Research in this laboratory is primarily concerned with understanding the cognitive and neural mechanisms underlying attention, perception, and action. We seek answers to questions such as how it is that the human brain encodes the vast arrays of sensory information and what proportion of this information enters our awareness for conscious perception. We are also concerned with how attention influences our perceptual representations of the external world and the effects of attention on subsequently related actions. Addressing these issues has led us to also become interested in how different areas of the brain are orchestrated with one another to provide coherent perceptions and actions in our everyday life.

 

Conscious and Unconscious Perception

We are actively examining the psychological and neural bases for unconscious processing of visual information. These studies, conducted in patients with hemispatial neglect or blindsight, in neurologically intact participants using visual masking paradigms, fMRI, as well as TMS of occipital cortex, have been consistently revealing that much of the visual information we are confronted with is processed without awareness either in early visual cortex or via the retinotectal pathway. The laboratory also explores how oscillatory activity, recorded using fast signal optical imaging (i.e., EROS) and/or through scalp or intracranial (i.e., ECoG, in collaboration with Mike Beauchamp and Dan Yoshor) electrodes, affects conscious perception.

 

Attention and Eye Movements

To understand how we select certain pieces of information for extensive processing, another related line of research in this laboratory has been focused on the cognitive architecture and neural mechanisms involved in generating eye movements and shifts of visual attention. We have shown that saccadic amplitudes are influenced by preceding reflexive shifts of visual attention, which demonstrates a link between attention and the oculomotor system. Also, using methods we developed for localizing the human frontal eye fields with transcranial magnetic stimulation (TMS), we have found that this link may be due to shared neural control of attention and saccades by this region of the brain. In a series of psychophysical, EEG, and TMS studies, we are investigating whether the neural circuitry involved in covertly shifting voluntary attention without eye movements are the same as those involved in the actual generation of saccades and how attention modulates alpha oscillatory activity.

 

Synesthesia and Multisensory Perception

Once some information is selected for more detailed processing, our perceptual systems are often times confronted with the task of integrating information from multiple sensory modalities. This laboratory is also actively researching the ways in which we integrate information from different sensory modalities to provide a coherent representation of an external stimulus. In particular, we have recently been investigating the influences of audition and vision on touch perception. These studies suggest that sounds and visual events can sometimes enhance touch perception in neurologically normal subjects. For example, we have found that hearing or seeing an event associated with a touch, as compared to not hearing or seeing such an event, increases tactile sensitivity. Furthermore, we have been examining the neural bases underlying auditory-tactile synesthesia, both in an acquired case after brain damage and in neurologically intact individuals, using fMRI, DTI, EEG, EROS, and TMS.