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General Psych 1 February 8-10, 2005 Classes #5-6

Biological Psychology Neural and Hormonal Systems – Module 3 How the Brain Governs Behavior – Module 4 Neurotransmitters – Module 3. General Psych 1 February 8-10, 2005 Classes #5-6. “So why do we have to study biology in a psych class?”.

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General Psych 1 February 8-10, 2005 Classes #5-6

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  1. Biological Psychology Neural and Hormonal Systems – Module 3How the Brain Governs Behavior – Module 4Neurotransmitters – Module 3 General Psych 1 February 8-10, 2005 Classes #5-6

  2. “So why do we have to study biology in a psych class?” • Let me use Phineas Gage to help answer this question…

  3. “He was no longer Gage…” • Several different angles of where the rod passed through his skull

  4. There is a Phineas Gage display in the Warren Medical Museum at Harvard University • This is what went through his brain (see below)…

  5. Biological Roots of Behavior • Franz Gall (1758-1828) – Austrian physicist who invented phrenology • He felt that bumps on the skull could reveal our mental abilities and character traits. • Introduced as being scientific but its use was exploited by quacks on gullible individuals

  6. Biological Roots of Behavior • Became similar to that of astrology, palm-reading and tarot • Although, ill-fated theory was laughed at by scientific community of that day – it may have had some validity • Localization of brain functions somehow hit the mark

  7. The Nervous System • Electrochemical communication system that enables us to think, feel, and behave • Complex beyond comprehension • Although, human brains are more complex our nervous systems and those of animals operate in a similar fashion – advantage of this is experimentation

  8. Major Components • Neurons: • Rapidly respond to signals and quickly send signals of their own • Glial cells: • Help neurons to communicate, keep chemical environment stable, secrete chemicals to help restore damage, and respond to signals from neurons – enable neurons to function

  9. Axons • Function: • Carries signals away from the cell body • Pass information along to other nuerons, or to muscles or glands • Type of Signal Carried: • The action potential, an all-or-nothing electrochemical signal that shoots down the axon to vesicles at the tip of the axon, releasing neurotransmitters

  10. Synapse • Very small gap between neurons • For communication to occur between cells, the signal must be transferred across this gap • Function: • Provides an area for the transfer of signals between neurons, usually between axon and dendrite

  11. Dendrite • Function: • Detects and carries signals to the cell body • Type of Signal Carried: • The postsynaptic potential, which is an electrochemical signal moving toward the cell body

  12. Receptors • Function: • Proteins on the cell membrane that receive chemical signals • Type of Signal Carried: • Recognizes certain neurotransmitters, thus allowing it to begin a postsynaptic potential in the dendrite

  13. Okay, so how do neurons actually transmit information? • A neuron: • Receives signals form other neurons through its branching dendrites and cell body • Then combines these signals in the cell body • And then transmits an electrical impulse down its axon

  14. Transmitting information… • The impulse is called the action potential which is a brief electrical charge that travels down the axon like a line of dominoes falling, each one tripping up the next • This is real electricity as a handful of neurons produce enough power to light up a flashlight • When electrical signals reach the end of the axon, they stimulate the release of chemical messengers – neurotransmitters

  15. Neurotransmitters • Function: • A chemical released by one cell that binds to the receptors on another cell • Type of Signal Carried: • A chemical message telling the next cell to fire or not to fire its own action potential

  16. The Nervous System • Allows researchers to study simple animals such as squids and sea slugs to help us better understand the organization of our own brains

  17. Divisions of the Nervous System • Consists of two systems • Central Nervous System • Brain and spinal cord • Peripheral Nervous System • Which connects the CNS to the rest of the body

  18. Organization of the Nervous System

  19. Peripheral Nervous System • Two components: • Somatic Nervous System • Transmits sensory input to the CNS from the outside world and directs motor output • Autonomic Nervous System • Controls glands and muscles of our internal organs – “automatic pilot”

  20. Autonomic Nervous System • Dual system: • Sympathetic Nervous System • Arouses the body • Parasympathetic Nervous System • Calms us down

  21. Neurons • Nerve cells (building blocks) – essentially identical to animals • Small samples of brain tissue from a person and a monkey are basically indistinguishable

  22. Endocrine System: Taking the slow lane • Unlike the speedy nervous system which zips messages from eyes to brain to hand in a fraction of a second, endocrine messages use the slow lane • May take several seconds or more as bloodstream carries a hormone from an endocrine gland to its target tissue

  23. Endocrine System • Hormones are chemical messengers • Influence all aspects of our lives – growth, metabolism, reproduction, moods, etc. • Strives for homeostasis (balance) by responding to stress, exertion, internal thoughts, etc.

  24. The Brain • Studying the brain: • Clinical observations • Manipulating the brain

  25. How does the brain govern behavior? • 3 Principle layers of the brain: (1) Brainstem (2) Limbic System • Hippocampus • Amygdala • Hypothalamus (3) Cerebral Cortex

  26. Brainstem (or Hindbrain) • The brain’s innermost region… • Begins where the spinal cord enters the skull and swells slightly forming the medulla • Towards the rear of the brainstem is the cerebellum – this is linked to memory and its major function is muscular control

  27. Limbic System • Hippocampus • This structure plays a key role in allowing us to store new information • Problems here may cause Alzheimer's – these individuals have trouble processing declarative memories • Milner (1968): the classic case of H.M.

  28. Limbic System • Amygdala • Emotional control center of the brain – major influence on aggression and fear • Emotional memories as well • Alzheimer’s ??? • Kluver and Bucy (1939) • Demasio (1994)

  29. Limbic System • Hypothalamus • Major influence on hunger, thirst, body temperature, and sexual behavior • Olds and Milner (1954)

  30. Cerebral Cortex • Makes us distinctively human – much higher developed than in animals • Motor Cortex – involved in the conscious initiation of voluntary movements in specific parts of the body including hand, knee, foot and head • Fritsch and Hitzig (1870) • Delgado (1969a) • Delgado (1969b) • Penfield (1975)

  31. Cerebral Cortex • Sensory Cortex – receives information from our senses • Visual cortex • visual info • Auditory cortex • auditory info • Somatosensory cortex • info from skin • Association cortex • involved in complex cognitive tasks associating words with images • Broca’s area (aphasia) • Wernicke’s area (aphasia)

  32. Neurotransmitters • Neurotransmitters are chemicals made by neurons and used by them to transmit signals to the other neurons • A chemical message telling the next cell to fire or not to fire its own action potential • More than 200 in our body all with different functions • Lets briefly discuss some of the most important ones…

  33. Serotonin • Facilitates a relaxed, sleepy feeling • Tryptophan which is an amino acid found in dairy products and turkey is converted into serotonin in the body • So, insomnia sufferers may be smart to listen to grandmother’s suggestion to drink a warm glass of milk before going to bed

  34. Some Illnesses Associated With Serotonin • Too low levels in depression and anxiety sufferers • Obesity may also be associated with low levels • Linked to aggression as well -- low levels in the brains of suicide victims

  35. Dopamine • High levels lead to pleasure • Makes person feel happy and active • Dopamine raises the body's temperature and increases metabolic rate • Gives you euphoric feelings and allows you to be active • Drug and alcohol abuse will block dopamine receptors and therefore a person needs to take more to get the same effect

  36. Illnesses Associated With Dopamine • Parkinson’s Disease – too low levels • Schizophrenia – too high levels • Tourette’s disorder – too high levels • Huntington’s disease – too high levels

  37. Norepinephrine • Plays a role in attention and arousal • Used by sympathetic nervous system to prepare us for action

  38. Illnesses Associated With Norepinephrine • Depression • chronic stress depletes this neurotransmitter and can lead to depression • Note: • Aerobic Exercise is found to protect the brain from this depletion – so go out and run a mile or two if your down in the dumps

  39. Epinephrine • Involved in energy and glucose metabolism

  40. Illnesses Associated With Epinephrine • Depression – too low levels

  41. Acetylcholine • Involved in voluntary movement, learning, memory, and sleep • Helps parasympathetic nervous system to slow our heart rate

  42. Illnesses Associated With Acetylcholine • Alzheimer’s disease – too low levels • Note: • Unfortunately, drugs used to increase acetylcholine to help restore normal levels appear to have small effects on improving memory

  43. GABA • Inhibits excitation and anxiety • Appears directly related to anxiety reduction

  44. Illnesses Associated With GABA • Anxiety disorders – too low levels • Huntington’s Disease – too low levels • GABA systems aren’t working and this allows dopamine systems to run wild • Huntington's disease is a hereditary disorder characterized by memory loss, abnormal movement and premature death • It affects 1 in 10,000 people, and children with an affected parent have a 50 percent chance of developing the disease • Epilepsy – too low levels

  45. Glutamate • Main excitatory neurotransmitter in the brain • Very important in learning and memory

  46. Illnesses Associated With Glutamate • Alzheimer’s disease – too low levels in hippocampus • Strokes – too high levels can cause neurons to die • ALS (Lou Gehrig’s Disease) – causes death in neurons in the spinal cord and brainstem

  47. Endorphins • Involved in pain reduction and pleasure • They enhance the release of dopamine • These natural opiates are released in response to pain and vigorous exercise

  48. Illnesses Associated With Endorphins • Use of artificial opiates can cause body to stop manufacturing its own – this can lead to drug addiction

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