Saccade LP at the presentation of target and distracting stimuli to the dominant and subdominant eye
The aim of this study was to estimate dependence of saccadic latency during stimulation of the dominant and subdominant eye in various conditions of presentation of target and distracting stimuli.
This results are the preliminary first part of a presaccadic ERP study. The main goal of this study is an analysis of presaccadic brain potentials in connection of processes of saccadic eye movement preparation.
Many environmental stimuli present a quasi-rhythmic structure at different timescales that the brain needs to decompose and integrate. Cortical oscillations have been proposed as instruments of sensory de-multiplexing, i.e., the parallel processing of different frequency streams in sensory signals. Yet their causal role in such a process has never been demonstrated. Here, we used a neural microcircuit model to address whether coupled theta–gamma oscillations, as observed in human auditory cortex, could underpin the multiscale sensory analysis of speech. We show that, in continuous speech, theta oscillations can flexibly track the syllabic rhythm and temporally organize the phoneme-level response of gamma neurons into a code that enables syllable identification. The tracking of slow speech fluctuations by theta oscillations, and its coupling to gamma-spiking activity both appeared as critical features for accurate speech encoding. These results demonstrate that cortical oscillations can be a key instrument of speech de-multiplexing, parsing, and encoding.
An extensive amount of research indicates that repeating target and distractor features facilitates pop-out search while switching these features slows the search. Following the seminal study by Maljkovic and Nakayama (1994), this “priming of pop-out” effect (PoP) has been widely described as an automatic bottom-up process that is independent of the observers’ expectations. At the same time, numerous studies highlight the crucial role of expectations in visual attention deployment. Our experiment shows that in contrast to previous claims, PoP in a classic color singleton search task is a mix of automatic processing and expectations. Participants searched for a uniquely colored diamond among 2 same-colored distractors. Target color sequences were either predictable (e.g., 2 red-target-green-distractors trials, followed by 2 green-target-red-distractors trials, and so on) or random. Responses were faster in predictable color sequences than randomly changing ones with equal number of repetitions of target colors on preceding trials. Analyses of observers’ eye movements showed that predictability of target color affected both latency and accuracy of the first saccade during a search trial. Our results support the idea that PoP is governed not only by automatic effects from previous target or distractor features but also by top-down expectations.
Differences in the parameters of memory-guided saccades and saccades to visual stimuli were demonstrated. Increases in the latent periods of memory-guided saccades as compared with saccades to visual stimuli provided evidence of slowing of saccade programming based on the extraction of information from working memory. Differently directed lateral differences were seen in the latent periods and durations of saccades to visual targets and memory-guided saccades, reflecting the leading role of the left hemisphere in the programming of saccades to visual stimuli and the right hemisphere in the programming of memory- guided saccades. Comparison of parameters of the temporospatial dynamics of initiation potentials P-1 and N-1, which develop in the last 100 msec of the latent periods of saccades, suggest that there are different mechanisms for the final step of programming saccades to visual stimuli and memory-guided saccades. Decreases in the latent period of the P-1 and N-1 peak potentials before memory-guided saccades may be evidence showing acceleration of the initiation processes for memory-guided saccades as compared with visually evoked saccades. This provides grounds for suggesting that the slowing of the programming of memory-guided saccades occurs at steps preceding saccade initiation.
One of the key advances in genome assembly that has led to a significant improvement in contig lengths has been improved algorithms for utilization of paired reads (mate-pairs). While in most assemblers, mate-pair information is used in a post-processing step, the recently proposed Paired de Bruijn Graph (PDBG) approach incorporates the mate-pair information directly in the assembly graph structure. However, the PDBG approach faces difficulties when the variation in the insert sizes is high. To address this problem, we first transform mate-pairs into edge-pair histograms that allow one to better estimate the distance between edges in the assembly graph that represent regions linked by multiple mate-pairs. Further, we combine the ideas of mate-pair transformation and PDBGs to construct new data structures for genome assembly: pathsets and pathset graphs.