Neuroscience and Behavior

1. Unit II Neuroscience and Behavior

2. Part I Neurons

3. A nerve cell • Basic unit of information processing; building block of the brain and nervous system • 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! Neuron

4. 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 neutral impulses • When it wears out • Alzheimer's (impedes transmissions affecting thought process) • Multiple sclerosis: interferes with muscle control (as message to muscles is impeded..) Structure

5. Neuron

6. Action Potential • Aneural impulse; a brief electrical charge that travels down an axon • Stimulated when neuron receives signals from sense receptors stimulated by heat, pressure or light • Generated by the movement of positively charged atoms in and out of channels in the axon’s membrane Communication

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

8. Neurons generate electricity from chemical events (like batteries) • The chemistry to electricity process involves the exchange of ions • Ions: electrically charged atoms Electrochemistry

9. 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) • 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! Ions

10. 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) Reaching a Neuron’s Threshold

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

12. Synapse (Where the action is) • Gap between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron • Tiny gap at this junction is called the synaptic gap or cleft (less than a millionth of an inch!) • Neurotransmitters • Chemical messengers that cross the synaptic gaps between neurons • Neurotransmitters bind to receptor sites (“lock and key”) on the receiving neuron • Influence whether it will generate a neural impulse • They are ions passed on to new neuron: exciting or limiting its readiness to fire • Reuptake • Excess neurotransmitters are reabsorbed by the sending neuron Neural Communication

13. Neural Communication

14. Part II Nervous System

15. Nervous System: the body’s electrochemical information network • Components of the Nervous System • Central Nervous System (CNS)-Internal command center made up of the brain and spinal cord • Peripheral Nervous System (PNS)-Connects CNS with sense receptors, muscles, and glands • Nerves: large bundles of neurons • Sensory Neurons: Info from tissues and organs to the CNS for processing • Motor Neurons: Info from CNS back out to the body • Interneurons: Complex system of neurons that processes info in the CNS • Reflex: Single sensory neuron+single motor neuron+interneuron The Nervous System

16. Two components: somatic and autonomic • Somatic: Allows us to move our skeletal muscles • Autonomic: Controls glands and muscles of our internal organs (e.g. heartbeat) • Operates on its own (but can be consciously overridden) • Autonomic Nervous System also has two components • Sympathetic: Arouses (reaction to stress—fight or flight) • Parasympathetic: Calms (when stress subsides) • Sympathetic and parasympathetic systems work together to keep us at a steady state Peripheral Nervous System

17. Peripheral Nervous System

18. Sneezing • Turning the page • High-fiving your friend • Kissing a date • Coughing • Digesting Somatic or Autonomic?

19. http://www.youtube.com/watch?feature=player_embedded&v=ivk_irrH1WYhttp://www.youtube.com/watch?feature=player_embedded&v=ivk_irrH1WY Nervous System Breakdown

20. Brain and Spinal Cord • Reflexes rely on the CNS • Action occurs without feeling: message stops at the spinal cord and never reaches the brain! • “Feeling” hits when the message reaches the brain • Brain is the computer of the body • Collection of neural networks • Learning allows us to build neural networks (think foreign languages!) Central Nervous System

21. Pain Reflex: sensory neuron, interneuron, motor neuron=simple, inborn response Reflexes

22. Neurons in the brain connect with one another to form networks Inputs Outputs The brain learns by modifying certain connections in response to feedback • Learning builds connections • Feedback! Output affects the process • Computer simulations using these networks also learn! • Neurons that fire together, wire together! Neural Network

23. Part II b Endocrine System

24. Communication method #2 • Chemical communication • Hormones • TissuebloodTissue • Hormones that affect the brain • Speed: sloooooow. Messages are slower and effects last longer The Endocrine System

25. Chemical Messengers • Move from tissue to tissue through the blood stream • Hormones that affect the brain influence interest in sex, food, and aggression Hormones

26. Adrenal: DANGER! Gland • Fight or flight response • Acrivitated by the autonomic nervous system • Location: top of kidney • Hormones: epinephrine (adrenal)/norepinephrine (non adrenal) • Effects: increased heart rate, blood pressure, blood sugar (energy!) • Pituitary: Master Gland • Sex Gland • Location: core of the brain, pea size • Controlled by the hypothalamus (part of the brain) • Hormones: Various sex hormones • Effects: Puberty, reproduction Useful place: http://www.hormone.org/hormones-and-health/what-is-the-endocrine-system/endocrine-glands-and-types-of-hormones Major Glands

27. Pituitary Adrenal Glands

29. Part III The Brain-Structure

30. Answer the following as true or false. • The larger the brain, the smarter the animal. • The brain’s structure is a better indicator of intelligence than it’s size. • The right side of the brain controls the right side of the body, and so on with the left. • You fall in love with your heart, not your brain. • Your brain uses 20% of your body’s energy, but makes up only 2% of your body’s weight. Pre-Test

31. Your brain is about the size of a cantaloupe and is wrinkled like a walnut. • Your brain feels like a ripe avocado and looks pink because of the blood running through it. • The baby’s brain grows 3x in size during its first year. • At birth, the human brain weighs 4/5 of a pound, while an adult’s weighs about 3 pounds. • Your brain generates about 25 watts of power while awake- or enough to illuminate a light bulb.

32. Contains about 100 billion neurons • Consumes about ¼ of the body’s oxygen • Spends most of the bodies calories • Is 70% water • Weighs about 3 pounds A Typical Human Brain

33. Basic (“Old”) Components of the Brain Works unconsciously (even while sleeping!) • Brainstem • Thalamus • Limbic System • Cerebral Cortex Advanced (“New”) Components of the Brain Sections of the Brain

34. Oldest section of the human brain • Central core of the brain • Begins where the spinal cord swells as it enters the skull • Responsible for automatic survival functions Brainstem

35. Medulla: first piece of the brainstem • Location: base of the brain above the spinal cord • Controls heartbeat and breathing • Pons • Above the medulla • Helps coordinate movement and facial expression • Connects midbrain to hindbrain • Reticular Formation • Structure: Finger shaped network of neurons • Location: spinal chord to the thalamus • Filters info from the spinal cord, essential for arousal and sleep The Brain Stem

36. The Cerebellum • Location: Rear of the brainstem • Structure: Baseball sized • Enables nonverbal learning and memory, allows us to judge time, regulate emotions, discriminate sound and texture, coordinates voluntary movement and maintains balance through fine muscle movements • Thalamus (THIS IS IN THE FOREBRAIN!!) • Location: Top of the brain stem • Structure: Egg-shaped • Receives info from the senses (minus smell), directs it to the proper area of the cortex, then takes replies and sends it to the medulla and cerebellum. Sensory switch board The Brain Stem Con’t

37. Cerebellum

38. Useful place: http://www.columbia.edu/cu/psychology/courses/1010/mangels/neuro/anatomy/structure.html • Controls thoughts and reasoning • Thalamus is technically part of the forebrain The Forebrain (New) Brain

39. Structure: Donut shaped system of neural networks • Components: hippocampus, amygdala, and hypothalamus • Location: border of brainstem and cerebral hemispheres • Associated with emotions: fear and aggression and drives: hunger and sex Limbic System

41. Structure: almond shaped neural clusters • Influence aggression and fear • Stimulation results in aggression, terror, and docility • Processing memory and perception of these emotions • Remember: One component for these emotions • Amygdala lesions created during psychosurgery do not always result in calmer humans Amygdala

42. Natural or laboratory inflicted destruction of brain tissues Lesions

43. Location: Below the thalamus; think hypo=below (as in hypothermia) • Functions • Performs body maintenance: pieces influence hungry, thirst, body temp, sexual behavior • Controls the pituitary • Closely linked to emotion • Commands come from other parts of the brain (for…neural impulses) and by monitoring blood chemistry (for…hormones) • Hypothalamus ALSO secretes hormones! • Reward center Hypothalamus

44. Predominant function is memory • When suffering from Alzheimer's this is the first area to show damage Hippocampus

45. Enables perception, thought, and speech • Cerebral cortex is to cerebral hemispheres as bark is to a tree • More cerebral cortexgreateradaptabilitility • Structure: wrinkled, 80% of weight is in the hemispheres, 20-23 billion nerve cells in the cortex! Cerebral Cortex

46. Glue Cells • Guide neural connections • Provide nutrients • Insulate Myelin • Clean extra ions and neurotransmitters • More sophisticated the brain, more glial cells Glial Cells

47. Four lobes of the cortex • Frontal Lobes • Parietal Lobes • Occipital Lobes • Temporal Lobes Lobes

48. Motor Cortex (Foerster and Penfield): arc shaped area in the back of the frontal lobe running from ear to ear • Left brain stimulation moves right side of the body and vice versa • Neural prosthetics Motor Functions

49. Somatosensory Cortex (Penfield): arc shaped area behind Motor Cortex in the front of the parietal lobe • More sensitive areas=larger brain area • Occipital Lobe: back of brain, receive visual information • Auditory Cortex in the Temporal Lobe: thumb shaped and above the ear, receive auditory information. Processes even “fake” sounds! Sensory Functions