Participants’ performance on the reaction time task at the group level.

<p>The group performance on the reaction time (RT) task is plotted as the mean and standard deviation of reaction times as a function of the stimulus onset asynchrony (SOA). A-only and V-only indicate reaction times to unisensory, auditory- and visual-only trials respectively. The complete list of SOAs is provided in the Methods section.</p

The reaction time- and temporal order judgment-defined temporal window of integration.

<p>Means and standard deviations of the boundaries of the temporal window of integration (TWI) defined by the reaction time (RT) and temporal order judgment (TOJ) tasks for the participants who displayed task demand-induced TWI malleability (red, n = 5) and for those who did not (blue, n = 6). n.s. not significant, *p<0.05.</p

Recalibration of the Multisensory Temporal Window of Integration Results from Changing Task Demands

<div><p>The notion of the temporal window of integration, when applied in a multisensory context, refers to the breadth of the interval across which the brain perceives two stimuli from different sensory modalities as synchronous. It maintains a unitary perception of multisensory events despite physical and biophysical timing differences between the senses. The boundaries of the window can be influenced by attention and past sensory experience. Here we examined whether task demands could also influence the multisensory temporal window of integration. We varied the stimulus onset asynchrony between simple, short-lasting auditory and visual stimuli while participants performed two tasks in separate blocks: a temporal order judgment task that required the discrimination of subtle auditory-visual asynchronies, and a reaction time task to the first incoming stimulus irrespective of its sensory modality. We defined the temporal window of integration as the range of stimulus onset asynchronies where performance was below 75% in the temporal order judgment task, as well as the range of stimulus onset asynchronies where responses showed multisensory facilitation (race model violation) in the reaction time task. In 5 of 11 participants, we observed audio-visual stimulus onset asynchronies where reaction time was significantly accelerated (indicating successful integration in this task) while performance was accurate in the temporal order judgment task (indicating successful segregation in that task). This dissociation suggests that in some participants, the boundaries of the temporal window of integration can adaptively recalibrate in order to optimize performance according to specific task demands.</p></div

Race model violation in the reaction time task at the individual participant level.

<p>In this plot, each participant is represented by one line and each stimulus onset asynchrony (SOA) by one column. The p value for violation of the race model is color-coded for each participant and each SOA. Red color indicates p values closer to 0.05, yellow color indicates p values closer to 0. White color indicates that the race model could not be confidently rejected. Participant 1 (bold number) is the exemplary participant illustrated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0071608#pone-0071608-g005" target="_blank">Figure 5</a>. None of the subjects displayed race model violation at SOAs beyond −120 ms and beyond +120 ms. Participants 1 to 5 (red numbers) displayed task-induced TWI malleability, whereas Participants 6 to 11 (blue numbers) did not.</p

Participants’ performance at the group level.

<p>The group performance on the temporal order judgment (TOJ) task is plotted as the proportion of “visual-first” responses as a function of the stimulus onset asynchrony (SOA, bold curve). The dashed lines represent the thresholds for above-chance performance on the TOJ task. The grayed area represents the SOAs where significant violation of the race model was observed on the reaction time task.</p

Results for an exemplary individual participant.

<p>The participant’s performance on the temporal order judgment (TOJ) task is plotted as the proportion of “visual-first” responses as a function of the stimulus onset asynchrony (SOA, filled circles). The psychometric function fitted onto these data is plotted as a continuous line. Dashed lines indicate the thresholds for above-chance performance. The grayed area represents the SOAs where significant violation of the race model was observed on the reaction time task.</p

Parameters of the psychometric function and priors for the Bayesian analysis.

<p><b>A.</b> The parameters that define the logistic function are illustrated: λ_A, lapse rate when the auditory stimulus precedes the visual stimulus by a long interval (large negative values of the stimulus onset asynchrony, SOA); λ_V, lapse rate when the visual stimulus precedes the auditory one (large positive values of the SOA); μ, location parameter; σ, shape parameter. In order to illustrate how the prior distributions selected for each parameter (illustrated in the following panels) affect the shape of the logistic function, the numerical values of the parameters were set to the maximum of their prior distribution. <b>B.</b> The beta distribution used as a prior for the lapse rates λ_A and λ_V. The maximum prior probability corresponds to λ = 0.05. <b>C.</b> The normal distribution used as a prior for the location parameter μ. The maximum prior probability corresponds to μ = 0. <b>D.</b> The gamma distribution used as a prior for the shape parameter σ. The maximum prior probability corresponds to σ = 50.</p

Common variant genotypes at 15q11.2 arssociated with differences in regional cortical volume, thickness, and surface area in a discovery cohort.

<p>(A) Aggregate -log p-values for single nucleotide polymorphisms (SNPs) are plotted against genomic position. P-values reflect the relationships between genotype in the discovery cohort and volume (left), surface area (middle), or thickness (right) across all regions of interest (ROIs). Significant associations (p_{permutation corrected}<0.05) appear above the horizontal red line. Linkage disequilibrium of top hits (diamonds) to typed variants is specified, and estimated recombination rates plotted (blue lines). r² in the legend indicates the correlation between genotype at each tag-SNP (circles) and genotype at the top hit (diamond). (B) Top aggregate p-values and their SNP descriptions for each trait examined in the full cohort and the Caucasian subset are summarized.</p

Evidence for genotype-dependent activation of <i>CYFIP1</i> by FOXP2.

<p>(A) rs4778298 (orange) associated with variation across the surface area of the left supramarginal gyrus is 2.2 kb upstream of <i>CYFIP1</i>^<i>short</i>. Seven linked variants (r²>0.9), and an expression probe specific for <i>CYFIP1</i>^<i>short</i> (Affymetrix 3583676), are shown. (B) A significant positive association between levels of <i>FOXP2</i> and <i>CYFIP1</i> is seen in human brain (r² = 0.36; p = 2.5x10^-5). (C) rs66903469-T is predicted to bind FOXP2 with 11.8-fold greater affinity than the alternate C allele. MA0593.1 corresponds to the position weight matrix for FOXP2 defined in JASPAR. (D) rs66903469-T (r² with rs4778298-C of 0.93), is strongly associated with increased levels of <i>CYFIP1</i>^<i>short</i> (p = 2.9x10^-5).</p

Individual regions of interest (ROIs) drive associations observed in the discovery cohort.

<p>(A) Pairwise analyses of the top signal for each of volume, surface area, and thickness from the discovery cohort determined that aggregate effects were attributable to individual ROIs (and see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0158036#pone.0158036.s006" target="_blank">S5 Table</a>). Post-hoc permutation testing, accounting for all 52 tag-SNPs and ROIs examined, found a significant association between rs4778298 genotype and the surface area of the left supramarginal gyrus (lh.SMG) in Caucasian subjects (p_{permutation corrected} = 7.5x10^-3). (B) Linear effects at the CC and lh.SMG were observed for rs12102024 and rs4778298, respectively, consistent with an effect of allele dosage. rh.ACC and CC correspond to right anterior cingulate cortex and corpus callosum, respectively.</p