The genetic architecture of the human cerebral cortex

The cerebral cortex underlies our complex cognitive capabilities, yet little is known about the specific genetic loci that influence human cortical structure. To identify genetic variants that affect cortical structure, we conducted a genome-wide association meta-analysis of brain magnetic resonance imaging data from 51,665 individuals. We analyzed the surface area and average thickness of the whole cortex and 34 regions with known functional specializations. We identified 199 significant loci and found significant enrichment for loci influencing total surface area within regulatory elements that are active during prenatal cortical development, supporting the radial unit hypothesis. Loci that affect regional surface area cluster near genes in Wnt signaling pathways, which influence progenitor expansion and areal identity. Variation in cortical structure is genetically correlated with cognitive function, Parkinson's disease, insomnia, depression, neuroticism, and attention deficit hyperactivity disorder

Electrophysiological measurement of information flow during visual search

Abstract The temporal relationship between different stages of cognitive processing is long debated. This debate is ongoing, primarily because it is often difficult to measure the time course of multiple cognitive processes simultaneously. We employed a manipulation that allowed us to isolate ERP components related to perceptual processing, working memory, and response preparation, and then examined the temporal relationship between these components while observers performed a visual search task. We found that, when response speed and accuracy were equally stressed, our index of perceptual processing ended before both the transfer of information into working memory and response preparation began. However, when we stressed speed over accuracy, response preparation began before the completion of perceptual processing or transfer of information into working memory on trials with the fastest reaction times. These findings show that individuals can control the flow of information transmission between stages, either waiting for perceptual processing to be completed before preparing a response or configuring these stages to overlap in time. Descriptors: Attention, ERPs, Visual processes, N2pc, LRP, Speed accuracy trade-off One of the oldest debates in psychology centers on the temporal relationship between cognitive operations. For example, it has been hypothesized that responding appropriately to an object that we encounter requires information to be processed in a sequence of discrete stages in which one stage must finish before the next can begin (Donders, 1868 The goal of the current study was to determine whether evidence for continuous information flow can be observed during visual search and, if so, to specify precisely which cognitive operations can be configured to overlap with one another in time using ERPs. The ERP technique is uniquely suited to address these questions because discrete ERP components have been shown to measure discrete aspects of cognition and are temporally precise, indexing the earliest and latest time points at which the underlying cognitive processes are operative To overcome this problem and enable the ability to directly compare components related to discrete processing stages, we examined the time course of two components that can be distinguished by their lateralized distributions, the perceptual attentionrelated N2pc and the response-related lateralized readiness potential (LRP), alongside a nonlateralized measure of the transfer of information into working memory, the P3b. The goal was to directly examine the temporal relationship between these components in order to provide a window into the temporal unfolding of cognitive processes from perceptual processing through response preparation in a typical visual search task The N2pc is lateralized on the scalp relative to the locus of spatial attention, and previous research in visual search tasks has demonstrated that the onset of the N2pc can be used to track when perceptual-level attention is deployed to an object. Critically, during search the N2pc is directly followed by the onset of a lateralized positivity (the Pd), which signals the termination of perceptua