Lecture 7. Instinctual behavior - psychiatry
Lecture 7. Instinctual behavior Bogdan Nemeș, MD, PhD Medical Education Dept. / Clinical Psychology and Mental Health Dept. Deﬁnitions Ê Instincts are automatic, involuntary, and unlearned behavior patterns that are consistently released in the presence of particular stimuli. Ê Examples of human instincts: Ê alimentary instinct – hunger and eating Ê sexual instinct – seeking sexual gratiﬁcation Ê aggresivity – the tendency to be aggressive Ê maternal instinct – ﬁercely protecting their young Hunger and eating Ê Biological mechanisms: Ê The role of stomach cues Ê The role of taste cues Ê The role of the brain: Ê Signals for hunger Ê Non-‐biological factors The role of stomach cues Ê People often get “hunger pangs” in the stomach when they are hungry and complain of having a “full stomach” after eating a large meal. Ê The stomach might control the hunger motive; but hunger is not that simple Ê People who have had their stomachs removed because of illness still experience hunger pangs when they do not eat and still eat normal amounts of food. The role of taste cues Ê People consume more food during a multicourse meal than when only one type of food is served. Ê This variation in consumption is due in part to the fact that the taste of a given food becomes less and less enjoyable as more of it is eaten. The role of the brain Ê Two regions of the hypothalamus (a structure in the forebrain) in particular have been studied: Ê the lateral area: Ê acts as a “start eating” center Ê if the lateral hypothalamus is electrically stimulated, one result is that the rats begin to eat vast quantities of food Ê when ﬁbers in the lateral area of the hypothalamus are destroyed rats stop eating almost entirely Ê the ventromedial nucleus: Ê acts as a “stop eating” center Ê if the ventromedial nucleus is electrically stimulated the rat stops eating Ê when ﬁbers in the ventromedial nucleus are destroyed the rat will eat far more than usual The role of the brain Ê The set-‐point concept: Ê It suggests that a homeostatic mechanism in the brain establishes a level – a set point – based on body weight or a related metabolic signal. Ê Normal subjects eat until their set point is reached, then stop until their brain senses a drop in desirable intake, at which time they eat again. Ê Destruction or stimulation of the lateral or ventromedial areas of hypothalamus may alter the set point Signals for hunger Ê The subjects brains “read” something in the blood that tells them when to eat Ê The level of glucose: Ê When the level of blood sugar drops, eating increases dramatically (“start eating” function) Ê CCK Ê During a meal, CCK (the hormone cholecystokinin) is released from neurons in the hypothalamus Ê Subjects injected with CCK do not only stop eating but also show other signs of being satiated such as grooming and sleeping (“stop eat” function) Non-‐biological factors in hunger and eating Ê Stimulate eating: Ê sights and smells of particular foods elicit eating because of prior associations Ê family customs and social occasions often include norms for eating in particular ways Ê stress is often associated with eating more Ê Inhibit eating: Ê Contemporary society values thinness, and thus can inhibit eating Ê Conditioned satiation occurs when certain foods are associated with satiety Ê Negative emotional reactions sometimes result in a loss of hunger Sexual behavior Ê Biological factors: Ê The role of hormones: Ê The organizational eﬀect Ê The activational eﬀect Ê Non-‐biological factors The role of hormones Ê The feminine hormones are: Ê Estrogens Ê Progestins; Ê The main ones are: Ê Estradiol Ê Progesterone Ê The masculine hormones are androgens Ê The main androgen is testosterone Ê Each of these hormones circulates in the bloodstream of members of both sexes, but relatively more androgens circulate in men and relatively more estrogens and progestins circulate in women Ê These hormones have both organizational and activational eﬀects The organizational eﬀect Ê Consists in permanent changes in the brain and the way an individual thereafter responds to hormones Ê The organizational eﬀects of hormones occur during very early development – prenatal in humans – when either a “male-‐like” or a “female-‐like” pattern of brain connections is laid down Ê The basic gender anatomic template is female Ê Individuals with the SRY gene on the Y chromosome develop androgen receptors, produce androgens and Mullerian duct inhibiting substance. Ê It is clear that there are regions of the human brain that are diﬀerent in males and females The activational eﬀect Ê Consists in reversible changes in behavior that remain as long as the hormone levels are elevated Ê In puberty, hormone levels rise and the activational eﬀects occur Ê There is a positive correlation between sexual activity and levels of hormones in the blood Ê Androgens are the critical hormones for activating sexual interests in both sexes, although estrogens may also activate sexual interest in women Non-‐biological factors involved in human sexual behavior Ê Sexual behavior is shaped more precisely by a lifetime of learning Ê Some sexual behaviors are learned as part of the development of gender roles Ê Other kinds of early sexual experiences may also be necessary for the development of sexual motivation and behavior Ê Attitudes toward sexual behavior change as cultural expectations change: Ê In a survey in the 1920s, most husbands wanted more frequent sexual contacts with their wives, whereas wives wanted less Ê In a similar survey in the 1970s, only 2% of wives said that intercourse was too frequent, and 32% thought it was too infrequent Age and sex Ê Prenatal Ê Genetic determination of sex Ê At birth Ê The sex statute is given Ê Counselling in case of anatomic ambiguity Ê 1st year Ê Genital responses appear Ê Touch and exporation of the esternal genitals appears Ê There have been cases of masturbation with orgasm Ê Familial handling of the child is also very important Age and sex Ê Childhood Ê At 2½ years gender awareness appears = acquisition of gender identity Ê Once acquisitioned it is very hard to change Ê Awareness about gender role appears Ê Awareness about external genital organs diﬀerences appears Ê Gender diﬀerences appear: Ê Girls have more developed verbal aptitudes Ê Boys have visuo-‐spatial and mathematical aptitudes more developed, and are more aggressive Ê Observation of parental behavior is key for learning healthy sexual behavior Age and sex Ê Childhood Ê At the age of 4: Ê Games with sexual connotations appear (doctor and nurse) Ê Interest about procreation Ê The need for intimacy in the bathroom and when putting on or taking oﬀ clothes appears Ê Curiosity about their own body persists, and also about other people’s intimate activities Ê By age of 5: Ê Children become reluctant in exposing their bodies Ê Awareness and interest in gender diﬀerences increase Ê Children can experience the full sexual response cycle, including orgasm, but they don’t seek sex partners and do not have mature sperm or ova. Age and sex Ê Pre-‐puberty: Ê Sexual games with children of the same or diﬀerent sex appear Ê The number of individuals that have experienced orgasm gradually increases Ê Puberty: Ê Maturation of sexual organs begins Ê On average puberty begins earlier in girls, than in boys Ê The age of onset has decreased over the past 150 years Age and sex Ê Adolescence: Ê Preocupations about: Ê Anatomical changes Ê Sexual instinct development Ê They have to face many issues: Ê Almost all boys and most girls masturbate Ê Sexual identity Ê Start of sex life Ê Pregnancy Ê Abortion Ê Sexually transmitted diseases Ê Sexual behavior is further developed through: Ê Masturbation, oftenly accompanied by imaginary experiences Ê First touches and kisses with diferent sex or same sex partners Ê First sexual experiences (intercourses) Age and sex Ê Young adulthood: Ê Individuals need to face the many options regarding: Ê Marriage Ê Having / Raising children Ê Lifestyle Ê Sex life rithm Ê Issues and conﬂicts regarding: Ê Conformism Ê Infertility Ê Pregnancy Ê Childbirth Ê Monotony Ê Low self-‐esteem Ê Career Ê Illness Ê It is supposed that a stable emotional and sexual bond has already been formed Ê Married couples have more frequent intercourses Ê Marturbation remains a form of disposing of sexual energy Age and sex Ê Full maturity (40-‐55): Ê For some – it is a relief, others show anxiety and hopelessness Ê The psysiologic intensity of sex diminishes. 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This reduction is usualy greater for men. Ê In women: Ê Menopause Ê Vaginal wall narrows Ê Less vaginal lubrication Ê Orgasm phase shortens and uterine contractions can become spastic and painful Ê In men: Ê Changes are gradual and have a later onset Ê Morning and night erections become less frequent Ê Erection takes longer Ê Angle of the erection changes Ê Volume of the ejaculate decreases Age and sex Ê Old age: Ê Reduction in intensity continues. Ê They can still enjoy it. Ê Inappropriate sexual behavior should lead to investigations for possible brain disease. The sexual response cycle Ê Appetitive phase Ê Initial sexual desire Ê Excitement phase Ê Clitoral / penile erection Ê Nipple erection Ê Skin ﬂushing Ê Breast / testicular enlargement Ê Increased muscle tension, heart and respiratory rates, and blood pressure Ê Plateau phase Ê Orgasm Ê Resolution The key triad Ê Most sexual dysfunctions in any of the phases are due to the key triad: Ê Problems in the relationship Ê Performance anxiety Ê Many persons mistakenly view sexual intercourse as a skill, ability, talent or performance rather than as a source of pleasure, and this is interfering with the autonomic components of sex: Ê Parasympathetic discharge for arousal and erection Ê Sympathetic discharge for orgasm Ê The goal of sex is procreation or pleasure. Ê Fear of consequences Sex and pregnancy Ê Sex can continue throughout pregnancy with some precautions. Ê There is no evidence that sex with one orgasm during the ﬁrst 2 trimesters poses a medical risk for mother and foetus. Ê There is no evidence that sex without orgasm during the 3rd trimester poses a medical risk for mother and foetus, although after the 34th week it is mechanically awkward. Ê In case of vaginal bleeding during pregnancy, seek immediate medical help. Ê Following delivery, women who had an episiotomy can resume sex when the episiotomy scar is healed, usually 2 – 4 weeks postpartum. Sexual behavior Ê Social and cultural factors often overweight biological determinants of human sexual behavior, but hormones have important organizational and activational eﬀects.