The effect of gender on planning: An fMRI study using the Tower of London task.

Since the introduction of brain mapping, evidences of functional gender differences have been corroborating previous behavioral and neuropsychological results showing a sex-specific brain organization. We investigated gender differences in brain activation during the performance of the Tower of London (TOL) task which is a standardized test to assess executive functions. Eighteen healthy subjects (9 females and 9 males) underwent fMRI scanning while solving a series of TOL problems with different levels of difficulty. Data were analyzed by modeling both genders and difficulty task load. Task-elicited brain activations comprised a bilateral fronto-parietal network, common to both genders; within this network, females activated more than males in dorsolateral prefrontal cortex (DLPFC) and right parietal cortex, whereas males showed higher activity in precuneus. A prominent parietal activity was found at low level of difficulty while, with heavier task demand, several frontal regions and subcortical structures were recruited. Our results suggest peculiar gender strategies, with males relying more on visuospatial abilities and females on executive processing.

Functional MR study of a motor task and the tower of London task at 1.0 T.

INTRODUCTION: The use of functional magnetic resonance imaging (fMRI) for clinical applications and basic neuroscience is constantly increasing. The discussion about minimum performance requirement for a correct implementation of fMRI is still open, and one of the critical points is the magnetic field strength. We tested the feasibility of fMRI at 1.0 T during motor and cognitive tasks. METHODS: Fourteen healthy subjects were scanned during a motor task and 12 while performing the Tower of London task. In the activated areas, the percentage signal change due to BOLD (blood oxygenation level dependent) contrast was analysed. To check basic image quality of the acquisition system we measured quality indices in a temporal series of images of a phantom. RESULTS: Motor and cognitive brain activations matched previous results obtained at higher field strengths. The mean percentage change over subjects in the motor task was in the range 1.3-2.6% for the primary motor area and 0.8-6.7% for the cerebellum. In the cognitive task, the mean percentage change over subjects was 0.7-1.2% for a frontal area and 0.6-2.8% for a parietal area. The percentage noise of the phantom temporal series was less than 0.4%. Percentage changes and signal to noise ratio, although lower than that obtained with high-field systems, allowed activation maps to be obtained in all subjects. CONCLUSION: Our results replicate previous fMRI results demonstrating reproducible motor-related brain activations and extend the field to a complex cognitive task, thus providing evidence of the safety for routine clinical use of 1-T equipment.

Primary prophylaxis with fluconazole against systemic fungal infections in HIV-positive patients.

OBJECTIVE: To investigate the efficacy of fluconazole prophylaxis against systemic fungal infections in HIV-positive patients. DESIGN: Open label treatment compared with historical controls. SETTING: Patients were seen at the Parkland Memorial Hospital HIV Clinic, Dallas, Texas, USA between 1 March 1990 and 28 February 1991. PATIENTS, PARTICIPANTS: Three hundred and thirty-seven historical controls were followed for 157 patient-years, and 329 fluconazole-treated patients for 145 patient-years. INTERVENTIONS: Fluconazole (100 mg daily) was administered to all patients with CD4 lymphocyte counts less than 68 x 10(6)/l seen at our HIV clinic after 1 March 1990. MAIN OUTCOME MEASURES: Lysis-centrifugation blood cultures were recorded monthly for all patients during both study periods. RESULTS: Twenty infections (16 cryptococcosis, four histoplasmosis) occurred in 337 historical reference control patients (product-limit 1-year incidence, 7.5 +/- 2.0/year). Four infections (one cryptococcosis, three histoplasmosis) occurred in the treated patient group (product-limit 1-year incidence, 1.8 +/- 0.9/year). CONCLUSIONS: Fluconazole warrants further evaluation for prophylaxis against systemic fungal infections in HIV-positive patients.