Biological Psychology

Reductionism: the attempt to explain complex phenomena by reducing them to combinations of simpler components. I. Nervous System Cells A. Neurons: the cells in your nervous system that process information. 1) Sensory Neurons: carry messages from sense receptor cells toward the central nervous system. 2) Motor Neurons: carry messages away from the central nervous system. 3) Interneurons: relay messages from sensory neurons to other interneurons or to motor neurons. They account for most of the neurons in the brain. B. Glia: other cells in the brain that insulate neurons and help to remove neuronal waste products. There are five times more glial cells in the brain than there are neurons.

Neuron C. Cell Body (soma): contains the nucleus of the cell. D. Dendrites: widely branching structures that receive transmissions from other neurons. E. Axon: a single, long, thin, fiber with branches near its tip. F. Myelin Sheath: aids in the transmission of impulses along the axon.

II. How does an axon send communication? A. Action Potential: an excitation that travels along an axon at a constant strength, no matter how far it must travel. This happens through a series of electrical and chemical processes. B. All-or-None Law: if an action potential occurs at all, it will always be of the same magnitude. C. Refractory Period: the period of rest during which a new nerve impulse cannot be activated in a segment of an axon.

D. Resting Potential: an electrical polarization across the membrane of an axon, with a negative charge inside the axon.

III. Where does neuronal communication occur? A. Synapse: the specialized junction between one neuron and another. A neuron releases a chemical that either excites or inhibits the next neuron.

B. Presynaptic Ending: one of the endings of the several branches at the end of an axon. C. Neurotransmitter: a chemical that has been stored in the neuron and that can activate receptors of other neurons. D. Postsynaptic Neuron: the neuron on the receiving end of the synapse.

E. What happens to neurotransmitters after release? 1) Reuptake: the neurotransmitter gets reabsorbed by the neuron that transmitted it. 2) The neurotransmitter could get metabolized and go back into the blood stream or exit the body through urine. 3) The neurotransmitter could return to the postsynaptic neuron and re-excite it.

IV. Neurotransmitters and Behavior A. Endorphins: reduce the sensation of pain and affect emotions. B. Acetylcholine: is important for memory. A deterioration of neurons that transmit this neurotransmitter may contribute to Alzheimer's Disease. C. Glutamate: is important for memory, emotional regulation, and learning. Low levels of this neurotransmitter can impair both the speed and overall ability to learn.

D. GABA: too little of this neurotransmitter can raise levels of anxiety. E. Norepinephrine and Serotonin: a decrease in these neurotransmitters is associated with depression. F. Dopamine: a gradual decay of the neurons that release this neurotransmitter causes… 1) Parkinson’s Disease: causes difficulty initiating voluntary movement, tremors, rigidity, and depressed mood.

V. The Nervous System and Behavior A. Central Nervous System: consists of the brain and the spinal cord. B. Peripheral Nervous System: composed of bundles of axons between the spinal cord and the rest of the body.

C. Breakdown of the Peripheral Nervous System: 1) Somatic Nervous System: is made up of the peripheral nerves that communicate with the skin and muscles (voluntary movements). 2) Autonomic Nervous System: controls the involuntary actions of the heart, stomach and other organs (involuntary movements).

D. Breakdown of the Autonomic Nervous System: 1) Sympathetic Nervous System: is the crisis management center. 2) Parasympathetic Nervous System: is in charge of long-term survival related functions, nutrition and energy conservation.

E. Embryological Development (1) The Forebrain becomes the cerebrum, cerebral cortex, and other higher structures. (2) The Midbrain and (3) The Hindbrain become the brainstem.

H. Cerebral Cortex: the outer covering of the forebrain. F. Cerebrum: consists of two separate hemispheres, left and right, and constitutes the bulk of the forebrain. G. Corpus Callosum: a thick bundle of axons crossing between the two hemispheres of the brain enabling them to communicate with each other. H. Cerebral Cortex: the outer covering of the forebrain. The cerebral cortex is comprised of… I. Gray Matter: the cell bodies of neurons. (Note: Gray matter is also found within deeper parts of the forebrain.) J. White Matter: the axons of neurons and constitutes the bulk of the deeper parts of the forebrain.

K. The Occipital Lobe: is at the rear of the head and contains many specialized areas for interpreting visual information.

L. The Parietal Lobe: contains… 1) Primary Somatosensory Cortex: the area of the brain that is specialized for body senses and awareness of the location of body parts.

M. The Temporal Lobes: are located on the sides of the head, near the ears and are the main processing areas for hearing and complex aspects of vision. 1) Visual Agnosia: difficulty remembering faces often because they can’t see the whole face.

N. The Frontal Lobe: contains... 1) Primary Motor Cortex: the area that is important for control of fine movements. 2) Prefrontal Cortex: is responsible for organization, planning of action, and aspects of memory.

O. Midbrain: controls many important functions such as the visual and auditory systems as well as eye movement and certain aspects of body movement.

P. Hindbrain: 1) The Cerebellum: important for coordination, balance, and timing. 2) Pons: involved in respiration, attention, sleep, and dreaming. 3) Medulla: involved in the regulation of heartbeat and respiration. 4) Pons and Medulla: control the muscles of the head (chewing, swallowing, etc.).

VI. Other Structures and Systems Q. Reticular Formation: regulates arousal in the brain. R. Spinal Cord: controls the muscles from the neck down, including both voluntary responses and reflexes. 1) Reflex: a rapid, automatic response to a stimulus. VI. Other Structures and Systems A. Thalamus: sends incoming sensory information to the appropriate area of the cerebral cortex. B. The Limbic System: involved in motivated behaviors, emotional states, memory, body temperature, & blood pressure. 1) Hypothalamus: helps to regulate emotional and motivated behavior and maintain homeostasis (the body’s internal equilibrium). 2) Amygdala: regulates emotional control and the formation of emotional memories. 3) Hippocampus: a vital structure for memory acquisition and processing.

C. The Endocrine System: a system of glands that release hormones into the bloodstream. 1) Hormones: chemicals that affect mood, behavior, and anatomy (e.g. testosterone “male sex hormone”, estrogen and progesterone “female sex hormones”). 2) The Pituitary Gland: governed by the hypothalamus, its most primary function is the secretion of growth hormones responsible for the growth of muscles, bones, and other glands. 3) The Pineal Gland: secretes the hormone melatonin, which helps regulate the sleep-wake cycle. 4) The Thyroid Gland: secretes the hormone thyroxin, which affects the body’s metabolism. 5) The Adrenal Glands: secretes hormones called cortical steroids, which aid in coping with stress.

VII. Measuring Brain Activity A. EEGs and MEGs: record electrical and magnetic activity in the brain. B. PET: provides a high-resolution picture of brain activity using radioactivity from chemicals injected into the bloodstream. C. fMRI: uses magnetic detectors outside the head to measure the amounts of hemoglobin and oxygen in different areas of the brain.

VIII. Experience and the Brain A. Nerve cell generation B. Learning changes the brain C. The “binding” problem D. The split-brain phenomenon