RESUMEN
Visual attention is widely considered a vital factor in the perception and analysis of a visual scene. Several studies explored the effects and mechanisms of top-down attention, but the mechanisms that determine the attentional signal are less explored. By developing a neuro-computational model of visual attention including the visual cortex-basal ganglia loop, we demonstrate how attentional alignment can evolve based on dopaminergic reward during a visual search task. Unlike most previous modeling studies of feature-based attention, we do not implement a manually predefined attention template. Dopamine-modulated covariance learning enable the basal ganglia to learn rewarded associations between the visual input and the attentional gain represented in the PFC of the model. Hence, the model shows human-like performance on a visual search task by optimally tuning the attention signal. In particular, similar as in humans, this reward-based tuning in the model leads to an attentional template that is not centered on the target feature, but a relevant feature deviating away from the target due to the presence of highly similar distractors. Further analyses of the model shows, attention is mainly guided by the signal-to-noise ratio between target and distractors.
Asunto(s)
Corteza Visual , Ganglios Basales , Humanos , Aprendizaje , Corteza Prefrontal , Recompensa , Percepción VisualRESUMEN
Research on the asymmetric effect of negative versus positive affective states (induced by gains or losses) on scope of attention, both at a perceptual and a conceptual level, is abundant. However, little is known about the moderating effect of anticipating gains or losses versus actually experiencing them and about any downstream consequences of these effects on goal-directed behaviour. In two studies, we show that gains versus losses induce qualitatively different processes. In Experiment 1, we demonstrate that the anticipation of monetary gains results in a narrowing of attentional scope, while experiencing gains broadens the scope of attention. We find the reverse pattern concerning monetary losses - while anticipation of monetary losses results in broadening of attentional scope, the actual experience of losses results in narrowing of attentional scope. Additionally, Experiment 2 replicates these findings and shows how differential attentional tuning as a function of the anticipation versus experience of gains versus losses modulates priming-induced goal-directed behaviour.
Asunto(s)
Objetivos , Motivación , Adolescente , Adulto , Atención , Emociones , Femenino , Humanos , Masculino , Adulto JovenRESUMEN
Here we examined with functional magnetic resonance imaging (fMRI) whether advanced age affects 2 mechanisms of attention that are widely thought to enhance signal processing in the sensory neocortex: gain and tuning. Healthy young and older adults discriminated faces under varying levels of object competition while fMRI was acquired. In young adults, cortical response magnitude to attended faces was maintained despite increasing competition, consistent with gain. Cortical response selectivity, indexed from repetition suppression, also increased only for attended faces despite increasing competition, consistent with tuning. Older adults exhibited intact gain, but altered tuning, with extrastriate cortical tuning determined by object salience rather than attention. Moreover, the magnitude of this susceptibility to stimulus-driven processing was associated with a redistribution of attention-driven competitive processes to the frontal cortices. These data indicate that although both gain and tuning are modulated by increased perceptual competition, they are functionally dissociable in the extrastriate cortices, exhibit differential susceptibility to advanced aging, and spare the frontal cortices a considerable processing burden through early selection.