Behavioral Neuroscience

1. Behavioral Neuroscience Using Your Mind to Study Your Brain

2. Behavioral Neuroscience • The Body’s Communication Networks • The Neuron • The Brain

3. The Case of Phineas Gage • Gage was a railroad construction foreman • An 1848 explosion forced a steel tamping rod through his head • Others said he was “…no longer Gage…” • Lost his job, worked as a sideshow exhibit

4. The Body’s Communication Networks The Nervous System The Endocrine System

5. Divisions of the Nervous System • Central Nervous System • Brain • Spinal cord • Peripheral Nervous System • Somatic • Autonomic

7. The Endocrine System • Endocrine system: Ductless glands that regulate growth, reproduction, metabolism, mood, and some behavior • Hormones: chemical messengers secreted into the bloodstream

8. The Endocrine System • The Endocrine System - The body's "slow," chemical communication system; a set of glands that secretes hormones into the bloodstream. • Pituitary Gland (Master Gland) - The endocrine system's most influential gland. Under the influence of the hypothalamus, the pituitary regulates growth and controls other endocrine glands. • Thyroid Glands - Produced the hormone thyroxin, which regulates the rate at which food is metabolized.

9. Endocrine System • Pancreas - Regulates the body's blood sugar level by releasing the hormones insulin and glucagon into the bloodstream. • Adrenal Glands - A pair of endocrine glands just above the kidneys. The adrenals secrete the hormones epinephrine (adrenaline) and norepinephrine (noradrenaline), which help to arouse the body in times of stress. • Ovaries and Testes - The sex glands, activated by the pituitary gland, which release the sex hormones responsible for secondary sex characteristics, and make reproduction possible.

10. The Withdrawal Reflex

11. The Neuron Structure of the Neuron The Neuron in Action How Neurons Communicate Neurotransmitters

12. Types of Neurons • Afferent (Sensory), - Relay messages from sense organs to the brain and spinal column • Efferent (Motor) - Convey messages from brain and spinal column to glands and muscles • Interneurons - Most Numerous; Carry information between neurons in the brain, and between neurons in the spinal cord

13. Structure of a Neuron

14. The Neuron • Cell Body - Contains the nucleus and carries out the metabolic functions of the neuron. • Myelin Sheath -- A layer of fatty cells segmentally encasing the fibers of many neurons; makes possible vastly greater transmission speed of neural impulses. • Dendrites - The bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body. • Axon - The extension of a neuron ending in branching terminal fibers through which messages are sent to other neurons or to muscles or glands.

15. The Neuron in Action • Action Potential • An electrical impulse that surges along an axon, caused by an influx of positive ions in the neuron • Threshold • The level of stimulation needed to trigger an action potential

16. Neurons: All or None Response • Neurons either “fire” an action potential or they do not • No halfway responses • Action potentials do not vary in intensity

17. Some Anatomy of A Neuron • Synapse - The junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. • Axon Terminal - The end of the slender extension of the neuron that transmits signals to the dendrites or cell body of other neurons, or to muscles or glands. • Synaptic Vesicles - Where the neurotransmitters are stored. • Synaptic Cleft - The tiny gap at the junction of the dendrite and the receiving neuron.

18. How Neurons Communicate • Axon terminals release neurotransmitter • Neurotransmitter enters synaptic gap • Neurotransmitter binds to receptors that it fits

19. Major Neurotransmitters • Acetylcholine (ACh) • Dopamine • Serotonin • Endorphins • Norepinephrine • Gamma amino butryic acid (GABA)

20. What Are Neurotransmitters? • Neurotransmitters - Chemical messengers that traverse the synaptic gaps between neurons. When released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether it will generate a neural impulse. • Acetylcholine - A neurotransmitter that, among its functions, triggers skeletal muscle contraction (but inhibits cardiac muscle contraction); also plays a role in learning, memory, and REM sleep.

21. More Neurotransmitters • Monoamines (Serotonin, Dopamine, epinephrine, norepinephrine) • Serotonin - Plays an important role in regulating mood, sleep, aggression, and appetite. • Dopamine - Plays a role in learning, attention, and movement; a deficiency is associated with Parkinson's Disease, while an oversensitivity is associated with some types of schizophrenia. • Epinephrine - Affects the metabolism of glucose, and cause nutrient energy to be released during exercise. • Norepinephrine - Stimulates the intake of carbohydrates, and plays a role in alertness.

22. Still More Neurotransmitters • Amino Acids • GABA - The main inhibitory neurotransmitter in the brain. • Glutamate - The primary excitatory neurotransmitter in the brain. • Endorphins - "Morphine within" - natural, opiatelike neurotransmitters linked to pain control and to pleasure.

23. The Brain Tools of Behavioral Neuroscience Regions of the Brain The Split Brain Brain: Growth & Reorganization

24. Tools of Behavioral Neuroscience • Clinical Case Studies • Experimental Interventions • Electrical Recordings • Brain-Imaging Techniques

25. Electroencephalogram

26. Positron Emission Tomography • Active areas have increased blood flow • Radioactive isotopes (small amounts) are placed in the blood • Sensors detect radioactivity • Different tasks show distinct activity patterns

27. Magnetic Resonance Imaging • Magnetic fields align certain ions and compounds • When field is removed, these molecules release energy as radio waves • Computer calculates tissue density from radio waves • Provides clear, 3D images

28. More Brain Scan Techniques • CT Scan - A series of x-ray photographs taken from different angles and combined by computer into a composite three-dimensional representation of a slice through the body. • fMRI - A newer brain imaging technique that can analyze both brain structure and activity, and can image locations of activity more precisely than the PET scan.

30. Brainstem • The primitive inner core • Medulla • Vital involuntary functions • Pons • Sleep and arousal • Reticular formation • Sleep, arousal, attention • Cerebellum • Motor coordination • Basal ganglia • Fine motor control

31. Limbic System • Thalamus • Sensory relay station • Amygdala • Fear, anger, aggression • Hippocampus • Memory formation • Hypothalamus • Regulates glands, autonomic NS

32. Cerebral Cortex in Animals

33. Lobes of the Cerebral Cortex

34. Brain Anatomy • Frontal lobes - The portion of the cerebral cortex lying just behind the forehead; involved in speaking and muscle movements and in making plans and judgements. • Brocha's Area -- An area of the left frontal lobe that directs the muscle movements involved in speech. • Motor cortex - An area at the rear of the frontal lobes that controls voluntary movements. • Parietal lobes - The portion of the cerebral cortex lying at the top of the head and toward the rear; includes the sensory cortex.

35. Brain Anatomy • Sensory Cortex -- front of the parietal lobes that registers and processes body sensations. • Occipital lobes - at the back of the head; includes the visual areas, each of which receives visual information from the opposite visual field. • Temporal lobes - roughly above the ears; includes the auditory areas, each of which receives auditory information primarily from the opposite ear. • Wernicke's Area -- An area of the left temporal lobe involved in language comprehension.

37. Language Processing • Speaking a written word involves at least five neocortical areas • Each area performs certain functions • The areas coordinate their actions • The brain acts as an integrated system

38. Left-Handedness Across the Life Span • Proportion of left handers drops with age • 15% of 10-year-olds • 5% of 50-year-olds • < 1% of 80-year-olds • Cause is unknown • Longevity hypothesis • Modification hypothesis

39. The Corpus Callosum • Millions of myelinated axons connecting the brain’s hemispheres • Provides a pathway for communication between the hemispheres • If surgically severed for treatment of epilepsy, hemispheres cannot communicate directly

40. Visual Processing • Both eyes send information to both hemispheres • Right half of the visual field goes to the right hemisphere • Left half of the visual field goes to the left hemisphere

41. Sperry’s Split-Brain Experiment • Split-brain subjects could not name objects shown only to the right hemisphere • If asked to select these objects with their left hand, they succeeded • The right side of the brain doesn’t control speech

42. The Talking Left Hemisphere • Brighter areas indicate higher activity levels • During hearing words, for example, auditory cortex and Wernicke’s area are most active

43. Neglect Syndrome • A patient with a stroke in the right hemisphere was asked to copy the model drawings • Typical of neglect syndromes, the left side of the model is almost completely ignored

44. Plasticity in Brain & Behavior • Some rats are housed alone in empty cages • Their littermate twins are group-housed in cages with toys, which are changed frequently • Richer environments led to heavier, thicker brains, more synapses, and better learning

45. Head Injury in Contact Sports • Concussion • Alteration of mental state caused by trauma to the head • Axons can be stretched, twisted, or subject to shear forces • Symptoms of concussion include slurred speech, confusion, dizziness, unconsciousness