Sonia Doallo

The time course of the effects of central and peripheral cues on visual processing: an event-related potentials study

OBJECTIVE The varying results of visual event-related potential (ERP) studies of central and peripheral cueing suggest that these types of cue may modulate stimuli processing with different time courses. The aim of this study was to investigate differences in the time course of facilitatory effects on the visual processing induced by peripheral and central cues. METHODS ERPs were recorded for visual target stimuli that were preceded by informative-central, informative-peripheral or uninformative-peripheral cues with stimulus onset asynchronies (SOAs) of 100, 300, 500 or 700 ms. RESULTS Validly cued stimuli elicited an enhanced P1 component with peripheral cueing at 100 ms SOA. P1 amplitude in valid trials was reduced at 300, 500 and 700 ms SOAs with uninformative-peripheral cueing, but only at 500 ms SOA with informative-peripheral cueing. With informative-central cueing, there was no validity effect on P1. CONCLUSIONS These results suggest that the automatic attraction of attention by a peripheral cue results in improved sensory processing at the cued location. This facilitation is replaced by an inhibitory effect when SOA increases, although cue informativeness may modulate this effect. Central cueing does not affect sensory processing at the P1 level.

Binge drinking trajectory and neuropsychological functioning among university students: A longitudinal study

BACKGROUND Adolescence is a time of considerable neurodevelopment. Binge drinking (BD) during this period increases the vulnerability to its neurotoxic effects. This longitudinal study aimed to investigate the relationship between BD trajectory over university years and neuropsychological functioning. METHODS Cohort-study. Two-year follow-up. A total of 89 university students were assessed: 40 Non-BD (at Initial and Follow-up), 16 Ex-BD (BD at Initial but not at Follow-up) and 33 BD (at both times). Neuropsychological assessment of working memory, episodic memory and executive abilities was carried out during their first (Initial) and third (Follow-up) academic year at the University of Santiago de Compostela. RESULTS BD subjects performed less well on the Wechsler Memory Scale-III (WMS-III) Logical Memory Subtest (immediate theme recall, P=.034; delayed theme recall, P=.037; and percent retention, P=.035) and committed more perseverative errors on the Self-Ordered Pointing Task (SOPT) (P=.021) than Non-BD. There were no differences between Ex-BD and Non-BD. CONCLUSIONS Binge drinking trajectory during adolescence is associated with neuropsychological performance. Persistent BD, but not Ex-BD, is associated with verbal memory and monitoring difficulties. This is compatible with the hypothesis that heavy alcohol use during adolescence may affect cognitive functions that rely on the temporomesial and dorsolateral prefrontal cortex.

Impact of Alcohol Use on Inhibitory Control (and Vice Versa) During Adolescence and Young Adulthood: A Review

AIMS Adolescence is usually the time when individuals first drink alcohol and this has been associated with relatively weak or immature inhibitory control. This review examines the changes on brain development and inhibitory function that take place during adolescence and youth as well as the relationship between inhibitory control and alcohol use at this early age. METHODS Narrative review of the chief studies related to (a) the development of inhibitory control during adolescence, (b) the deficits in the inhibitory ability in alcohol use disorders and (c) the effects of acute alcohol intake and binge drinking on inhibitory control in adolescents and young adults. RESULTS Inhibitory control processes are developing during adolescence and youth. Poor inhibitory functions may predispose the individual to alcohol misuse. Likewise, acute and binge alcohol drinking may impair the inhibitory control and compromise the ability to prevent or stop behaviour related to alcohol use. CONCLUSION Poor inhibitory control can be both the cause and the consequence of excessive alcohol use. Adolescence and young adulthood may be a particularly vulnerable period due to (a) the weak or immature inhibitory functioning typical of this stage may contribute to the inability of the individual to control alcohol use and (b) alcohol consumption per se may alter or interrupt the proper development of inhibitory control leading to a reduced ability to regulate alcohol intake. Further longitudinal research is needed to evaluate the interaction between inhibitory control dysfunction and alcohol use in both situations.

Effects of a Persistent Binge Drinking Pattern of Alcohol Consumption in Young People: A Follow-Up Study Using Event-Related Potentials

AIMS The objective of this study was to examine brain activity related to visual attention processes in youths who had maintained a binge drinking (BD) pattern of alcohol consumption for >2 years. METHODS The participants were 57 university students (26 binge drinkers: BDs) with no personal or family history of alcoholism or psychopathological disorders in first-degree relatives. Event-related potentials (ERPs) were recorded while participants performed a visual oddball task (twice within a 2-year interval). The latency and amplitude of the P3b component of the ERPs were analysed. RESULTS The P3b amplitude was larger in young BDs than in aged-matched controls at both evaluation times, and the difference was more pronounced after 2 years of maintenance of a BD pattern of consumption. The larger P3b amplitude was associated with an earlier onset of regular drinking and with a greater quantity and intensity of consumption. CONCLUSIONS These findings suggest that young BDs exhibit anomalies in neural activity involved in attentional/working memory processes, which increase after 2 years of maintenance of BD. This anomalous neural activity may reflect underlying dysfunctions in neurophysiological mechanisms as well as the recruitment of additional attentional/working memory resources to enable the binge drinkers to perform the task adequately.

Evolution of the binge drinking pattern in college students: neurophysiological correlates

It is well known that alcohol impairs response inhibition and that adolescence is a critical period of neuromaturation where cognitive processes such as inhibitory control are still developing. In recent years, growing evidence has shown the negative consequences of alcohol binge drinking on the adolescent and young human brain. However, the effects of cessation of binge drinking on brain function remain unexplored. The objective of the present study was to examine brain activity during response execution and inhibition in young binge drinkers in relation to the progression of their drinking habits over time. Event-related potentials (ERPs) elicited by a Go/NoGo task were recorded twice within a 2-year interval in 57 undergraduate students (25 controls, 22 binge drinkers, and 10 ex-binge drinkers) with no personal or family history of alcoholism or psychopathological disorders. The results showed that the amplitude of NoGo-P3 over the frontal region correlated with an earlier age of onset of regular drinking as well as with greater quantity and speed of alcohol consumption. Regression analysis showed that NoGo-P3 amplitude was significantly predicted by the speed of alcohol intake and the age of onset of regular drinking. The group comparisons showed that, after maintaining a binge drinking pattern for at least 2 years, binge drinkers displayed significantly larger NoGo-P3 amplitudes than controls, whereas ex-binge drinkers were in an intermediate position between the two other groups (with no significant differences with respect to controls or binge drinkers). These findings suggest that binge drinking in young people may impair the neural functioning related to inhibitory processes, and that the cessation of binge drinking may act as a brake on the neurophysiological impairments related to response inhibition.

Modulations of the visual N1 component of event-related potentials by central and peripheral cueing

OBJECTIVE The aim of this study is to investigate the effects of the central and peripheral cueing on N1 component of the event-related potentials (ERPs) and the time course of these effects. METHODS ERPs were recorded while participants performed a discrimination task on the height of target bars, which were presented after informative-central, informative-peripheral or uninformative-peripheral cues with stimulus onset asynchronies (SOAs) of 100, 300, 500 or 700 ms. RESULTS Peripheral cues (informative and uninformative) elicited stronger effects of cue validity on N1 300 ms after cue onset, whereas central cues led to a more sustained validity effect on N1, with later stronger effects, at 500 ms SOA. CONCLUSIONS The present data showed that central and peripheral cues affected to the level of processing reflected by the N1 component, but there were differences in the time course of these effects. Attentional orienting in response to central cueing resulted in a sustained validity effect on N1, relative to the more transitory activation of the process reflected by the N1 validity effect in this peripheral cueing task. SIGNIFICANCE This study provides a detailed within-subject analysis of the time course of the effects of central and peripheral cueing on N1.

Larger Mid-Dorsolateral Prefrontal Gray Matter Volume in Young Binge Drinkers Revealed by Voxel-Based Morphometry

Binge drinking or heavy episodic drinking is a high prevalent pattern of alcohol consumption among young people in several countries. Despite increasing evidence that binge drinking is associated with impairments in executive aspects of working memory (i.e. self-ordered working memory), processes known to depend on the mid-dorsolateral prefrontal cortex (Brodmann areas 46 and 9), less is known about the impact of binge drinking on prefrontal gray matter integrity. Here, we investigated the effects of binge drinking on gray matter volume of mid- dorsolateral prefrontal cortex in youths. We used voxel-based morphometry on the structural magnetic resonance images of subjects reporting a persistent (at least three years) binge drinking pattern of alcohol use (n = 11; age 22.43±1.03) and control subjects (n = 21; age 22.18±1.08) to measure differences in gray matter volume between both groups. In a region of interest analysis of the mid-dorsolateral prefrontal cortex, after co-varying for age and gender, we observed significantly larger gray matter volume in the left mid-dorsolateral prefrontal cortex (Brodmann areas 46 and 9) in binge drinkers in comparison with control subjects. Furthermore, there was a significant positive correlation between left mid-dorsolateral prefrontal cortex volume and Self-Ordered Pointing Test (SOPT) total errors score in binge drinkers. The left mid-dorsolateral prefrontal cortex volume also correlated with the quantity and speed of alcohol intake. These findings indicate that a repeated exposure to alcohol −that does not meet criteria for alcohol dependence− throughout post-adolescent years and young adulthood is linked with structural anomalies in mid-dorsolateral prefrontal regions critically involved in executive aspects of working memory.

Covert orienting of visuospatial attention in the early stages of aging

Electrophysiological and behavioral responses were recorded in healthy young (19–23 years) and older (56–66 years) subjects during the execution of a visuospatial attention task. The objective was to test whether covert orienting of visuospatial attention (COVAT) is sensitive to the early stages of aging. All subjects responded faster to targets following valid than invalid cues. The amplitude of the P1 component of visual event-related potentials (ERP) was larger to targets following central valid cues at all SOAs. Subtle age-related changes were observed in P1 amplitude under peripheral cueing. Furthermore, older subjects presented longer reaction times (RTs) and lower P1 amplitudes regardless of the attention condition.

Long-term memories bias sensitivity and target selection in complex scenes

In everyday situations, we often rely on our memories to find what we are looking for in our cluttered environment. Recently, we developed a new experimental paradigm to investigate how long-term memory (LTM) can guide attention and showed how the pre-exposure to a complex scene in which a target location had been learned facilitated the detection of the transient appearance of the target at the remembered location [Summerfield, J. J., Rao, A., Garside, N., & Nobre, A. C. Biasing perception by spatial long-term memory. The Journal of Neuroscience, 31, 14952–14960, 2011; Summerfield, J. J., Lepsien, J., Gitelman, D. R., Mesulam, M. M., & Nobre, A. C. Orienting attention based on long-term memory experience. Neuron, 49, 905–916, 2006]. This study extends these findings by investigating whether and how LTM can enhance perceptual sensitivity to identify targets occurring within their complex scene context. Behavioral measures showed superior perceptual sensitivity (d′) for targets located in remembered spatial contexts. We used the N2pc ERP to test whether LTM modulated the process of selecting the target from its scene context. Surprisingly, in contrast to effects of visual spatial cues or implicit contextual cueing, LTM for target locations significantly attenuated the N2pc potential. We propose that the mechanism by which these explicitly available LTMs facilitate perceptual identification of targets may differ from mechanisms triggered by other types of top–down sources of information.

Reward associations magnify memory-based biases on perception

Long-term spatial contextual memories are a rich source of predictions about the likely locations of relevant objects in the environment and should enable tuning of neural processing of unfolding events to optimize perception and action. Of particular importance is whether and how the reward outcome of past events can impact perception. We combined behavioral measures with recordings of brain activity with high temporal resolution to test whether the previous reward outcome associated with a memory could modulate the impact of memory-based biases on perception, and if so, the level(s) at which visual neural processing is biased by reward-associated memory-guided attention. Data showed that past rewards potentiate the effects of spatial memories upon the discrimination of target objects embedded within complex scenes starting from early perceptual stages. We show that a single reward outcome of learning impacts on how we perceive events in our complex environments.