Notes

Selective Sensory Attention in Cognitive Neuroscience "It is the taking possession by the mind in clear and vivid form, of one out of what seem several simultaneously possible objects or trains of thought ... It implies withdrawal from some things in order to deal effectively with other,..." - William James in Principles of Psychology (1890)

"Attention is the flexible control of limited computational resources" - Lindsay (2020)

Function of Selective Attention

• In primates, 10ˆ6 retinal ganglion cell axons can carry about 1 MB/s of visual information (already compressed).
• This is too much to be handled in real-time by the brain (there are many other sensory domains that feed data into the brain).
• Some fraction of sensory input is selected for processing by higher-level, cognitive routines, while the non-attended portion of the input is processed at a reduced bandwidth.
• Attention is common to all animals.

Bottom-Up Attention Something immediately draws our eye to the Toblerone and the Matterhorn. This something is visual saliency.

Visual Saliency

• Single map that encodes saliency is feed by multiple feature maps. Which features draw the gaze independent of the task is unknown. Typically, these are faces, orientations, color and intensity.
• After detecting the most salient location, its salience is inhibited.
• Single cell evidence for salience map in the initial response of LIP and FEF neurons in primates.

Nowadays DL is exploited to predict saliency spots in pictures. They take ground truth data and train neural networks to predict saliency points in images with higher accuracy than older models. Such models are also exploited to work in the other direction and help in designing images to convey attention towards specific points of the figure.

Top-Down Attention

• Is flexible and task dependent.
• Can last indefinitely with effort.
• Spatial based, feature-based and object based are forms of top-down attention.
• A close relationship between neuronal mechanics controlling eye gaze and selective attention (LIP, FEF, V4, SC).

Selective Top-Down Attention Neural Signals have been measured in Primates. The primates watch a screen and fix the white dot. Then the three stimuli went on and the cue went on (the central dot that changes color). The researchers used electrophysiology to record the activity of individual neurons in the visual cortex of monkeys as they performed a visual search task. The goal of the task was to detect a target stimulus among a set of distractors. The researches found that attentional modulation was present in both feedforward and feedback signals in the visual cortex, with top-down attentional signals strengthening target-selective responses and suppressing responses to distractors. This study provides evidence for the role of top-down attentional signals in modulating both feedforward and feedback processing in the primate visual cortex, and suggests a mechanism by which attention can selectively enhance target representation and improve perceptual processing.

The paper "Selective Top-Down Attention Modulates Feedforward and Feedback Neural Signals in Primates" by Paperi et al. (2017) investigated the effect of top-down attention on feedforward and feedback signals in primate brains. The study found that when attention was directed towards a particular visual stimulus, both feedforward and feedback signals increased in the regions of the brain responsible for processing that stimulus, demonstrating that top-down attention can modulate both feedforward and feedback signals. These results suggest that attention plays a crucial role in shaping neural processing in the visual system, and that top-down attention can dynamically influence feedforward and feedback signals to enhance processing of behaviorally relevant information.