Verbal Fluency Tasks: Influence of Age, Gender, and Education and Normative Data for the Spanish Native Adult Population.

Objective: Phonological and semantic verbal fluency (VF) tasks are frequently used to assess language and executive functions in both clinical and research settings. F, A, and S are the most commonly used letters in phonological tasks across languages and cultures. Unfortunately, the lack of norms for the native Spanish population for these letters, and for certain semantic categories such as “proper names,” may lead to misinterpretation of scores due to demographic differences. The aim of the present study was to provide normative data for F, A, and S and for “proper names,” “animals,” and “fruits and vegetables” for the native Spanish population. Method: 257 healthy subjects took part in the study (ages: 17–100 years, 3–20 years of education). Correlation, multiple regression, and t-tests were used to select the most appropriate variables for stratification. Results: Education was the best predictor of performance in all tasks, followed by age. Given that t-test results showed no differences related to gender, with the only exception of the semantic category “animals,” this variable was not considered for stratification. Consequently, the data were stratified in two education levels (<13, ≥13 years of education) and in two age levels (<60, ≥60) within the low-educational level group. Mean, standard deviation, and percentile scores for each group are provided. Conclusions: The present norms provide a reference for clinicians assessing VF. This data may also facilitate comparisons with other normative studies in cross-cultural and cross-linguistic research.pre-print369 K

Components determining the slowness of information processing in parkinson’s disease.

Introduction Bradyphrenia is a key cognitive feature in Parkinson's disease (PD). There is no consensus on whether information processing speed is impaired or not beyond motor performance. Objective This study aims to explore which perceptual, motor, or cognitive components of information processing are involved in the slowdown affecting cognitive performance. Methods The study included 48 patients with PD (age: 63, 3 ± 8, 18; HY I-III; UPDRS 15,46 ± 7,76) and 53 healthy controls (age: 60,09 ± 12,83). Five reaction time (RT) tasks were administered to all participants. The average RT in each of the tasks and the percentage of correct answers were measured. Patients with PD were in "ON state" at the time of the evaluation. Perceptual, motor, and cognitive components were isolated by means of a series of ANCOVAs. Results As expected, the motor component was slowed down in patients with PD. Moreover, while patients with PD showed slower RT than controls in all tasks, differences between groups did not exponentially increase with the increasing task complexity. ANCOVA analyses also revealed that the perceptual and sustained alert component resulted to be slowed down, with no differences being found in any of the remaining isolated cognitive components (i.e., response strategy-inhibition, decisional, visual search, or interference control). Conclusions The results revealed that slowness of information processing in PD was mainly associated with an impaired processing speed of the motor and perceptual-alertness components analyzed. The results may help designing new neurorehabilitation strategies, focusing on the improvement of perceptual and alertness mechanisms.post-print534 K

An information theoretical approach to task-switching: evidence from cognitive brain potentials in humans

This study aimed to clarify the neural substrates of behavioral switch and restart costs in intermittently instructed task-switching paradigms. Event-related potentials (ERPs) were recorded while participants were intermittently cued to switch or repeat their categorization rule (Switch task), or else they performed two perceptually identical control conditions (NoGo and Oddball). The three tasks involved different task-sets with distinct stimulus-response associations in each, but identical visual stimulation, consisting of frequent colored shapes (p = 0.9) and randomly interspersed infrequent black shapes (p = 0.1; &lsquo;+&rsquo; and &lsquo;x&rsquo; symbols). Behavioral restart costs were observed in the fi rst target responses following all black shapes in the Switch and NoGo tasks &ndash; but not in the Oddball task &ndash; and corresponded with enhanced fronto-centrally distributed early cue-locked P3 activity (peak latency 325&ndash;375 ms post-cue onset at the vertex). In turn, behavioral switch costs were associated with larger late cue-locked P3 amplitudes in the Switch task only (peak latency 400&ndash;450 ms post-cue onset at mid-parietal sites). Together with our information theoretical estimations, ERP results suggested that restart and switch costs indexed two neural mechanisms related to the preparatory resolution of uncertainty: (1) the intermittent re-activation of task-set information, and (2) the updating of stimulus-response mappings within an active task set, as indexed by early and late cue-locked P3 activations, respectively. In contrast, target-locked P3 activations refl ected a functionally distinct mechanism related to the implementation of task-set information. We conclude that task-switching costs consist of both switch-specifi c and switch-unspecifi c processes during the preparation and execution stages of task performance

An information theoretical approach to task-switching: Evidence from cognitive brain potentials in humans

This study aimed to clarify the neural substrates of behavioral switch and restart costs in intermittently instructed task-switching paradigms. Event-related potentials (ERPs) were recorded while participants were intermittently cued to switch or repeat their categorization rule (Switch task), or else they performed two perceptually identical control conditions (NoGo and Oddball). The three tasks involved different task-sets with distinct stimulus-response associations in each, but identical visual stimulation, consisting of frequent colored shapes (p = 0.9) and randomly interspersed infrequent black shapes (p = 0.1; \u27+\u27 and \u27x\u27 symbols). Behavioral restart costs were observed in the first target responses following all black shapes in the Switch and NoGo tasks - but not in the Oddball task - and corresponded with enhanced fronto-centrally distributed early cue-locked P3 activity (peak latency 325-375 ms post-cue onset at the vertex). In turn, behavioral switch costs were associated with larger late cue-locked P3 amplitudes in the Switch task only (peak latency 400-450 ms post-cue onset at mid-parietal sites). Together with our information theoretical estimations, ERP results suggested that restart and switch costs indexed two neural mechanisms related to the preparatory resolution of uncertainty: (1) the intermittent re-activation of task-set information, and (2) the updating of stimulus-response mappings within an active task set, as indexed by early and late cue-locked P3 activations, respectively. In contrast, target-locked P3 activations reflected a functionally distinct mechanism related to the implementation of task-set information. We conclude that task-switching costs consist of both switch-specific and switch-unspecific processes during the preparation and execution stages of task performance. © 2008 Barceló, Periáñez and Nyhus

The role of low and high spatial frequencies in exogenous attention to biologically salient stimuli.

Exogenous attention can be understood as an adaptive tool that permits the detection and processing of biologically salient events even when the individual is engaged in a resource-consuming task. Indirect data suggest that the spatial frequency of stimulation may be a crucial element in this process. Behavioral and neural data (both functional and structural) were analyzed for 36 participants engaged in a digit categorization task in which distracters were presented. Distracters were biologically salient or anodyne images, and had three spatial frequency formats: intact, low spatial frequencies only, and high spatial frequencies only. Behavior confirmed enhanced exogenous attention to biologically salient distracters. The activity in the right and left intraparietal sulci and the right middle frontal gyrus was associated with this behavioral pattern and was greater in response to salient than to neutral distracters, the three areas presenting strong correlations to each other. Importantly, the enhanced response of this network to biologically salient distracters with respect to neutral distracters relied on low spatial frequencies to a significantly greater extent than on high spatial frequencies. Structural analyses suggested the involvement of internal capsule, superior longitudinal fasciculus and corpus callosum in this network. Results confirm that exogenous attention is preferentially captured by biologically salient information, and suggest that the architecture and function underlying this process are low spatial frequency-biased

White matter clusters in which FA showed a significant positive association with BOLD activity at intraparietal sulci (rIPS and lIPS) and middle frontal gyrus (MFG) ROIs (<b>Figure 3</b>) (p<0.01, unc., cluster threshold = 30).

<p>Statistical maps are overlaid on the average of normalized FA images from the n = 36 sample itself (presented in neurological convention: R = R). IC = internal capsules (green), SLF = superior longitudinal fasciculus (red), CC = corpus callosum (blue).</p

Average response of intraparietal sulci (rIPS and lIPS) and right middle frontal gyrus (rMFG) ROIs in response to Biological Saliency and Spatial Frequency.

<p>Error bars depict standard error of means. HSF = high spatial frequency distracters, LSF = low spatial frequency distracters.</p

Clusters showing biologically Salient>Neutral significant differences (p<0.001, unc., cluster threshold = 30) after applying an inclusive mask containing voxels significantly associated with behavior (p<0.05, FWE corrected, cluster threshold = 0). Coordinates correspond to the peak voxel within each ROI. BA = Brodmann area; rIPS = right intraparietal sulcus; lIPS = left intraparietal sulcus; rMFG = right middle frontal gyrus.

<p>Clusters showing biologically Salient>Neutral significant differences (p<0.001, unc., cluster threshold = 30) after applying an inclusive mask containing voxels significantly associated with behavior (p<0.05, FWE corrected, cluster threshold = 0). Coordinates correspond to the peak voxel within each ROI. BA = Brodmann area; rIPS = right intraparietal sulcus; lIPS = left intraparietal sulcus; rMFG = right middle frontal gyrus.</p