Yusuf Ozgur Cakmak

The pathways connecting the hippocampal formation, the thalamic reuniens nucleus and the thalamic reticular nucleus in the rat

Most dorsal thalamic nuclei send axons to specific areas of the neocortex and to specific sectors of the thalamic reticular nucleus; the neocortex then sends reciprocal connections back to the same thalamic nucleus, directly as well indirectly through a relay in the thalamic reticular nucleus. This can be regarded as a ‘canonical’ circuit of the sensory thalamus. For the pathways that link the thalamus and the hippocampal formation, only a few comparable connections have been described. The reuniens nucleus of the thalamus sends some of its major cortical efferents to the hippocampal formation. The present study shows that cells of the hippocampal formation as well as cells in the reuniens nucleus are retrogradely labelled following injections of horseradish peroxidase or fluoro‐gold into the rostral part of the thalamic reticular nucleus in the rat. Within the hippocampal formation, labelled neurons were localized in the subiculum, predominantly on the ipsilateral side, with fewer neurons labelled contralaterally. Labelled neurons were seen in the hippocampal formation and nucleus reuniens only after injections made in the rostral thalamic reticular nucleus (1.6–1.8 mm caudal to bregma). In addition, the present study confirmed the presence of afferent connections to the rostral thalamic reticular nucleus from cortical (cingulate, orbital and infralimbic, retrosplenial and frontal), midline thalamic (paraventricular, anteromedial, centromedial and mediodorsal thalamic nuclei) and brainstem structures (substantia nigra pars reticularis, ventral tegmental area, periaqueductal grey, superior vestibular and pontine reticular nuclei). These results demonstrate a potential for the thalamo‐hippocampal circuitry to influence the functional roles of the thalamic reticular nucleus, and show that thalamo‐hippocampal connections resemble the circuitry that links the sensory thalamus and neocortex.

GABAA receptor mediated transmission in the thalamic reticular nucleus of rats with genetic absence epilepsy shows regional differences: Functional implications

The aim of the present study was to investigate the effect of local injections of the GABA(A) receptor antagonist, bicuculline, into the rostral and caudal parts of the thalamic reticular nucleus (TRN), on the generation of spike-and-wave discharges in Genetic Absence Epilepsy Rats from Strasbourg (GAERS). Spike-and-wave discharges are important in the pathophysiology of absence epilepsy and generated by the cortico-thalamo-cortical pathway, where GABA has a significant role, particularly in the TRN. Artificial cerebrospinal fluid or bicuculline was administered to rostral or caudal parts of TRN of GAERS through a stereotaxically placed guide cannula. Administration of bicuculline produced opposite effects according to the injection site. Administration into the caudal TRN produced statistically significant increases in the duration of spike-and-wave discharges, whereas injections into the rostral TRN produced significant decreases. Correspondingly, distinct patterns of afferent connections have been demonstrated with the wheat-germ-agglutinin horseradish peroxidase (WGA-HRP) retrograde tracing method in control non-epileptic rats and GAERS for the rostral and caudal parts of the TRN. Injection of WGA-HRP tracer showed no detectable difference regarding the rostral and caudal connections between GAERS and Wistar animals. Rostral parts of TRN have thalamic and cortical connections that are primarily motor and limbic whereas for the caudal parts these connections are primarily sensory. Further, the rostral parts receive inputs from the substantia nigra pars reticularis and the ventral pallidum that the caudal part lacks. The extent to which these connectional differences may be responsible for the functional differences demonstrated by the bicucculine injections remains to be explored.

The high 2D:4D finger length ratio effects on atherosclerotic plaque development.

BACKGROUND The index finger to ring finger length ratio (2D:4D) of the right hand are affected by prenatal testosterone levels in male. To date, it has been determined that the high 2D:4D ratio is related to the myocardial infarction, however no research has revealed the relationship between the high 2D:4D ratio whose coronary artery shows atherosclerotic plaque development. OBJECTIVE The aim of this study was to display the relationship between the 2D:4D ratio and atherosclerosis formation in male autopsy cases. METHODS We designed a study in 100 heterosexual male autopsies whose mean age was 21.4+/-2.47 (range between 17 and 25). The 2nd and 4th digits were measured on the palmar surface of the right hand and taken the right coronary artery to show the atherosclerotic plaque development. RESULTS AND CONCLUSION Grade 3 group had significantly higher 2D:4D ratio compared to Grade 1 and Grade 2 groups (p=0.02 for both).

Connections of the zona incerta to the reticular nucleus of the thalamus in the rat

This study demonstrated that there is a pathway from the zona incerta to the thalamic reticular nucleus. Injections of horseradish peroxidase or Fluorogold were made, using stereotaxic coordinates, into the rostral, intermediate or caudal regions of the thalamic reticular nucleus of adult Sprague–Dawley rats. The results show that the different regions of the thalamic reticular nucleus have distinct patterns of connections with the sectors of the zona incerta. In terms of the relative strength of the connections, injections made into the rostral regions of the thalamic reticular nucleus showed the highest number of labelled cells within the rostral and ventral sectors of the zona incerta; injections made into the intermediate regions of the thalamic reticular nucleus showed labelled cells in the dorsal and ventral sectors; while injections to the caudal regions of the thalamic reticular nucleus showed only a few labelled cells in the caudal sector of the zona incerta. Previous studies have shown that the zona incerta projects to the higher order thalamic nuclei but not first order thalamic nuclei. The labelling observed in the present study may represent collaterals of zona incerta to higher order thalamic nuclei projections.

A review of the potential effect of electroacupuncture and moxibustion on cell repair and survival: the role of heat shock proteins

In recent years, a considerable amount of research has been focused on the underlying mechanisms of electroacupuncture and moxibustion assisted tissue repair. Intracellular protein denaturation is a significant pathological step of acute conditions such as stroke, myocardial infarction and acute pancreatitis. Protein aggregation can be observed after the protein denaturation step in chronic diseases of the central nervous system like Alzheimers and Parkinsons disease, and also in other chronic system diseases including cataract formation. Heat shock proteins (HSPs) are fundamental for intracellular protein repair and work by preventing protein aggregation and assisting denaturated proteins to refold. Further, HSPs can also function for extracellular cell signalling. The focus of this review is to analyse the data studying electroacupuncture and moxibustion induced HSPs, and how acupuncture can survive cells from apoptosis under stress.

A Reminder of the Anatomy of the Recurrent Artery of Heubner

Previous accounts of the recurrent artery of Heubner show serious inconsistencies concerning the origins, dimensions and numbers of the artery. In the present study, based on 54 (38 male, 16 female) human autopsy brains the common type of the recurrent artery of Heubner was present bilaterally in 46 cases (85.2%), while in 6 (11.1%) cases it was present only on one side (4 on the right, 2 on the left). Unilateral vessels were seen only in the male autopsy brains. The recurrent artery of Heubner could not be identified in 2 brains (3.7%). Multiple Heubner arteries were not observed in the present study. No gender differences were observed regarding the origin and dimensions of the recurrent artery of Heubner. 76 recurrent arteries of Heubner arising from the junction of the anterior cerebral artery (ACA) and anterior communicating artery (ACoA) (79.2%) had a mean diameter of 0.66+/-0.11 mm. In 14 arteries the artery derived from the A2 segment of the ACA (14.6%) and the mean diameter was 0.66+/-0.17 mm; in 6 arteries it originated from the A1 segment of the ACA (6.2%) and the mean diameter was 0.47+/-0.15 mm. The average diameter was calculated as 0.67+/-0.12 mm and ranged between 0.40 and 0.90 mm, irrespective of sex or side. A detailed anatomical knowledge of the recurrent artery of Heubner is important when considering vascular surgery in this area.

Improving testicular blood flow with electroacupuncture-like percutaneous nerve stimulation in an experimental rat model of testicular torsion.

The purpose of this study was to determine the blood‐flow‐enhancing effect of electroacupuncture (EA) in an experimental rat model of testicular torsion.

Provotella‐derived hydrogen sulfide, constipation, and neuroprotection in Parkinson's disease

A recent article by Scheperjans et al. reported that the gut microbiome is altered in Parkinson’s disease (PD) patients. In their detailed analysis, Provotella was found to be decreased in PD patients. The researchers explained that the negative effect of a reduced Provotella population on PD is owing to decreased levels of health-promoting neuroactive short-chain fatty acids and vitamins, such as thiamine and folate, which are synthesized with the aid of Provotella. However, the researchers failed to note a much stronger link between Provotella and the protection of dopaminergic neurons in PD: hydrogen sulfide. Hydrogen sulfide is a gaseous gut neurotransmitter that is secreted by Provotella and that exerts a protective effect on dopaminergic neurons in rat PD models. In the case of a reduced Provotella population, both the increase in gut permeability and constipation symptoms of PD can be explained by altered hydrogen sulfide levels. In the case of a reduced Provotella population in PD patients, it can be assumed that hydrogen sulfide levels are decreased and that the human body may lose the ability to initiate neuroprotective mechanisms in response to hydrogen sulfide. As the researchers stated, it has been shown that the Provotella abundance is positively associated with gut permeability. Moreover, the researchers reported that increased gut permeability may lead to local and systemic exposure to bacterial endotoxins. Considering that hydrogen sulfide is a gaseous neurotransmitter that exerts protective effects on dopaminergic neurons, it may be theorized that the human body increases gut permeability to enhance the benefits of a decreased level of gut hydrogen sulfide under the conditions of a reduced Provotella population. Additionally, in PD patients, constipation is one of the first signs of disease. Constipation may represent a conjoint mechanism underlying the increase in gut permeability to increase hydrogen sulfide absorption. In conclusion, considering the decreased levels of hydrogen sulfide in the PD patient gut in combination with the data showing increased gut permeability and constipation in PD patients and the neuroprotective effects of hydrogen sulfide on dopaminergic neurons in rat PD models, hydrogen sulfide may act as a sole or contributing factor with vitamins and short-chain fatty acids to mediate the mechanisms underlying the link between the reduction in the Provotella population and PD.

Decreasing bleeding due to uterine fibroid with electroacupuncture

OBJECTIVE To report the usefulness of electroacupuncture (EA) for the management of menorrhagia due to submucous uterine fibroid. DESIGN Case report. SETTING University hospital. PATIENT(S) A 48-year-old woman with a symptomatic submucous uterine fibroid, who presented with severe menorrhagia. INTERVENTION(S) Electroacupuncture. MAIN OUTCOME MEASURE(S) Doppler ultrasonographic assessment of uterine blood flow and number of pads used during menorrhagia. RESULT(S) Doppler ultrasound revealed decreased blood flow of the uterine artery with EA stimulation. With repetitive sessions of EA fewer pads were used during menorrhagia. CONCLUSION(S) We present the first human case in which decreasing uterine artery blood flow with EA improved menorrhagia due to uterine fibroma. Electroacupuncture could be a useful, alternative, and relatively noninvasive tool for the management of fibroids with menorrhagia as a severe complaint.

Inhibition of Pre-Supplementary Motor Area by Continuous Theta Burst Stimulation Leads to More Cautious Decision-making and More Efficient Sensory Evidence Integration.

Decisions are made based on the integration of available evidence. The noise in evidence accumulation leads to a particular speed–accuracy tradeoff in decision-making, which can be modulated and optimized by adaptive decision threshold setting. Given the effect of pre-SMA activity on striatal excitability, we hypothesized that the inhibition of pre-SMA would lead to higher decision thresholds and an increased accuracy bias. We used offline continuous theta burst stimulation to assess the effect of transient inhibition of the right pre-SMA on the decision processes in a free-response two-alternative forced-choice task within the drift diffusion model framework. Participants became more cautious and set higher decision thresholds following right pre-SMA inhibition compared with inhibition of the control site (vertex). Increased decision thresholds were accompanied by an accuracy bias with no effects on post-error choice behavior. Participants also exhibited higher drift rates as a result of pre-SMA inhibition compared with the vertex inhibition. These results, in line with the striatal theory of speed–accuracy tradeoff, provide evidence for the functional role of pre-SMA activity in decision threshold modulation. Our results also suggest that pre-SMA might be a part of the brain network associated with the sensory evidence integration.