## 5 Discussion  
The mechanisms of burnout are still poorly understood, especially in neuroimaging studies. The relationship between its neuronal substrate components and cognitive performance may be more complex than previously thought [45]. Results from neuroimaging studies indicate that the brain structures of patients with burnout that are related to emotion, motivation, and empathy differ significantly from the same structures in healthy control subjects. These brain structures include the thalamus, hippocampus, amygdala, caudate, striatum, dorsolateral prefrontal cortex (DLPFC), anterior cingulate cortex (ACC), posterior cingulate cortex (PCC), anterior cerebral hemisphere (AI), inferior frontal gyrus (IFG), middle frontal gyrus (MFG), temporoporarietal junction (TPJ), and grey matter (GM). The ACC is also known to show alterations on PET imaging in burnout patients [10], as are the insular cortex and hippocampus. According to two recent cross-sectional meta-analyses, both AI and ACC are involved in empathy [43,44]. Several behavioral studies indicate a strong association between job burnout and empathy [46, 47, 48, 49, 50, 51, 52]. Interestingly, there are two conflicting theories regarding job burnout and empathy:  
* the conventional compass fatigue theory which maintains that occupational burnout is associated with excessive empathy [53];
* which maintains that occupational burnout is associated with reduced emotional regulation, which causes a disconnect between felt and expressed emotions [54]. Preliminary studies have shown that a model of empathy is emerging in which connections between mirror neurons and other brain structures may facilitate the observed components of empathy [55,56]. Thus, on the basis of the results of the aforementioned studies, it can be postulated that there is a direct link between empathy and mirror neurons, as lack of empathy is one of the sub-elements of burnout syndrome. Further research should be conducted to verify this hypothesis, with the ultimate goal being the development of a biomarker to diagnose occupational burnout. Figure 3: Computational fuzzy-based model of the HPA axis (own concept). Brain structures such as the amygdala, hippocampus, caudate, and putamen are different in burnout individuals due to the nature of the neurophysiological functions of these structures. The amygdala and hippocampus are part of the limbic system, which plays an important role in memory, emotion, emotional learning and behavior, motivation, and reward. A theory can be formulated about burnout syndrome in relation to the limbic system and its structures: it has a direct impact on all three main dimensions of burnout syndrome: emotional exhaustion, depersonalization, and lack of personal achievement. The striatum functions as an input nucleus to the basal ganglia--its main function is to receive excitatory input from cortical and subcortical structures. Input to the striatum allows the basal ganglia to integrate information from different cortical and subcortical areas and allows the basal ganglia to initiate our body movements and, also importantly, the motor expression of our emotions [57]. This provides a basis for further research in this area in the search for information on the correlation between the caudate ganglion, putamen, and occupational burnout. EEG studies in patients with burnout have found reduced P300 amplitude, lower peak alpha frequency, and reduced beta power [1], with power being mainly associated with burnout, but with gender being a significant predictor [17]. Neuronal generators of P300 are mainly cortical (medial temporal area, superior temporal area, and inferior parietal area), but can be located in the hippocampus and amygdala [58]. As the hippocampus is part of the limbic system, it plays a role in visceral and endocrine functioning, as well as in the expression of emotions and emotional behavior [57].