Attentional grasp in far extrapersonal space after thalamic infarction Anna M. Barrett a, b, *, Ronald L. Schwartz c , Gregory P. Crucian a, b , Manho Kim d , Kenneth M. Heilman a, b a Department of Neurology, University of Florida College of Medicine, Florida, USA b VA Medical Center, Gainesville, FL, USA c Department of Neurology, University of Florida Health Science Center, Jacksonville, FL, USA d Department of Neurology, Massachusetts General Hospital, Boston, MA, USA Received 4 January 1999; received in revised form 5 October 1999; accepted 11 October 1999 Abstract Studies of animals and humans with focal brain damage suggest that attention in near and far extrapersonal space may be mediated by anatomically separate systems. Thalamic lesions have been associated with spatial neglect, but whether asymmetric attention speci®c to near or far space occur after thalamic damage has not been explored. It is also unclear if thalamic injury can induce contralesional defective response inhibition. We tested a woman with a left thalamic infarction who reported that, when driving, she had a tendency to veer towards people or objects on the right side of the road. Our patient and four controls performed a line bisection task with a laser pointer in near and far extrapersonal space. The experimenter marked each bisection either from the right of the presented line (right- distractor, RD) or the left (left-distractor, LD). RD and LD trials were pseudo-randomized. Our patient performed similarly to controls (mean À0.7 mm, controls À0.6 mm) on the line bisection task in near space. In far space she erred signi®cantly rightward compared to her performance in near space ( p < 0.001). Controls performed similarly in near and far space. The experimenter position did not aect our patient's performance on near line bisections, nor did controls demonstrate a distractor eect for the near condition. In the far condition, however, our patient showed a signi®cant distractor eect (LD À3.3 mm, RD 35.3 mm, p < 0.001). Controls also demonstrated a distractor eect in the far condition (LD À6.4 mm, RD 0.7 mm, p < 0.01), though of much smaller magnitude. Our results suggest that frontal-thalamic systems regulating visual attention may be disrupted by thalamic infarction. Such damage may produce an attentional grasp speci®c to far extrapersonal space. Published by Elsevier Science Ltd. Keywords: Thalamus; Attention; Stroke 1. Introduction Attention and action in near extrapersonal space may be mediated by an anatomically separate brain system from attention and action in far extrapersonal space. Holmes and Horrax [22] and Brain [3] reported a patient whose ability to reach for and localize objects diered within and outside arms' length. Rizzolatti and colleagues [35] found in primates that the neglect of dierent regions of extrapersonal space appear to be related to dierent frontal anatomic areas. Using selective frontal resections, they showed that unilateral damage to area 6 produced de®cits in near space (the peribuccal region) whereas damage to the frontal eye ®elds (area 8) produced de®cits with more distant objects. The near/far dissociation can also be produced by subcortical damage in areas pro- Neuropsychologia 38 (2000) 778±784 0028-3932/00/$ - see front matter Published by Elsevier Science Ltd. PII: S0028-3932(99)00144-X www.elsevier.com/locate/neuropsychologia * Corresponding author. Section of Neurology, PO Box 850, Penn- sylvania State University College of Medicine, Hershey, PA 17033, USA. Tel.: +1-352-392-3491; fax: +1-352-392-6893. E-mail address: abarrett@psghs.edu (A.M. Barrett).