Thinking About Psychology: The Science of Mind and Behavior 2e

1. Thinking About Psychology: The Science of Mind and Behavior 2e Charles T. Blair-Broeker Randal M. Ernst As before, with much thanks to:

2. Neuroscience and Behavior

3. Neuroscience – scientific study of the nervous system

4. Nervous system- body’s primary communication network • The nervous system is closely linked to the endocrine system – system of glands that secrete hormones into the blood stream.

5. Nervous System • The electrochemical communication system of the body • Sends messages from the brain to the body for movement • Brings information to the brain from the senses

6. Neurons: The Building Blocks of the Nervous System

7. Neuron • A nerve cell; the basic building block of the nervous system • There may be as many as 100 billion neurons in the brain • Neurons perform three basic tasks • Receive information • Carry the information • Pass the information on to the next neuron

8. Parts of the Neuron

9. Parts of the Neuron - Dendrites Dendrite – The branching extensions of a neuron that receive information and conduct impulses toward the cell body

10. Parts of the Neuron - Soma Soma – The cell body of a neuron, which contains the nucleus and other parts that keep the cell healthy

11. Parts of the Neuron - Axon Axon – The extension of a neuron through which neural impulses are sent

12. Parts of the Neuron – Myelin Sheath

13. Parts of the Neuron - Terminals Axon terminals – The endpoint of a neuron where neurotransmitters are stored

14. Glial Cells • Specialized support cells for the neurons • More numerous (10x) than neurons • Structural support • Nutrition • Remove waste • Perhaps involved in communication between neurons, enhances speed

15. Types of Neurons • Sensory Neurons (aka afferent neurons) • Tell us about the environment; share information from specialized receptor cells (in various sense organs) with the brain; also carry info from skin and organs to the brain • Motor Neurons (aka efferent neurons) • Gets us moving; sends info to the muscles and glands • Interneurons(aka relay or connector neurons) • Share info between neurons (there are more of these than the previous two)

17. Quick question? What’s the longest axon in your body? {Remember most neurons are terribly small} It’s found on the motor neuron that works your big toe. For a basketball player (7’) it’s 4 feet long; for most people it’s about 3 feet long.

18. How Neurons Communicate:The Neural Impulse Module 6: The Nervous System and the Endocrine System

19. Action Potential • A neural impulse; a brief electrical charge that travels down the axon of a neuron • Considered an “on” condition of the neuron A neuron has to re-set itself after every reaction for the next reaction. Na+ is moved back out while K+ is moved back in. One protein pumps both potassium and sodium out with the use of energy because both are moving against the concentration gradients. The nerve re-sets itself by pumping 3 Na+ out and 2 K+ in, which is not an equal exchange. Active transport proteins in the membrane are responsible for pumping Na+ out and K+ in. These proteins require a great deal of energy, or ATP Changes in charge across the membrane causes ion channels to open and close. In response to depolarization, Na+ channels open quickly and close slowly. While K+ channels open slowly and close slowly in response to depolarization.

20. Each neuron requires a minimum level of stimulation from other neurons to be activated (stimulus threshold). • While waiting to be stimulated it is said the neuron is polarized. • In this state the axon’s interior is more negatively charged than the exterior fluid surrounding the axon. • This condition is due to primarily to different ions: potassium and sodium. • While the neuron is at resting potential (-70 mv), the fluid surrounding the fluid surrounding the axon contains a larger concentration of sodium ions than does the fluid within the axon. The fluid within contains a larger concentration of potassium.

21. Once stimulated by other neurons or sense receptors, neuron depolarizes beginning action potential…Na+ rush in and K+ rush out and charge of axon is momentarily changed to +30mv (this is the action potential) it happens at each segment of the axon and it goes through the whole process at each segment until it reaches the end and it goes from start to finish through the neuron due to the all-or-nothing principle. After the action potential there is a refractory period where the neuron repolarizes and makes it negative inside and positive outside again(another progressive segment by segment movement) and we’re back at the resting potential.

23. Action Potential

24. Refractory Period • The “recharging phase” during which a a neuron, after firing, cannot generate another action potential • Once the refractory period is complete the neuron can fire again

25. Refractory Period

26. Resting Potential • The state of a neuron when it is at rest and capable of generating an action potential • The neuron is set and ready to fire

27. Resting Potential

28. All-or-None Principle • The principle stating that if a neuron fires it always fires at the same intensity • All action potentials are of the same strength. • A neuron does NOT fire at 30%, 45% or 90% but at 100% each time it fires.

29. What’s the speed of Neuron Communication? • The fastest neural messages zoom around at 270 mph • The slowest neural messages creep by at 2 mph • These speeds are based on: • the size of the axon (the greater the diameter, the faster it moves) • the myelin sheath (myelinated neurons are faster than non)

30. A Neural Chain

31. A Neural Chain

32. A Neural Chain

33. A Neural Chain

34. A Neural Chain

35. How Neurons Communicate:Communication Between Neurons Module 6: The Nervous System and the Endocrine System

36. Types of Neural Communication • Electrical • almost instantaneous; only 1% ‘talk’ this way • Chemical • involves neurotransmitters; 99% of neurons engage in this 1-way conversation

37. Chemical communication occurs when the presynaptic neuron (message sending) creates a chemical substance (neurotransmitter) that diffuses across the synaptic gap and is detected by the postsynaptic neuron (receiving neuron).

38. Synapse • The point of communication between two neurons • The tiny, fluid filled gap between the axon terminal of one neuron and the dendrite of another neuron, synaptic gap. • The action potential cannot jump the gap

39. Presynaptic neuron is activated, it generates an action potential that travels to the end of the axon. • The end of the axon has several small branches called axonterminals. • Floating in the interior fluid of the axon terminals are tiny sacs called synaptic vesicles. • The synaptic vessels hold special chemical messengers manufactured by the neuron called neurotransmitters. • NT cross the synaptic gap and attach to the receptor sites on the dendrites surrounding neurons, synaptic transmission. • They will then detach and are reabsorbed by the presynaptic neuron so they are recycled and reused, reuptake.

40. Neurotransmitters

42. 3. After attachment, what happens? Usually - reuptake - the neuro- transmitters, detach and are reabsorbed by the presynaptic neuron, to be used again

43. NT communicates either an excitatory message or an inhibitory message.

44. Excitatory Effect • A neurotransmitter effect that makes it more likely that the receiving neuron will generate an action potential or “fire”.

45. Inhibitory Effect • A neurotransmitter effect that makes it less likely that the receiving neuron will generate an action potential or “fire”

46. The effect of the NT depends on the receptor site on to which it binds, could have an excitatory effect on one and an inhibitory on another. • On average, each neuron in the brain communicates directly with 1,000 other neurons. Thus, there are up to 100 TRILLION synaptic interconnections. • There are nearly a thousand times more synaptic connections in your brain than there are stars in the entire galaxy!!

47. NT and Their Effects • Physical functioning • Psychological functioning • Too much or too little can have devastating effects Yet they are present in extremely tiny amount in our brains! • Effects can be the result of complex interactions of different NT and NT have different effects in different areas of the brain.

48. Acetylcholine • 1st neurotransmitter discovered • Present in all motor neurons • Stimulates muscles to contract (heart and stomach too) • Also useful in learning, memory & general thinking • Patients with Alzheimer’s have very little Ach as well as a depletion of other NT • Nerve gas causes Ach to be continuously released causing severe muscle spasms that suffocate the victim. Atropine blocks Ach receptor sites saving victims from the nerve gas.

49. http://www.psychologytoday.com/blog/brain-babble/201208/paralyze-your-face-fight-depressionhttp://www.psychologytoday.com/blog/brain-babble/201208/paralyze-your-face-fight-depression

50. Dopamine • Useful in movement, attention, learning and pleasurable sensations • Addiction to drugs (e.g. nicotine and cocaine) related to how the drugs increase dopamine’s activity in the brain • Parkinson’s is caused – in part – by deterioration of dopamine producing neurons in the brain; counteracted some by L-dopa • Too much dopamine is associated with hallucinations in schizophrenia (drugs work to block dopamine receptors and decrease levels in the brain)