Unit 1: Biological Bases of Behavior

Neuron

Nerve cell that transmits signals

Glial Cells

Support cells for neurons; provide nutrients and insulation

Dendrites

Branch-like structures on the neuron that receive signals

Cell body (soma)

Neuron control center, contains the nucleus

Axon

Long fiber that sends signals away from the cell body

Myelin Sheath

Fatty covering that speeds up neural signals

Terminal Buttons

End of axons that release neurotransmitters

Synapse

Gap between neurons where communication occurs

Receptor Sites

Areas on dendrites that receive neurotransmitters

Threshold

Minimum signal needed to trigger a neuron (-55mV)

Action Potential

The electrical impulse that travels down an axon

All-or-None Principle

A neuron either fires completely or not at all

Neural Firing

The process of a neuron sending an electrical signal

Excitatory Neurotransmitters

Increase the chance of a neuron firing

Inhibitory Neurotransmitter

Decrease the chance of a neuron firing

Acetylcholine

Neurotransmitter for movement and memory

Dopamine

Neurotransmitter for pleasure, movement, and reward

Endorphins

Neurotransmitters that reduce pain and boost mood

Serotonin

Neurotransmitter for mood, sleep, and appetite

Afferent Neurons (Sensory Neurons)

Carry signals to the brain

Efferent Neurons (Motor Neurons)

Carry signals from the brain to the muscles

Central Nervous System

Brain and spinal cord

Spinal Cord

Transmits signals between the brain and the body

Peripheral Nervous System

All nerves outside the brain and spinal cord

Somatic Nervous System

Controls voluntary movements

Autonomic Nervous System

Controls involuntary functions

Sympathetic Nervous System

Activates “fight or flight” response

Parasympathetic Nervous System

Calms the body after stress

Psychoactive Drugs

Substances that alter brain function

Agonists

Drugs that enhance neurotransmitter activity

Antagonists

Drugs that block neurotransmitter activity

Stimulants

Drugs that increase alertness and energy (ex: caffeine, cocaine)

Depressants

Drugs that slow down body functions (ex: alcohol)

Hallucinogens

Drugs that alter perception and reality (ex: LSD)

Opiates

Pain-receiving drugs that mimic endorphins (ex: heroin, morphine)

Hindbrain

Controls basic life functions (ex: breathing, heart rate)

Medulla

Controls heart rate and breathing

Pons

Involved in sleep and facial expressions

Cerebellum

Coordinates movement and balance

Midbrain

Connects hindbrain and forebrain; controls simple movements

Reticular Formation

Regulates alertness and attention

Forebrain

Controls complex thought, emotions, and behavior

Thalamus

Brain’s “sensory relay station”, processing and transmitting sensory information

Hypothalamus

Regulates hunger, thirst, body temp, and hormones (homeostasis)

Amygdala

Processes emotion, especially fear and agression

Hippocampus

Involved in memory formation

Limbic System

Emotional and memory center of the brain

Cerebral Cortex

Outer layer of the brain involved in higher thinking

Brain Lateralization

The brain’s two halves have different functions

Corpus Callosum

Connects the two hemispheres of the brain

Lobes

Four major sections of the brain (Frontal, parietal, occipital, and temporal)

Association Area

Integrates info for higher mental processes

Frontal Lobes

Control thinking, planning, and voluntary movement

Broca’s Area

Controls speech production

Wernicke’s Area

Controls language comprehension

Motor Cortex

Controls voluntary movements

Parietal Lobes

Processes touch, temperature, pain, and sense of body position

Sensory Cortex

Processes sensory input

Occipital Lobes

Processes visual information

Temporal Lobes

Processes auditory information and language

Brain Plasticity

Brain’s ability to adapt and reorganize

Lesions

Tissue destruction in the brain; studied for effects on behavior

Electroencephalogram (EEG)

Measures brain waves

CAT/CT Scan

X-ray imaging of brain structure

MRI Scan

Detailed brain images using magnetic fields

PET Scan

Shows brain activity using glucose

Functional MRI (pMRI)

Measures brain activity and structure in real time

REM Sleep

Rapid Eye Movement sleep, linked to dreams

Narcolepsy

Sudden, uncontrollable sleep attacks

Sleep Apnea

Breathing stops repeatedely during sleep

Freudian Dream Interpretation

Dreams reflect unconscious desires

Activation-Synthesis Dream Theory

Dreams are random brain activity

Information-Processing Dream Theory

Dreams help process daily experiences

Transduction

Converting stimuli into neural signals

Sensory Habituation

Brain filtering out unimportant stimuli

Energy Senses

Vision, hearing, and touch

Chemical senses

Taste and smell

Cornea

Transparent layer that protects the eye

Pupil

Opening of the eye that controls light intake

Lens

Focuses light onto the retina

Retina

Light sensitive layer that processes images

Optic Nerve

Sends visual info to the brain

Feature Detectors

Neurons that respond to specific stimuli

Rods and Cones

Detect light and dark; detect color

Bipolar Cells and Ganglion Cells

Process visual signals before they reach the optic nerve

Fovea

Central point of sharp vision

Blind Spot

Area where optic nerve leaves the eye (no receptors)

Trichromatic Theory

Color vision based on red, green, and blue

Opponent-Process Theory

Colors are processed in opposing pairs (red-green; blue-yellow)

Cochlea

Spinal shaped organ that converts sound into neural signals

Pitch Theories

Explain how we perceive different frequencies of sound

Nerve Deafness

Hearing loss due to damaged hair cells in the cochlea

Gate-Control Theory

Spinal cord controls pain signals to the brain

Vestibular Sense

Sense of balance and spatial orientation

Kinesthetic Sense

Awareness of body position and movement

Absolute Threshold

Minimum stimulus needed for detection 50% of the time

Subliminal Messages

Stimuli below conscious awareness

Difference Threshold (Just-Noticeable Difference)

Smallest detectable difference between stimuli

Weber’s Law

The greater the stimuli, the bigger the change needed to notice a difference