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Biological bases of
behavior
Unit III
Neural communication
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Neurons
How Neurons Communicate
How Neurotransmitters Influence Us
How drugs and other chemicals alter neurotransmission
Neurons
• A nerve cell; the basic cuilding block of the nervous system
• Dendrites
• Neurons bushy, branching extensions that receive messages and conduct impulses toward the cell body
• Axon
• The neuron extension that passes messages through its branches to other neurons or to muscles or
glands
• Myelin sheath
• A fatty tissue layer segmentally encasing the axons of some neurons; enables vastly greater transmission
speed as neural impulses hip from one node to the next
Motor neurons
Action potential
• A neural impulse
• A brief electrical charge that travels down an axon
• Sent from neurons when stimulated by signals from our senses or when triggered by
chemical signals from neighboring neurons.
• Speeds range from:
• 2 mph
• 180 mph
• Still 3 million times slower than that of electricity through a wire.
Action potential
Refractory period
• A period of inactivity after a neuron has fired
All-or-none Response
• Either all are going to fire or no neurons are going fire.
• Much like a gun.
How neurons communicate
• Synapse
• The junction between the axon tip of the sending neuron and the dendrite or cell body
of the receiving neuron.
• Neurotransmitters
• Chemical messengers that cross the synaptic gaps between neurons. When released by
the sending neuron.
• Reuptake
• The sending neuron reabsorbs the excess neurotransmitters.
How neurotransmitters influence us
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Acetocholine (Ach)
Dopamine (DA)
Serotonin
Norepinephrine (NE)
GABA (gamma-aminobutyric acid)
Endorphins
Glutamate
DRRRRUUUUGGGSSSSS
• Agonist
• A molecule that, by binding to a receptor site, stimulates a response.
• Antagonists
• A molecule that, by binding to a receptor site, inhinites or blocks a response.
September 15th, 2014
• The nervous system
• Objectives:
• Understand the functions of the PNS, CNS, and Endocrine system
• Begin to finalize the brain project
Nervous system
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PNS
CNS
Sensory neurons
Motor neurons
nerves
Peripheral nervous system
• Two components of the PNS:
• Somatic
• Enables voluntary control of our skeletal muscles
• Autonomic
• Controls our glands and the muscles of our internal organs, influencing such functions as
glandular activity, heartbeat, and digestion.
Autonomic Nervous system
• Has two important functions:
• Sympathetic nervous system
• Arouses and expends energy.
• If something alarms or challenges you
• Parasympathetic nervous system
• Will produce the opposite effects, conserving energy as it clams you by decreasing you
heartbeat, lowering your blood sugar, and so forth.
Central nervous system
• BRAIN AND SPINAL CORD
• Spinal cord:
• Two-way highway connecting the peripheral nervous system and the brain
• Ascending neural fibers send up sensory information, and descending fibers send back
motor-control information.
• This neural pathways govern our reflexes
• Our automatic responses to stimuli
Endocrine system
• The body’s “slow” chemical communication system
• A set of gland that secrete hormones into the bloodstream
• Hormones:
• Chemical messengers that are manufactured by the endocrine glands travel through the
bloodstream and affect other tissues.
The endocrine system
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Thyroid
Parathryroid
Pancreas
Pituitary
Adrenal
Testes
Ovaries
Endocrine system
Sensation Vs. Perception
• Sensation:
• The process by which our sensory receptors and nervous system receive and represent
stimulus from our environment
• Perception:
• The process of organizing and interpreting sensory information, enabling us to
rcognize meaningful objects and events
Bottom-up Processing
• Analysis that begins with the sensory receptors and works up to the brains
integration of sensory information
top-down processing
• Information processing guided by higher-level mental processes, as when we
construct perceptions drawing on our experience and expectations
• Selective attention:
• The focusing of conscious awareness on a particular stimulus.
Selective Inattention
• Inattentional blindness:
• Failing to see visible objects when our attention is directed elsewhere
• Change Blindness:
• Failing to notice changes in the environment
We’re going to stick to one Sensation
and one sensation only
Objective:
- Discuss sensation and perception individually
Sensory Adaptation
• This is our ability to adapt to unchanging stimuli
• Example: the smell of an odor in a room that you smell at first will no longer be there
the longer you are in the room.
• The phenomenon of sensory adaptation focuses our attention on informative changes
in stimulation by diminishing our sensitivity to constant or routine odors, sounds, and
touches
Vision
• The stimulus input: Light energy:
• The hue and brightness we perceive in a light depends on the wavelength and intensity of
that ray.
• The working of the EYE:
• After entering the eye and being focused by the lens, light waves strike the retina.
• The rods in the eye sensitive to light
• The cons in the eye color-sensitive
• These convert the light into the neural impulses, which are coded by the retina before going to the
optic nerve.
Visual information processing
• The feature detectors within the cortex, respond to specific features of the
visual stimulus.
• The color, movement, depth, and form are processed separately and
simultaneously.
• The brains representation incorporates our assumptions, interests, and
expectations.
Color vision
• Young-Helmholtz trichromatic (three-color) theory
• Three cones in the eye. Each is most sensitive to the wavelengths of one of the three
primary colors. (red, green, or blue)
• Afterimages
Hearing
• The Stimulus Input: Sound Waves
• The pressure waves we experience as sound vary in frequency and amplitude, and
correspondingly in perceived pitch and loudness.
• We localize sound by detecting minute differences in the intensity and timing of the
sounds received by each ear.
• Hearing loss and Deaf Culture
Other important senses
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Touch
Taste
Smell
Body Position and Movement
Perception is nine
tenths of the law
Perception
• Selective attention
• Perceptual illusions
• Perceptual organization
• Form
• Depth
• Motion
• Perceptual
Perceptual interpretation
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Sensory Deprivation and Restored Vision
Perceptual Adaptation
Perceptual Set
Human Factor
Extrasensory perception
• ESP is to believe that the brain can perceive without sensory input.