Neurons and the nervous systems

1. Neurons and the nervous systems October 2010

2. Q1 - Parts of the neuron • Dendrites • Cell body • Axon • Axon segments • Axon terminals • Synapse • Myelin sheath

3. How neurons work • Neurons are cells - with walls, nucleus, etc • Q2 - Neurons receive information • Receive both excitatory and inhibitory messages • Q3 The neuron exceeds threshold when

4. What does fire mean? • By “firing,” the neuron transmits a signal to either the receptor of another neuron or to some other body structure (eg, muscles) • Q4 - When neurons fire, it is “all or nothing”. • When it “fires,” it sends neurotransmitters into the synapse (or synaptic gap) where other neurons can receive them

5. Neurotransmitters Q5 • They are chemical compounds that are used in the brain and the body. • Most are associated with one or more physical or brain functions. • Excess or deficit of certain NTs is associated with different psychological and physical diseases - schizophrenia, Parkinson’s

6. Q6 - An action potential • A neuron fires! • www.sheatech.net/axon.swf • Refractory phase

7. After NTs released • See p 57 - diagram • Receptor sites on next neuron • Reuptake – Q7 • Note - NTs are not used up or destroyed in the synapse

8. NTs you should know • Q8 - Dopamine • Acetylcholine (Ach) • Q9 - Serotonin • Norepinephrine • Q10 - GABA • Glutamate • Q11 - Endorphins

9. Q12 Nervous system hierarchy P… C…. B.. SC S… A.. P S

10. Kinds of neurons • Q13 - Sensory neuron - afferent • Motor neuron - efferent • Q14 - Interneuron (and reflexes) • Mirror neurons

11. Misc facts • Q15 - Neural networks • Q16 - Antagonist / agonist • Q17 - Nerve - a nerve is a bundle .. • Q18 – Spinal cords • Graphic on pg 62

12. Endocrine system Glands, hormones and behavior

13. Endocrine system • _____ messenger system Q19 • Controlled by ____________ which is controlled by ________________ • Hormones • Q20 • norepinephrine

14. Controlling structures • Hypothalamus- Q21 • Controls _________________ • Produces _________________ • Other brain functions ….. • Pituitary –Q22 • Produces both _________________________ • Controls ______________________________

15. Adrenal (“next to kidneys”) Q23 • Arousal • Produces ________________________ • Fight or flight • Pancreas Q24 • Produces • Produces • Thyroid controls ___________ Q25 • Pineal - melatonin - bio rhythms Q26

16. Sex and the endocrine system • Ovaries Q27 • Testes • Primary sex characteristics • Secondary sex characteristics

17. The Brain

18. Q28 - Brain research • MRI • fMRI • CAT scan • PET scan • Ablation / lesion • EEG

19. Brainstem – Q29 • Medulla - • Pons - • Reticular Formation -

20. Thalamus – Q30 • Thalamus - the sensory switchboard

21. Cerebellum – Q31 • Non-verbal • All non-conscious

22. Limbic system – Q32 • Hypothalamus • Amygdala • Hippocampus • Pituitary gland

23. Cerebral cortex • Assume many parts of the brain are involved in most mental processes • Temporal lobes are not the only parts involved in hearing, right brain / left brain, etc • We will identify major functions of different parts - not necessarily all their functions, nor all the parts of the brain involved in different functions

24. Structure • Glial cells - Q33 • 2 hemispheres • Lobes – Q34 • Cortexes - motor, sensor • Association areas

25. Cortexes – Q35 • Sensory cortex • Motor cortex

27. Lobes – Q36 • Frontal • Parietal • Occipital • Temporal

28. Association areas • Q37 • Is it true that we use only 10% of our brains?

29. Q38 - Reading aloud - see pg 81 • Text to visual cortex as graphics • Angular gyrus interprets picture as auditory code • Wernicke’s area interprets auditory code as language • Broca’s area controls speech using the motor cortex • Motor cortex controls lips, tongue, etc

30. Brain plasticity • Q39 • What do we mean by plasticity?

31. Corpus callosum • Q40 • How is the corpus involved in seizure treatment?

32. Split brains • Q41 - HE * ART experiment • Q42 – Who was Phineas Gage? • Q43 - right side functions • left side functions

33. Nature vs nurture Or what the heck is heritability?

34. Q44 - Behavioral genetics • The study of how genes and environment interact to affect our behavior, personality • Heritability - the extent to which differences between groups of people can be attributed to genetics

35. Q45 - Genes • Genome • Chromosomes • Genes • DNA

36. Twins and adoptees – Q46 • Q47 - MZ’s and DZ’s - monozygotes and dizygotes • MZ’s share 100% of genetic material • DZ’s share 50% • All siblings share 50% (on average) • Adoptees share environment with adopted family • MZ’s and DZ’s may not share environment

38. Q48 - Shared environment • Assumption is that living in the same home with same parents and same general environment will cause children to be similar • And different from kids from another family

39. Shared environment • Seems reasonable • Except it doesn’t seem to happen

40. Evidence • Similarities among MZA’s, MZ’s, DZ’s, DZA’s • Low correlations between traits of adopted child and adopted parents • Multiple adoptees in one family don’t become similar • Large differences among natural siblings

41. Why do siblings differ? • They are different genetically • How “shared” is the shared environment? • Pre-natal influences • Birth order effects? • Age and sex of older sibs • Unique experiences - injury, illness

43. Another intelligence study

44. Generally it appears that the higher the genetic relatedness, the higher the correlation of IQ scores • Appears that IQ has a high degree of heritability

45. How about schizophrenia? • Predict: • Will both identical twins be schizophrenic? • How about fraternal twins? • Child of schizophrenic parents? • Sibling of schizophrenic?

46. Q49

47. Once again the closer the genetic relationship, the higher concordance • That argues for a high level of heritability - that is, we can explain the differences by genetics

48. Let’s look at that IQ slide again

50. Can’t we argue that the more we share environment, the closer our IQ scores will be?