Behavioral analysis Phenotype Genotype X Environment PHENOTYPE the
Behavioral analysis
Phenotype = Genotype X Environment PHENOTYPE – the observable or measurable properties and characteristics of an individual as produced by its genotype and the environment GENOTYPE – the genetic make-up of an individual (the one that you’re born with and the one that is operating at a particular moment) ENVIRONMENT – broadly defined: ambient conditions, developmental conditions, social conditions, internal milieu GENE-ENVIRONMENT INTERPLAY: Gene-environment correlation; Gene-environment interaction
DEFINITION OF BEHAVIOR Behavior seen as a function of an organism's environment BEHAVIORISM Behavior seen as a function of an organism's mental processes – COGNITIVE SCIENCE Behavior seen as a function of an organism's biology – NEUROSCIENCE, BEHAVIORAL GENETICS
GENETIC AND EPIGENETIC THEORIES OF INFORMATION PROCESSING DNA RNA Proteins Epigenetic networks (open) FUNCTION
MOLECULAR NEUROSCIENCE BEHAVIORAL GENETICS – WHAT IS IT ALL ABOUT? Research in behavioral genetics examines the effects of genotype and environment on a range of phenotypic traits such as anxiety, intelligence, sexual orientation, antisocial behavior etc. • Gene for aggression • Gene for homosexuality • Gene for memory • Gene for fear…
WHO ARE THE SUBJECTS OF STUDY? HUMANS – families; twins: mono-/dizygous, reared together or apart; isolated populations ANIMALS – rodents, flies, fish, nematodes - normal, genetically segregating populations - selected lines - inbred strains (incl. recombinant and congenic strains) - genetically altered animals (gene amplification, knock-out, mutagenesis)
How to correlate behaviors with gene functions? Behavioral analysis of mutants?
GENETIC APPROACHES TO BRAIN-BEHAVIOR RELATIONSHIPS REVERSE GENETICS – genotype driven FORWARD GENETICS – phenotype driven
The ethics of animal use • Utilitarianism: the view that an action is right if and only if it produces a better balance of benefits and harms than available alternative actions • Consider the “U. S. Government Principles for the Utilization and Care of Vertebrate Animals Used in Testing, Research, and Training”
U. S Government Principles (summary) • Procedures involving animals should be designed and performed with due consideration of their relevance to human or animal health, the advancement of knowledge, or the good of society. • The animals selected for a procedure should be of an appropriate species and quality and the minimum number required to obtain valid results. [Alternative] methods…should be considered. • Proper use of animals, including the avoidance or minimization of discomfort, distress, and pain when consistent with sound scientific practices, is imperative. • Procedures with animals that may cause more than momentary or slight pain or distress should be performed with appropriate sedation, analgesia, or anesthesia. • Animals that would otherwise suffer severe or chronic pain or distress that cannot be relieved should be painless killed at the end of the procedure or, if appropriate, during the procedure.
U. S Government Principles (continued) • The living conditions of animals should be appropriate for their species and contribute to their health and comfort…. veterinary care shall be provided as indicated. • Investigators and other personnel shall be appropriately qualified and experienced for conducting procedures on living animals. • …exceptions…should be made by…an appropriate review group such as an IACUC
The three “R’s”: a consensus in the research community • Reduce • Refine • Replace
www. jax. org/phenome Paigen K, Eppig JT. A mouse phenome project. Mamm Genome. 2000 Sep; 11(9): 715 -7. Moldin SO et al. Trans-NIH neuroscience initiatives on mouse phenotyping and mutagenesis. Mamm Genome. 2001 Aug; 12(8): 575 -81. Grubb SC et al. A collaborative database of inbred mouse strain characteristics. Bioinformatics. 2004 Nov 1; 20(16): 2857 -9.
IACUC • Must have at least a laboratory animal veterinarian, a scientist, and a community member not affiliated with the institution and who does not use animals in research • Reviews all facilities and programs twice a year; identifies and ensures correction of any deficiencies • Reviews “Protocols”, the researcher’s or teacher’s proposal for animal use • Monitors animal use; can suspend any animal activity that does not meet standards
The protocol review process (simplified)
IACUC Protocol Review • Does the research address an important question? • Does the research require the use of animals? • Is the research necessary, in that it does not needlessly repeat previous work? • Is the experience of each animal in the study adequately described and justified?
Factors control behaviors The three “E’s”: • Epigenetic factors • Environmental factors • Experimenter
Epigenetic sources of behavioral differences in mice (Francis DD et al. Nat Neurosci 6: 445 -6, 2003) Crabbe JC and Phillips TJ (Nat Neurosci 6: 440 -2, 2003) Mother nature meets mother nurture
Intrauterine position in mice according to number of flanking males (0 M to 2 M). In mice, 2 M fetuses are exposed to a higher level of androgens than 1 M or 0 M. Females adjacent to males become partially masculinized in their behavior, and 2 M fetuses, both male and female, show increased body weight, greater aggression and territoriality, and enhanced male traits including reproductive behavior (Ryan & Vandenbergh 2002). In rat, overall litter male/female composition may be more important than precise intrauterine position (reviewed by Ryan & Vandenbergh 2002). Conversely, proximity to female fetuses influences male physiological development: prostate glands of males flanked by two females were enlarged compared to controls (Timms et al. 1999); estradiol is implicated (vom Saal et al. 1997). Lathe, R. (2004) The individuality of mice. Genes, Brain & Behavior 3 (6), 317 -327.
Environmental factors • Housing environment • Enriched environment • Experimental environment
Experimental procedures Experiments without habituation ---- Experiments demanding habituation This order was chosen in the attempt to go from the least stressful to the most stressful test. Animals were received at least 2 weeks prior to the beginning of testing and given at least these 2 weeks for acclimation. They were group housed, 3– 5/cage, and were at least 8 weeks of age at the start of the experimental series in order to minimize variability due to developmental factors. In addition, two partners (EMBL and Harwell) tested the influence of cage enrichment on behaviour in this test battery. Results are currently being analysed and will be compared and evaluated in the next workpackage meeting at the end of April/04. The “working” SOPs will be audited accordingly.
Hierarchical Strategy for Phenotypic (Behavioral) Analysis in Transgenic Mice Rogers et al. , 1997 – SHIRPA Crawley and Paylor, 1997 Gold LH (1999) Psychopharmacol. 147: 2 -4
Two words of behavior • Habituation • Sensitization
Repeated stimulations make one boring or sensitive? Stephen Jay Gould on the evolution of Mickey Mouse
Supernormal stimuli? vs.
Repeated stimulations
Repeated stimulation Elicited behavior is not plastic, but can change with repeated stimulation. Habituation effect Decreased response with repeated stimulation. Sensitization effect Increased response with repeated stimulation.
Habituation effect Response Trials
Dishabituation
Dishabituation effect Response Trials
Spontaneous recovery Retention Interval Response Trials
Location of habituation processes Sensory adaptation Habituation Fatigue
How is habituation different from sensory adaptation and fatigue? • Sometimes the habituated response will not recover after for a long time. • (Long Term Habituation)
Habituation will be slower for stimuli which have a higher salience (i. e. , intensity)
Dishabituation following the presentation of a novel stimulus.
Generalization gradient of a habituated response.
Fashion and quality of experiments
Sensitization effect Response Trials
Sensitization (Arousal) In general Sensitization effects can be influenced by similar parameters as habituation. However, generalization is greater in Sensitization. - Following exposure to cutaneous pain, rats’ reactivity to a wide range of auditory stimuli is increased. Sensitization can be thought of as “arousal”.
Habituation and Sensitization in Aplysia
Sensitization Pathway Increased serotonin release
Dual-Process theory of Habituation and Sensitization 2 underlying processes exist – 1) A Habituation process – 2) A Sensitization process The observable behavior is the sum of these two processes. The habituation effect is observed when the habituation process is greater than the sensitization process.
Dual Process examples Habituation effect Sensitization effect
Groves and Thompson (1970) S-R System: Habituation is thought to occur in the reflex arc. State System: Sensitization is thought to occur in the part of the nervous system that determines general responsiveness.
Infant attention
Looking Time Trials
Opponent Process Theory of Motivation
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