Graded visual attention modulates brain responses evoked by task-irrelevant auditory pitch changes

Previous studies suggested that auditory change-specific neural responses are attention-independent and reflect central auditory processing. The automaticity of the brain's response to infrequent changes in pitch within a series of auditory tone pips was examined in parallel functional magnetic resonance imaging (fMRI) and event-related potential (ERP) studies. Subjects performed a continuous perceptual-motor visual tracking task at two levels of difficulty while simultaneously hearing a series of task-irrelevant standard tone pips and infrequent pitch-deviant tones. fMRI results revealed that the unattended pitch-deviant tones strongly activated superior temporal and frontal cortical regions. These activations were significantly modulated by the tracking difficulty of the primary task. ERP results revealed that the amplitude of the scalp-negative component evoked by deviant tones (MMN) was attenuated during the more difficult tracking task. Our results demonstrate that the brain's response to task-irrelevant sensory changes is strongly influenced by intermodal attentional demands.     

Effects of acute aspartame and acute alcohol ingestion upon the cognitive performance of pilots

Anecdotal evidence has associated the artificial sweetener aspartame with a number of symptoms of central nervous system (CNS) dysfunction. There are, however, little scientific data concerning the effect of aspartame upon complex mental operations such as those necessary for flying an aircraft. Thirteen pilots were tested in a double-blind study using the SPARTANS cognitive test battery of aviation-relevant information-processing tasks. These tasks relate to perceptual-motor abilities, spatial abilities, working memory, attentional performance, risk taking, processing flexibility, planning and sequencing ability. Subjects were tested over five sessions consisting of pretest and posttest controls and three randomly ordered treatment sessions. The treatment conditions involved an aspartame dose of 50 mg/kg body weight, a placebo condition, and an ethyl alcohol (0.1% BAL) condition as the positive control. No detectable performance decrements were associated with the aspartame condition, although decrements in psychomotor and spatial abilities were detected in the ethanol condition. Results were found to be consistent with prior flight-simulator studies of alcohol, but do not appear to support the concerns expressed in anecdotal testimony regarding the deleterious effects of aspartame upon cognitive performance.     

Possible decontamination of pancreatin with gamma rays and chemical agents

Certain pre-conditions given, the microbial contamination of pancreatin in powder form can be reduced below international standard values. However, each of the methods whether physical or chemical, causes a variable loss of activity depending on the methods applied and the concentration of the decontaminating agent used. Therefore during preparation of this complex enzymatic compound, highly aseptic conditions must be kept in all stages of the process to avoid an increase of germal contamination. For a final toxicological assessment of the decontaminated products, further tests are required.     

Test-retest and between-site reliability in a multicenter fMRI study

In the present report, estimates of test-retest and between-site reliability of fMRI assessments were produced in the context of a multicenter fMRI reliability study (FBIRN Phase 1, www.nbirn.net). Five subjects were scanned on 10 MRI scanners on two occasions. The fMRI task was a simple block design sensorimotor task. The impulse response functions to the stimulation block were derived using an FIR-deconvolution analysis with FMRISTAT. Six functionally-derived ROIs covering the visual, auditory and motor cortices, created from a prior analysis, were used. Two dependent variables were compared: percent signal change and contrast-to-noise-ratio. Reliability was assessed with intraclass correlation coefficients derived from a variance components analysis. Test-retest reliability was high, but initially, between-site reliability was low, indicating a strong contribution from site and site-by-subject variance. However, a number of factors that can markedly improve between-site reliability were uncovered, including increasing the size of the ROIs, adjusting for smoothness differences, and inclusion of additional runs. By employing multiple steps, between-site reliability for 3T scanners was increased by 123%. Dropping one site at a time and assessing reliability can be a useful method of assessing the sensitivity of the results to particular sites. These findings should provide guidance toothers on the best practices for future multicenter studies.     

Effects of Diabetic Ketoacidosis on Visual and Verbal Neurocognitive Function in Young Patients Presenting with New-Onset Type 1 Diabetes

Objective:To evaluate the effects of diabetic ketoacidosis (DKA) on neurocognitive functions in children and adolescents presenting with new-onset type 1 diabetes.Methods:Newly diagnosed patients were divided into two groups: those with DKA and those without DKA (non-DKA). Following metabolic stabilization, the patients took a mini-mental status exam prior to undergoing a baseline battery of cognitive tests that evaluated visual and verbal cognitive tasks. Follow-up testing was performed 8-12 weeks after diagnosis. Patients completed an IQ test at follow-up.Results:There was no statistical difference between the DKA and non-DKA groups neither in alertness at baseline testing nor in an IQ test at follow-up. The DKA group had significantly lower baseline scores than the non-DKA group for the visual cognitive tasks of design recognition, design memory and the composite visual memory index (VMI). At follow-up, Design Recognition remained statistically lower in the DKA group, but the design memory and the VMI tasks returned to statistical parity between the two groups. No significant differences were found in verbal cognitive tasks at baseline or follow-up between the two groups. Direct correlations were present for the admission CO2 and the visual cognitive tasks of VMI, design memory and design recognition. Direct correlations were also present for admission pH and VMI, design memory and picture memory.Conclusion:Pediatric patients presenting with newly diagnosed type 1 diabetes and severe but uncomplicated DKA showed a definite trend for lower cognitive functioning when compared to the age-matched patients without DKA.