Enhanced Cortical Processing of Cardio-Afferent Signals in Anorexia Nervosa

in Clinical Neurophysiology (2019), 130(9), 1620-1627

Objective: To assess cardiac interoception in anorexia nervosa (AN) using a multidimensional approach. Methods: We assessed the physiological dimensions of cardioception, i.e. the peripheral signal itself ... [more ▼]

Objective: To assess cardiac interoception in anorexia nervosa (AN) using a multidimensional approach. Methods: We assessed the physiological dimensions of cardioception, i.e. the peripheral signal itself (heart rate, HR, and heart rate variability, HRV) and its cortical representation (heartbeat evoked potentials, HEPs), and the psychological dimensions of interoceptive accuracy (heartbeat perception) and interoceptive sensibility (confidence ratings). Electroencephalogram (EEG) and electrocardiogram (ECG) were recorded concurrently during rest and while performing a heartbeat perception task in a sample of 19 female in-patients with AN (DSM-5) and 19 healthy control women (HC). Results: HEPs, defined as mean EEG amplitude in a time window of 455-595 ms after the Rpeak of the ECG, were significantly larger in the AN than in the HC group across conditions (p = .002, d = 1.06). There was a trend toward better heartbeat perception in AN, but no group differences in HR, HRV, and confidence ratings. Conclusions: Individuals with AN showed an interoceptive profile of heightened cortical processing, a trend toward heightened interoceptive accuracy, and unaltered cardiac autonomic activation and interoceptive sensibility. Significance: In terms of neurobiological models of AN, enhanced cortical representations of interoceptive signals might reflect a mechanism, which promotes fasting by alleviating negative body states. [less ▲]

Neuromuscular correlates of subthalamic stimulation and upper limb freezing in Parkinson's disease.

in Clinical Neurophysiology (2016)

OBJECTIVE: The pathophysiology of deep brain stimulation mechanisms and resistant freezing phenomena in idiopathic Parkinson's disease (iPD) remains incompletely understood. Further studies on the ... [more ▼]

OBJECTIVE: The pathophysiology of deep brain stimulation mechanisms and resistant freezing phenomena in idiopathic Parkinson's disease (iPD) remains incompletely understood. Further studies on the neuromuscular substrates are needed. METHODS: We analyzed 16 patients with advanced iPD and bilateral subthalamic nucleus stimulation, and 13 age- and gender-matched healthy controls. Patients were tested after overnight withdrawal of medication with 'stimulation off' (StimOff) and 'stimulation on' (StimOn). Subjects performed continuous tapping of the right index finger with simultaneous recordings of biomechanical registration, EMG of finger flexors and extensors, and EEG. First, we analyzed EEG and EMG spectral measures comparing StimOff with healthy controls and StimOff with StimOn (irrespective of freezing). Second, we contrasted 'regular (unimpaired) tapping' and 'freezing' resistant to subthalamic neurostimulation as obtained in StimOn. RESULTS: iPD showed increased intermuscular coherence around 8Hz in StimOff that was reduced in StimOn. This 8Hz muscular activity was not coherent to cortical activity. 'Freezing' episodes showed increased muscle activity of finger flexors and extensors at 6-9Hz, and increased cortical activity at 7-11Hz. During transition from regular tapping to 'freezing' the cortical activity first increased over the left sensorimotor area followed by a spread to the left frontal and right parietal areas. CONCLUSIONS: We identified neuromuscular motor network features of subthalamic neurostimulation therapy and resistant upper limb freezing that point to increased low-frequency muscular and cortical activity. SIGNIFICANCE: Together, our findings demonstrate several motor network abnormalities associated with upper limb freezing that may translate into future research on freezing of gait in iPD. [less ▲]