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.

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.

Objective - to investigate the neurophysiological basis of secondary generalization of partial epileptic seizures. Patients and methods - inter-ictal, resting-state EEG functional connectivity (EEGfC) was evaluated and compared: patients with exclusively simple partial seizures (sp group) were compared to patients with simple partial and secondary generalized seizures (spsg group); patients with exclusively complex partial seizures (cp group) were compared to patients with cp and secondary generalized seizures (cpsg group); the collapsed sp+cp group (spcp) was compared to those who had exclusively secondary generalized seizures (sg group). EEGfC was computed from 21-channel waking EEG. 3 minutes of waking EEG background activity was analyzed by the LORETA Source Correlation (LSC) software. Current source density time series were computed for 23 pre-defined cortical regions (ROI) in each hemisphere, for the 1-25 Hz very narrow bands (1 Hz bandwidth). Thereafter Pearson correlation coefficients were calculated between all pairs of ROI time series in the same hemisphere. Z-scored correlation coefficients were compared at the group level (t-tests and correction for multiple comparisons by local false discovery rate, FDR). Results - Statistically significant (corrected p<0.05) EEGfC differences emerged at specific frequencies (spsg > sg; cpsg > cp), and at many frequencies (sg > spcp). The findings indicated increased coupling between motor cortices and several non-motor areas in patients with partial and sg seizures as compared to patients with partial seizures and no sg seizures. Further findings suggested increased coupling between medial parietal-occipital areas (structural core of the cortex) and lateral hemispheric areas. Conclusion - increased inter-ictal EEGfC is associated with habitual occurrence of secondary generalized seizures.

[There have been attempts to treat obesity with medicines for nearly 100 years, since the discovery of ephedrine. For decades amphetamine derivates and agents stimulating or inhibiting the release of noradrenaline and dopamine have been applied. However, most of theses drugs had to be gradually withdrawn, due to their adverse effects on the cardiovascular and central nervous system or their sympaticotonic effect. Dexfenfluramine (Isolipan), which was introduced in the 90s, did not have such side effects, but it turned out to potentially cause valvular heart disease. Finally, sibutramin (Reductil) was introduced, which again had to be withdrawn in 2010 due to its hypertensive and cardiovascular side effects. After all, we were left without any appetite-suppressant drugs. Orlistat therapy, (Xenical 120 mg, alli 60 mg - OTC), which inhibits the absorption of fat, can eliminate only 30% of the consumed food’s fat content, at the price of gastrointestinal side effects. The latest result of research carried out wordwide is that in 2012 the FDA approved commercial distribution of the selective 5HT2/c serotonin agonist lorcaserin (Belviq), which enhances satiety, in the USA. Unfortunately, in 2013 the EMEA temporarily postponed the lauch of this drug, until certain adverse effects are excluded. For diabetic patients, the GLP-1 agonist exenatid and the GLP-analog liraglutid, which can also reduce body weight, are available in the form of injections.]

[Insulin aspart (B28 Asp-insulin), which is produced by recombinant DNA technology, is a fast-acting insulin analogue. Due to the aspartate for proline substitution at position 28 of the Bchain, the insulin molecule's tendency for selfassociation is diminished, therefore, insulin aspart rapidly dissociates into dimeric and monomeric forms and absorbs quickly and easily after subcutaneous administration. Compared to human regular insulin, insulin aspart has a faster onset of activity, a higher plasma peak and a shorter duration of action. Overall, the pharmacokinetic profile of insulin aspart better mimics the physiological postprandial insulin secretion. Therefore, insulin aspart can be used for prandial insulin substitution in order to decrease postprandial blood glucose excursion. It should be administered immediately before meals, but some observations suggest that it can also be used after finishing meal. This allows a more flexible lifestyle for patients. Insulin aspart can be used in both type 1 and type 2 diabetes. Compared to regular human insulin, a moderate decrease in the HbA1c values and fewer nocturnal hypoglycaemic events are expected from insulin aspart use. Insulin aspart is appropriate for pump treatment as well. It has recently been approved for use in pregnancy, whereas for children and adolescents the expected benefits should be weighed against the more modest clinical experience available. Similarly to other insulin analogues, results of long-term clinical investigations with insulin aspart with regard to the development of complications are not yet available.]