Chapter 3: Biopsychology

3.1 Human Genetics Evolution by Natural Selection (1859) Charles Darwin’s theory Organisms that are best adapted to their environment are more likely to survive, reproduce, and pass on genetic information

Genetic Variation Occurs through recombination of genetic material (sexual reproduction) Chromosome Gene Deoxyribonucleic Acid (DNA) Mutation—a random change— may also occur

Genetic Variation Genotype: An individual’s genetic makeup Phenotype: An individual’s inherited physical traits

Epigenetics: Gene-Environment Interactions Studies of identical and fraternal twins have helped us learn about the influence of environmental factors on the expression of our genes, or epigenetics.

3.2 Cells of the Nervous System

Nervous system The body’s electrochemical communication circuitry Made up of: nerve cells (neurons)— conduct impulses and glial cells (glia)— support cells

Structure of a neuron— 4 main parts Cell body (soma): Keeps neuron alive and determines whether it will send a message Dendrites: Receive information from other neurons and transmit toward the cell body Axon: Extending fiber that conducts impulses away from the cell body to other cells Terminal buttons: Area where chemical messengers (neurotransmitters) are secreted by the neuron

How neurons communicate Myelin sheath wraps around the axon of some neurons and speeds neural transmission Neurotransmitter enters synapse (gap between neurons) Neurotransmitter temporarily binds to receptors—sites on receiving neuron’s membrane

Action Potential The electrical signal that travels down the axon, from the cell body to the terminal buttons, resulting in a release of neurotransmitter into the synapse

3.3 Parts of the Nervous System Functions of the nervous system include: Gathering and processing information Producing responses to stimuli Coordinating workings of different cells

Human Nervous System Central Nervous System Brain Housed in the skull Approx. 3 lbs Mostly comprised of neurons and glia Spinal cord Comprised of neurons and supportive tissue Runs from base of brain down center of back Protected by spinal column Peripheral Nervous System Somatic Nervous System Controls skeletal muscles Allows for voluntary movement Autonomic Nervous System Controls muscles of internal organs Regulates blood vessels, glands, internal organs

Autonomic Nervous System Sympathetic Nervous System *Arouses the body *Uses energy *”Fight or flight” response Parasympathetic Nervous System *Calms the body *Conserves energy

Sympathetic nervous system:

Parasympathetic nervous system:

Biofeedback A method for gaining control over the autonomic nervous system One learns using feedback from equipment that measures biological functions (e.g., body temperature, blood pressure, sweat response, muscle tension, brain activity)

3.4 The Brain and Spinal Cord

Brain stem Medulla Responsible for certain automatic functions such as breathing and heart rate Pons Involved in sleeping, waking, and dreaming

Cerebellum Regulates movement and balance Involved in remembering simple skills and acquired reflexes Plays a part in: Analyzing sensory info Solving problems

Thalamus Relays sensory messages to the cerebral cortex Includes all sensory messages except those from olfactory bulb (smell)

Limbic system A group of brain areas involved in emotional reactions, motivated behavior, and memory— includes: Amygdala Hippocampus Hypothalamus

Amygdala Responsible for Arousal Regulation of emotion Initial emotional response to sensory information

Hippocampus  Responsible for storage of new information in memory  Enables us to form spatial memories for navigating the environment

Hypothalamus Involved in: Emotions Drives vital to survival Fear Hunger Thirst Reproduction Feeling rewarded Regulating autonomic nervous system

Pituitary gland Small endocrine gland which releases hormones and regulates other endocrine glands Works in conjunction with hypothalamus

The endocrine system Endocrine glands release hormones into the bloodstream… …Hormones regulate growth, metabolism, sexual development and behavior, and other functions.

The cerebral cortex Largest brain structure In charge of most sensory, motor, and cognitive processes Divided into two halves, called hemispheres

Lobes of the cerebral cortex Occipital lobes Vision (visual cortex) Parietal lobes Body sensation (somatosensory cortex) Temporal lobes Memory, perception, emotion, hearing (auditory cortex) Frontal lobes Emotion, planning, creative thinking, personality, and movement (motor cortex)

Phineas Gage’s frontal lobe damage Gage was a railroad construction foreman An 1848 explosion forced a steel tamping rod through his head Others said he was “no longer Gage” Lost his job, worked as a sideshow exhibit

Corpus callosum Millions of myelinated axons connecting the brain’s hemispheres Provides a pathway for communication If surgically severed to treat epilepsy, resulting in a “split-brain” condition, the hemispheres cannot communicate directly

Lateralization Specialization of the two cerebral hemispheres for particular operations

Motor control and the hemispheres Left hemisphere controls right side of body Right hemisphere controls left side of body

Broca’s area Left hemisphere controls speech production

What is the object in your left hand? If someone with a split brain is blindfolded and asked what they are holding in their left hand, can they do it?

Plasticity The brain’s ability to change and adapt in response to experience Reorganizing or growing new neural connections

Brain imaging: Electroencephalography(EEG) A recording of neural activity detected by electrodes placed on the scalp

Brain imaging: Computerized Tomography (CT Scan) Multiple X-rays are combined to show cross-sections of brain tissue

Brain imaging: Positron Emission Tomography (PET Scan) Active areas have increased blood flow. Sensors detect radioactivity. Different tasks show distinct activity patterns. A method for analyzing biochemical activity in the brain, using injections of a glucose-like substance containing a radioactive element

Brain imaging: Magnetic Resonance Imaging (MRI) Magnetic fields allow for detection of energy/radio waves. Computer calculates tissue density from radio waves. Provides clear 3D images fMRI provides pictures of activity by measuring blood flow Method for studying body and brain tissue