Decomposing neural representational patterns of discriminatory and hedonic information during somatosensory stimulation.

The ability to interrogate specific representations in the brain, determining how, and where, difference sources of information are instantiated can provide invaluable insight into neural functioning. Pattern component modelling (PCM) is a recent analytic technique for human neuroimaging that allows the decomposition of representational patterns in brain into contributing sub components. In the current study, we present a novel PCM variant that tracks the contribution of pre-specified representational patterns to brain representation across areas, thus allowing hypothesis-guided employment of the technique. We apply this technique to investigate the contributions of hedonic and non-hedonic information to the neural representation of tactile experience. We applied aversive pressure and appetitive brush to stimulate distinct peripheral nerve pathways for tactile information (C-/CT-fibers respectively) while patients underwent fMRI scanning. We performed representational similarity analyses with pattern component modeling to dissociate how discriminatory vs. hedonic tactile information contributes to population code representations in the human brain. Results demonstrated that information about appetitive and aversive tactile sensation is represented separately from non-hedonic tactile information across cortical structures. This also demonstrates the potential of new hypothesis-guided PCM variants to help delineate how information is instantiated in the brain. Synthesis Statement This work provides a novel brain imaging analyses that enables the decomposition of brain states into subcomponent states each associated with distinct patterns of experience or information. This technique is applied to human neuroimaging data acquired during hedonic touch to demonstrate a dual role of somatosensation in affective and sensory experience.The analytic advancement highlights exciting new developments in human neuroscience, allowing for the decomposition of human experience into discrete representation state both within and across brain areas.