Neuronal effects of auditory distraction on visual attention

Selective attention in the presence of distraction is a key aspect of healthy cognition. The underlying neurobiological processes, have not, however, been functionally well characterized. In the present study, we used functional magnetic resonance imaging to determine how ecologically relevant distracting noise affects cortical activity in 27 healthy adults during two versions of the visual Sustained Attention To Response Task (SART) that differ in difficulty (and thus attentional load). A significant condition (noise or silence) by task (easy or difficult) interaction was observed in several areas, including dorsolateral prefrontal cortex (DLPFC), fusiform gyrus (FG), posterior cingulate (PCC), and pre-supplementary motor area (PreSMA). Post hoc analyses of interaction effects revealed deactivation of DLPFC, PCC, and PreSMA during distracting noise under conditions of low attentional load, and activation of FG and PCC during distracting noise under conditions of high attentional load. These results suggest that distracting noise may help alert subjects to task goals and reduce demands on cortical resources during tasks of low difficulty and attentional load. Under conditions of higher load, however, additional cognitive resources may be required in the presence of noise.     

White matter in aphasia: A historical review of the Dejerines’ studies

The Objective was to describe the contributions of Joseph Jules Dejerine and his wife Augusta Dejerine-Klumpke to our understanding of cerebral association fiber tracts and language processing.     

The neural basis of updating: Distinguishing substitution processes from other concurrent processes

Sörqvist, P. & Sætrevik, B. (2010). The neural basis of updating: Distinguishing substitution processes from other concurrent processes. Scandinavian Journal of Psychology, 51, 357–362. Most previous studies of updating processes have not been able to contrast processes of substituting items in memory with other concurrent processes. In the present investigation, we used a new task called “number updating” and an fMRI protocol to contrast the activation of trials that require item substitution (adding a new item to the working memory representation and suppressing an old item) with trials that involve no substitution (discarding the new item). Trials that require item substitution activated the dorsolateral prefrontal cortex, the posterior medial frontal cortex and the parietal lobes, areas typically seen activated for working memory tasks in general. Trials that do not require substitution activated the anterior medial frontal cortex. Studies examining executive functions have associated this area with cognitive conflict, and may represent suppression of the substitution processes.     

Consciousness wanted,attention found: Reasons for the advantage of the left visual field in identifying T2 among rapidly presented series

Everyday experience suggests that people are equally aware of events in both hemi-fields. However, when two streams of stimuli are rapidly presented left and right containing two targets, the second target is better identified in the left than in the right visual field.This might be considered evidence for a right-hemisphere advantage in generating conscious percepts. However, this putative asymmetry of conscious perception cannot be measured independently of participants’ access to their conscious percepts, and there is actually evidence from split-brain patients for the reverse, left-hemisphere advantage in having access to conscious percepts. Several other topics were studied in search of the responsible mechanism, among others: Mutual inhibition of hemispheres, cooperation of hemispheres in perceiving midline stimuli, and asymmetries in processing various perceptual inputs. Directing attention by salient cues turned out to be one of the few mechanisms capable of modifying the left visual-field advantage in this paradigm. Thus, this left visual-field advantage is best explained by the notion of a right-hemisphere advantage in directing attention to salient events. Dovetailing with the pathological asymmetries of attention after right-hemisphere lesions and with asymmetries of brain activation when healthy participants shift their attention, the present results extend that body of evidence by demonstrating unusually large and reliable behavioral asymmetries for attention-directing processes in healthy participants.     

Selecting the Right Tool For the Job

There are competing ethical concerns when it comes to designing any clinical research study. Clinical trials of possible treatments for Ebola virus are no exception. If anything, the competing ethical concerns are exacerbated in trying to find answers to a deadly, rapidly spreading, infectious disease. The primary goal of current research is to identify experimental therapies that can cure Ebola or cure it with reasonable probability in infected individuals. Pursuit of that goal must be methodologically sound, practical and consistent with prevailing norms governing human subjects research. Some maintain that only randomized controlled trials (RCTs) with a placebo or standard-of-care arm can meet these conditions. We maintain that there are alternative trial designs that can do so as well and that sometimes these are preferable to RCTs.     

Left orbital frontal activation in pathological anxiety

Twelve patients with anxiety disorder were studied with respect to regional cerebral blood flow (rCBF) using a 32-detector system with the 133 Xe inhalation technique. Measurements were taken during a rest condition and during anxiety induction. Anxiety relevant to the patient's psychological disorder was induced with a projective test, the meta-contrast technique (MCT). Increased blood flow in the orbital frontal region of the left hemisphere was observed in each of the 11 subjects who showed evidence of experiencing anxiety during the procedure. In a second study four additional anxiety patients were studied with a high-resolution (254-detector)Xe rCBF system. In addition to the anxiety and resting conditions, a neutral verbalization condition was added to control for the verbal aspects of the anxiety induction procedure. The results again showed the experience of anxiety to be accompanied by increased blood flow in the left orbital frontal region, with the patients showing this flow increase to be greater in the posterior, paralimbic, areas of the region. These results are consistent with previous suggestions of left hemisphere involvement in anxiety. They also suggest that imaging methods may allow research into what appears to be exaggerated corticolimbic activity in this disorder.     

Validity and reliability of electroencephalographic frontal alpha asymmetry and frontal midline theta as biomarkers for depression

Electroencephalographic (EEG) frontal alpha asymmetry (FAA) and frontal midline (FM) theta have been suggested as biomarkers for depression and anxiety, but have mostly been assessed in small and non‐clinical studies. In a clinical sample of 79 adults with depression (ICD‐10: F32), resting EEG and scales of depression (MADRS) and anxiety (HADS‐A) were measured at intake and after 3 months. FAA and FM theta values were referenced to a normative population database. Internal consistency, test‐retest reliability, and correlations with psychiatric tests were examined. Reliability was sufficient. However, FAA and FM theta values were close to the general population, and correlations with psychiatric tests were mostly small and non‐significant, with the exception of FAA on F7–F8 z‐scores and HADS‐A. We conclude that the validity of FAA and FM theta and therefore their potential as biomarkers for depression and anxiety remain unclear.     

Progress in Executive-Function Research: From Tasks to Functions to Regions to Networks

ABSTRACT— It has long been observed that damage to the frontal cortex affects a person's ability to control thought, behavior, and emotion while sometimes leaving fundamental processes such as vision, hearing, and long-term memory intact. Such observations have led theoreticians to suppose that a set of executive control functions exists, at the top of the hierarchy of mental processes. To study these executive functions and their relation to the frontal cortex and its subregions, researchers have long employed several now-classic cognitive tests in patients with brain damage. Yet until recently it has proved difficult to reliably localize the putative executive functions to discrete regions. This article illustrates how recent progress in executive-functions research has been driven by the coupling of sophisticated neuroscience techniques with advances in experimental psychology. Taking examples from recent studies, it shows how experimental tasks may be decomposed into cognitive components that can be localized to discrete—but structurally connected—brain regions. What emerges is a new ontology for executive function in terms of which cognitive components exist and of how, and when, they are recruited during task performance.