personality changes • Prefrontal cortex: brain region particularly concerned with social phenomena (e.g., following norms). Patients with injury to this region often have profound disturbances in their ability to get along with others • Lobotomy: deliberate damaging of the prefrontal cortex; used in the late 1940s early 1950s • Left patients lethargic and emotionally flat, and much easier to manage in mental hospitals, but it also left them disconnected from their social surroundings

19. What Is the Genetic Basis of Psychological Science? • Explain how genes are transmitted from parent to offspring • Discuss the goals and methods of behavioral genetics • Explain how both environmental factors and experience influence genetic expression

20. What Is the Genetic Basis ofPsychological Science? • The term genetics is typically used to describe how characteristics are passed along to offspring and to the processes involved in turning genes “on” and “off” • Genetic predispositions are important in determining the environments we select for ourselves • Biology and environment mutually influence each other

21. Genes Affect Behavior • A person’s abilities and psychological traits are influenced by the interaction of genes and environment • Behavioral genetics: the study of how genes and environment interact to influence psychological activity • People are born like “undeveloped photographs”: The image has been captured, but the way it eventually appears depends on the development process

22. Social and Environmental Contexts Influence Genetic Expression • Caspi et al. (2002) followed more than 1,000 New Zealanders from birth until adulthood • Every few years information was collected about the participants • When the participants were 26 years old, investigators examined which factors predicted who had become a violent criminal • Mistreatment at home + low MAO gene accounted for nearly 50 percent of criminality • Study is a good example of how genes and social context interact to affect behavior (phenotype)

24. How Does the Brain Change? • Explain how environmental factors and experience influence brain organization. • Describe sex differences in brain structure and function.

25. How Does the Brain Change? • Despite the great precision and the specificity of its connections, the brain is extremely malleable • Plasticity: a property of the brain that allows it to change as a result of experience, drugs, or injury

26. The Interplay of Genes and Environment Wires the Brain • Nature and nurture constantly interact to affect DNA’s activity and the products of that activity • Brain plasticity reflects the interactive nature of our biological and environmental influences

27. Cell Identity Becomes Fixed Over Time • As an embryo develops, each cell becomes more and more committed to its identity • Tissue transplanted early enough completely transforms into whatever type is appropriate for its new location; transplanting cells too late may disfigure the organism • Many people are excited about the possibility of transplanting fetal cells because they are undeveloped enough to become any type of tissue

28. Experience Fine-Tunes Neural Connections • Experience is important for normal brain development and maybe even more so for superior development • Example: • One group of rats was raised in a “normal” lab environment (featureless boxes with bedding at the bottom, plus dishes for food and water); another group was raised in an enriched environment • The “enriched” group developed bigger, heavier brains than the first group (Rosenzweig, Bennett, & Diamond, 1972)

29. Culture Affects the Brain • Our cultural experiences contribute to different patterns of brain activity • Example: • One group of participants in Japan and another group in the United States were shown pictures of both neutral and fearful facial expressions portrayed by Japanese and American faces. • Activity in the amygdala was greatest when participants viewed fearful expressions within their own cultural group (Chiao et al., 2008)

31. The Brain Rewires Itself throughout Life • Although brain plasticity decreases with age, the brain can grow new connections among neurons and even grow new neurons into very old age • The rewiring and growth within the brain represents the biological basis of learning

32. Change in the Strength of Connections Underlies Learning • Changes in the brain due to experience are mainly in the strength of existing connections • Hebb’s “fire together, wire together” catchphrase: When two neurons fire simultaneously, the synaptic connection between them strengthens • Entirely new connections can grow between neurons. • Neurogenesis: New neurons are produced in some brain regions (e.g., the hippocampus) • Neurogenesis may underlie neural plasticity

33. Changes in the Brain • Wiring in the brain is affected by amount of use (e.g., recall the London taxi drivers) • Phantom limb: the intense sensation that an amputated body part still exists • Phenomenon suggests that the brain has not reorganized in response to the injury and that the missing limb’s cortical representation remains intact • An amputee who has lost a hand may, when his or her eyes are closed, perceive a touch on the cheek as if it were on the missing hand (Ramachandran&Hirstein, 1998)

35. The Puzzles of Synesthesia • Synesthesia: For synesthetes, sensory experiences are crossed • One man reported the he hates driving because the sight of road signs tastes to him like a mixture of pistachio ice cream and ear wax (McNeil, 2006) • The brain area involved in seeing colors is physically close to the brain area involved in understanding numbers, thus people with color/number synesthesia, may have some connections or cross-wiring between brain areas (Ramachandran& Hubbard, 2001)

36. Females’ and Males’ Brains Are Similar and Different • Females and males differ in their life experiences and hormonal makeup, which leads to differences between their brains • Males tend to have larger brains • Females and males may solve some complex problems differently, with females using language-related brain regions and males using spatial-related brain regions (Haier et al., 2005) • Brain areas important in processing language are more likely to be found in both halves of females’ brains than in males’ brains

38. The Brain Can Recover from Injury • Following an injury in the cortex, the surrounding gray matter assumes the function of the damaged area • Radical hemispherectomy: After the surgical removal of an entire cerebral hemisphere, the remaining hemisphere eventually takes on most of the lost hemisphere’s functions • One of the most exciting (and controversial) areas of neurological research is the transplantation of human fetal tissue (stem cells) into the brain to repair damage • Instead of using fetal stem cells, new methods are emerging that allow researchers to create stem cells by reprogramming adult cells