Breathlessness-related Brain Activation: Electroencephalogram Dipole Modeling Analysis

Dyspnea is the feeling of shortness of breath and is a primary symptom of cardiopulmonary disease. Dyspneic symptoms include sensations such as labored respiration, chest tightness, air hunger, and uncomfortable or unpleasant urges to breathe. In this study, we investigated the brain areas associated with dyspnea using electroencephalogram dipole (EEG/DT) modeling. We hypothesize that good temporal resolution of EEG/DT recordings will enable determination of the neuroanatomical substrates of dyspnea in time course measures of inspiration. We measured EEG and respiration simultaneously during CO2 rebreathing, which induced dyspnea in the subjects and allowed us to find inspiration-related potentials during dyspnea. The waveform of the potentials was composed of a negative peak at 100ms and a positive peak at 250ms. Our EEG/DT modeling estimated their source generators in the left superior frontal and left orbitofrontal cortex (OFC) at 100ms after inspiration onset. In the next 100ms, the anterior cingulate cortex was activated, followed by the superior frontal and OFC. At 200ms to 300ms, dipoles finally converged in the left insula and amygdala. The first component of inspiration-related potentials thus involved frontal areas that play a role in the intention to inspire and emotional guidance, while the late component incorporated areas related to emotional reaction. We suggest that dyspnea with increasing ventilation could involve intentions or efforts to continue inspiration activities, and consequently, the perception of dyspnea could be associated with unpleasant emotions

Amygdala Response During Anticipatory Anxiety in Patients with Tension-type Headache

Tension-type headache (TTH) is the most prevalent primary headache disorder, affecting 0.5%〜4.8% of the population worldwide. Psychological factors play an important role in the pathogenesis of TTH. For instance, depression and anxiety are thought to enhance central sensitization, and thus increase the frequency of headaches. In this study, we used the Minnesota Multiphasic Personality Inventory (MMPI) and measures of anxiety to analyze personality traits associated with TTH. Specifically, we were interested in the relationship between these variables, respiratory responses, and brain activity. Our results showed that individuals with TTH had significantly higher state anxiety scores compared with healthy controls. In addition, individuals with TTH showed a greater increase in RR during a stressful task involving anticipation of an electrical stimulation. During anticipatory anxiety, there was bilateral amygdala (AMG) activation in TTH patients, while only the right AMG was activated in healthy controls. Interestingly, patients in the TTH group with high levels of state anxiety and high scores on schizophrenia scales had the following MMPI personality traits: peculiar perception, poor familial relationship, difficulties concentrating, and lack of deep interest. We suggest that the psychological factors associated with the above-mentioned brain activation might induce peripheral muscle pressure, which then triggers headaches