The timing and strength of each heartbeat is signalled in chunks to the brain by arterial baroreceptors. This is the basis of the interoceptive representation of cardiovascular arousal.
Recent studies show that fear signals are judged more fearful during heartbeats (when baroreceptors are activated) than between heartbeats (when baroreceptors are quiescent). At the limit of perception, fear signals are more easily detected during heartbeats than between heartbeats.
The enhancement of fear processing by heartbeats indicates a selective, differential influence of physiology on motivationally relevant functions as the processing of painful stimuli is inhibited by heartbeats.
Physiological fluctuations in the body dictate sensory sampling and the contents of perceptual consciousness.
Characterisation of these selective cardiac interoceptive effects will inform emotional neuroscience and may lead to new treatment approaches for anxiety.