Chapter 3 The Biological Bases of Behavior Communication
Chapter 3: The Biological Bases of Behavior
Communication in the Nervous System § Hardware § Glia § structural support and insulation § memory formation § chronic pain § psychological disorders § Neurons – communication § Soma – cell body § Dendrites – receive § Axon – transmit away
Figure 3. 1 Structure of the neuron
Neural Communication: Insulation and Information Transfer § Myelin sheath – speeds up transmission § Terminal button – end of axon; secretes neurotransmitters § Neurotransmitters – chemical messengers § Synapse – point at which neurons interconnect
The Neural Impulse: The Action Potential § Stimulation causes cell membrane to open briefly § Positively charged sodium ions flow in § Shift in electrical charge travels along neuron § The Action Potential § All – or – none law
Figure 3. 2 The neural impulse
The Synapse: Chemicals as Signal Couriers § Synaptic cleft § Presynaptic neuron § Synaptic vesicles § Neurotransmitters § Postsynaptic neuron § Receptor sites
Figure 3. 3 The synapse
Figure 3. 4 Overview of synaptic transmission
Neurotransmitters § Specific neurotransmitters work at specific synapses § Lock and key mechanism § Agonist – mimics neurotransmitter action § Antagonist – opposes action of a neurotransmitter § 15 – 20 neurotransmitters known at present § Interactions between neurotransmitter circuits
Table 3. 1 Common Neurotransmitters and Some of their Functions
Organization of the Nervous System § Central nervous system (CNS) § Afferent = toward the CNS § Efferent = away from the CNS § Peripheral nervous system § Somatic nervous system § Autonomic nervous system (ANS) § Sympathetic § Parasympathetic
Figure 3. 6 Organization of the human nervous system
Figure 3. 7 The central and peripheral nervous systems
Figure 3. 8 The autonomic nervous system (ANS)
Studying the Brain: Research Methods § § § Electroencephalography (EEG) Damage studies/lesioning Electrical stimulation (ESB) Transcranial magnetic stimulation (TMS) Brain imaging – § computerized tomography § positron emission tomography § magnetic resonance imaging (MRI) § Functional magnetic resonance imaging (f. MRI)
Brain Regions and Functions § Hindbrain – vital functions – medulla, pons, and cerebellum § Midbrain – sensory functions – dopaminergic projections, reticular activating system § Forebrain – emotion, complex thought – thalamus, hypothalamus, limbic system, cerebrum, cerebral cortex
The Cerebrum: Two Hemispheres, Four Lobes § Cerebral Hemispheres – two specialized halves connected by the corpus callosum § Left hemisphere – verbal processing: language, speech, reading, writing § Right hemisphere – nonverbal processing: spatial, musical, visual recognition
The Cerebrum: Two Hemispheres, Four Lobes § Four Lobes: § § Occipital – vision Parietal - somatosensory Temporal - auditory Frontal – movement, executive control systems
Figure 3. 16 Structures and areas in the human brain
Figure 3. 18 The cerebral hemispheres and the corpus callosum
Figure 3. 19 The cerebral cortex in humans
Figure 3. 20 The primary motor cortex
Mirror Neurons § An area just forward of the primary motor cortex is where “mirror neurons” were first discovered accidentally in the mid-1990 s. § May play a role in the acquisition of new motor skills, § the imitation of others, § the ability to feel empathy for others, § and dysfunctions in mirror neuron circuits may underlie the social deficits seen in autistic disorders.
The Plasticity of the Brain § The brain is more “plastic” or malleable than widely assumed § Aspects of experience can sculpt features of brain structure § Damage to incoming sensory pathways or tissue can lead to neural reorganization § Adult brain can generate new neurons neurogenesis
Figure 3. 21 Language processing in the brain
The Endocrine System: Glands & Hormones § Hormones – chemical messengers in the bloodstream § Pulsatile release by endocrine glands § Negative feedback system § Endocrine glands § Pituitary – “master gland, ” growth hormone § Thyroid – metabolic rate § Adrenal – salt and carbohydrate metabolism § Pancreas – sugar metabolism § Gonads – sex hormones
Genes and Behavior: The Field of Behavioral Genetics § Behavioral genetics = the study of the influence of genetic factors on behavioral traits § Chromosomes – strands of DNA carrying genetic information § Human cells contain 46 chromosomes in pairs (sex-cells – 23 single) § Each chromosome – thousands of genes, also in pairs
Research Methods in Behavioral Genetics § Family studies – does it run in the family? § Twin studies – compare resemblance of identical (monozygotic) and fraternal (dizygotic) twins on a trait § Adoption studies – examine resemblance between adopted children and their biological and adoptive parents
Figure 3. 27 Genetic relatedness
Figure 3. 30 Twin studies of intelligence and personality
Evolutionary Psychology: Behavior in Terms of Adaptive Significance § Based on Darwin’s ideas of natural selection § Reproductive success key § Adaptations – behavioral as well as physical § Fight-or-flight response § Taste preferences § Parental investment and mating
The ‘Split Brain’ studies Surgery for epilepsy : cut the corpus callosum Roger Sperry, 1960’s special apparatus ◦ picture input to just one side of brain ◦ screen blocks objects on table from view Verbal Nonverbal left right hemisphere
The ‘Split Brain’ studies n Picture to right brain q q can’t name the object left hand can identify by touch “What did hand, “Using yourdid left see? ” Pick you up you what see? ” you saw. ” § Picture to left brain § can name the object § left hand cannot identify by touch ? ? I saw an Verbal apple. left Nonverbal right hemisphere
UCLA Study Found that the women’s corpus callosum to be 23% larger than men’s. This may be the reason for more hemispheric chit chat. Also may help explain why women have better intuition.
Yale Study • 19 men and 19 women asked to determine if two nonsense words rhymed. • All 19 men had left frontal lobe light up • 11 of 19 women had that plus lighting behind right eyebrow • Left brain (reason) Right brain (feelings) • Thus women draw on feelings as well as reason when they use words.
Phineas Gage tamping iron 3 feet 7 inches long weighed 13 1/2 pounds 1 -1/4 inches in diameter at one end (not circumference as in the newspaper report) tapered over a distance of about 1 -foot to a diameter of 1/4 inch at the other went in point first under his left cheek bone and completely out through the top of his head landed about 25 to 30 yards behind him
En-Gaging… § Phineas was knocked over; may not have lost consciousness § most of the front part of the left side of his brain was destroyed § returned home to Lebanon, New Hampshire after 10 weeks § transforming Gage into an untruthful, short-tempered, psychopathic, braggart. § careless or unreliable and slovenly in his personal habits § having less sexual drive but fewer inhibitions in talking about sex § Other people have miraculously survived severe metal rod head trauma § Late ’ 70 s - construction worker who fell on an iron bar § 2003 in Truckee, CA: 18 -inch-long drill thrust into eye socket & through his skull, pushing his brain hemispheres aside (the doctors had to remove it by unscrewing it)
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