SOSC 2GENERAL PSYCHOLOGY

Chapter 2: The Biological Basis of Behavior

Neuropsychologists: Psychobiologists who study the brain’s influence on behavior.

Neuroscience: The study of the brain and the nervous system.

Psychobiology: The area of psychology that focuses on biological foundations of behavior and mental processes.

Neurons: Individual cells that are the smallest unit of the nervous system.

Dendrites: Short fibers that branch out from the cell body and pick up incoming messages.

Axon: Single long fiber extending from the cell body; it carries outgoing messages

Nerve (or tract): Group of axons bundled together.

Myelin sheath: White fatty covering found on some axons.

Sensory (or afferent) neurons: neurons that carry messages from sense organs to the spinal cord or brain.

Motor (or efferent) neurons: neurons that carry messages from the spinal cord or brain to the muscles and glands.

Interneurons (or association neuron): neurons that carry messages from one neuron to another.

Glial cells (or glia): cells that insulate and support neurons by holding them together, provide nourishment and remove waste products, prevent harmful substances from passing into the brain, and from the myelin sheath.

Neural impulse: the firing of a nerve cell

Synaptic space (or synaptic cleft): Tiny gap between the axon terminal of one neuron and the dendrites or cell body of the next neuron.

Synapse: area composed of the axon terminal of one neuron, the synaptic space, and the dendrite or cell body of the next neuron.

Synaptic Transmission-Communication between neurons. When a neural impulse reaches the end of an axon, tiny oval sacs, called synaptic vesicles, at the end of most axons release varying amounts of chemical substances called neurotransmitters. These substances travel across the synaptic space and affect the next neuron.

Terminal button (or synaptic knob): structure at the end of an axon terminal branch.

Synaptic vesicles: tiny sacs in a terminal button that release chemicals into the synapse.

Neurotransmitters: chemicals released by the synaptic vesicles that travel across the synaptic space and affect adjacent neurons.

Receptor sites: locations on a receptor neuron into which a specific neurotransmitter fits like a key into a lock.

Major Neurotransmitters and Their Effects:1. Acetylcholine (ACh) – distributed widely throughout the central

nervous system, where it is involved in arousal, attention, memory, motivation, and movement. Involved in muscle action through presence at neuromuscular junctions. Degeneration of neurons that produce ACh has been linked to Alzheimer’s disease. Too much ACh can lead to to spasms and tremors; too little, to paralysis or torpor.

2. Dopamine – involved in a wide variety of behaviors and emotions, including pleasure. Implicated in schizophrenia and Parkinson’s disease.

3. Serotonin – involved in the regulation of sleep, dreaming, mood, eating, pain, and aggressive behavior. Implicated in depression.

4. Norepinephrine – affects arousal, wakefulness, learning, memory, and mood.

5. Endorphins – involved in the inhibition of pain. Released during strenuous exercise. May be responsible for “runner’s high.”

Neural plasticity: the ability of the brain to change in response to experience.

Neurogenesis: the growth of new neurons.

Central nervous system: division of the nervous system that consists of the brain and spinal cord.

Peripheral nervous system: division of the nervous system that connects the central nervous system to the rest of the body.

The divisions of the brain.

PARTS OF THE BRAIN AND THEIR FUNCTIONS:Central Core Medulla: regulates respiration, heart rate,

blood pressure.Hind-brain Pons: regulates sleep-wake cycles

Cerebellum: regulates reflexes and balance; coordinates movement.

Mid-brain Thalamus: major sensory relay center; regulates higher brain centers and peripheral nervous system.Hypothalamus: influences emotion and motivation; govern stress reactions.Reticular formation: regulates attention and alertness.

Limbic System Hippocampus: regulates formation of new memories.

Amygdala: governs emotions related to self-preservation.

Cerebral Cortex Frontal lobe: goal-directed behavior; concentration; emotional control and temperament; voluntary movements; coordinates messages from other lobes; complex problem solving; involved in many aspects of personality.Parietal lobe: receives sensory information; visual/spatial abilitiesOccipital lobe: receives and processes visual information.Temporal lobe: smell and hearing; balance and equilibrium; emotion and motivation; some language comprehension; complex visual processing and face recognition.

The limbic system: ring of structures that play a role in learning and emotional behavior.

Cerebral cortex: the outer surface of the two cerebral hemispheres that regulates most complex behavior.

Frontal lobe: part of the cerebral cortex that is responsible for voluntary movement; it is also important for attention, goal-directed behavior, and appropriate emotional experiences.

Primary motor cortex: the section of each frontal lobe responsible for voluntary movement.

Occipital lobe: receives and interprets visual information

Parietal lobe: receives sensory information from throughout the body.

Primary somatosensory cortex: area of the parietal lobe where messages from the sense receptors are registered.

Temporal lobe: helps regulate hearing, balance and equilibrium, and certain emotions and motivations.

The two cerebral hemispheres. Each hemisphere specializes in processing specific types of information.

Corpus callosum: a thick band of nerve fibers connecting the left and right cerebral cortex.

Processing of speech and language. Broca’s and Wernicke’s areas, generally found only on the left side of the brain, work together, enabling us to produce and understand speech and language.

TOOLS FOR STUDYING THE NERVOUS SYSTEM: Microelectrode Techniques – used to study the functions of

individual neurons. Macroelectrode Techniques – used to obtain a picture of the

activity in a particular region of the brain. The EEG is one such technique.

Structural Imaging – family of techniques used to map structures in a living brain.

o Computerized axial tomography (CAT or CT) – permits three-dimensional imaging of a living human brain.

o Magnetic resonance imaging (MRI) – produces pictures of inner brain structures.

Functional Imaging Techniques – family of techniques that can image activity in the brain as it responds to various stimuli.

o EEG imaging – measures general brain activity on a millisecond-by-millisecond basis through electrodes pasted to the scalp.

o Magnetoencephalography (MEG) and Magnetic Source Imaging (MSI) – two procedures that are similar to EEG imaging but have greater accuracy.

o Positron Emission Tomography (PET) Scanning and Single Photon Emission Computed Tomography (SPECT) – two techniques that use radioactive energy to map exact regions of brain activity.

o Functional Magnetic Resonance Imaging (fMRI) – measures the movement of blood molecules in the brain, pinpointing specific sites and details of neuronal activity.

Spinal cord: complex cable of neurons that runs down the spine, connecting the brain to most of the rest of the body.

Peripheral nervous system (PNS) – links the brain and spinal cord to the rest of the body, including the sensory receptors, glands, internal organs, and skeletal muscles.

Somatic nervous system: the part of the PNS that carries messages from the senses to the CNS and between the CNS and the skeletal muscles.

Autonomic nervous system: the part of the PNS that carries messages between the CNS and the internal organs.

The sympathetic and parasympathetic divisions of the autonomic nervous system. The sympathetic division generally acts to arouse the body, preparing it for “fight or flight.” The parasympathetic follows with messages to relax.

Endocrine system plays a key role in helping to coordinate and integrate complex psychological reactions.

Endocrine glands: release hormones into the bloodstream.

Hormones: chemical substances released by the endocrine glands; they help regulate bodily activities.

The glands of the endocrine system. Endocrine glands secrete hormones that produce widespread effects on the body.

Genetics: study of how traits are transmitted from one generation to the next.

Behavior genetics: study of the relationship between heredity and behavior.

Genes: segments of DNA that control the transmission of traits; they are found on the chromosomes.

Chromosomes: pairs of threadlike bodies within the cell nucleus that contain the genes.

Deoxyribonucleic acid (DNA): complex molecule in a double-helix configuration that is the main ingredient of chromosomes and genes and that forms the code for all genetic information.

Human genome: the full complement of genes within a human cell.

The 23 pairs of chromosomes found in every normal human cell. The 2 members of 22 of these pairs look exactly alike. The 2 members of the 23rd

pair, the sex chromosomes, may or may not look alike. Females have equivalent X chromosomes, while males have one X and one Y chromosome, which look very different.

REFLECTION:

1. Compare the operation of the endocrine system to that of the nervous system.

2. Why are psychologists interested in hormones?3. Explain the relative influence of heredity and environment in

shaping behavior.

Reference: Feldman, R. S. (2010). Understanding Psychology. 9th Edition. McGraw Hill Companies, Inc. Morris, C.G.,et al. (2007). Psychology Concepts and Applications. Pearson Education, Inc. New Jersey.

Prepared by:Mrs. Maria Angela L. Diopol

Instructor