A Top-Down and Bottom-Up Component of Visual Attention

A new constituent of visual attention theory is proposed based on research in an animal model system. That showed that the neuromodulators released by efference from that animal's brain can accelerate or retard the potentials produced by visual stimulation of that animal's photoreceptors. Such a possibility has never been considered in human behavioral research even though it has been clearly demonstrated that attention can alter the temporal window of visual perception. We therefore propose that attention theory should include new top-down and bottom-up components (TBC) with a top-down component that involves efferents that go from the brain to the photoreceptors and a bottom-up component that involves consequent neuromodulatory alterations of the timing of the afferent photoreceptor potentials evoked by light stimuli. Not long ago, it would have been infeasible to test the validity of TBC in humans. However, newly developed multifocal electroretinogram (mfERG) technology makes it possible to obtain comfortable and objective measures of the timing of human retinal potentials while obtaining quantitative behavioral measures of both the observer's state of attention and of visual performance. If the present prediction is confirmed by such measures, it would allow the mfERG technique to be used for both the objective diagnosis of and the quantitative evaluation of treatments for a variety of attention disorders. These would include attention deficit hyperactivity disorders as well as several psychoses that involve attentional difficulties. The costs of testing TBC are modest; the potential benefits of applying this neurocomputational technology to assist sufferers could be substantial.