Brain Structures and Sex Chapter 7 Biology of Sex Pages 193 197 Network of brain structures are involved in sexual activity mostly animals but tech like fMRI has made humans more involved Medial PreOptic Area MPOA of hypothalamus Stimulation of MPOA in rates increased copulation Sexually dimorphic nucleus of MPOA different sizes larger in male rats Depends on prenatal exposure to testosterone Medial Amygdala large cluster of nuclei embedded in to anterior frontal lobes Active during copulation in both males and females Stimulation causes dopamine release in MPOA Ventromedial Nucleus VMN of hypothalamus Active during copulation in females Destruction reduces responsiveness to males Neurotransmitters and Sex Dopamine and serotonin increases in MPOA in rats supposedly in humans too Norepinephrine increases in men and women during sex Dopamine increases in Nucleus Accumbens part of network that stimulates reward In male rats increases also with new female Coolidge effect Sensory Stimuli and Sex Interplay of internal hormonal conditions and external stimuli Tactual Auditory Visual Use pictures of face body etc and asked to rate it on a number scale research has shown that across cultures that faces with bilateral symmetry are consistently judged as more attractive Body symmetry is another important determinant of sexual attractiveness hard to maintain as you go down the body from head to feet Why symmetry ancient phenomenon of vertebrates oldest are fish animals that swim move must be bilaterally symmetrical to control and streamline swimming May be indicative of genetic fitness hard to maintain with environment genetic mutations etc Not going to be attracted to someone that doesn t smell good Chemical system Receptors for smell are found in nasal cavity highly modified sensory neurons finger like projections are olfactory cilia dendrites Action potentials travel down olfactory nerve axons Ventral side of frontal lobe tiny holes in bone to let the axons out Olfactory Normal smelling system Pheromones airborne chemicals released by an animal that have a physiological or behavioral effect on another animal of the same species used to regulate sexual behavior in many species Female gypsy moth attracts males from 2 miles away some species rely on this entirely for sex Humans at first it was not believed pheromones mattered VomeroNasal Organ VNO cluster of receptors for pheromones in nose very small microscopic sends signals to MPOA and VMN of hypothalamus Generates electrical potentials to suspected pheromones May be pheromonal influence even in humans 1st to make claim pheromones affect humans McClintock study on menstrual synchrony Studying menstrual cycle of students and noticed that cycles tended to be more synchronized in women living in close proximity to each other Evolutionary advantage in social species everyone in family has babies at the same time which makes it easier to take care of brood genes in next generation inclusive fitness safety in numbers Confirmed due to pheromones Men rate photographs and voice recordings of women higher when sniffing inhalers containing suspected pheromones from the women Exposed to pheromones higher rating than those who did not smell it Men rate t shirts of more attractive women highest on sexiness smell itself not pleasant Correlation between ranking of t shirts and the ranking of pictures Men using after shave containing suspected male pheromone report more sexual activity than controls highly suspect study may have been sponsored by after shave company also self report study Pheromonal influence on sexual behavior of humans is still controversial debate centered around how much of an effect it has Chapter 8 Emotion and the Nervous System Pages 224 226 E motion E Ex out motion Movere to move Movement of mind soul feeling e g happiness Body s response e g smiling higher heart rate Smiling somatic N S Heart rate Autonomic Sympathetic N S Relationship between emotional experience and body James Lange theory late 1800s Perception of specific patterns of physiological arousal specific emotional experience I feel said because I cry rather than I cry because I feel sad Dominated scientific arena for a while but then it ran into problems Cannon s criticism 1920 autonomic nervous system responds the same way in different emotions perception of physiological responses cannot account for variety of emotional experiences Schachter Singer s 1962 Cognitive Theory Identification of emotions relies on a cognitive assessment of the external stimulus situation physiological arousal contributes only to the intensity of an emotion Epinephrine experiment both groups given an injection did not know but control knew what effects would come of epinephrine that will turn on sympathetic response exposed to same external stimulus of waiting room with another person who would act ecstatic or angry then answer questionnaire clear difference between control and experimental group experimental group s answer depended on how the other person was acting in the room control group felt nothing just had a higher heart rate due to injection