Chapter 2 The Biological Basis of Behavior

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

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

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

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

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

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

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

Neuron Toilet Worksheet

**review chart on page 54** 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**

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

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

The Brain (cont.)

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

The Limbic System The Limbic System is a 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. Preview Question 6: What are the functions of limbic system structures?

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

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.

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