Chapter Three The Biological Foundations of Behavior PDF

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Chapter Three: The Biological Foundations of Behavior ● Learning Objective-The connection between the brain and the body is very strong, and psychology as a science is shifting toward an emphasis on the biological model.

Big Ideas ● ● ● ●

What are the divisions of the nervous system? What are neurons and how do they work? What are the functions of the major regions of the brain? How do genes influence human behavior?

What are the divisions of the nervous system?

● The Peripheral Nervous System is the nervous system that doesn’t include the brain and spinal cord, and is divided into two parts ○ Somatic Division- voluntary ○ Autonomic Division- automatic ■ Sympathetic (arousal)- happens during time of stress, when someone jumps out behind you, or something unexpected happens, it is basically the Fight or Flight response. It’s main purpose is to keep us alive. ■ Parasympathetic (calming)- takes your body back to homeostasis after it has been aroused from an emergency, a bear attack, etc.

What are neurons and how do they work?

● Our neural network has 100 billion neurons ● An increase in myelin helps speed up reactions and helps make movements smoother and more sophisticated ● The Neural Impulse ○ At rest, a neuron is negatively charged (resting potential) ○ As an electrical message sweeps through, it changes the neuron to positive for just a blip of time, then the neuron is back to negative (action potential) ○ All-or-nothing Principle: neuron either fires or does not fire ■ Must reach a threshold before firing ■ Strength does NOT vary ■ Speed CAN vary ■ Speed is controlled by how thick the myelin is and the length of the axons ■ The longer the axon, the slower the electrical message ● Synapses and Neurotransmitters ○ Synapse: space between axon of sending neuron and dendrites of receiving neuron ○ Neurotransmitters: chemicals that carry messages across the synapse, released by terminal buttons ■ Fit like a lock and key to receptor sites on the receiving neuron ■ Excitatory- fire ■ Inhibitory- don’t fire ○ Reuptake: the re-absorption of neurotransmitters the brain sucks up leftover neurons ■ Selective Serotonin Reuptake Inhibitors (SSRIs) ■ 13% of Americans take an antidepressant, most long-term ● Most popular category of drug ■ Antidepressants are SSRIs they inhibit serotonin from being reabsorbed into the brain, which makes the next neuron more likely to fire

What are the functions of major regions of the brain? ● Hindbrain ○ Medulla- breathing and reflexes ○ Cerebellum- balance and coordination ○ Pons- sleep and arousal ● Midbrain ○ communication between eyes, ears, and brain ○ Reticular Formation ○ Reward Dopamine pathways ○ Hindbrain+Midbrain=Brain Stem ● Forebrain ○ Limbic System (emotion and memory) ■ Hippocampus- involved in memory ■ Amygdala- involved in fear and anger ■ The hippocampus and amygdala are so close together to keep us alive, it tells us what not to do over and over again ○ Hypothalamus- maintains internal homeostasis ■ The four F’s- fight, flight, feeding and fornication (sex) ○ Thalamus- transit station of the brain, takes signals from the lower brain to the higher brain, tells your brain when you’re tired, then transfers this signal to the higher brain to tell you what to do about it ○ Cerebral Cortex- most intelligent portion of your brain (newest) ■ Wrinkled outer layer of your brain ■ Responsible for all higher brain functions ● Forebrain= Limbic System+Cerebral Cortex ● Brain Structures and Function ○ Occipital- vision ○ Parietal-sensory information and motor control ○ Temporal- hearing

○ Frontal- decision, planning, and coordination ● The Brain’s Hemispheres ○ Hemispheres operate contralaterally ■ Lateralization- the dominance of one hemisphere ○ Specialization is not the same as Dominance ○ Hemispheres communicate via the Corpus Callosum ● Genes and Behavior ○ Dominant-recessive genes principle: dominant genes override recessive genes ■ Recessive genes appear only if both genes in a pair are recessive

■ ○ Behavior genetics: the study of heredity’s influence on behavior ■ Genes and environment will always depend on each other ○ What happens if one set of twins marries another set of twins and has children? ■ You couldn’t be able to see a difference and know who which child belongs to ■ The children would technically be siblings because they have the same genetic DNA, even though they are cousins...