Abstract This neuroimaging study investigated the neural mechanisms of the effect of conversation on visual event detection during a driving-like scenario. The static load paradigm , established as ...predictive of visual reaction time in on-road driving, measured reaction times to visual events while subjects watched a real-world driving video. Behavioral testing with twenty-eight healthy volunteers determined the reaction time effects from overt and covert conversation tasks in this paradigm. Overt and covert conversation gave rise to longer visual event reaction times in the surrogate driving paradigm compared to just driving with no conversation, with negligible effect on miss rates. The covert conversation task was then undertaken by ten right-handed healthy adults in a 4-Tesla fMRI magnet. We identified a frontal–parietal network that maintained event detection performance during the conversation task while watching the driving video. Increased brain activations for conversation vs. no conversation during such simulated driving was found not only in language regions (Broca's and Wernicke's areas), but also specific regions in bilateral inferior frontal gyrus, bilateral anterior insula and orbitofrontal cortex, bilateral lateral prefrontal cortex (right middle frontal gyrus and left frontal eye field), supplementary motor cortex, anterior and posterior cingulate gyrus, right superior parietal lobe, right intraparietal sulcus, right precuneus, and right cuneus. We propose an Asynchrony Model in which the frontal regions have a top–down influence on the synchrony of neural processes within the superior parietal lobe and extrastriate visual cortex that in turn modulate the reaction time to visual events during conversation while driving.
To determine regions of brain activation associated with menopausal hot flashes and sweating.
Controlled laboratory study.
University medical center.
Symptomatic postmenopausal women and asymptomatic ...eumenorrheic women.
None
Brain activation measured by functional magnetic resonance imaging.
Significant (
P<.001) areas of activation during hot flashes in symptomatic women included the insula and anterior cingulate cortex. Sweating in the eumenorrheic women was associated (
P<.001) with activity in the anterior cingulate and superior frontal gyrus.
Activation of the insular cortex is associated with the “rush of heat” described during menopausal hot flashes. Thermoregulation in humans appears to be represented in a distributed cortico-subcortical network rather than in a single localized structure.
The application of neuroimaging techniques such as functional magnetic resonance imaging (fMRI) to the investigation of driver behaviour represents a promising complimentary approach to traditional ...research methodologies. In this study, we used whole brain fMRI to identify the neural correlates and key brain systems involved in visual event detection during a limited form of simulated driving. Participants were imaged during several conditions that differed with respect to the task and associated demands on attention. Multiple neural systems including fronto-parietal, cingulate, and cerebellar networks were associated with detecting and responding to the target events. We interpret these findings as reflecting interrelated neural processes associated with visual attention, attention control and allocation, stimulus processing, response selection, execution and timing, all of which are critical during driving. Differences in the simulated driving tasks and associated attention demands indicated a greater role for fronto-parietal and cerebellar networks. This pattern suggests differences related to motor coordination and control, vigilance, preparatory motor processes, and the timing of the motor responses. We conclude that visual event detection performed as part of even a limited simulated driving environment engages multiple interconnected cortical and sub-cortical neural systems working in concert. The newly emerging area of transportation imaging research not only offers exciting research opportunities to investigate driving as a complex human activity, but the findings can also be applied to the design of more efficient and safer vehicle control systems and operator interfaces.
The D0 Silicon Microstrip Tracker Ahmed, S.N.; Aoki, M.; Åsman, B. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2011, Letnik:
634, Številka:
1
Journal Article
Recenzirano
Odprti dostop
This paper describes the mechanical design, the readout chain, the production, testing and the installation of the Silicon Microstrip Tracker of the D0 experiment at the Fermilab Tevatron collider. ...In addition, we describe the performance and operational experience of the detector during the experiment data collection between 2001 and 2010.
Using single-molecule polymerase chain reaction, the frequency of spontaneous and radiation-induced mutation at an expanded simple tandem repeat (ESTR) locus was studied in DNA samples extracted from ...sperm and bone marrow of Atm knockout (Atm+/−) heterozygous male mice. The frequency of spontaneous mutation in sperm and bone marrow in Atm+/− males did not significantly differ from that in wild-type BALB/c mice. Acute exposure to 1 Gy of γ-rays did not affect ESTR mutation frequency in bone marrow and resulted in similar increases in sperm samples taken from Atm+/− and BALB/c males. Taken together, these results suggest that the Atm haploinsufficiency analysed in our study does not affect spontaneous and radiation-induced ESTR mutation frequency in mice.
Abstract Estimates of cancer risks posed to space-flight crews by exposure to high atomic number, high-energy (HZE) ions are subject to considerable uncertainty because epidemiological data do not ...exist for human populations exposed to similar radiation qualities. We assessed the leukemogenic efficacy of one such HZE species, 1 GeV (56)Fe ions, a component of space radiation, in a mouse model for radiation-induced acute myeloid leukemia. CBA/CaJ mice were irradiated with 1 GeV/nucleon (56)Fe ions or (137)Cs gamma rays and followed until they were moribund or to 800 days of age. We found that 1 GeV/nucleon (56)Fe ions do not appear to be substantially more effective than gamma rays for the induction of acute myeloid leukemia (AML). However, (56)Fe-ion-irradiated mice had a much higher incidence of hepatocellular carcinoma (HCC) than gamma-irradiated mice, with an estimated RBE of approximately 50. These data suggest a difference in the effects of HZE iron ions on the induction of leukemia compared to solid tumors, suggesting potentially different mechanisms of tumorigenesis.
Exposure to sparsely ionising gamma- or X-ray irradiation is known to increase the risk of leukaemia in humans. However, heavy ion radiotherapy and extended space exploration will expose humans to ...densely ionising high linear energy transfer (LET) radiation for which there is currently no understanding of leukaemia risk. Murine models have implicated chromosomal deletion that includes the hematopoietic transcription factor gene, PU.1 (Sfpi1), and point mutation of the second PU.1 allele as the primary cause of low-LET radiation-induced murine acute myeloid leukaemia (rAML). Using array comparative genomic hybridisation, fluorescence in situ hybridisation and high resolution melt analysis, we have confirmed that biallelic PU.1 mutations are common in low-LET rAML, occurring in 88% of samples. Biallelic PU.1 mutations were also detected in the majority of high-LET rAML samples. Microsatellite instability was identified in 42% of all rAML samples, and 89% of samples carried increased microsatellite mutant frequencies at the single-cell level, indicative of ongoing instability. Instability was also observed cytogenetically as a 2-fold increase in chromatid-type aberrations. These data highlight the similarities in molecular characteristics of high-LET and low-LET rAML and confirm the presence of ongoing chromosomal and microsatellite instability in murine rAML.
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