Over the second half of the 19th century, numerous theories arose concerning mechanisms involved in understanding of action, imitative learning, language development and theory of mind. These explorations gained new momentum with the discovery of the so called “mirror neurons”. Rizzolatti’s work inspired large groups of scientists seeking explanation in a new and hitherto unexplored area of how we perceive and understand the actions and intentions of others, how we learn through imitation to help our own survival, and what mechanisms have helped us to develop a unique human trait, language. Numerous studies have addressed these questions over the years, gathering information about mirror neurons themselves, their subtypes, the different brain areas involved in the mirror neuron system, their role in the above mentioned mechanisms, and the varying consequences of their dysfunction in human life. In this short review, we summarize the most important theories and discoveries that argue for the existence of the mirror neuron system, and its essential function in normal human life or some pathological conditions.

Interest in the hippocampal formation and its role in navigation and memory arose in the second part of the 20th century, at least in part due to the curious case of Henry G. Molaison, who underwent brain surgery for intractable epilepsy. The temporal association observed between the removal of his entorhinal cortex along with a significant part of hippocampus and the developing severe memory deficit inspired scientists to focus on these regions. The subsequent discovery of the so-called place cells in the hippocampus launched the description of many other functional cell types and neuronal networks throughout the Papez-circuit that has a key role in memory processes and spatial information coding (speed, head direction, border, grid, object-vector etc). Each of these cell types has its own unique characteristics, and together they form the so-called “Brain GPS”. The aim of this short survey is to highlight for practicing neurologists the types of cells and neuronal networks that represent the anatomical substrates and physiological correlates of pathological entities affecting the limbic system, especially in the temporal lobe. For that purpose, we survey early discoveries along with the most relevant neuroscience observations from the recent literature. By this brief survey, we highlight main cell types in the hippocampal formation, and describe their roles in spatial navigation and memory processes. In recent decades, an array of new and functionally unique neuron types has been recognized in the hippocampal formation, but likely more remain to be discovered. For a better understanding of the heterogeneous presentations of neurological disorders affecting this anatomical region, insights into the constantly evolving neuroscience behind may be helpful. The public health consequences of diseases that affect memory and spatial navigation are high, and grow as the population ages, prompting scientist to focus on further exploring this brain region.

[Nowadays, the focus of genetic, neurobiological, neuropsychological and psychosocial research is on a more accurate discovery of the etiology of mental illnesses, especially with regard to the role and complex interactions of certain risk factors. It is increasingly challenging to interpret the results of different aspects and methodologies in a coherent theoretical framework, as this can only lead to a more accurate understanding of the complexity and mechanism of the psychiatric disorders. The main aim of this paper to overview recent studies on etiological background of mental disorders and to present the most important aspects of the Research Domain Criteria (RDoC) system. Review of reports from comprehensive studies published in the most important psychiatric journals over the past five years summarizing new findings on the etio­logy of mental disorders. Although current classifications indicate that mental disorders are strictly distinct diagnostic categories, new findings suggest that these marked differences in symptomatic, genetic, and neurobiological backgrounds are not detectable, as many mental disorders have been identified as having common molecular genetic risk factors, which may indicate common neurobiological pathomechanisms. Research results support the need for a rethinking of psychiatric nosology on an etiological basis and represent an important step forward in the more accurate exploration of the neurobiological background factors of mental disorders and thus in the development of more targeted therapeutic approaches. The development of the RDoC system can be a great help in this, as this dimensional approach offers the possibility of integrating the - often diffuse or even contradictory - neuroscientific research findings into a unified theoretical framework for the etiology, nosology and treatment of mental disorders. ]

The relationship among obstructive sleep apnea syndrome (OSAS), type 2 diabetes mellitus (DM2) and obesity is very complex and multi-directional. Obesity and increased visceral fat are important perpetuating factors for DM2 in patients with OSAS. On the other hand, OSAS itself leads to obesity by causing both leptin and insulin resistance as a consequence of activation of the sympathetic nervous system. Risk for developing DM2 further increases in patients with OSAS and obesity. Data regarding effects of positive airway pressure (PAP) therapy, gold standard treatment for OSAS, on glycemic control were inconsistent due to variability in duration of and adherence to PAP therapy. In our cohort study we investigated effects of PAP treatment on glucose metabolism in normal-weighted non-diabetic OSAS patients, in obese non-diabetic OSAS patients, and in OSAS patients with DM2. We prospectively analyzed 67 patients diagnosed with OSAS and documented to be effectively treated with PAP therapy for three months. Apnea-hypopnea index was highest in the diabetic group, being significantly higher than in the normal-weighted group (p=0.021). Mean HOMA values were significantly higher in obese (p=0.002) and diabetic group (p=0.001) than normal-weighted group; the differences were still significant after PAP therapy. HbA1c levels were significantly higher in diabetic group compared to those in normal-weighted (p=0.012) and obese (p=0.001) groups. After PAP treatment, decrease in HbA1c levels were significant in normal-weighted (p=0.008), obese (p=0.034), and diabetic (p=0.011) groups. There was no correlation with the change in HbA1c levels and age (p=0.212), BMI (p=0.322), AHI (p=0.098) or oxygen levels (p=0.122). Our study showed that treatment of OSAS by PAP therapy offers beneficial effect on glucose metabolism, not only in diabetic patients, but also in obese and normal-weighted OSAS patients. Although data regarding overall effects of PAP therapy on glycemic control present contradictory results in the literature, it should be emphasized that duration and adherence to PAP therapy were main determinants for beneficial outcome of treatment.

[Despite of the symptoms of vertigo have been known since thousands of years, it was evident by the research of the pioneer scientists of the 19th century (Flourens, Ménière, Breuer and others) that dizziness can also be attributed to inner ear disfunctions. The discovery of the vestibulo-ocular reflex was an important milestone (Endre Hőgyes, 1884). The vestibulo-ocular reflex stabilizes images on the retina by rotating the eyes at the same speed but in the opposite direction of head motion. The milestone discovery of Hőgyes by stimulating individual labyrinth receptors and recording the activity of eye muscles were verified by János Szentágothai in 1950. Low-frequency lesions of the angular vestibulo-ocular reflex can be investigated by caloric test (Robert Bárány,1906), high-frequency lesions by head impulse test (Gabor Michael Halmagyi and Ian Stewart Curthoys, 1988).]