Attenuated heartbeat-evoked potentials in functional neurological disorder

Area of Science:

• Neuroscience
• Psychiatry
• Psychology

Background:

• Functional neurological disorders (FND) involve disrupted interoception, the awareness of internal bodily signals.
• Previous research on interoception in FND is inconsistent, focusing mainly on accuracy and self-report, neglecting neural markers and attentional effects.

Purpose of the Study:

• To investigate interoceptive accuracy, self-report, and neural markers (heartbeat-evoked potentials) under attentional modulation in FND patients.
• To explore group differences in interoception between FND patients and healthy controls across interoceptive and exteroceptive attention conditions.

Main Methods:

• Assessed interoceptive accuracy via a heartbeat counting task and self-report using questionnaires in 44 FND patients and 48 controls.
• Measured heartbeat-evoked potentials (HEPs) under conditions of focusing on heartbeats versus external sounds.
• Analyzed group differences in behavioral and neurophysiological measures, controlling for cardiac covariates.

Main Results:

• FND patients reported lower interoceptive self-awareness and greater difficulty focusing on heartbeats, but showed no significant difference in objective accuracy.
• Global field analyses revealed reduced overall neural activity and frontal deactivation in FND patients during interoceptive attention.
• Attenuated frontal-lateralized HEPs were observed in FND patients, particularly under interoceptive attention, indicating altered neural processing.

Conclusions:

• Despite preserved behavioral accuracy, FND is associated with altered interoceptive processing, including reduced self-report and impaired neural responses.
• Attentional mechanisms significantly modulate interoceptive processing in FND, with notable neural differences in frontal regions.
• This study identifies objective neural markers of interoceptive dysfunction in FND, emphasizing the importance of attention in its pathophysiology.