Emotion stimulus processing in narcolepsy with cataplexy

Abstract

SUMMARYReported brain abnormalities in anatomy and function in patients with narcolepsy with cataplexy led to a project based on qualitative electroencephalography examination and analysis in an attempt to find a narcolepsy with cataplexy-specific brain-derived pattern, or a sequence of brain locations involved in processing humorous stimuli. Laughter is the trigger of cataplexy in these patients, and the difference between patients and healthy controls during the laughter should therefore be notable. Twenty-six adult patients (14 male, 12 female) suffering from narcolepsy with cataplexy and 10 healthy controls (five male, five female) were examined. The experiment was performed using a 256-channel electroencephalogram and then processed using specialized software built according to the scientific research team's specifications. The software utilizes electroencephalographic data recorded during elevated emotional states in participants to calculate the sequence of brain areas involved in emotion processing using non-linear and linear algorithms. Results show significant differences in activation (pre-laughter) patterns between the patients with narcolepsy and healthy controls, as well as significant similarities within the patients and the controls. Specifically, gyrus orbitalis, rectus and occipitalis inferior are active in healthy controls, while gyrus paracentralis, cingularis and cuneus are activated solely in the patients in response to humorous audio stimulus. There are qualitative electroencephalographic-based patterns clearly discriminating between patients with narcolepsy and healthy controls during laughter processing. IN TROD UCTI ONDespite numerous quality research projects and a recent major update in classification, narcolepsy remains to be an illness with a rather complicated diagnostic process (American Academy of Sleep Medicine, 2014). One of the examinations a patient often goes through is electroencephalography (EEG), which is used to rule out epilepsy or any other brain-related disorder diagnosable by this method. Clinical (qualitative) qEEG results do not discriminate between narcolepsy diagnostic groups; nothing like typical 'narcolepsy type 1 or 2' patterns were ever described or confirmed. There is a study focused on EEG correlates of cataplexy, but not for human subjects (Kushida et al., 1985). Many forms of EEG analysis were used in narcolepsy with cataplexy (NC) research -from clinical, qualitative inspection of the native recording (resting state without stimulation), across frequency mapping up to event-related potentials and even source localization. A group from Vienna published interesting studies in qEEG from patients with narcolepsy, treated by modafinil, and found significant differences in alpha-2, beta-2 and beta-3 bands as well as a slowing of the dominant frequency and the centroids of the alpha, beta and total power spectrum confirming vigilance decrement in narcolepsy (Saletu et al., 2004(Saletu et al., , 2005. The group used equipment with 21 channels for recording, thus...

Narcolepsy and emotional experience: a review of the literature

“…Neurophysiological and neurochemical findings support the hypothesis of the involvement of the limbic system in the physiopathology of cataplexy [e.g., 20, 67, 68, 74, 75], and this could explain the relationship between cataplexy and emotional inputs. Furthermore, behavioral studies suggest an impairment in emotions processing in NC, like a possible coping strategy to avoid or reduce in frequency cataplexy attacks [97, 98, 106] and, consistently, these patients could use these coping strategies even during sleep, avoiding unpleasant MSA through lucid dreaming [138, 140]. Moreover, about dreaming in NC, we have pointed out that these patients report peculiar dream contents, characterized by more vivid, bizarre and frightening contents than those of healthy subjects [113, 131, 134, 135, 141].…”

“…Other studies investigated the humor stimuli processing in NC, considering that the most frequent emotional trigger for the cataplexy seems to be the laughter [e.g., 8, 9]. For example, Susta et al [106] used a protocol using audio recordings aimed to trigger laughter in NC patients and controls. They registered cortical brain activity by quantitative electroencephalography (qEEG) source localization to calculate the sequence of brain areas involved in laughter processing.…”

“…Most of these studies clearly showed how reactions to emotional stimuli are different in NC patients compared to controls [87, 97, 98, 106]. Some works found emotional reactions significantly different between NC patients and controls in response to unpleasant situations [97, 111], while others in response to pleasant situations [98, 106]. The heterogeneous results among pleasant and unpleasant stimuli may depend on methodological differences, like a different input use (e.g., visual, audio) or output measure (e.g., muscular, autonomic, cognitive, hemodynamic and behavioral responses, qEEG, H-reflex).…”

“…Considering all these findings [124, 125], the crucial role of emotions in narcolepsy [4, 6–9, 69, 97, 98, 106, 111] and an impairment of the limbic system in these subjects (e.g., [11, 67, 68, 74, 75]), the investigation on emotional experience during MSA for this sleep disorder deserves interest. Narcoleptic patients often report an abundant production of vivid, bizarre and frightening MSA [130].…”

Idiopathic Hypersomnia—A Dynamic Simulation Model

“…The data obtained in the interview were used to construct a dynamic simulation model to answer the question of whether the patient-reported course of the disease can be explained by the dynamics of the other parameters obtained from the structured interview. Our research project used the system dynamics methodology, which uses a system of differential equations to capture the dynamics of the phenomena under study (18,19). System dynamics have been used repeatedly to describe complex systems and model sleep.…”