Special CNS Seminar
Title: Linking Cognitive Changes in Neuronal Responses to Perception
Visual attention dramatically improves subjects' ability to see and also modulates the responses of visual and oculomotor neurons. Despite hundreds of studies demonstrating the co-occurrence of behavioral and neuronal effects of attention, the relationship between neuronal modulations and improved performance remains unknown. Two dominant hypotheses have guided previous work: that attention 1) improves visual information coding or 2) changes the way visual information is read out by downstream areas involved in decision-making. By recording from groups of neurons at multiple stages of visuomotor processing, we showed that neither of these hypotheses account for observed perceptual improvements. Instead, our data suggest a novel hypothesis: that the well known effects of attention on firing rates and shared response variability in visual cortex reshape the representation of attended stimuli such that they more effectively drive downstream neurons and guide decisions without explicitly changing the weights relating sensory responses to downstream neurons or behavior. Implementing behavioral flexibility by changing the activity in visual cortex is very different than how computational models implement flexibility (e.g. by changing weights relating different nodes of the network or by reducing noise). This mechanism may be a biologically simple way to implement flexibility, and our preliminary experiments suggest that it is at work in other cognitive processes like arousal and task switching. In general, our work shows that constraining our analyses by the animals' behavior and the simultaneous recordings from multiple brain areas can greatly clarify the relationship between attention, neuronal responses and behavior.