Network asymmetry of motor areas revealed by resting-state functional magnetic resonance imaging.

There are ample functional magnetic resonance imaging (fMRI) studies on functional brain asymmetries, and the asymmetry of cerebral network in the resting state may be crucial to brain function organization. In this paper, a unified schema of voxel-wise functional connectivity and asymmetry analysis was presented and the network asymmetry of motor areas was studied. Twelve healthy male subjects with mean age 29.8 ± 6.4 were studied. Functional network in the resting state was described by using functional connectivity magnetic resonance imaging (fcMRI) analysis. Motor areas were selected as regions of interest (ROIs). Network asymmetry, including intra- and inter-network asymmetries, was formulated and analyzed. The intra-network asymmetry was defined as the difference between the left and right part of a particular functional network. The inter-network asymmetry was defined as the difference between the networks for a specific ROI in the left hemisphere and its homotopic ROI in the right hemisphere. Primary motor area (M1), primary sensory area (S1) and premotor area (PMA) exhibited higher functional correlation with the right parietal-temporal-occipital circuit and the middle frontal gyrus than they did with the left hemisphere. Right S1 and right PMA exhibited higher functional correlation with the ipsilateral precentral and supramarginal areas. There exist the large-scale hierarchical network asymmetries of the motor areas in the resting state. These asymmetries imply the right hemisphere dominance for predictive motor coding based on spatial attention and higher sensory processing load for the motor performance of non-dominant hemisphere.

Enhancement of axonal regeneration of retinal ganglion cells in adult rats by etomidate: involvement of protein kinase C.

PURPOSE: To investigate the effect of etomidate (ET) on axonal regeneration of retinal ganglion cells (RGCs) in adult rats. METHODS: The optic nerve was transected intraorbitally at 1 mm from the optic disc, and an autologous peripheral nerve was transplanted onto the ocular ON stump in adult rats. Then the animals were treated with ET, Gö6976, ET combined with Gö6976, phorbol-12-myristate-13-acetate (PMA), or ET combined with PMA. Four weeks after grafting, the number of regenerating RGCs labeled retrogradely with neuronal retrograde tracer was counted in all animals, and the activity of membrane protein kinase C (mPKC) and cytoplasmic PKC (cPKC) was measured in ET-treated animals. RESULTS: The number of regenerating RGCs significantly increased when the dose of ET was increased from 2 mg/kg to 6 mg/kg, whereas the ratio of mPKC activity to cPKC activity significantly decreased in ET-treated animals. Gö6976, a potent conventional PKC inhibitor, also significantly increased the number of regenerating RGCs. However, the number of regenerating RGCs in animals treated with Gö6976 alone was significantly lower than in those treated with ET at 6 mg/kg. Combined treatment with ET at 6 mg/kg and Gö6976 did not increase the number of regenerating RGCs. In contrast, PMA, a potent PKC activator, partially abolished the positive effect of ET on the axonal regeneration of axotomized RGCs. CONCLUSIONS: These results suggest that ET promotes axonal regeneration of RGCs in adult rats, in part by inhibiting conventional PKC.

[Effect of renal artery embolization using 2-poly-hydroxyethyl-methacrylate as a liquid embolic agent: a study in rabbits].

OBJECTIVE: To assess the effect of a liquid embolic agent 2-poly-hydroxyethyl -methacrylate (2-P-HEMA) for renal artery embolization in rabbits. METHODS: The precipitation time of different concentrations (2%, 3.5%, 5%, 6.5%, 8% and 9.5%) of 2-P-HEMA dissolved in different solutions (ethanol, ethanol/iobitridol, and ethanol/Bi2O3) were determined in flowing water. The mixtures of 2-P-HEMA (2%, 5%, and 8%) with ethanol/ Bi2O3 were injected into the renal arteries of the rabbits, and the artery-embolizing effects were assessed using angiography at 2 and 12 weeks after the injection, with also macroscopic and microscopic examination of the embolized kidneys. RESULTS: The mixtures of 2-P-HEMA and ethanol formed flocculent precipitation a few seconds after injection into flowing water, and the precipitation time showed no significant variations with the concentration of 2-P-HEMA in the mixture. Low and moderate concentrations of 2-P-HEMA could pass through the microcatheter smoothly with little injection resistance, and resulted in complete occlusion of the renal arteries without adhesion to the microcatheter. Angiography at 2 and 12 weeks detected no recanalization of the occluded renal arteries. Macroscopically, the lumen of the renal arteries was found to be occluded by the embolic agents, and deep penetration of the embolic agents into the glomerular arteries was observed microscopically. The mixture containing high-concentration 2-P-HEMA was difficult to deliver through the microcatheter due to high injection resistance. CONCLUSION: 2-P-HEMA can be rapidly precipitated after injection into flowing water, and allows complete embolization of the renal arteries of rabbits at proper concentrations, suggesting its great potential as an endovascular liquid embolic agent.

[Anatomy of the sphenoidal sinus in transsphenoidal approach through a single nostril].

OBJECTIVE: To study the anatomy of the sphenoid sinus for safe pituitary adenoma resection via transsphenoidal approach through a single nostril. METHODS: Eight fresh adult cadavers and the magnetic resonance images (MRI) of the sphenoidal sinus of 5 adults were observed. In anteroposterior axes, the root of the nasal columella was defined as the point O, the inferior border of the sphenoidal sinus anterior wall as point B, the superior border of the spheniodal sinus anterior wall as point C, and the midpoint of the sellar floor as point D. Line OA ran through the point O in parallel with the maxillary alveolar process. Angle AOB', angle AOC' and angle AOD' were the supplementary angles of angle AOB, angle AOC and angle AOD respectively, and angle AOB', angle AOC', angle AOD', OB, and BC were measured. RESULTS: In the 8 fresh adult cadavers, angle AOB', angle AOC', angle AOD', OB, and BC were (43.2+/-4.3) degrees, (22.9+/-3.0) degrees, (35.4+/-4.1) degrees, 66.3+/-3.6 mm, and 20.9+/-1.5 mm, respectively, with 2 cases having ethmoid cell superior to the sphenoid bone; in the MRI of 50 adults, the measurements were (44.1+/-5.5) degrees, (25.7+/-6.4) degrees, (34.2+/-5.9) degrees, 68.7+/-4.9 mm, and 23.3+/-3.1 mm, respectively, with 15 cases having ethmoid cell superior to the sphenoid bone. Two independent-sample t test and Chi-square test revealed no significant differences in the measurements between the two groups (P>0.05). CONCLUSION: Preoperative MRI facilitates safe opening of the anterior wall of the spheniodal sinus and the sellar floor, and the best angle between the axis of the speculum and line OA was 39 degree.

[Neuronavigation-assisted microanatomical study of the facial nerve canal through the transpetrosal approach].

OBJECTIVE: To study the value of neuronavigation in the transpetroal approach, and to provide anatomic data for the protection of the nerves in the facial nerve canal (FNC) during surgeries. METHODS: Simulated surgery through the transpetroal approach was performed on 16 sides of 8 adult cadaver heads with the assistance by neuronavigation. The anatomy of the facial nerve and the relationship of related structures were observed and the distances from the utmost external edge of the mastoid to different segments of the FNC were measured. RESULTS: Neuronavigation was successful with all the FNC, with the mean error of less than 0.9 mm. The FNC could be divided into 3 segments, the labyrinthine, the tympanic and the mastoid segments, stretching 3.6+/-1.2 mm, 11.2+/-2.5 mm and 16.1+/-3.6 mm respectively and with diameters of 1.2+/-0.3 mm, 1.4+/-0.1 mm and 1.7+/-0.2 mm, respectively. CONCLUSION: Neuronavigation may help protect the FNC during surgical procedures, and a thorough knowledge of the anatomic features of the FNC can be significant for preservation of the facial nerves.

Early diagnosis of cerebral infarction with near-infrared spectroscopy: an experimental study.

OBJECTIVE: To monitor the changes in the blood flow and blood-oxygen content in rat cerebral tissue with focal cerebral infarction using near-infrared spectroscopy (NIRS), so as to verify the value of NIRS in early diagnosis of cerebral infarction. METHODS: Focal cerebral infarction models were established in 16 rats by injecting silk threads into the internal carotid artery. The bilateral blood flow and blood-oxygen content were monitored with NIRS in the models and also in 16 normal rats receiving saline injection to serve as blank control group. RESULTS: Focal cerebral infarction in rats caused the decrement in blood-oxygen content and the increase in blood flow. No changes were observed in the control group after saline injection (P >0.05). CONCLUSION: In the earlier stages of focal cerebral infarction, blood-oxygen decreases while blood flow increases in the infarcted area. NIRS provides real-time, non-invasive monitoring of blood volume and blood-oxygen content in the cerebral tissue.

Microanatomical and neuroendoscopic studies of the internal auditory meatus and its surrounding structures.

OBJECTIVE: To observe the morphology of the internal auditory meatus in relation with its surrounding structures in Chinese people, for the purpose of providing microanatomical reference for surgeries adopting retro-sigmoid approach. METHODS: The retro-sigmoid surgical approach was simulated on 5 fresh specimens of human head, in which the internal auditory meatus and its surrounding structures were observed through a neuroendoscope and a surgical microscope. The distances from the posterior inferior edge of the internal auditory meatus to the central point of the posterior edge of the sigmoid sinus and to the posterior edge of the posterior semicircular canal were measured. RESULTS: The internal auditory meatus was located at the center of the medial surface of the petrous bone, and the cranial nerve VII ran through its anterior-superior part while the cranial nerve VIII through its posterior-inferior part. After forming an arterial loop at the internal auditory meatus, the anterior-inferior cerebellar artery branched into 1 to 3 internal auditory arteries. The distance from the posterior-inferior edge of the internal auditory meatus to the central point of the posterior edge of the sigmoid sinus was 32.15+/-1.76 mm on the left side, and 33.34+/-1.57 mm on the right, and the distance to the posterior edge of the posterior semicircular canal was 12.51+/-2.15 mm on the left side, and 13.26+/-2.44 mm on the right. CONCLUSION: Thorough knowledge of the microanatomy of the internal auditory meatus and its surrounding structures is of crucial importance to preserve the functions of the cranial nerves VII and VIII in the surgical removal of acoustic neuroma.