(Kranz & Ishai, 2006) Melody Sinclair-Brooks PSYC 260 Introduction Hypothesis Methods Results Discussion My Opinion Face perception is mediated by a distributed neural system in the human brain The response to faces is modulated by cognitive factors such as: attention visual imagery emotion However, the effects of gender and sexual orientation on peoples response to faces is currently unknown. Kranz & Ishai expected a significant relationship between the gender of the image presented and the sexual preference of the participant. Greater response to an image will correspond to a greater activation in the reward circuitry regions of the brain Sexual Preference Brain activation Response The reward circuitry consists of the dopaminergic pathways in the brain These circuits are evolutionarily important for natural rewards such as food, music, and sex Heterosexual men and homosexual women are expected to respond more to female faces. Heterosexual women and homosexual men are expected to respond more to male faces. Researchers used fMRI to test whether subjects would respond more to their sexually preferred faces... 40 normal, right-handed subjects with normal vision (Mean age ± SD = 26 ± 3 years) 10 heterosexual women & 10 homosexual women 10 heterosexual men & 10 homosexual men Stimuli were projected onto a translucent screen placed at the feet of the subject Subjects viewed: Grayscale photographs of faces (3 runs each) and Assessed facial attractiveness (5 runs each) Each run: Participants were shown images of faces alternating with images of phase scrambled faces within a period of 30s They had 21s for viewing and 12s for attractiveness rating Face (3s) Phase-scrambled face (3s) Each stimulus was presented for 3 seconds, with no blank periods between the stimuli i. Viewing Condition: During the viewing condition, 60 male and 60 female unfamiliar, famous, and emotional faces were presented ii. Attractiveness assessment: During the assessment of facial attractiveness, 100 male and 100 female faces were presented Reaction times were recorded. The order of runs was randomized across subjects. ii. Attractiveness assessment (cont’d): Subjects pressed 1 of 3 buttons to indicate whether a face was: attractive neutral unattractive Independent Variables: Face or Phase-Scrambled face Sexual Preference Dependent Variables: Attractiveness rating Brain activation Whole body MR scanner (Philips Medical Systems, Best, The Netherlands) Changes in the blood-oxygenation-level-dependent MRI signal were measured High resolution structural images were collected in the same session for all the subjects (180 axial slices) The high-resolution anatomical images were used to build a 3D brain atlas fMRI data analyzed in BrainVoyager QX Version 1.3 (Brain Innovation, Maastricht, The Netherlands) All volumes were corrected for motion artifacts, realigned, and spatially smoothed with a 5mm FWHM Gaussian filter. inferior occipital gyrus (IOG) lateral fusiform gyrus (FG) superior temporal sulcus (STS) amygdala intraparietal sulcus (IPS) caudate putamen mediodorsal nucleus of the thalamus (mdT) anterior cingulate cortex (ACC) insula inferior frontal gyrus (IFG) medial orbitofrontal cortex (OFC) The fMRI images for faces were subtracted from the fMRI images of the scrambled faces This difference indicated the activation for the brain areas when faces were being viewed Scrambled Face signal – Face signal =Activation According to their attractiveness score According to the mean of the parameter estimates that was calculated for attractive, neutral, and unattractive male and female faces Between-subjects random-effects analyses to control for any random effects between subjects There was a significant interaction between stimulus gender and the sexual preference of the subject in the thalamus (mdT) and medial orbitofrontal cortex (OFC) Heterosexual men and homosexual women responded more to female faces Heterosexual women and homosexual men responded more to male faces mdT= mediodorsal nucleus of the thalamus OFC = medial orbitofrontal cortex Regardless of gender or sexual orientation, participants had very similar assessments of attractiveness of both male and female faces. Activation in the medial orbitofrontal cortex (OFC): The OFC is involved in representing the reward value of sensory stimuli: including beautiful faces, abstract positive and negative reinforcers Activation in the thalamus (mdT) : it is reciprocally connected to the OFC and will therefore show similar patterns of activation Facial beauty is considered an indicator of reproductive fitness – perhaps why men and women equally notice and respond to beauty of the same and opposite sex Recent studies have reported that facial beauty evokes activation in the reward circuitry regions of the brain... I WANT I YOUR BABIES. Male and female face stimuli evoke similar neural activation within a distributed cortical network that includes: Visual, Limbic, and Prefrontal regions Sexually relevant faces elicit stronger neural responses in the reward circuitry Kranz & Ishai analyzed many brain regions, doing a thorough investigation Perhaps they could have included diagrams for the procedure when explaining the steps as it was not crystal clear and provide an example of the phase-scrambled faces used Future research could investigate the effect of peoples’ ethnic background on assessing attractiveness and activating certain brain areas Thank you.