The representation of heart contractions in some auditory parts of the temporal cortex in a non-anesthetized cat

The inquiry into how cortical neurons respond to interoceptive signals remains a complex puzzle, central to understanding self-awareness in advanced mammals, including humans. A fundamental aspect under scrutiny is whether neural networks in the cerebral cortex of animals can accurately reflect internal bodily states, particularly cardiac activity. To investigate this, we conducted a study on neurons within the temporal cortex of awake and sleeping cat, employing a unique setup enabling continuous differential recording of local potentials in specific cortical regions, alongside monitoring the cardiogram. Our findings revealed intriguing insights. While the primary auditory cortex (AI) exhibited minimal cellular activity synchronized with heartbeats, the secondary auditory zones within the temporal cortex – the anterior ectosylvian sulcus and the posterior ectosylvian gyrus – displayed synchronization with heart rate. This synchronization was particularly evident in local potentials, with certain neurons within these zones responding to sounds and also exhibiting rhythmic activity aligned with heart contractions. Notably, the complexity of phase histograms derived from the cardiogram period suggests that this synchronization is not attributable to artifacts but rather represents genuine neural responses. Our observations prompt consideration of a hypothesis regarding primary self-awareness in both humans and animals. We propose that this phenomenon emerges from the dynamic interaction of two neural ensembles: one representing external sensory input and the other reflecting interoceptive signals, notably from the heart. This interplay between external and internal stimuli may underpin the fundamental experience of the consciousness of self in highly developed organisms.