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Introduction Learning processes like classical conditioning are involved in mediating sexual behavior. Yet, the neural bases underlying these processes have not been investigated so far. Aim The aim of this study was to explore neural activations of classical conditioning of sexual arousal with respect to sex differences and contingency awareness. Methods In the acquisition phase, a geometric figure (CS+) was presented for 8 seconds and was followed by highly sexual arousing pictures (UCS), whereas another figure (CS−) predicted neutral pictures. Ratings and contingency awareness were assessed after the entire conditioning procedure. Forty subjects (20 females) were classified into one of four groups according to their sex and the development of contingency awareness (aware females, aware males, unaware females, and unaware males). Main Outcome Measures Blood oxygen level dependent (BOLD) responses measured by functional magnetic resonance imaging (fMRI), skin conductance responses (SCRs), and subjective ratings. Results fMRI analysis showed two effects (awareness and sex) when comparing CS+ with CS−: (i) aware compared to unaware subjects showed enhanced differentiation (e.g., ventral striatum, orbitofrontal cortex, occipital cortex); and (ii) men showed increased activity compared to women in the amygdala, thalamus, and brainstem. CS+ and CS− ratings differed in aware subjects only. However, no conditioned SCRs occurred in any group. Conclusion The increased activity in men is in line with theories postulating that men are generally more prone to conditioning of sexual arousal. Further, contingency awareness seems to be an important factor in appetitive learning processes, which facilitates conditioning processes.

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In an fMRI study, effects of contingency awareness on conditioned responses were assessed in three groups comprising 118 subjects. A differential fear-conditioning paradigm with visual conditioned stimuli, an electrical unconditioned stimulus and two distractors was applied. The instructed aware group was informed about the contingencies, whereas the distractors prevented contingency detection in the unaware group. The third group (learned aware) was not informed about the contingencies, but learned them despite the distractors. Main effects of contingency awareness on conditioned responses emerged in several brain structures. Post hoc tests revealed differential dorsal anterior cingulate, insula and ventral striatum responses in aware conditioning only, whereas the amygdala was activated independent of contingency awareness. Differential responses of the hippocampus were specifically observed in learned aware subjects, indicating a role in the development of contingency awareness. The orbitofrontal cortex showed varying response patterns: lateral structures showed higher responses in instructed aware than unaware subjects, the opposite was true for medial parts. Conditioned subjective and electrodermal responses emerged only in the two aware groups. These results confirm the independence of conditioned amygdala responses from contingency awareness and indicate specific neural circuits for different aspects of fear acquisition in unaware, learned aware and instructed aware subjects.