Sex differences in learning processes of classical and operant conditioning

Neural activations of the acquisition of conditioned sexual arousal: effects of contingency awareness and sex

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.