Short-term head-out whole-body cold-water immersion facilitates positive affect and increases interaction between large-scale brain networks

Abstract An emerging body of evidence indicates that short-term immersion in cold water facilitates positive affect and reduces negative affect. However, neural mechanisms underlying these effects remain largely unknown. For the first time, we employed functional magnetic resonance imaging (fMRI) to identify topological clusters of networks coupled with behavioural changes in positive and negative affect after a 5-min cold-water immersion. Perceived changes in positive affect were associated with feeling more active, alert, attentive, proud and inspired, whilst changes in negative affect reflected reductions in distress and nervousness. The increase in positive affect was supported by a unique component of interacting networks, including the medial prefrontal node of the Default Mode Network, a posterior parietal node of the Frontoparietal Network, anterior cingulate and rostral prefrontal parts of the Salience Network and Visual Lateral Network. This component emerged as a result of a focal effect confined to few connections. Changes in negative affect were associated with a distributed component of interacting networks at a reduced threshold. Affective changes after cold water immersion occurred independently of each other, supporting the bivalence model of affective processing. Interactions between large-scale networks linked to positive affect indicate integrative effects of cold-water immersion on brain functioning.