2011 Boston Meeting: Hugo Critchley, MBChB, DPhil, MRCPsych
Afferent Influences on Self and Emotion in Health and Sickness
Invited address by Hugo Critchley, MBChB, DPhil, MRCPsych, Chair in Psychiatry at Brighton and Sussex Medical School and Co-Director of the Sackler Center for Consciousness Science
Kicking off the 51st meeting with the first invited talk of the season, Dr. Hugo Critchley presented recent advances in a decades-long line of research focusing on interoceptive awareness-or consciousness of internal body states-and how variation in this awareness relates to differences in physical and mental health.
Beginning with evidence he and colleagues have unearthed for direct links between activity in the Anterior Cingulate Cortex (ACC) and the autonomic nervous system, Critchley went on to propose that the ACC might represent an area where information from the body is integrated with conscious awareness, suggesting that-per Shachter and Singer's formative work in psychophysiology-afferent information from the viscera and the heart are essential to sorting out how we feel in any given moment. And indeed, evidence for visceral afferent communication of peripheral information comes from-for example-experiments in which patients were given a typhoid vaccine (which causes inflammation in several key sites around the body). The 2009 study showed that the vaccine (but not a placebo injection) also induced changes in feeling states, such that patients who'd received the vaccine reported greater fatigue and confusion, as well as increased negative moods.
Individual differences in levels of this interoceptive awareness, too, appear to matter, according to Critchley. For example, in experiments where individuals' heart beats are paired with a sequence of tones, those who have a more acute awareness of internal states-as indexed by their ability to track the accuracy of the heartbeat-tone pairings-also appear to have more acute emotional responses as measured by self-report. These more finely-tuned internal representations of self also have implications beyond just emotional responding. For example, variability in interoceptive awareness can predict response in the classic "rubber hand" experiment. In these studies, an individual subject watches as their own hand-usually hidden from view-is stroked at the same time as a rubber hand. The typical subject quickly reports a feeling of ownership and embodiment of the fake hand; however, those higher in interoceptive awareness seem less susceptible to this illusion-they don't embody the rubber hand, suggesting those with more accurate internal representations of self also have more accurate representations of the boundaries of the self.
In closing, Critchley emphasized that multiple sites and mechanisms contribute to this unified sense of self; multiple neural sources generate visceral states, and even more appear to be responsible for neural and mental representations of these states, as well as complex processes that integrate information about these states with information about behavior. In short, according to Critchley's research, emotional feeling states arise not only from dynamic interactions of the individual with its environment, but also from a complex and cascading chain reaction occurring within the individual.