PSYC550 Biological Bases of Behavior

1. PSYC550 Biological Basesof Behavior Research Methods and Ingestion

2. Experimental Ablation • experimental ablation • The removal or destruction of a portion of the brain of a laboratory animal; presumably, the functions that can no longer be performed are the ones the region previously controlled. • excitotoxic lesion • A brain lesion produced by intracerebral injection of an excitatory amino acid, such as kainic acid. • 6-hydroxydopamine (6HD) • A chemical that is selectively taken up by axons and terminal buttons of noradrenergic or dopaminergic neurons and acts as a poison, damaging or killing them.

3. Experimental Ablation • sham lesion • A placebo procedure that duplicates all of the step of producing a brain lesion except for the one that actually causes the brain damage. • stereotaxic surgery • Brain surgery using a stereotaxic apparatus to position an electrode or cannula in a specified position of the brain. • bregma • The junction of the sagittal and coronal sutures of the skull; often used as a reference point for stereotaxic brain surgery.

5. Experimental Ablation • stereotaxic atlas • A collection of drawings of sections of the brain of a particular animal with measurements that provide coordinates for stereotaxic surgery. • sterotaxic apparatus • A device that permits a surgeon to position an electrode or cannula into a specific part of the brain.

7. Experimental Ablation • fixative • A chemical such as formalin; used to prepare and preserve body tissue. • formalin • The aqueous solution of formaldehyde gas; the most commonly used tissue fixative. • perfusion • The process by which an animal’s blood is replaced by fluid such as a saline solution or fixative in preparing the brain for histological examination. • microtome • An instrument that produces very thin slices of tissues.

9. 1. 2. 4. 3. 10 Which of these is an MRI? • This one? • This one? • How about this one? • Or this one? • This one? • This one? • How about this one? • Or this one? • This one? • This one? • How about this one? • Or this one?

10. Microscopy • transmission electron microscope • A microscope that passes a focused beam of electrons through thin slices of tissues to reveal extremely small details. • scanning electron microscope • A microscope that provides three-dimensional information about the shape of the surface of a small object by scanning the object with a thin beam of electrons. • confocal laser scanning microscope • A microscope that provides high-resolution images of various depths of thick tissue that contains fluorescent molecule by scanning the tissue with light from a laser beam.

12. Visualizing • computerized tomography (CT) • The use of a device that employs a computer to analyze data obtained by a scanning beam of X-rays to produce a two-dimensional picture of a slice through the body. • magnetic resonance imaging (MRI) • A technique whereby the interior of the body can be accurately imaged; involves the interaction between radio waves and a strong magnetic field.

13. Computed Tomography • CT is readily available, fast, and inexpensive • Great for identifying hemotomas • Iodine contrast medium can be used to enhance visualization of vasculature (hyperdense) to detect • Neoplasms • Inflammation

14. Contrast Agent

15. Magnetic Resonance Imaging Expose protons in hydrogen atoms in body to a large magnet Aligns protons and essentially turns the body into a resonating magnet Forces the protons to spin at an angle relative to the magnetic field, at varying frequencies Produces a radio frequency that can be read and interpreted.

16. MRI (T2 on Right)

17. Recording and Stimulating Neural Activity • FOS • A protein produced in the nucleus of a neuron in response to synaptic stimulation. • positron emission tomography (PET) • The use of a device that reveals the localization of a radioactive tracer in a living brain.

20. Visualizing and Siphoning • functional MRI (fMRI) • A modification of the MRI procedure that permits the measurement of regional metabolism in the brain. • microdialysis • A procedure for analyzing chemicals present in the interstitial fluid though a small piece of tubing made of a semipermeable membrane that is implanted in the brain.

23. Genetic Methods • Twin Studies • Adoption Studies • Targeted Mutations • Antisense Oligonucleotides

24. Genetic Methods • Targeted mutation • A mutated gene (also called a “knockout gene”) produced in the laboratory and inserted into the chromosomes of mice; fails to produce a functional protein. • Antisense Oligonucleotides • A mutated portion of an RNA strand is inserted and fails to produce functional protein

25. Ingestion! Insert Segue Here

26. Physiological Regulatory Mechanisms • homeostasis • The process by which the body’s substances and characteristics (such as temperature and glucose level) are maintained at the optimal level. • ingestive behavior • Eating or drinking. • system variable • A variable that is controlled by a regulatory mechanism, for example, temperature in a heating system. • set point • The optimal value of the system variable in a regulatory mechanism.

29. Drinking • intracellular fluid • The fluid contained within cells. • extracellular fluid • All body fluids outside cells; interstitial fluid, blood plasma, and cerebrospinal fluid. • intravascular fluid • The fluid found within the blood vessels. • interstitial fluid • The fluid that bathes the cells, filling the space between the cells of the body (the “interstices”).

30. Drinking • osmometric thirst • Thirst produced by an increase in the osmotic pressure of the interstitial fluid relative to the intracellular fluid, thus producing cellular dehydration. • osmoreceptor • A neuron that detects changes in the solute concentration of the interstitial fluid that surrounds it.

33. Drinking • OVLT (organum vasculosum of the lamina terminalis) • A circumventricular organ located anterior to the anteroventral portion of the third ventricle, served by fenestrated capillaries and thus lacks a blood-brain barrier. • subfornical organ (SFO) • A small organ located in the confluence of the lateral ventricles, attached to the underside of the fornix; contains neurons that detect the presence of angiotensin in the blood and excite neural circuits that initiate drinking.

35. 10 You get thirsty when you lose a lot of blood. • Strongly Agree • Agree • Disagree • Strongly Disagree

36. Drinking • volumetric thirst • Thirst produced by hypovolemia. • renin • A hormone secreted by the kidneys that causes the conversion of angiotensinogen in the blood into angiotensin. • angiotensin • A peptide hormone that constricts blood vessels, causes the retention of sodium and water, and produces thirst and a salt appetite.

38. Drinking • nucleus of the solitary tract • A nucleus of the medulla that receives information from the visceral organs and from the gustatory system. • medial preoptic nucleus • A small nucleus situated around the decussation of the anterior commissure; plays a role in thirst stimulated by angiotensin.

40. 10 A “starvation diet” can make you gain weight. • Strongly Agree • Agree • Disagree • Strongly Disagree

41. Eating at the Set Point • Glucostatic Theory • Lipostatic Theory • “Set Points” • Mutable by behavior

43. Eating: Some Facts About Metabolism • fasting phase • A phase of metabolism during which nutrients are not available from the digestive system; glucose, amino acids, and fatty acids are derived from glycogen, protein, and adipose tissue during this phase. • absorptive phase • The phase of metabolism during which nutrients are absorbed from the digestive system; glucose and amino acids constitute the principal source of energy for cells during this phase, and excess nutrients are stored in adipose tissue in the form of triglycerides.

45. What Starts a Meal? • ghrelin • A peptide hormone released by the stomach that increases eating; also produced by neurons in the brain. • glucoprivation • A dramatic fall in the level of glucose available to cells, can be caused by a fall in the blood level of glucose or by drugs that inhibit glucose metabolism. • lipoprivation • A dramatic fall in the level of fatty acids available to cells; usually caused by drugs that inhibit fatty acid metabolism.

47. Brain Mechanisms • arcuate nucleus • A nucleus in the base of the hypothalamus that controls secretions of the anterior pituitary gland; contains NPY-secreting neurons involved in feeding and control of metabolism. • paraventricular nucleus (PVN) • A nucleus of the hypothalamus located adjacent to the dorsal third ventricle; contains neurons involved in control of the autonomic nervous system and the posterior pituitary gland.

49. 10 Which of the following best describes volumetric thirst? • When the interstitial fluid is significantly different from the intracellular fluid • When there is considerable fluid loss • When the CSF levels in the ventromedial hypothalamus raise significantly • When you watch a movie in which there is a lot of sand, but no water

50. 10 Which of the following imaging techniques makes use of x-rays? • Computerized Tomography • Magnetic Resonance Imaging • Positron Emission Tomography • Functional Magnetic Resonance Imaging