title: Canceling out both the real and the spectral lines.
abstract: Neglect patients typically show motor perseveration while canceling targets on the ipsilesional side. This behavior can be influenced by the presence vs. absence of targets on the (neglected) contralesional side (). As alternative explanations, the authors proposed (i) directional hypokinesia--the patient cannot perform reaching movements towards detected left-sided targets, and thus carries on canceling on the right side, and (ii) allochiria--the patient misperceives left-sided targets as located on the right side, and cancels them there. We report here data from a patient (EZ) that might confirm the second hypothesis. EZ was presented with 19 displays in which the number and position of cancellation targets on both sides were varied systematically. EZ showed motor perseveration while canceling, but this tendency did not vary across conditions. Interestingly though, EZ also drew cancellation marks in the empty space between the ipsilesional targets, and this phenomenon was significantly more intense when there were more targets on the neglected side. As EZ's comments suggested, such a behavior might reflect the attempt to cancel out delusional targets. Our speculation is that those objects were generated by allochiria.
authors.affiliation: International School for Advanced Studies, Trieste, Italy. alessio.toraldo@unipv.it
authors.forename: Alessio
authors.initials: A
authors.lastname: Toraldo
authors.forename: Martina
authors.initials: M
authors.lastname: Gandola
authors.forename: Simona
authors.initials: S
authors.lastname: Loffredo
authors.forename: Anna
authors.initials: A
authors.lastname: Rancati
authors.forename: Gabriele
authors.initials: G
authors.lastname: Zanardi
authors.forename: Gabriella
authors.initials: G
authors.lastname: Bottini
mesh_terms: D000368:Aged; D005260:Female; D005364:Field Dependence-Independence; D007839:Functional Laterality; D006801:Humans; D010364:Pattern Recognition, Visual; D010468:Perceptual Disorders / Q000175:diagnosis* / Q000209:etiology / Q000523:psychology; D010470:Perceptual Masking; D013028:Space Perception; D020521:Stroke / Q000150:complications* / Q000175:diagnosis / Q000523:psychology