Neurophysiological investigations of drug resistant epilepsy patients treated with vagus nerve stimulation to differentiate responders from non-responders

Background and purpose In patients treated with vagus nerve stimulation (VNS) for drug resistant epilepsy (DRE), up to a third of patients will eventually not respond to the therapy. As VNS therapy requires surgery for device implantation, prediction of response prior to surgery is desirable. It is hypothesized that neurophysiological investigations related to the mechanisms of action of VNS may help to differentiate VNS responders from non-responders prior to the initiation of therapy. Methods In a prospective series of DRE patients, polysomnography, heart rate variability (HRV) and cognitive event related potentials were recorded. Polysomnography and HRV were repeated after 1 year of treatment with VNS. Polysomnography, HRV and cognitive event related potentials were compared between VNS responders (>= 50% reduction in seizure frequency) and non-responders. Results Fifteen out of 30 patients became VNS responders after 1 year of VNS treatment. Prior to treatment with VNS, the amount of deep sleep (NREM 3), the HRV high frequency (HF) power and the P3b amplitude were significantly different in responders compared to non-responders (P = 0.007; P = 0.001; P = 0.03). Conclusion Three neurophysiological parameters, NREM 3, HRV HF and P3b amplitude, were found to be significantly different in DRE patients who became responders to VNS treatment prior to initiation of their treatment with VNS. These non-invasive recordings may be used as characteristics for response in future studies and help avoid unsuccessful implantations. Mechanistically these findings may be related to changes in brain regions involved in the so-called vagal afferent network

Heart rate, electrodermal responses and frontal alpha asymmetry to accepted and non-accepted solutions and drinks

Consumers' physiological responses, such as heart rate, electrodermal responses and frontal alpha activity can enhance the understanding of the consumers' food experience. This study looked at physiological responses of the autonomic nervous system (heart rate, electrodermal responses) as a measure for level of arousal, and to responses of the central nervous system (frontal alpha asymmetry, FAA) as a measure for approach/withdrawal motivational tendency, to accepted (liked) and non-accepted (disliked) solutions and drinks. Participants (n = 32, age range: 18-34 years) were presented with a universally accepted (sucrose) and non-accepted (caffeine) solution, a personally selected accepted and non-accepted drink, and plain water. Heart rate, heart rate variability, electrodermal activity and electro-encephalography for FAA at F7 and F8 (10/20 system, 25 channels, 256 Hz) were registered during tasting. Statistical analysis consisted of linear mixed model analyses. We found a significantly higher heart rate during tasting of the personally selected non-accepted drink and a significantly lower latency of the electrodermal response during tasting of the universally non-accepted solution and personally selected non-accepted drink. No significant results were observed for FAA. This is one of the first studies that examined physiological responses including frontal alpha asymmetry during actual tasting. This study provides an exploratory method to obtain implicit measurement of acceptance and food product-elicited emotion through physiological responses and supports the importance of the inclusion of implicit measures, next to explicit measures, in sensory evaluation of food products

Epistemics and frontotemporal dementia

We explore how patients with the behavioural variant of frontotemporal dementia (bvFTD) display different degrees of understanding when reporting on their experience of being ill. Using the methods of conversation analysis, we examine thevideo-recordings of bvFTD patients who had participated in clinical follow-up interviews with a doctor. Patient responses to the doctor’s questions were analyzed with respect to the action undertaken (i.e., confirmation vs. denial) and the epistemic stance (i.e., certainty vs. uncertainty) that was conveyed. We found that although patient denials of being ill were conveyed with certainty, these patients were unable to elaborate on their denials, thus generating an implication that they are not aware of their illness and its effects on their lives. By contrast, patients who confirmed being ill tended to produce expanded responses that either revealed the patient’s primary access to knowledge or the patient’s difficulty in understanding the doctor’s question