Neural Communication Biology of Behavior Notes Part I

Neural Communication Biology of Behavior, Notes Part I Chapter 2 – Myers Psychology

From Skull Bumps to Biology • Phrenology – Franz Gall, early 1800 s – Bumps on the skull could reveal mental abilities or traits – Skull size readings diagnosed patients – Wrong, but directed attention to functionalism • Biological Psychology: concerned with the links between biology and behavior (also called neuropsychology)

• Neuron: a nerve cell; the basic building block of the nervous system – Billions with tens of thousands of connections

The Neuron Dendrites – receive messages from other cells and conduct impulses toward the cell body Cell Body – the cell’s life-support center Axon – the extension of a neuron through which messages are sent to other neurons or to muscles or glands Myelin Sheath – a layer of fatty cells covering the axon, helps speed neural impulses Terminal branches of axon – form junctions with other cells

What do neurons do? • handle the information-processing function of the nervous system • speed of communication between neurons - up to 330 miles per hour – Doesn’t take us long to form thoughts from sensory perception • i. e. smell = what’s cooking where is it being cooked? who’s doing the cooking? • Entire process in a second or less

How do neurons communicate? Synapse: junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The tiny gap at the junction is called the synaptic gap. Neurotransmitters: chemical messengers that traverse the synaptic gaps between neurons Agonist – mimic neurotransmitters Example: Morphine mimics endorphins Antagonist – block neurotransmitters Example: Poison blocks muscle movement

Electrical Charges • Neurons that are resting (not receiving or transmitting information) – negatively charged in a positively charged environment • Polarized – Ion channels are closed • When dendrites receive neurotransmitters from neighboring neurons: – ion channels open up and let positive ions depolarize the neuron

How neurons form impulses… Action Potential: a neural impulse; the electrical charge of an activated neuron; a brief electrical charge that travels down an axon - depends upon the kind of neurotransmitter housed by the neuron. **Neurons that are stimulated cause a brief electrical charge; if strong enough, the nerve fires **ALL OR NOTHING Threshold: level of stimulation required to trigger a neural impulse; excitatory signals minus inhibitory signals must equal a minimum intensity

Neurotransmitter Examples • Acetylcholine (Ach) – Enables muscle action, learning, and memory – **Brains of those suffering from Alzheimer’s have deteriorating Ach-producing neurons • Endorphins – natural neurotransmitters linked to pain control and pleasure – **”Runner’s High” is an example of endorphin release