Cerebellar Asymmetry and Cortical Connectivity in Monozygotic Twins with Discordant Handedness

Handedness differentiates patterns of neural asymmetry and interhemispheric connectivity in cortical systems that underpin manual and language functions. Contemporary models of cerebellar function incorporate complex motor behaviour and higher-order cognition, expanding upon earlier, traditional associations between the cerebellum and motor control. Structural MRI defined cerebellar volume asymmetries and correlations with corpus callosum (CC) size were compared in 19 pairs of adult female monozygotic twins strongly discordant for handedness (MZHd). Volume and asymmetry of cerebellar lobules were obtained using automated parcellation.CC area and regional widths were obtained from midsagittal planimetric measurements. Within the cerebellum and CC, neurofunctional distinctions were drawn between motor and higher-order cognitive systems. Relationships amongst regional cerebellar asymmetry and cortical connectivity (as indicated by CC widths) were investigated. Interactions between hemisphere and handedness in the anterior cerebellum were due to a larger right-greater-than-left hemispheric asymmetry in right-handed (RH) compared to left-handed (LH) twins. In LH twins only, anterior cerebellar lobule volumes (IV, V) for motor control were associated with CC size, particularly in callosal regions associated with motor cortex connectivity. Superior posterior cerebellar lobule volumes (VI, Crus I, Crus II, VIIb) showed no correlation with CC size in either handedness group. These novel results reflected distinct patterns of cerebellar-cortical relationships delineated by specific CC regions and an anterior-posterior cerebellar topographical mapping. Hence, anterior cerebellar asymmetry may contribute to the greater degree of bilateral cortical organisation of frontal motor function in LH individuals

The effect of a small dose of ketamine on postoperative analgesia and cytokine changes after laparoscopic cholecystectomy

Background and objectives: In this study we assesed the effect of a small dose of ketamine on the production of TNFα, IL-1β and IL-6 and the postoperative pain in patients undergoing laparoscopic cholecystectomy. Methods: Fifty patients undergoing laparoscopic cholecystectomy were randomized in two equal groups. Patients in the ketamine group after induction in anesthesia received ketamine – 025 mg/kg-1. At the same time patients from the control group received sodium chloride. Postoperatively, the pain was assessed with VAS at periods of 30 min at 1, 2, 4, 8, 18, 24 and 48 hours. TNFα, IL-1β and IL-6 were evaluated before surgery at 4, 18 and 24h after the operation. Results: Differences of mean values of TNFα and IL-1β between the two groups in the postoperative period were not significant. Mean values of IL-6 in the investigated group A were significantly lower than the mean values of IL-6 in the investigated group B after the 4th hour (p = 0.00990), after the 18th hour (p = 0.00133) and as after the 24th hour following surgery (p = 000860). the difference in pain intensityaccording to the VAS scale was also statistically significantly smaller in group A after 30 min, 1,2,8 and 12 hours after surgery. Conclusions: The addition of a small-dose of ketamine in patiens undergoing laparoscopic cholecystectomy resulted in attenuation of secretion of TNFα, IL-1β, IL-6 and reduction of postoperative pain. Key words: ketamine, postoperative pain, proinflammatory cytokines