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Lecture 3

Lecture 3 - Sexual Behavior (Part 2)

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University of Toronto Mississauga
Emis Akbari

PSY398H5S – Motivational Systems Lecture 3 – January 17, 2013 Continuation from last lecture  Hormones not always enough to stimulation copulation o Influences from environment
 o Social cues very important  (Affect engagability, arousal, etc; PEI shortens is male put with a new female  1) Coolidge Effect o Enhanced mating in sated males if new female presented  2) Mating in nature o Not at all like most laboratory tests
 usually multiple males/females mating together females in control of pacing o Receive fewer intromissions, at a slower pace vaginocervical stimulation during paced mating different optimizes luteal function, ensures implantation “vaginal code” o In wild pacing is better because they can run around/ hide. Pacing helps the female in higher chances of getting pregnant. Males find pacing attractive - the run. Males cant corner the female like in lab experiments  3) Stimulus value (attractivity) of females differ depends on age, hormonal status o Males like females that are younger then themselves o With an older female, male will less likely engage in copulation Individual Differences in Sexual Activity in Rodents:  Once thought that it was due to differences in T  Castrated and retested o Low T group stopped mating first  All given back same dose of T o Behavior went back to original levels, not the same level  Animals do not differ because of differences in T differences reflect differences in target tissue sensitivity o AR/ER content in mPOA Novel Environments Disrupt Sexual Behavior  Virgins - no ejaculation in new habitat; mounts and intromissions are comparatively less  Experienced rats no difference in new habitats  Motivation to have sex once u has already had esex over rides the environment. Even in new environment expert rats have sex unlike the virgin males Pfaus and Pinel, 1989  Experiment 1:  With increase in alcohol dosage, mounts, intromission and ejaculations decrease  Experiment 2: o Virgin males dont know the difference bet receptive and non receptive females. o They mount both. o After experience, they only mount the receptive females. o With 0% and 0.5% alcohol, males mount all the time and with 1% alcohol mounts are 50% Kippin and Pfaus, 2001 PSY398H5S – Motivational Systems Lecture 3 – January 17, 2013  The Development of Olfactory Conditioned Ejaculatory Preferences in the Male Rat I. o Nature of the Unconditioned Stimulus  RATIONALE - Do male rats show selective mating  EXPERIMENT 1 – Sexually trained males (intromissions only) with either almond odour or no odour – tested in a tria  EXPERIMENT 3- Sexually trained males (PEI) with either almond odour or no odour – tested in a trial  RESULTS: Males preferred females with the odour they were tested with Conditioning and Sexual Behavior  How strong is the motivation to have sex????
  Pfaus et al. found that an initially aversive stimulus paired with copulation can acquire conditional appetitive properties.  Cadaverine – an airborne polyamine given off by decaying flesh and is innately aversive to rats  Males were either paired with cadaverine scented (C + E) females, Estrous females (E) or habituated with cadaverine prior to testing (C)  Cadaverine acquired conditional appetitive properties  Peters, 1983
  Learned aversions to copulation???  Male rats received lithium chloride injections immediately after a sexual encounter  First not affected
  Eventually after 5-10 trials of pairing, male rats developed aversions and stopped copulating entirely  Persisted after males placed in a novel environment and extinguished after 4 non- reinforced trials Sexual Behavior in Humans  Kinsey reports (1940s) - descriptions of male sexual responses o Not quantitative, just descriptive  In humans, two components
 o Sex drive/libido (appetitive)
 o Sexual performance/potency (consummatory) o Hormones probably necessary for both  No universal sexual position (not a stereo-typed behaviour) o Face-to-face most popular Role of Testosterone  Sexual activity begins at puberty
 •13.5 years old for boys in N. America •17 years old for average first intercourse  Sexual activity peaks during 20s, then declines  Levels of circulating T parallel sexual activity over age o With reduced T, sexual activity decreases with decline in age, T and sexual activity decrease  However, effects of castration vary:
 o In general, half stop all sexual activity
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