PerceptualandMotorSkilh, 1994, 78, 1147-1152. O Perceptual and Motor Skills 1994 N O SPECIFIC EFFECTS OF CALORIC STIMULATION ON THE VISUAL-IMAGERY PROCESSES O F NORMAL SUBJECTS ' DAVID ALWAY LAWRENCE I. SHOTLAND Cognitive Neuroscience Section Hearing Section, Nmro-otology Branch Medical Neurology Branch National Institute on Deafness and National Institute of Neurological Other Communicative Disorders Disorders and Stroke PAOLO NICHELLI ILDEBRANDO AWOLLONIO Cognitive Neuroscience Section Medical Neurology Branch National Institute of Neurological Disorders and Stroke Cognitive Neuroscience Section Medical Neurology Branch National Institute of Neurological Disorders and Stroke Clinica Neurologica Universifa di Milano JORDAN GRAFMAN Cognitive Neuroscience Section, Medical Neurology Branch National Institute of Neurological Disorders and Sboke Summary.-Recent research indicates that neglect can be temporarily, but only partially, ameliorated by activating the contralateral hemisphere via caloric stimulation and other techniques. In this study, we evaluated whether caloric stimulation could be used to manipulate visual-imagery processes in normal subjects. 11 normal subjects par- ticipated in a quantitative visual-imagery task while undergoing caloric stimulation. Neither side of report nor ear of caloric stimulation affected performance. Possible rea- sons for this negative result are reviewed. Caloric stimulation was first used by Silberpfennig (8) and more exten- sively by Rubens (7) to improve transiently the performance of patients with visual neglect on a variety of tasks designed to evaluate inattention. Caloric stimulation is a technique whereby warm or cool water is circulated in the ear canal, unilaterally increasing or decreasing the firing of acceleration sen- sors in the horizontal semicircular canal. The increased or decreased firing of these sensors via vestibular nuclei in the brainstem and other nuclei causes a periodic horizontal movement of the eyes (nystagmus), dizziness, and some- times nausea (4). It was subsequently found that caloric stimulation could not only transiently ameliorate the symptoms of visual neglect (3, 9, 11) but 'We thank Dr. Karen IUlew for contributing her otolaryngological expertise to the study. Please send all correspondence and requests for reprints to Jordan Grafman, Ph.D., Cognitive Neu- roscience Section, Medical Neurology Branch, National Institute of Neurological Disorders and Stroke, Building 10, Room 5S209, Bethesda, Maryland 20892, USA. E-Mail: JGR@CU.NIH. GOV.