Vestibular Stimulation to Treat Hemispatial Neglect

• Line bisection: Line bisection requires the participant to indicate the midpoint of a horizontal line by dividing it into two equal sections. Neglect patients typically place their mark to the right of center (86), with longer lines producing larg
  
• Star Cancellation: Cancellation requires the subject to scan through a printed sheet containing a set of various symbols and place a mark through one specific subset. Relative to line bisection, this task places a much greater emphasis on the proc
  
• Straight-ahead pointing: This test provides a more specific measure of their perception of body midline, and any associated egocentric bias. It requires the participant to indicate the precise point at which a small, slow moving stimulus crosses s
  
• Visual Search: While these standard clinical tests described above are sensitive to the overall severity of neglect, they provide little quantitative data on the dynamic aspects of attentional distribution. To address this, patients will perform a
  
• In the present study, patients will search for an inverted T surrounded by distractors that appear as Ts of different orientations (upright, 900 or 2700). This kind of 'conjunction' search has been shown to place high demands on attention and therefor
  
• Based on our previous experience, we anticipate that the bisection, cancellation and pointing tasks will each take around 5 minutes to complete, with the visual search task taking around 10 minutes
  

The purpose of the current proposal is to pilot a new and potentially improved treatment for neglect. The procedure involves the delivery of transcutaneous small-amplitude current to the vestibular nerves that lie directly below the mastoid bones. With the intention of boosting activity in the damaged left hemisphere, positive and negative current is delivered to the left and right mastoids respectively. While successfully used to rehabilitate gait and balance disorders, the procedure has only once been applied to neglect.

In the present investigation, we will first confirm and then optimize the conditions under which galvanic vestibular stimulation (GVS) ameliorates neglect. This in turn will justify subsequent work (in a later funding cycle) that will demonstrate the safety and efficacy of the treatment on a much larger clinical scale, and merit the construction of a miniaturized portable device.