New, unusual, and changing events are important environmental cues, and the ability to detect these types of stimuli in the environment constitutes a biologically significant survival skill. We used ...event-related potentials to examine whether sensory and cognitive neural responses to unattended novel events are modulated by the complexity of a primary visuomotor task. Event-related potentials were elicited by unattended task-irrelevant pitch-deviant tones and novel environmental sounds while study participants performed a continuous visuomotor tracking task at two levels of difficulty, achieved by manipulating the control dynamics of a joystick. The results revealed that increased task complexity modulated evoked sensory and cognitive event-related potential components, indicating that detection of change and novelty in the unattended auditory channel is resource-limited.
Activity within fronto-striato-temporal regions during processing of unattended auditory deviant tones and an auditory target detection task was investigated using event-related functional magnetic ...resonance imaging. Activation within the middle frontal gyrus, inferior frontal gyrus, anterior cingulate gyrus, superior temporal gyrus, thalamus, and basal ganglia were analyzed for differences in activity patterns between the two stimulus conditions. Unattended deviant tones elicited robust activation in the superior temporal gyrus; by contrast, attended tones evoked stronger superior temporal gyrus activation and greater frontal and striatal activation. The results suggest that attention enhances neural activation evoked by auditory pitch deviance in auditory brain regions, possibly through top-down control from the dorsolateral prefrontal cortex involved in goal-directed selection and response generation.
Background: Prior studies suggest that auditory hallucinations of “voices” arise from activation of speech perception areas of the cerebral cortex. Low frequency transcranial magnetic stimulation ...(TMS) can reduce cortical activation.
Methods: We have studied three schizophrenic patients reporting persistent auditory hallucinations to determine if low frequency TMS could curtail these experiences. One hertz stimulation of left temporoparietal cortex was compared with sham stimulation using a double-blind, cross-over design.
Results: All three patients demonstrated greater improvement in hallucination severity following active stimulation compared to sham stimulation. Two of the three patients reported near total cessation of hallucinations for ⩾ 2 weeks.
Conclusions: TMS may advance our understanding of the mechanism and treatment of auditory hallucinations.
Using X-ray powder and single crystal diffraction a new phase Y0.915Ni4.12B has been found ((191)P 6/mmm, hP113; a=14.9085(10) Å, c=6.9196(8) Å) which may be considered a defect structure of the ...YNi4B structure. X-ray powder patterns measured down to 15 K do not show any structural phase transition. The temperature dependence of the lattice parameters of Y0.915Ni4.12B was determined by Rietveld refinement. A maximum of the thermal expansion coefficients near 200 K could be observed.
The goal of this study was to determine the influence of emotional input on the early and late components of the contingent negative variation (CNV) component, which is a slow-wave ...electrophysiological potential that is elicited during anticipation of an effortful cognitive task.
Electrophysiological correlates of the processing of visual information were studied in epileptic patients with electrodes chronically implanted on the surface of striate and extrastriate cortex. In ...separate experiments patients viewed faces, letter strings (words and non-words), numbers, and control stimuli. A negative potential, N200, was evoked by faces, letter strings, and numbers, but not by the control stimuli. N200 was recorded bilaterally from discrete regions of the fusiform and inferior temporal gyri. These category-specific face, letter-string, and number "modules" vary in location. In most cases there was no overlap in the location of face and letter-string modules, suggesting a mosaic of functionally discrete regions. In some cases letter-string and number N200s were recorded from the same location, suggesting that these modules may be less spatially and functionally discrete. Face N200-like potentials can be recorded from temporal scalp, allowing the possibility of studying early face processing in normal subjects. Longer-latency face-specific potentials were recorded from the inferior surface of the anterior temporal lobe. Potentials evoked by colored checkerboards were recorded from a region of the fusiform gyrus posterior to the fusiform region from which category-specific N200s were recorded. These results suggest that there are several processing streams in inferior extrastriate cortex. In addition to object recognition systems previously proposed for faces and words, our preliminary results suggest a separate system dealing with numbers. Postulated systems dealing with larger manipulable objects and animals have not been detected.
A growing number of investigators are studying ketamine effects in healthy human subjects, but concerns remain about its safety as a research tool. Therefore, it is timely to revisit the safety of ...subanesthetic doses of ketamine in experimental psychopharmacology studies.
To report on the safety of laboratory studies with subanesthetic doses of ketamine in healthy humans using an existing dataset.
Medically healthy subjects with no personal or familial Axis I psychotic spectrum disorders were administered subanesthetic doses of ketamine by intravenous infusion in a series of clinical investigations from 1989 to 2005. The safety of ketamine administration was monitored in these subjects.
Four hundred and fifty subjects received at least one dose of active ketamine. Eight hundred and thirty three active ketamine and 621 placebo infusions were administered. Ten adverse mental status events were documented in nine subjects/infusions that were deemed related to ketamine administration (2% of subjects, 1.45% of infusions). All but one adverse reaction resolved by the end of the test session. The side effects in the remaining individual were no longer clinically significant within 4 days of the test session. No residual sequelae were observed.
Ketamine administration at subanesthetic doses appears to present an acceptable level of risk for carefully screened populations of healthy human subjects in the context of clinical research programs that intensively monitor subjects throughout their study participation.
The crystal structures of two K
Cs
BSi
solid solutions have been refined at room temperature by the Rietveld method:
= 0.12,
= 12.6858(4) Å,
= 7.66%,
= 5.56% and
= 0.50,
= 12.8480(2) Å,
= 7.64%,
= ...3.10%. They are isostructural to cubic KBSi
with the space group
4̅3
. The structure is built up from (Si,B)O
tetrahedra linked in four-, six- and eightfold rings which are forming a three-dimensional borosilicate framework. The framework contains large cavities that are placed in continuous channels along the 111 directions. The Cs and K atoms occupy the positions in the channels statistically. Thermal behaviour of KBSi
and K
Cs
BSi
has been studied by high-temperature powder X-ray diffraction within the temperature range of 293-1073 K. A new tetragonal polymorph of KBSi
has been found
under heating. The new polymorphic
4̅3
(cubic) –
3̅
(cubic) transition and the new
3̅
cubic polymorphic phase has been proposed for K
Cs
BSi
from our experimental and literature data on crystal structures and thermal expansion of leucites. The structural relaxation under cationic (K, Cs) substitutions and under heating has been investigated.
The purpose of this pilot study was to subjectively and objectively measure workload and performance levels among radiation oncologists performing a computerized performance test before and after ...introducing neurofeedback as a measurable intervention. The intervention consisted of eight neurofeedback sessions, each 28 minutes in length divided into four separate seven-minute training periods, targeting cortical alpha/theta/beta activity in both temporal lobes (C5 alpha/theta, C5 beta, C6 beta, and C6 alpha/theta). The inhibit frequencies for C5 and C6 alpha/theta were 2-4 Hz and 15-30 Hz while the reward frequencies were 5-7 Hz and 8-11 Hz. The inhibit frequencies for beta C5 and beta C6 were 1-12 Hz and 22-30 Hz while the reward frequency was 15-18 Hz. All sensors were referenced to linked ears. Eight subjects were recruited for this pilot study. Workload was assessed subjectively using the NASA Task Load Index (NASA-TLX) instrument, and objectively using electroencephalography (EEG) data analysis. Performance was subjectively assessed using flow-state survey, and objectively assessed based on time-to-test completion and performance-based errors. Statistical differences in pre- vs. post-intervention scores of i) NASA-TLX, time-to-test completion, and performance-based errors were tested using matched pairs t-test; ii) perceived performance as quantified by the flow-state survey using Wilcoxon signed-rank test; and iii) and pre vs. post temporal lobes EEG changes that were acquired during a continuous performance test using analysis of variance (ANOVA). Analysis indicated significant reductions in NASA-TLX (p = .01); significant increases in theta power (training reword; 4-7Hz; p < .01), and reduction in high-alpha/low-beta power (training reword; 13Hz, p < .01) suggesting improved information processing performance; and significant improvements in subjective performance (flow-state survey: p < .01). No significant differences were found in objective continuous performance test measures (time-to-test completion, and performance-based errors; p > .05). Future research is needed to further quantify the impact of neurofeedback on radiation oncology providers’ workload and performance.
Le but de cette étude était de mesurer subjectivement et objectivement la charge de travail et le niveau de performance parmi des radiooncologues réalisant une tache informatisée, avant et après l’administration d’une session de neurofeedback. Huit participants ont été recrutés pour cette étude pilote. La charge de travail était évaluée subjectivement en utilisant le questionnaire NASA Task-Load-Index (NASA-TLX), et objectivement en utilisant l’analyse de données par électroencéphalographie. Les performances ont été évaluées subjectivement en utilisant un questionnaire d’état de « flow », et objectivement en se basant sur le temps de complétion du test et la performance basée sur les erreurs. Les différences statistiques entre les scores de la période pré- et post-intervention du i) NASA-TLX, du temps de complétion du test et de la performance basée sur les erreurs ont été évalué en utilisant des test t pour des échantillons appariés ; ii) la performance perçue telle que quantifiée par le questionnaire d’état de flow a été évaluée en utilisant le test de rangs signés de Wilcoxon ; iii) et les changements EEG pré- et post-intervention dans les lobes temporaux, acquis tout au long de la réalisation de la tâche, ont été mesurés par l’analyse de variance (ANOVA). Les analyses ont indiqué une réduction significative dans le NASA-TLX (p=0.01) ; un accroissement significatif de la puissance spectrale Theta (p<0.01), et une réduction dans la bande de puissance high-Alpha/low-Beta (p<0.01), suggérant une amélioration de la performance de traitement d’information ; et des améliorations significatives de la performance subjective (questionnaire d’état de flow : valeur de p<0.001). Aucune différence significative n’a été trouvée pour les mesures objectives de performance continues (temps de complétion de la tâche, performance basée sur les erreurs ; p>0.05). Une future recherche est nécessaire pour quantifier davantage l’impact du neurofeedback sur la charge de travail et la performance des radiooncologues.
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