The document summarizes research on the neural bases of human sexuality, attraction, love and pair bonding. It discusses studies showing that: 1) Specific brain regions are involved in sexual arousal, attraction and pleasure responses, including regions related to reward and motivation. 2) Hormones like testosterone, dopamine and oxytocin play important roles in sexual desire, appeal/attraction, satisfaction and romantic attachment. 3) Comparative research on prairie voles provides insights into the neurochemistry of monogamous pair bonding.

1. El cerebro erótico: rutas neurales de amor y sexo Barcelona: La Esfera de los Libros, 2006 Adolf Tobeña Depto. Psiquiatria. Instituto de Neurociencias. Universidad Autónoma de Barcelona. Bellaterra.

3. Evolutionary roots: Primate affections?... Parental care, playful/attachment and sex behaviors Or monogamous bird‘s mating systems???....

4. SocioSexual rules in Apes HUMANS: - Imperfect monogamy (Serial monogamy, moderate polyginia..…) - Preference for a partner + frequent scanning for alternatives + collateral matings - High behavioural/social flexibility

6. Scatterplot of men (top) and women (down) in the 2-dimensional space defined by their attraction to men (x axis) and women (y axis) Lippa RA (2006), Psychological Science , 17, 1, 46-52. 1767 subjects (687 males and 1080 females) , mostly Psychology students from California State University, Fullerton, answering privately (through internet) valid questionnaires and scales about sexual attraction . HOMO/HETERO ATTRACTION/PREFERENCES

7. Erotic brain: motivational/performance systems

8. Hypothalamic sex-regulating areas: anterior/preoptic and medial regions - Sexual identity/orientation - Sexual motivation/performance

9. Cameron JL (2004), in RE Dahl and LP Spear (Eds.): Adolescent brain development, Annals NYAS, Vol. 1021, 110-123.

10. Mean youth values of steroid hormones in each sex Females (N=81) Males (N=102) Follicular Luteal DHEAS (ng/ml) 1,32 (0,64) 1,3 (0,62) 2,07(0,93) AD (ng/ml) 3,8 (2,56) 5,99 (2,78) 0,99 (0,6) DHEA (ng/ml) 6,24 (6,5) 3,2 (3,4) 1,48 (1,03) LH (miu/ml) 15,06 (6,17) 30,,57 (17,6) 10,75 (4,8) T (ng/ml) 0,6 (0,4) 0,73 (0,4) 4,98 (2,56) TEBG (nmol/l) 57,8 (21,7) 67,4(33,9) 46,75( (13,7) FTI 0,04 (0,04) 0,04 (0,03) 41,8 (26,6) P (ng/ml) 1,08 (1,23) 4,53 (5,73) - E (ng/ml) 0,066 (0,058) 0,19 (0,10) - DHEA= Dihidroepiandrosterone; AD: Androstenodione; LH: Luteinizing hormone; T= Testosterone; TEBG=Testosterone binding globuline; FIT= Free testosterone; P= Progesterone; E= Estradiol. From Udry (1990).

12. Body form and healthy/young attributes as a source of sexual cues Salient/Appealing Cues + Neural Templates for physical attractiveness SEXUAL ADVERTISING QUALITIES OF THE HUMAN BODY-SKIN

16. Physical Beauty/Sex appeal variations : - Age - Race/Ethnicities - Culture/Fashion …. Continuities : - Feminine morph/faces/bodies (estrogenic) - Masculine morph/faces/bodies (androgenic)

17. Neural systems for reward and addiction: from actions, to habits to compulsions. Everitt BJ and Robbins TW (2005) Nature Neuroscience , 8, 1481-9. Green arrows: Glutamate Orange arrows: Dopamine Pink arrows. GABA ATTRACTION SYTEMS: FACES

18. Aharon I et al. (2001) Neuron ,32, 537-551.

19. Aharon I et al. (2001) Neuron ,32, 537-551.

20. Knut K, Kampe W, Frith ChD, Dolan RJ and Frith U (2004), Nature , 413, 589-590.

21. Knut K, Kampe W, Frith ChD, Dolan RJ and Frith U (2004), Nature , 413, 589-590.

22. Bare skin + Gaze + Gesture as salient/sexy cues Neural systems for reward and addiction: from actions, to habits to compulsions. Everitt BJ and Robbins TW (2005) Nature Neuroscience , 8, 1481-9. Green arrows: Glutamate Orange arrows: Dopamine Pink arrows: GABA Sexual stimuli Sex-appeal cues and reward systems

24. Redouté J et al (2000) Human Brain Mapping , 11, 162-177. EROTIC IMAGING

25. Redouté J et al (2000) Human Brain Mapping , 11, 162-177. Stimuli N= neutral videos; H= Humorous videos; A: nonarousing women pictures; B: moderately arousing women pictures; C. highly arousing women pictures; S: Explicit heterosexual coitus videos.

26. Redouté J et al (2000) Human Brain Mapping , 11, 162-177.

27. Miyagawa Y et al (2007), Neuroimage , 36, 830-842. Six healthy heterosexual men, age= 30-39 years, sexually mature (T and semen measures), had penile recordings and PET scans while viewing sexually explicit intercourses (S) vs. control clips (N,M). Left Figure: specific activations at the ventral right putamen during sexual plateau (Sp). Differences in activation also obtained on the left anterior hypothalamus, ACC, insula and right posterior parieto/temporal regions .

28. Giorgiadis JR et al (2006), European Journal of Neuroscience , 24, 3305-3316. 12 heterosexual women volunteers, mean age 34 years, range 21-47, accompanied by their partners who manually stimulated them during the PET scan sessions. In addition to main effects (Figure) there were specific results patterns in the contrasts Stim vs. Rest, Orgasm vs. Rest and Orgasm vs. Stim.

29. Giorgiadis JR et al (2006), European Journal of Neuroscience , 24, 3305-3316. Positive correlations between sexual arousal (perceived) and rectal pressure with regional blood flow PET-scan measures. Significant level in this figure is P < .001. Superimposed on T1-weighted MR standard single subject image from SPM99.

30. Men and women differ in amygdala response to visual sexual stimuli Hamman S et al (2004), Nature Neuroscience , 7, 411-416. Average fMRI signal change for males and females for couples, opposite-sex and neutral stimuli (vs. fixation baseline), for ROIs in the left amygdala, right amygdala and hypothalamus . Couples = couples stimuli; O.S. = opposite-sex stimuli; Neutral = neutral stimuli. Error bars indicate s.e.m. Regions of significant overlap (conjunction) between group activations for males and females . The statistical conjunction between the activation maps for males and females ( P < 0.05 corrected, 10 contiguous voxels) for the couples stimuli versus neutral, non-sexual stimuli. ( a ) Axial view ( z = -4) showing common activation in ventral striatum and occipital cortex. Color bar indicates maximal Z values. ( b ) Brain-surface rendered view of the same map, showing parieto-temporal-occipital and frontal activations spanning regions associated with visual processing, attention, and motor and somatosensory function. Regions in red surpassed a P < 0.05 corrected threshold. The right hemisphere is on the bottom of the image.

33. Intensity 1 2 3 4 Time (Years) Love/sex kynetics: Passion ( red ); Affect/companionship ( green )

35. Hormonal changes when falling in love Marazitti D and Canale D (2004) Psychoneuroendocrinology , 29, 931-936. Depts. of Psychiatry and Endocrinology, Pisa University, (Italy).

36. Hormonal changes when falling in love Marazitti D and Canale D (2004) Psychoneuroendocrinology , 29, 931-936. When subjectes were retested 12-24 months later no differences remained!!!

37. Prairie voles: a model for monogamous love Ethology of pair bonding : Sue Carter and Carroll Horbaugh Neurobiology of Affective Attachments : Larry Young and Thomas Insel National Institutes of Mental Health, Bethesda Washington DC

38. Prairie voles: ethology of monogamous fusion

39. Sexual maturity main regulators: Hypothalamic-Hypophysis-Gonadal interactions

40. OXYTOCIN RELEASE AND STIMULATION

41. Pair bonding neurochemistry in Prairie Voles Partner preference test

42. A neurochemical map of pair-bonding mechanisms in monogamous voles From detailed neuroanatomy to transgenic/transpecies manipulations

43. Donaldson JR and Young L (2008), Science , 322, 900-904.

44. Donaldson JR and Young L (2008), Science , 322, 900-904.

45. Donaldson JR and Young L (2008), Science , 322, 900-904.

46. Walum H et al (2008) PNAS , 105, 37, 14153-14157. 552 twin pairs and their spouses (Swedish Registry), mostly white middle class, born between 1944-1971. 82% married and 18% cohabiting. 238 MZ.

49. The neural correlates of maternal and romantic love Andreas Bartels and Semir Zeki Wellcome Department of Imaging Neuroscience, University College London, London, UK Neuroimage (2004), 21, 1155-1166.

50. The neural correlates of maternal and romantic love Andreas Bartels and Semir Zeki Neuroimage (2004), 21, 1155-1166 Activations with maternal love Maternal love activations: viewing own child vs. acquaintance child same age

51. The neural correlates of maternal and romantic love Andreas Bartels and Semir Zeki Neuroimage (2004), 21, 1155-1166 Contrasting maternal (n=19) versus romantic (n=17) female populations.

52. The neural correlates of maternal and romantic love Andreas Bartels and Semir Zeki Neuroimage (2004), 21, 1155-1166 Specific and Overlapping areas

54. The neural correlates of maternal and romantic love Andreas Bartels and Semir Zeki Neuroimage (2004), 21, 1155-1166 Same deactivated areas: maternal (oc-ac) and romantic (lover – friend)

56. Regions rich in Oxytocin and Vasopressin receptors : fMRI activations Maternal and romantic love Bartels A and Zeki S (2004), Neuroimage , 21, 1155-1166

57. Gordon I et al (2008) Psychophysiology , 45, 349-352. 45 students (21 males, 24 females), with a mean age of 24,6 years (SD=3,2) voluntereed for a small payment. In a subsample (N=18), hormonal mesures were repeated; consistency of OT levels, R=0,93.

59. El cerebro erótico: rutas neurales de amor y sexo Barcelona: La Esfera de los Libros, 2006