Effects of neurofeedback therapy in healthy young subjects.

PURPOSE: Neurofeedback refers to a form of operant conditioning of electrical brain activity, in which desirable brain activity is rewarded and undesirable brain activity is inhibited. The research team aimed to examine the efficacy of neurofeedback therapy on electroencephalogram (EEG) for heart rate, electrocardiogram (ECG) and galvanic skin resistance (GSR) parameters in a healthy young male population. METHODS: Forty healthy young male subjects aged between 18 to 30 years participated in this study. Neurofeedback application of one session was made with bipolar electrodes placed on T3 and T4 (temporal 3 and 4) regions and with reference electrode placed on PF1 (prefrontal 1). Electroencephalogram (EEG), electrocardiogram (ECG) and galvanic skin resistance (GSR) were assessed during Othmer neurofeedback application of one session to regulate slow wave activity for forty minutes thorough the session. Data assessed before neurofeedback application for 5 minutes and during neurofeedback application of 30 minutes and after neurofeedback application for 5 minutes throughout the session of 40 minutes. Means for each 5 minutes, that is to say, a total 8 data points for each subjects over 40 minutes, were assessed. RESULTS: Galvanic skin resistance increased and heart rate decreased after neurofeedback therapy. Beta activity in EEG increased and alfa activity decreased after neurofeedback therapy. CONCLUSIONS: These results suggest that neurofeedback can be used to restore sympathovagal imbalances. Also, it may be accepted as a preventive therapy for psychological and neurological problems.

The effect of autogenous vein grafts on nerve repair with size discrepancy in rats: an electrophysiological and stereological analysis.

Aside from anatomical repairs, the reestablishment of sensory and motor innervations for proper functional recovery is one of the fundamental objectives of reconstructive surgery. The heterotopic transfer of autologous tissues is likely to result in a size discrepancy between the donor and recipient nerves, which will have a negative influence on regeneration. Twenty Wistar albino female rats were used in a study that was divided into two main groups: tibial-peroneal (TP) and peroneal-tibial repair (PT). Both types of nerves were exposed on the hind legs with the nerves cut on the right side, while the proximal stump of the tibial nerve and distal stump of the peroneal nerve were sutured to each other. These groups are also called end-to-end neurorrhaphy groups (EtoE). On the left side, the tibial and peroneal nerves were cut on the same level as on the right side. After the end-to-end epineural suturing of the nerve, the vein graft was slid over to the repair zone under irrigation. These are called the vein graft group (VG). All processes mentioned above were also done for the PT group. On the 90th postoperative day, anesthetized animals were fixed prone on a board, with the nerves carefully dissected for electrophysiological recording. Stereological methods for an estimation of the total number of myelinated fiber, a mean axonal cross-section area and the thickness of the myelin sheet were used. In TP and PT groups, nerve conduction velocities were found to be higher within the VG group. Nevertheless; the difference was only significant in the PT group. In both TP and PT groups, the increase in the axon number, axon area and myelin thickness were statistically different in favor of the vein graft sides. An appearance of vacuoles and degenerated pertinacious material within the myelin sheath of EtoE sides was seen. A histomorphological examination of the sections proximal to, from, and distal to the repair zone over three months revealed less epineural scarring, a thinner epineurium, more regenerated axons and fewer inflammatory cells in groups where vein grafting was used, because the vein graft provided additional mechanical and chemical support in the size discrepancy of the nerve regeneration.

Prenatal exposure to a non-steroidal anti-inflammatory drug or saline solution impairs sciatic nerve morphology: a stereological and histological study.

The toxic effect of non-steroidal anti-inflammatory drugs (NSAIDs) during development has been widely investigated. While it has been shown that these drugs impair central nervous development and compromise the neural activity, the effects of these substances on the development of peripheral nerves are still not clarified. In the present study, sciatic nerves withdrawn from three experimental groups of 4-week-old rats, prenatally exposed to either saline solution, or diclofenac sodium, and controls not exposed to any substance, were evaluated in terms of axon number, cross-sectional area of axon and myelin sheet thickness as well as of the ultrastructure of nerve fibers. Comparisons of stereological estimations among these three groups showed that axon number and mean axon cross-sectional area, but not average myelin sheet thickness, were significantly decreased in rats that were exposed to both diclofenac sodium and also to the saline solution, in comparison of the control group. Electron microscope analysis revealed, in both treated groups, deterioration of myelin sheaths that was more pronounced in rats that were exposed to diclofenac sodium. Altogether, these findings show that the prenatal administration of both diclofenac sodium and saline solution impairs peripheral nervous system development, thus suggesting that this potential teratogenic effect should be also taken into consideration in the clinical use of these substances in pregnant patients.

Protective effects of melatonin and omega-3 on the hippocampus and the cerebellum of adult Wistar albino rats exposed to electromagnetic fields.

The purpose of the study was to investigate the effects of pulsed digital electromagnetic radiation emitted by mobile phones on the central nervous system of the adult Wistar albino rats. The study evaluated structural and functional impacts of four treatment arms: electromagnetic field (EMF) exposed; EMF exposed + melatonin treated group (EMF + Mel); EMF exposed + omega-3 (ω3) treated group (EMF + ω3); and control group (Cont). The 12-weeks-old rats were exposed to 900 MHz EMF for 60 min/day (4:00-5:00 p.m.) for 15 days. Stereological, biochemical and electrophysiological techniques were applied to evaluate protective effects of Mel and ω3. Significant cell loss in the CA1 and CA2 regions of hippocampus were observed in the EMF compared to other groups (p < 0.01). In the CA3 region of the EMF + ω3, a significant cell increase was found compared to other groups (p < 0.01). Granular cell loss was observed in the dentate gyrus of the EMF compared to the Cont (p < 0.01). EMF + ω3 has more granular cells in the cerebellum than the Cont, EMF + Mel (p < 0.01). Significant Purkinje cell loss was found in the cerebellum of EMF group compared to the other (p < 0.01). EMF + Mel and EMF + ω3 showed the same protection compared to the Cont (p > 0.05). The passive avoidance test showed that entrance latency into the dark compartment was significantly shorter in the EMF (p < 0.05). Additionally, EMF had a higher serum enzyme activity than the other groups (p < 0.01). In conclusion, our analyses confirm that EMF may lead to cellular damage in the hippocampus and the cerebellum, and that Mel and ω3 may have neuroprotective effects.

Estimation of numerical density and mean synaptic height in chick hippocampus 24 and 48 hours after passive avoidance training.

The effects of passive avoidance learning on synaptic morphology and number in the dorsolateral hippocampus of chick were investigated at 24 and 48 h after training. Chicks of both sexes were used. The numerical density of synapses and mean synaptic height were determined using design-based quantitative electron microscopic techniques. Our results suggest that after training there is a significant increase in synaptic density in the dorsolateral hippocampus of chicks at both 24 and 48 h, and also that the mean synaptic height was significantly different between trained and control groups. The increase in synaptic density was due to shaft (type II) synapses. It is known that during synaptogenesis, shaft synapses are formed first and are then converted to spine synapses. The only hemispheric asymmetry was found in the 24 h water-trained (W-trained) males where the numerical density of spine synapses was significantly higher in the left hippocampus. No significant differences due to gender in either numerical synaptic density or synapse height were observed at either 24 and 48 h. Comparison of the 24 h with 48 h groups showed an increase in shaft synaptic density over time in the W-trained groups, and an increased density of both shaft and spine synapses with time in methylanthranilate-trained (MeA-trained) chicks. These results demonstrate that the dorsolateral hippocampus of the chick shows synaptic changes at both 24 and 48 h after training and implicates this region in the long-term memory process.

Enhancement of nerve regeneration and orientation across a gap with a nerve graft within a vein conduit graft: a functional, stereological, and electrophysiological study.

In this study, the right sciatic nerves of 40 rats were used to determine whether a nerve graft within a vein graft might accelerate and facilitate axonal regeneration, compared with a nerve graft alone. The animals were separated into four groups, as follows: group 1, sham control; group 2 (control), segmental nerve resection and no repair; group 3, segmental nerve resection and nerve grafting; group 4, segmental nerve resection and reconstruction with a nerve graft within a vein conduit graft. For all groups, sciatic functional indices were calculated before the operation and on postoperative days 7 and 90. On postoperative day 90, the sciatic nerves were reexposed and nerve conduction velocities were recorded. The sciatic nerves were harvested from all groups for counting of the myelinated axons with a stereological method. No statistically significant differences with respect to return of gait function, axon count, or nerve conduction were noted between groups 3 and 4 (p > 0.05). However, functional recovery in group 4 on postoperative day 90 was significant, compared with group 2 (p < 0.05); the recovery difference between groups 2 and 3 was not significant (p > 0.05). This study was not able to demonstrate any functional benefits with the use of a nerve graft within a vein graft, compared with standard nerve grafting.

Examination of age-dependent effects of fetal ethanol exposure on behavior, hippocampal cell counts, and doublecortin immunoreactivity in rats.

Ethanol is known as a potent teratogen having adverse effects on brain and behavior. However, some of the behavioral deficits caused by fetal alcohol exposure and well expressed in juveniles ameliorate with maturation may suggest some kind of functional recovery occurring during postnatal development. The aim of this study was to reexamine age-dependent behavioral impairments in fetal-alcohol rats and to investigate the changes in neurogenesis and gross morphology of the hippocampus during a protracted postnatal period searching for developmental deficits and/or delays that would correlate with behavioral impairments in juveniles and for potential compensatory processes responsible for their amelioration in adults. Ethanol was delivered to the pregnant dams by intragastric intubation throughout 7-21 gestation days at daily dose of 6 g/kg. Isocaloric intubation and intact control groups were included. Locomotor activity, anxiety, and spatial learning tasks were applied to juvenile and young-adult rats from all groups. Unbiased stereological estimates of hippocampal volumes, the total number of pyramidal and granular cells, and double cortin expressing neurons were carried out for postnatal days (PDs) PD1, PD10, PD30, and PD60. Alcohol insult during second trimester equivalent caused significant deficits in the spatial learning in juvenile rats; however, its effect on hippocampal morphology was limited to a marginally lower number of granular cells in dentate gyrus (DG) on PD30. Thus, initial behavioral deficits and the following functional recovery in fetal-alcohol subjects may be due to more subtle plastic changes within the hippocampal formation but also in other structures of the extended hippocampal circuit. Further investigation is required.

Stereological evaluation of volumetric asymmetry in healthy human cerebellum.

OBJECTIVES: Age-related volumetric differences in brain anatomy or volumetric brain analyses in many disorders are of interest. Delineating the normal anatomical cerebellar volume is of importance for both the anatomists and clinicians. In the present study, we aimed to evaluate the cerebellar volume using a stereological technique and to determine the possible volumetric asymmetry depending on age and gender. MATERIALS AND METHODS: Volumetric asymmetry of cerebellar hemispheres was evaluated using stereological method on the magnetic resonance images (MRI) of healthy male and female subjects. Randomly selected individuals (27 males, 27 females) aged between 10-86 years who have normal brain MRI were enclosed in the study. All the subjects were right handed. The individuals were divided into three groups according to age as 18-34 (young), 35-60 (middle aged) and 60-84 (elder) and their MRI images were analyzed. The data set were analyzed by two factor repeated measure analysis. RESULTS: Although the cerebellum was smaller between young and middle aged groups and also middle aged and elder groups, there were no any statistically significant differences between compared groups' mean (P > 0.05). There were not statistically differences according to sex and age groups (P > 0.05). CONCLUSIONS: There was no cerebellar asymmetry between compared groups. The stereological evaluation of cerebellar asymmetry in humans correlate with both gender and age groups is of importance for both clinicians and anatomists. The technique is simple, reliable, unbiased and inexpensive.

Detailed spectral profile analysis of penicillin-induced epileptiform activity in anesthetized rats.

Penicillin model is a widely used experimental model for epilepsy research. In the present study we aimed to portray a detailed spectral analysis of penicillin-induced epileptiform activity in comparison with basal brain activity in anesthetized Wistar rats. Male Wistar rats were anesthetized with i.p. urethane and connected to an electrocorticogram setup. After a short period of basal activity recording, epileptic focus was induced by injecting 400IU/2 microl penicillin-G potassium into the left lateral ventricle while the cortical activity was continuously recorded. Basal activity, latent period and the penicillin-induced epileptiform activity periods were then analyzed using both conventional methods and spectral analysis. Spectral analyses were conducted by dividing the whole spectrum into different frequency bands including delta, theta (slow and fast), alpha-sigma, beta (1 and 2) and gamma (1 and 2) bands. Our results show that the most affected frequency bands were delta, theta, beta-2 and gamma-2 bands during the epileptiform activity and there were marked differences in terms of spectral densities between three investigated episodes (basal activity, latent period and epileptiform activity). Our results may help to analyze novel data obtained using similar experimental models and the simple analysis method described here can be used in similar studies to investigate the basic neuronal mechanism of this or other types of experimental epilepsies.

A calcium channel blocker flunarizine attenuates the neurotoxic effects of iron.

Iron is a metal highly concentrated in liver and brain tissue, and known to induce neuronal hyperactivity and oxidative stress. It has been established that iron levels rise in the brain in some neurodegenerative diseases such as Parkinson's and Alzheimer's diseases (AD). A body of evidence indicates a link between neuronal death and intracellular excessive calcium accumulation. The aim of the present study was to investigate the effects of a calcium antagonist, flunarizine, on neurotoxicity induced by intracerebroventricular (i.c.v.) iron injection. For this reason rats were divided into three groups as control, iron and iron+flunarizine groups. Animals in iron and iron+flunarizine groups received i.c.v. FeCl(3) injection (200 mM, 2.5 microl), while control rats received the same amount of saline into the cerebral ventricles. Rats in iron+flunarizine group also received i.c.v. flunarizine (1 microM, 2 microl) following FeCl(3) injection. All animals were kept alive for ten days following the operation and animals in iron+flunarizine group received intraperitoneal (i.p.) flunarizine injections once a day (10 mg/kg/day) during this period. After ten days, rats were sacrificed. The total numbers of neurons in hippocampus of all rats were estimated with the latest, unbiased stereological techniques. Findings of the present study suggest that flunarizine may attenuate the neurotoxic effects of iron injection by inhibiting the cellular influx of excessive calcium ions.

Hippocampal volume in schizophrenia and its relationship with risperidone treatment: a stereological study.

The purpose of this study was to assess the significance of the hippocampal volume differences and its relation with risperidone treatment in schizophrenia. In schizophrenic patients who were on risperidone treatment (n = 11) and in healthy volunteers (n = 11), volumes of the hippocampi were estimated using magnetic resonance images (MRIs). A detailed systematic series of coronal MRIs of the entire brain (3 mm thickness, T(1)-weighted, TR/TE 400/10 ms) was obtained for each subject. All estimations were done according to Cavalieri's method by a modified point-counting grid placed on surface areas of hippocampal slices. The mean right and left hippocampal volumes in schizophrenics and control subjects were 1059.4 and 1003.2 mm(3), and 1780.1 and 1589.1 mm(3), respectively. The corresponding coefficients of errors were 0.05 and 0.068, and 0.059 and 0.081, respectively. The volumes of left and right hemispheres were not significantly different in both schizophrenic patients and controls (p > 0.05). However, a statistically significant difference (p < 0.05) was found between hippocampal volumes of the schizophrenic patients and controls. In conclusion, the hippocampal volume of the schizophrenic patients is significantly smaller than of the healthy controls. The patients who responded well to risperidone treatment had significantly greater hippocampal volumes than the patients who did not respond properly. Thus, hippocampal volume may be a predictor of the treatment response of schizophrenics to risperidone.