Neuroscience and Biological psychology

1. Everything psychological is also biological. AP Psych Myers, Ch. 2 Neuroscience and Biological psychology

2. The Mystery of the Human Brain • The brain is not completely understood. • How does our brain organize and communicate with itself? • How do our heredity and our experiences work together to wire our brain? • How do memories work in the brain? • Biological psychology – a branch of psychology concerned with the links between biology and behavior. • Scientists have discovered partial answers to these questions but much is left to discover!

3. Early Brain Research • Phrenology – theory that the shape of and bumps on the skull could reveal mental abilities and character traits. • Early 1800s – mid-20th century (used to justify racism and discrimination) • Quackery (fraudulent medical practice) • Correctly focused attention on the idea that various brain regions have certain functions

4. Contemporary Brain Research • In the last century, scientists have discovered that the body is made of cells. • Nerve cells (neurons) conduct electricity to “talk” to one another by sending chemical messages across a tiny gap that separates them.

5. Neurons

6. Neuron • Nerve cell • Building block of the nervous system • Found all over the body • Brain • Legs • Eyes • Anywhere there are nerves – We will mainly focus on the basic neuron (below)

7. Dendrites • The bushy extensions of a neuron that receive messages Dendrites

8. Soma • Cell body • Contains nucleus – DNA, genetics, etc Soma

9. Axon • The extension of a neuron through which electrical messages pass • Like the “backbone” of a neuron, if broken, the neuron dies. AXON

10. DENDRITES LISTEN… … AXONS SPEAKThe dendrites can receive messages to make the neuron fire or not fire. If the message is to “fire,” the axon will send the message to the axon terminals.

11. Multiple sclerosis – a disease in which the myelin sheath degenerates resulting in a slowing of all communication to muscles and the eventual loss of muscle control Myelin Sheath • Layer of fatty tissue on the axon that… • Protects axon • Speeds neural impulse (the message) • Made of glial cells, which also bind neurons together. Myelin Sheath

12. Axon Terminals • Branches at the end of an axon that send messages to the dendrites of another neuron. • End in axon terminal buttons – contain vesicles that hold neurotransmitters Axon Terminals Axon Terminal Buttons

13. Action Potential • A neural impulse in the form of a brief electrical charge that travels down the axon • A neuron fires an impulse when it receives a signal from sense receptors or by the neurotransmitters from another neuron. Direction of ACTION POTENTIAL

14. Synapse • The junction between neurons. • Synaptic gap, synaptic cleft, etc • Less than a millionth of an inch wide Synapse

15. I need 5 volunteers… • Stand next to each other facing the class. • Hold hands. • The person farthest to the RIGHT wants to send a message to the person farthest to the LEFT (without actually talking)– how will we do this? • When you feel the squeeze of your right hand, squeeze the right hand of the person beside you.

16. Right hand and arm • DENDRITES • Chest • SOMA • Left arm • AXON • Left hand • AXON TERMINALS

17. How Nerve Impulses Work • Threshold - the level of stimulation required to trigger a neural impulse. • “all-or-none/nothing” principle It either fires… … or it doesn’t.

18. How Nerve Impulses Work • Resting potential – the electrical charge of a neuron at rest. • Ions – electrically charged molecules • Inside axon: overall - • Outside axon: overall + “I’m so HAPPY (+) that I’m OUTSIDE playing!”

19. How Nerve Impulses Work Neuron receives chemical message. • Axon’s ion channels (holes in the axon membrane) open, allowing Na+ ions inside. • Ion channels open like a domino effect, traveling from the soma to the axon terminal. • After the impulse passes, the neuron dips below resting potential and cannot fire. The “ion pump” flushes out positive ions as it releases K+ ions outside. Less than 1/100 of a second.

20. How Neurons Communicate • Neurotransmitters - chemical messengers that travel across the synaptic gap between neurons • Action potential reaches the axon’s terminal buttons. • Buttons release neurotransmitters (chemicals) • Travel across the synapse • Bind/connect to receptor sites on the next neuron’s dendrites

21. Neurotransmitters • Lock-and-key relationship between the neurotransmitter and the receptor site. • When the neuron receives neurotransmitters, it will fire/not fire

22. Dopamine Serotonin Neurotransmitters • Many types of neurotransmitters that affect us differently and are found in different parts of the brain Chart on pg. 58

24. Endorphins “Happy people don’t kill their husbands!” • Natural, opiate-like neurotransmitters linked to pain control and pleasure • Inhibit (block) pain • Ex: Runner’s high • One of the top suggested remedies for depression is exercise naturally produce chemicals that will stimulate pleasure and happiness INTERACTIVE NEURON

25. Brain, Neurotransmitters, and Other Chemicals • Cocaine, heroin, morphine, anti-depressants, anti-psychotics, etc manipulate the production of neurotransmitters. • Too much manipulation  brain may stop naturally producing similar transmitters. • When the medication or drug is withdrawn, the brain may be deprived of the neurotransmitters until the it can naturally start producing its own again. • Explains the uncomfortable withdrawal period when a drug addict ceases using the drug.

26. Brain, Neurotransmitters, and Other Chemicals • Various drugs and substances can effect communication at the synapse, by exciting or inhibiting a neuron to fire. • Agonist – molecules that are similar to neurotransmitters and can mimic their effects. • Eg: the venom of a black widow spider floods the brain with agonists similar to ACh which results in muscle contractions, convulsions, and even death. • Antagonist – a molecule that block a neurotransmitter’s release • Eg: Botulin (a poison in improperly canned food), causes paralysis by blocking the release of ACh from the sending neuron.

27. Neural Networks • Interconnected neural cells; with experience, networks can learn and strengthen • Neurons can receive and send information from and to many neurons at the same time. • Neurons cluster to work in groups to produce shorter, faster connections (bound together by glial cells). • Experience causes neural networks to grow and strengthen eg: practicing the piano builds neural connections that help this behavior.

28. IMPORTANT • Communication WITHIN a neuron… • ELECTRICAL – action potential • Communication BETWEEN neurons… • CHEMICAL - neurotransmitters

29. Nervous System

30. Central Nervous System (CNS) • The brain and the spinal cord

31. Peripheral Nervous System (PNS) • the sensory and motor neurons that connect the CNS to the rest of the body. • Everything but the brain and spinal cord

32. Nerves • In the PNS • Neural cables • Connect the CNS to muscles, glands, and sense organs • Ex: optic nerve connects the eye to the brain • Eye = sense organ • Optic nerve = PNS • Brain = CNS

33. Nervous System Neurons • Information travels through the nervous system in 3 type of neurons. • Sensory neurons – (aka afferent neurons) carry incoming information from the senses to the CNS • Interneurons – CNS neurons that internally communicate between sensory inputs and motor outputs • Motor Neurons – (aka efferent neurons) carry out going information from the CNS to muscles and glands Sensory feel… Inter interpret… Motor move

34. The Spinal Cord and Reflexes • CNS is the highway between the brain and the PNS. However, sometimes the body can react without the message reaching the brain. • Reflex – simple, autonomic, inborn response to a sensory stimulus, such as the knee-jerk response. • Reflex pathway = 1 sensory neuron + 1 communication interneuron + 1 motor neuron • Ex: simple pain reflex, simple knee-jerk reflex

35. The Spinal Cord and Reflexes • Simple pain reflex – hand jerks away when touching a hot surface. • The movement is initiated in the spinal cord. • Later, the pain is perceived in the brain. • Short delay between movement and sensation.

36. What happens if the Spinal Cord is severed? • Paralysis because sensory messages cannot reach brain and motor messages cannot leave brain • Paraplegia - patient can still move two limbs • Quadriplegia - all four limbs are paralyzed • Most famous case in recent times was the actor Christopher Reeves ( d. 2004)

38. Replicating Neural Pathways in the Body • Everyone stand in a circle in the hallway and await further instructions… • Shoulder squeeze • Wrist squeeze

39. Somatic and Autonomic Nervous Systems • Somatic – controls the body’s skeletal muscles • Running, dancing, etc • Autonomic – controls the glands and the muscles of internal organs • Heartbeat, digestion, sweating Somatic – Skeletal Autonomic - Automatic

40. Sympathetic and Parasympathetic Nervous Systems • Sympathetic – arouses the body • When someone is in crisis, we feel sympathy for them • Parasympathetic – calms the body • Parasympathetic - paralyzing

41. Let’s Put It All Together!

42. The Endocrine System

43. Endocrine System • The body’s “slow” chemical communication systemmade of glands that secrete hormones into the bloodstream • Hormones – chemical messengers manufactured by glands • Travel slowly in the bloodstream • When hormones act on the brain, they can trigger interest in sex, food, aggression, “flight or fight” • Gland - An organ in the body that secretes a substance for use somewhere else in the body

44. Hormones vs Neurotransmitters Hormones Neurotransmitters • chemical messengers for the endocrine system • Travel in the blood stream • Chemical messengers in the brain • Travel in the brain in the synapse between neurons The endocrine system tries to keep a balance in the body while we respond to feelings of stress, anger, fear, and exertion.

45. Adrenal Gland • Pair of glands above the kidneys that release adrenaline and noradrenalin which helps to arouse the body in times of stress • Increase heart rate, blood pressure, and blood sugar for energy • Hormones can last in the bloodstream after the triggering event. Daughter Lifts Car Off Dad

46. Pituitary Gland • Small pea-shaped gland in the limbic system of the brain • Most influential gland – “master” gland • Regulates growth (growth hormone) and controls other glands • Controlled by the hypothalamus Gigantism – caused by a tumor on the pituitary gland

48. The Brain

49. The Brain • Brain size ≠ Intelligence • Brain structure and complexity = Intelligence

50. Older Brain Structures • Perform unconscious simple tasks necessary for survival… • Breathing • Coordinating movement • Heartbeat • Brainstem • Medulla • Pons • Reticular formation • Thalamus • Cerebellum