1. The Biological Basis of Behavior
Chapter 3:
The Biological Basis of Behavior

2. Biological Psychology Physiology of Behavior
Biopsychology
Brain & Behavior
Scientific study of the biological and mental processes of behavior

3. Neurons
Neurons or nerve cells: Individual cells in the nervous system that receive, integrate, and transmit information through chemical or electrical transmission
3 basic types :
Sensory Neurons
Motor Neurons
Interneurons

4. Neurons Dendrite Receives information Cell Body or Soma
Contains nucleus, keeps cell alive
Axon
Transmits information to another neuron
Axon Terminal Buttons
Secretes chemicals called neurotransmitters located at the end of the axon
Axon Terminal
Buttons

5. Neurons Myelin Sheath Protects axon and speeds up message
Nodes of Ranvier
Tiny gaps in the myelin sheath
What is damage to the myelinated sheath called?
Multiple Sclerosis (MS)

6. Communication Between Neurons
Two ways information is transmitted:
Electrical
Chemical

7. Electrical Electrical Synapses:
membranes of the two cells actually touch, and share proteins
communication passes directly from one membrane to the next
very fast
rare, found only in the heart and the eye

8. Chemical
Synapse: the point of communication between neurons at the synaptic cleft
Presynaptic neuron: message-sending
Postsynaptic neuron: message-receiving
Synaptic Vesicles: little sacs inside Axon
Terminal Button contain chemicals called
Neurotransmitters

9. Chemical Synaptic cleft/gap: the gap between the
axon terminal button of one neuron and the
dendrite of the adjoining neuron
Neurotransmitters: chemical created by
neuron that transmits information from one
neuron to another
Synaptic transmission neurotransmitters
are released, cross the synaptic gap, attach
to receptor sites

10. Chemical Receptors: post-synaptic neurons have
specific binding sites for neurotransmitters 
Reuptake: neurotransmitters reabsorbed
or recycled by presynaptic neuron

11. 1 5 2 4 3 Neurons Neurotransmitter molecules in synaptic vesicles
Reuptake of neurotransmitters sponged up by the presynaptic neuron 2
Release of neurotransmitter molecules into synaptic cleft 4
Destruction (by enzymes) or Breakdown
When a neurotransmitter and a receptor molecule combine, reactions in the cell membrane cause a postsynaptic potential, or PSP - a voltage change at the receptor site on a postsynaptic cell membrane.
After producing postsynaptic potentials, some neurotransmitters either become inactivated by enzymes, or drift away. Most neurotransmitters, however, are reabsorbed into the presynaptic neuron through reuptake - a process in which neurotransmitters are sponged up from the synaptic cleft by the presynaptic membrane. 3
Binding of neurotransmitters at receptor sites on postsynaptic membrane

12. Neurons: How The Message Gets Its Power
Action Potential: a brief electrical impulse that travels along the axon
See it in Action
Threshold: each neuron has a minimum level to be activated
All-or-None Law: sufficiently stimulated- action potential occurs, not sufficiently stimulated—action potiential does not occur!
Absolute Refractory Period: mimimum length of time until another action potential can begin
Resting Potential: stable negative charge of a neuron and no signal is being transmitted –70 millivolts
Video

13. Neurotransmitter Chemicals
Neurotransmitters: Affect learning, memory, mood, behavior and mental illness
Acetylcholine: muscle control; contributes to regulation of attention, arousal and memory.
Dopamine: Pleasure, Learning, Emotion, Motivation, Movement, (not enough) Parkinson’s, (too much) Schizophrenia
Serotonin: Mood, Appetite, Sleep, Depression
Norepinephrine: Stress, learning, ADHD, depression
Endorphins: Pain Reliever; Drug Addiction
Video

14. Studying the Brain
EEG (Electroencephalograph) – electrodes record brain wave patterns
CAT/CT (Computerized Axial Tomography) – cross sectional series of X-Rays
MRI (Magnetic Resonance Imaging) – magnetic fields identify tissue types
fMRI (functional Magnetic Resonance Imaging) – magnetic field identifies structure & function
PET (Positron Emission Tomography) –decay of radioactive material used to visualize brain activity & use of nutrients

15. Nervous System Central Nervous System (CNS)
Peripheral Nervous System (PNS)

16. Central Nervous System
Central Nervous System (CNS):
Brain and Spinal Cord;
interprets, processes and responds to incoming information

17. Peripheral Nervous System
Peripheral Nervous System (PNS): Links all of the nerves outside of Central Nervous System to the body
2 Divisions of the PNS:
Somatic Nervous System: sensory info
Autonomic Nervous System: involuntary functions
Sympathetic: mobilizes fight or flight
Parasympathetic: conserves resources

18. Autonomic Nervous System
Sympathetic – activates organs and glands; fight/flight stress response
Parasympathetic – calms body, recovery

19. Brainstem
Midbrain
Hindbrain

20. Brainstem
Midbrain
Hindbrain:
Medulla
Pons
Cerebellum

21. Brainstem: contains the hindbrain and midbrain and connects the spinal cord to the rest of the brain
Midbrain: helps process auditory and visual information
Hindbrain: connects spinal cord to brain
Medulla: Controls vital functions, (breathing, heart rate, digestion)
Pons
Cerebellum: balance, muscle movements, motor skills

22. Forebrain/Cerebrum
Forebrain or Cerebrum: involved in complex behaviors and cortex mental processes which are divided into 2 hemispheres
The hemispheres are divided into four lobes:
Frontal lobe: thinking, planning, reasoning, self-control and voluntary muscle movements
Temporal lobe: Processes auditory information
Occipital lobe: Processes visual information
Parietal lobe: Processes bodily sensations

23. Frontal Lobes Control Thinking, planning, judgment, impulse control
Broca’s area: L frontal lobe; production of language
Broca’s aphasia: damage/loss of speech
Association Areas: sensory and motor information is combined and associated with stored knowledge.
Motor Cortex: Movement; signals to spinal cord & cerebellum
Damage

24. Cerebrum
Cerebral cortex
Corpus callosum
Cerebral Cortex: higher cognitive processes (ie: thinking, language, reasoning)
Corpus Callosum *
R & L Brain connection
split brain
Cerebral Hemispheres * (in most people)
R = perceptual skills, drawing pictures
L = language, math
Cerebellum
Medulla

25. Limbic System
Limbic System: group of forebrain structures involved in emotion, motivation, learning, and memory
Hippocampus: Memory formation
Amygdala: Aggression, fear, anger, disgust, stress and other emotions. Also involved in learning and in memory formation, especially emotional memories.

26. Limbic System
Thalamus: Involved in regulating levels of awareness, attention, motivation, and emotions
Hypothalamus: regulates both divisions of the autonomic nervous system and behaviors related to survival, such as eating, drinking, frequency of sexual activity, fear, and aggression
Links nervous system to endocrine system via pituitary gland

27. ENDOCRINE SYSTEM Hormones = Glands that secrete hormones
Chemical messengers in the bloodstream.
Hormones help regulate emotions and behaviors.

28. Plasticity
The brain’s ability to change its structure and function in response to experience or damage