Neuroscience, Genetics and Behavior

1. Neuroscience, Genetics and Behavior

2. True or False? • “Basic biological processes underlie all human behavior.” • Various branches of psychology rest on this foundation.

3. Biological Psychology(or Psychobiology) • The most significant transformation in modern psychology • AKA Biopsychologists, behavioral neuroscientists, behavior geneticists, physiological psychologists, neuropsychologists…

4. An intro to neuroscience…Explain the following… • “Modern psychology views each individual as a biopsychosocial system.” • “Everything psychological is simultaneously biological.” • “The mind is what the brain does..” • “A brain simple enough to be understood is too simple to produce a mind able to understand it.”

5. Introducing the neuron… • Simple definition: • a nerve cell • The incredible neuron…. • basic unit of information processing or,… building block of the brain. (and nervous system) • Affects everything we do…

6. A vastly complex system… Facts about neurons: • 100 billion neurons in the human brain and CNS! (and 400 trillion synapses!) • A grain of sand-size part of the human brain holds 100,000 neurons!

7. Neural Structure • Dendrite (receives impulse) • Branching extensions of a neuron / receive messages / conduct impulses toward the cell body • Axon (transmits impulse) • extension of a neuron, ending in branching terminal fibers, through which messages are sent to other neurons or to muscles or glands Remember: “Axons speak, dendrites listen…” • Myelin Sheath(speeds impulse) • a layer of fatty cells segmentally encasing the fibers of many neurons • Speeds transmission of neural impulses

8. Neural Structure • So what happens when the myelin sheath begins to wear out? • Alzheimer's (impedes transmissions affecting thought process) • Multiple sclerosis: interferes with muscle control (as message to muscles is impeded..)

9. Neural Structure

10. Neural Communication “an electrochemical process…” • “Neural communication is a conversation between cells that generates our thoughts, actions, moods and memory.”

11. Neural Communication • Action Potential • a brief electrical charge that travels down an axon • Stimulated when neuron receives signals from sense receptors stimulated by heat, pressure or light

12. Neural Communication“What one neuron tells another neuron is simply how much it is excited.” • Each neuron has a threshold… • the level of stimulation required to trigger an action potential (or neural impulse) • Determined by excitatory and inhibitory triggers that determine the action potential (neural impulse)

13. Neural Communication… • Neurotransmission = electro-chemical process • The chemistry to electricity process involves the exchange of ions • Ions: electrically charged atoms

14. Ions… • Resting Potential • Fluid inside a resting axon has negatively charged atoms • Fluid outside the axon membrane has positively charge atoms • Natural state of inside / outside ions = resting potential • Axon’s surface is selectively permeable (it decides what it allows in..)

15. Reaching a Neuron’s Threshold… • When the neuron fires… • Axon opens gates (selectively permeable) and +charged sodium ions flood the membrane • +sodium ions cause depolarization • Depolarization causes reaction as axons pass the impulse down the chain (like dominoes) • Opens and closes 100-1000 times /second!

16. Reaching a Neuron’s Threshold… • Refractory Period • Once impulse has been passed, the axon pumps +ions back out of membrane, and thus recharges • All or none response • Increased stimulus does not increase the action potential’s intensity (a gun either fires or doesn’t)

17. Cell body end of axon Direction of neural impulse: toward axon terminals Neural Communication

18. Neural Communication • Synapse (Where the action is…) • junction between the axon of the sending neuron and the dendrite of the receiving neuron • synaptic gap or cleft (less than a millionth of an inch!) • Neurotransmitters • chemical messengers that carry the impulse (“message”) from one neuron to the next • neurotransmitters bind to receptor sites(“lock and key” • Thus ions passed on to new neuron: exciting or inhibiting its readiness to fire..

19. Neural Communication • Reuptake • Excess neurotransmitters are reabsorbed by the sending neuron

20. Neural Communication

21. Neurotransmitters • About 75 have been discovered • We will study 7-8

22. Neurotransmitters(Take notes on last 2 listed)

23. GABA Inhibitory neurotransmitter Undersupply = seizures, tremors, insomnia Glutamate Excitatoryneurotrasmitter Involved in memory Too much = migraines, seizures Excitotoxicity: “excite a neuron to death” (glial cells help prevent…) Chinese food- MSG (glutamate) = headaches Neurotransmitters

24. Neurotransmitters • Acetylcholine [ah-seat-el-KO-leen] • ACh • triggers muscle contraction (movement, learning, memory) • Undersupply = Alzheirmer’s

25. Neurotransmitters • Endorphins [en-DOR-fins] • “morphine within” • natural, opiate-like neurotransmitters • linked to pain control and to pleasure • “Runners high” • Opium, heroine addicts: brain stops producing natural opiates, thus “withdraws”

26. Neurotransmitters… • Norepinephrine • Mood • Too much = mania / too little = depression • Imbalance = bipolar disorder

27. Neurotransmitters • Serotonin • Sleep, eating, mood • Related to depression • Prozac (anti-depressant drug) raises serotonin levels

28. Neurotransmitters • Dopamine • Perceptual awareness, muscle control • Too much = Schizophrania (up to 6x more dopemine) • A Beautiful Mind / The Soloist • Too little = Parkinson’s Disease (tremors: Muhammad Ali)

29. Drugs Affect Neurotransmission • Drugs can be used to affect communication at the synapse • Agonists excite, or mimic the neurotransmittors / or block reuptake (drug addicts and withdraw) • Antagonists block, or inhibit neurotransmitters signal (examples=Botox/ botulism blocks Ach) A complicated process: Brain has blood-brainbarrier that blocks out unwanted chemicals

30. Dopamine Pathways Neural Communication Serotonin Pathways

31. Remember… • Communication within the neuron is……. • Electrical • Communication between neurons is…. • chemical

32. Make up 90% of brain’s cells Protect, nourish neurons Current research suggests possible action potentials, debate as to role… See p. 45: Alchemy of Mind Glial cells (Glia)

33. An Alchemy of Mind Explain fully each of the following quotes from your reading. • “Neurons speak an elite pidgin neither chemical nor electrical but a lively buzz that joins the two, an electrochemical lingo all their own.” • “It is important to realize that what one neuron tells another neuron is simply how much it is excited.” • It is a small liquid space, as is the air between two whispering lovers, yet so much life happens there. Each junction is a bazaar full of commerce, intrigue and possibility. In the brain, everything depends on almost nothing, a lively space….” • “Coexisting as they must, both neurons and glia are dependable, dependent… central to the brain’s social fabric and perpetual hum.”

34. The Nervous System • Nervous System • the body’s speedy, electrochemical communication system • consists of all the nerve cells of the PNS and CNS • Central Nervous System (CNS) • the brain and spinal cord (encased in bone) • Peripheral Nervous System (PNS) • connect the central CNS to the rest of the body’s sense receptors

35. Nervous system Peripheral Central (brain and spinal cord) Autonomic (controls automatic action of internal organs and glands) Somatic (Skeletal) (controls voluntary movements of skeletal muscles) Sympathetic (arousing: flight or fight) Parasympathetic (calming) The Nervous System

36. The Autonomic Nervous System • Autonomic Nervous System • part of the PNS: controls the glands and the muscles of the internal organs (involuntary) • A Dual System • Sympathetic Nervous System • arouses the body, mobilizing its energy in stressful situations (“Fight or flight”, or “sympathy in crisis”) • Parasympathetic Nervous System • calms the body, conserving its energy • “paramedics to calm down”- lowers heartbeat etc.

37. The Nervous System

38. The Nervous System

39. The Peripheral Nervous System • Links CNS to body’s sense receptors • For each of the following, identify it as a function of the Somatic or Autonomic Nervous System. • Sneezing • Turning the page • Scratching your head • Breathing • Kissing your date • Digesting your food

40. Communication in the Nervous System • Nerves • neural “cables” containing millions of axons • part of the PNS (carry PNS info) • connect the CNS with muscles, glands, and sense organs • Extend through the body

41. Communication in the Nervous System • 3 neurons that carry info in the nervous system • Sensory Neurons (afferent: millions!) • neurons that carry incoming information from the sense receptors to the central nervous system • Motor Neurons (efferent: millions) • carry outgoing information from the CNS to muscles and glands • Interneurons (billions!) • CNS neurons that internally communicate / process sensory and motor neurons (most complex)

42. The Central Nervous System • “The motherboard of our humanity…” • 10’s of billions of neurons • Brain and spinal cord • Spinal cord: Information highway connecting PNS to the brain

43. Reflexes • Spinal Reflex: Autonomic response to stimuli (Single sensory neuron, single motor neuron, interneuron:…..Brain’s not involved!)

44. Pain Reflex • Sensory neuron, interneuron, motor neuron • a simple, automatic, inborn response to a sensory stimulus

45. The Brain • Center for all sensory information and voluntary movement (receives, interprets, decides…) • Without the brain…no pain or pleasure, no voluntary movement

46. Neurons in the brain connect with one another to form networks Inputs Outputs The brain learns by modifying certain connections in response to feedback Neural NetworksA Complex Mystery… • Neural Networks • interconnected neural cells • with experience, networks can learn, as feedback strengthens or inhibits connections that produce certain results • computer simulations of neural networks show analogous learning

47. In other words… • “Neurons that fire together... wire together.”

48. The Endocrine System • The body’s 2nd communication system • Interconnected with nervous system

49. Endocrine System • ES glands produce hormones • Hormones travel through bloodstream to affect body • Influences growth, mood, metabolism, reproduction etc. • Thus ES works to keep body in balance in response to stress, exertion, thoughts etc. • “Snail mail”- Much slower to process, several seconds, but lasts longer…

50. Important Glands… • Pituitary Gland (the master gland..) • Pea sized, in middle of brain • Influences growth • Influences other Endocrine glands’ release of hormones • Controlled by hypothalamus (brain) • Brain – pituitary – other glands – hormones – brain (complex system: blend of Endocrine system and nervous systems)