Biological Bases of Behavior explains how the body and brain produce behavior and mental processes. Expect questions that name a structure, chemical or drug from a short scenario, plus questions on sleep and the senses. Know what each part does, and be ready to read a small study about heredity or the brain.
- nature and nurture
- Nature is inherited, predisposed characteristics. Nurture is external experience, such as family and education. The two interact to shape behavior and mental processes.
- Example: A child's musical talent may reflect musical parents (nature) plus years of lessons and encouragement at home (nurture).
- central nervous system
- The brain and spinal cord, which interact with all processes in the body.
- Example: A signal from a touched fingertip travels up the spinal cord to the brain, which decides how to respond.
- neuron
- A neural cell that transmits information. Dendrites receive messages and the axon sends them on.
- Example: In a reflex arc, a sensory neuron, an interneuron and a motor neuron pull your hand from a hot pan.
- brain stem
- The structure at the base of the brain, including the medulla, that controls basic functions such as breathing and heart rate.
- Example: Damage to the medulla can stop breathing even when the rest of the brain is intact.
- circadian rhythm
- A cycle of about 24 hours, such as the sleep/wake cycle. Jet lag and shift work disrupt it.
- Example: After flying across several time zones, a traveler feels sleepy at noon and wide awake at midnight.
- absolute threshold
- The minimum stimulus energy needed to detect a stimulus at least 50% of the time.
- Example: The faintest scent of perfume a volunteer notices on half of the test trials marks her absolute threshold for it.
- twin study
- Research comparing identical and fraternal twins to estimate how much heredity affects a trait. It is non-experimental, so it shows correlation, not cause.
- Example: If identical twins share a trait far more often than fraternal twins, heredity probably contributes to it.
- peripheral nervous system
- Nerves relaying messages between the central nervous system and the rest of the body. It includes the somatic (voluntary) and autonomic (involuntary) systems.
- Example: Waving to a friend uses somatic nerves; your racing heart on seeing them uses autonomic nerves.
- action potential
- The brief electrical signal a neuron fires when depolarization from resting potential reaches threshold. It is all-or-none, followed by a refractory period.
- Example: Stepping on a tack depolarizes sensory neurons in your foot past threshold, and signals race along their axons.
- cerebellum
- The structure that coordinates muscle movement and balance and supports some procedural learning.
- Example: After cerebellar damage, a pianist's movements turn clumsy and she can't walk a straight line.
- NREM sleep
- Sleep Stages 1 through 3, identified by EEG patterns, which shortens across the night. Hypnagogic sensations occur as Stage 1 begins.
- Example: Drifting off, you suddenly feel as if you are falling: a hypnagogic sensation of initial Stage 1.
- sensory adaptation
- Diminished sensitivity to a constant, unchanging stimulus over time.
- Example: After a few minutes, you no longer notice your watch on your wrist.