04/05/2017
This is the main finding of a study by Alberto Zani, Head of the Brain Cognitive Electro-Functional Imaging Lab of the Institute of Bioimaging and Molecular Physiology of the National Research Council (CNR-IBFM), in collaboration with Alice Mado Proverbio, an affiliate of the "NeuroMI - Milan Center for Neuroscience "and a Professor of Cognitive Neuroscience at the University of Milan-Bicocca. The paper has been published in Scientific Reports Nature. "To investigate the influence of functional alertness and/or attention on brain processing of distracting or conflicting information, a sample of students has been subjected to different experimental conditions in which sequences of contiguous strings of arrows were presented to them. From trial to trial, the direction of the central arrow signaled to the students which hand to use to press a button for the measurement of their reaction times to the appearance of the arrows in one of two alternative points of the visual field, regardless of the direction of the flanking arrows, which could point to the same (congruent) or to the opposite (incongruent) direction of the central one" explained Zani. "Each string of arrows was randomly preceded by a different kind of pre-cueing so to induce, alternatively, in the brain 4 different states of alertness and orienting of attention towards a certain direction, as it can be thought it might occur with road signs, at a crossroads, to any motorist: (1) no signal: that is, a state devoid of any cue prior to the "reflexive" reaction to the arrows (such as, e. g., the one to a pedestrian or a car); (2) a cue on the center of the visual space (like the signals of intersection and preselection placed at the center of a crossroads, such as those in the picture), to generate a state of pre-alert; (3) a cue presented simultaneously in the two visual field points at which the arrows could appear, to induce a maximum alert and a wide visual focusing, (such as the double signals of opposite direction - Rome / Rome - in the picture), associated, in this case, to an obvious decisional conflict; (4) and, finally, the presentation of a single cue at the point where, later on, the arrows would have followed (as the direction signals unique to location confirmation or to exit roads), so as to induce both a state of alert and a " voluntary "orienting of attention prior to the appearance of the latter stimuli. During these experimental conditions, we also recorded brain bioelectric activity (EEG-ERP), which was, later on, analyzed as a function of the different functional states induced and the congruency of the arrows presented" continued Zani. "In the incongruent condition, the speed of participants’ motor response to the arrows was slowed both in the presence and/or absence of alert, but not when the arrows were preceded by the voluntary orienting of attention toward the point of the visual field at which they would then have been shown" said Alice Mado Proverbio. "The analysis of brain waves as a function of the arrows congruency also revealed the occurrence of a so-called Conflict Negativity, (CN), between 250-450 ms after the presentation of the latter in the EEG sensors over the frontal and prefrontal areas of the head (Fig. 2). As with reaction times, the negative peak of this wave was slowed down in the various alert conditions followed by a reflexive orienting of attention to the arrows compared to that found for the voluntary orienting of attention (Fig. 3). As for CN amplitude, the voluntary orienting condition elicited a peak of greater amplitude than that of generic alert, which, in turn, elicited a higher peak than the one devoid of any alert "continued Mado Proverbio." The data are relevant because the Conflict Negativity proved to be a valuable marker of the different neural and behavioral responses related to the processing and reduction of psychomotor conflict induced in the brain by the various cueing contexts, unlike what proposed by current neurocognitive theory that considers the executive control a process not affected by the functional states during which it takes place" stated Zani.
"It 's also important that the topographic mapping of the voltage of this bioelectric neuromarker as a function of the different pre-cueing conditions (Fig. 4) indicated the activation of brain medial anterior cingulate cortex for the voluntary attention condition and of the dorsolateral prefrontal cortex of the right hemisphere for the alerting and reflexive attention conditions " continued Zani. "In general, the data revealed how the brain processes otherwise relevant and interfering or conflicting information depending on its various functional states; a knowledge that has to be borne in mind in the design of environments and machines ergonomically devoid of conflicting setups and command switches, so as to allow their most efficient control where safety is concerned. Above all, however, they have substantial implications for both psychological and neuropsychological clinical practices: (1) in the definition of brain and mental processes underlying cognitive and emotional conflict as well as the decisional instability of patients suffering from anxiety or manic-depressive disorders, and (2) for diagnosing executive control psychomotor deficits in frontal brain-damaged patients, as well as for the rehabilitation programs of these deficits, in relation to the neuromotor functions affected, the injured areas, and their hemispheric lateralization".
Captions
Figure 1. Road signs
Figure 2. Brain bioelectric responses to incongruent (incong.) and congruent (cong.) target-arrow and flanker patterns obtained at fronto-central scalp (FC1 and FC2) homologous scalp sensors as a function of the four pre-cueing conditions - NC = No Cue; CC = Center Cue; 2C = Double cue; LC = Local Cue validly informative of target spatial location - grand-averaged over the students’ sample. Overimposed onto these grand-averaged brain responses, the conflict-related DWs computed subtracting responses to the congruent arrows from responses to the incongruent ones, are also drawn. In the DWs for all cueing conditions a clear-cut post-target conflict negativity (CN) was obtained.
Figure 3. Mean peak latency values and their variation across the sample volunteers (or standard errors, S. E.) of target-related CN as obtained from the differences between the incongruent and congruent flankers conditions as a function of pre-cueing types, namely, NC = No Cue; CC = Center Cue; 2C = Double cue; LC = Local Cue validly informative of target spatial location in the visual field.
Figure 4. Timeline of rainbow-colors-coded scalp-recorded bioelectrical potential maps computed on the difference-waves obtained by subtracting brain responses to congruent from those to incongruent targets in between 250-430 ms after their appearance (i. e., from 750 to 930 ms post-cue delivery or omission), with 10 ms steps, as a function of each pre-cued attention condition: NC = No Cue; CC = Center Cue; 2C = Double cue; LC = Local Cue validly informative of target spatial location. Note that a larger CN shows earliest starting and fading latencies in response to the conflicting information when the spotlight of spatial attention has been already oriented to its location prior than the occurrence of the latter information, namely, for LC with respect to all the other cueing conditions.
Per informazioni:
Alberto Zani
responsabile del Laboratorio di Imaging Elettrofunzionale Cognitivo dell'Istituto di bioimmagini e fisiologia molecolare del Consiglio nazionale delle ricerche (Ibfm-Cnr)
alberto.zani@ibfm.cnr.it
Ufficio stampa:
Emanuele Guerrini
Ufficio stampa Cnr
emanuele.guerrini@cnr.it
06.4993.2644
Responsabile Unità Ufficio stampa:
Marco Ferrazzoli
marco.ferrazzoli@cnr.it
ufficiostampa@cnr.it
06 4993 3383
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