Androgens modulate neural networks of empathetic processes in female-to-male tanssexuals
Androgens Modulate Neural Networks of EmpatheticProcesses in Female-to-Male TranssexualsZ. Ye1, R. Kopyciok1, B. Mohammadi1,2, U. M. Krämer1, C. Brunnlieb1, M. Heldmann1, A. Samii2, T. F. Münte11University of Lübeck, Germany 2International Neuroscience Institute, GermanyUnivariate AnalysisPerformed with SPM8 on the basis of general linear model (p < 0.05corrected at cluster level).• Brain responses to emotional cues in the medial prefrontal cortex(mPFC) and posterior superior temporal sulcus (pSTS) decreasedduring hormonal treatment.Network AnalysisPerformed with the Brain Connectivity Toolbox on the basis of graphtheory• Each cerebral hemisphere was segmented into 45 regions according tothe Automated Anatomical Labeling.• Correlations were computed for every possible pair of regions toconstruct the connectivity matrix.• The connectivity matrix was systematically threshold to generate 99undirected binary matrix with costs from 0.01 to 0.99 at 0.01 intervals.• A small world network has both high global efficiency and high localefficiency. The brain network behaved like the small world networkwhen cost = 0.12~0.23 (small-world regime).• Statistics were performed in the samll-world regime. Alpha levels werecontrolled with permutation (p < 0.05 corrected).• Left and right middle cingulate cortex (LMC/RMC), left middletemporal gyrus (LMT) and right superior temporal gyrus (RST) wereregional hubs of which centrality did not change when androgen levelchanged.AcknowledgmentsDeutsche Forschungsgemeinschaft• DFG, SFB 779, TP A5 to TFM• KR 3691/1-1 to UMKGerman Federal Department ofResearch BMBF (to TFM).More info: Thomas.firstname.lastname@example.org (Prof. Dr. T. F. Münte)MethodsTranssexuals and hormonal treatment• Female-to-male transsexuals (n = 8, mean 28 years): Each was scannedtwice, once before (pre-test) and once during hormonal therapy (post-test; 12months after the treatment began).• Hormone administration route and schedules were heterogeneous, asdefined by the attending endocrinologist.Healthy controls: Females (n = 31, mean 24 years) and Males (n = 30,mean 27 years)Research QuestionsWomen usually show higher sensitivity than men to emotional and socialcues and are therefore better in showing empathy with others and inthe deciphering of other’s intentions and mental states. These sexdifferences have been linked to hormonal levels. However, it remainsunclear how hormones modulate neural mechanisms underlyingempathic processes. Here we assess effects of chronic hormonaltreatment in a group of female-to-male transsexuals before and duringandrogen therapy with functional magnetic resonance imaging (fMRI).We ask two questions.Q1: How is brain activity in response to emotional and/or social cuesmodulated during hormonal treatment in transsexuals (pre- vs. post-test)? ( Univariate analysis)Q2: How are neural networks of empathic processes modulated duringhormonal treatment in transsexuals? Do same differences show up inhealthy females vs. males? ( Graph theoretical analysis)Stimuli and task• Black-and-white drawingsdepicting emotionallynegative or neural (Emotvs. Neut) social situationsinvolving one or twopersons (One vs. Two)• Participants watched thepictures during threesessions and completed arecognition after eachsession.Data acquisition• Collected on 3T Siemens scanner using EPI sequence, with 2000-msTR, 30-ms TE and 80°flip angle.• 32 transversal slices; 192 mm*192 mm field of view; 3-mm thickness,0.75-mm gap; 3 mm*3 mm in-plane resolution.• MPFC and pSTS responses to social cues also decreased duringhormonal treatment.• Functional connections within frontal regions, those between frontaland temporal lobes, and those between frontal and striatal structureswere stronger when androgen level was low (transsexuals beforehormonal treatment and healthy females).• Functional connections within limbic system was stronger whenandrogen level was high (transsexuals after hormonal treatment andhealthy males).