Neural Processes of Touch and Pain: From Detection to Retention

Touch and pain are fundamental dimensions of human experience, enabling us to perceive, interpret, and adapt to the state of the body and its interaction with the world around us. Both belonging to the somatosensory system, these modalities constitute distinct yet complementary perceptual phenomena. However, fundamental questions remain regarding the precise neural mechanisms through which touch and pain are represented, maintained, and integrated within the human brain. This thesis comprises four empirical chapters that, using transcranial magnetic stimulation (TMS) alongside behavioural paradigms and psychophysiological measurements, investigated these processes across perceptual, cognitive, and motor domains. First, we examined the causal and temporal role of the primary somatosensory cortex (S1) in tactile detection, demonstrating that S1 plays a causal but temporally constrained role in encoding tactile input leading to conscious awareness. Second, we investigated the contributions of S1 and the secondary somatosensory cortex (S2) to the short-term retention of painless and painful tactile input, revealing that this retention does not depend on S1 or S2 and likely engages distributed, modality-independent networks beyond these regions. Third, we explored the malleability of associative pain learning by testing whether affective working memory engagement could disrupt or weaken consolidated learning, revealing that conditioned pain memories are resistant to such interference. Finally, we assessed how tactile and nociceptive afferent inputs modulate the motor system, finding that while pain exerts a direct inhibitory effect on motor output, it does so independently of transient tactile sensorimotor interactions. Together, these findings indicate that touch and pain engage distinct but interacting neural systems that dynamically support perception, action, and memory. These results support the idea of a distributed, context-dependent model of touch and pain, in which underlying neural processes flexibly adapt to behavioural goals and environmental demands.