Chapter 2 The Biological Basis of Behavior

1. Chapter 2The Biological Basis of Behavior

2. Introduction • The brain is the control center of everything that we say and do! • Complex organ • Billons of cells • Overlapping pathways and networks • Plasticity= ability to adapt to new environmental conditions • Psychobiology= biological bases of behavior and mental processes

3. Introduction • Neuroscience= study of the brain and nervous system • Neuropsychologists= study brain’s influence on behavior

4. Neurons • Aka nerve cells • Body contains approximately 100 billion • Varies widely in size and shape • Specialized to receive and transmit information

6. Neuron Types • Sensory neurons= carry messages from sense organs to the spinal cord or brain • Motor neurons= carry messages from the spinal cord or the brain to the muscles and glands • Interneurons= carry messages from one neuron to another • Glial cells= hold neurons in place, provide nourishment, remove waste, prevent harmful substances to passing into the brain

7. The Neural Impulse • Yes-no, on-off electrochemical impulses • Ions= electrically charged particles • Resting Potential = electrical charge across a neuron membrane • Excess (+) ions on outside, (--) on the inside • Neural Impulse= the firing of a nerve cell • Polarization= a resting neuron; (--) on inside • Depolarization= inflow of (+) sodium ions • sets off a chain reaction

9. The Neural Impulse (cont) • Threshold of Excitation= the level the impulse must exceed to cause a neuron to fire • All-or-none law= the neuron will fire or it won’t • Absolute refractory period= time after a neuron has fired that it WILL NOT fire not matter what the impulse

10. The Synapse • Neurons are NOT connected • Tiny space between called synaptic space • Terminal button= end of axon branch • Synaptic Vesicles = tiny sacs in terminal button that release chemicals into the synapse • Neurotransmitters= chemicals release by the synaptic vesicles

11. Neuron Toilet Worksheet

13. Neurotransmitters • Acetylcholine (Ach)= acts where neurons meet skeletal muscles • Role in arousal, attention, memory, & motivation • Linked to Alzheimer’s disease • Dopamine= assoc. with voluntary movement, learning, memory & emotions • Parkinson’s disease • Serotonin= “mood molecule” (sets emotional tone) • Half empty or half full • Endorphins= turn down neurons that transmit pain messages to the brain. • **review chart on page 54**

14. Neurotransmitters • Imbalances have been linked to mental illness • Schizophrenia (over abundance of dopamine) • Depression (undersupply of serotonin & norepinephrine)

16. Nervous System Organization • Includes the brain and the spinal cord • Contains 90 % of the body’s neurons • Peripheral Nervous System= division of the nervous system that connects the CNS to the rest of the body

17. The Brain (cont.)

20. The Brain (cont.) • Cerebellum= sense of balance and coordinating body’s actions

21. The Limbic System The Limbic Systemisa doughnut-shaped system of neural structures at the border of the brainstem and cerebrum, associated with emotions such as fear, aggression and drives for food and sex. It includes the hippocampus, amygdala, and hypothalamus.

22. Amygdala The Amygdala [ah-MIG-dah-la] consists of two lima bean-sized neural clusters linked to the emotions of fear and anger.

23. Hypothalamus The Hypothalamus lies below (hypo) the thalamus. It directs several maintenance activities like eating, drinking, body temperature, and control of emotions. It helps govern the endocrine system via the pituitary gland.

24. The Brain (cont.) • Midbrain= important for hearing and sight • Pain is registered here (one of many) • Thalamus= “relay station” for incoming messages from the sense receptors (except for smell) • Reticular Formation= ALERT system; network of neurons • Pons- regulate sleep wake cycles • Medulla= regulates respiration, heart rate, blood pressure