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The "Landmark Task" is designed to tease apart two major factors in determining line bisection errors in spatial neglect: one whose general nature is perceptual, the other whose nature is motor. On critical test trials, the subject is required to point to whichever end of a mid-transected line is judged as nearer to the transection. Seven out of eight(More)
BACKGROUND AND PURPOSE Intracranial vascular malformations (IVMs) are an important cause of intracranial hemorrhage, epilepsy, and long-term disability in adults. There are no published prospective, population-based studies dedicated to the detection of any type of IVM (cavernous malformations, venous malformations, and arteriovenous malformations [AVMs] of(More)
The rightward line bisection errors made by patients with visuospatial neglect can be explained as due to a spatially misdirected response, which would be predicted on either of two accounts. An alternative view, however, is that such patients actually misperceive the left half of a horizontal line as being shorter than the right half. We have tested this(More)
Event-related potentials (ERPs) were recorded in a three stimulus oddball task from 16 patients who had sustained a severe closed head injury at least 6 months before testing, and from 16 control subjects. The stimuli comprised a random sequence of frequent non-target tones (P = 0.70), rare target tones (P = 0.15), and rare novel sounds (P = 0.15). The task(More)
It has been previously reported that a substantial proportion of newly referred neurology out-patients have symptoms that are considered by the assessing neurologist as unexplained by 'organic disease'. There has however been much controversy about how often such patients subsequently develop a disease diagnosis that, with hindsight, would have explained(More)
Event-related potentials (ERPs) were recorded during a continuous recognition memory task for visually presented words, with a 6 item lag between the first and second presentation of each word. The subjects consisted of: (i) a control group of patients with primary generalized epilepsy; (ii) patients who had undergone either a left or a right anterior(More)
Event-related potentials (ERPs) were recorded for visually presented words in young and older participants while they performed two tasks. In the indirect task, participants responded to occasional target words. Some of the nontarget words were repeated after a single intervening trial, and others were repeated after a mean of 10 trials. In the direct task(More)
Single photon emission computed tomography (SPECT) used in conjunction with HM-PAO (Ceretec-Amersham International) was used to image regional cerebral blood flow (rCBF) in 28 patients with medically intractable complex partial seizures during or soon after a seizure, and interictally. Changes from interictal rCBF were seen in 26/28 (93%) patients. The main(More)
Patients with Parkinson's disease (PD) show impairments on tasks that require them to switch attention between two perceptual dimensions (extradimensional (ED) shifting). It has been suggested that ED shifting deficits can be caused by two separate mechanisms, 'learned irrelevance' and 'perseveration'. This study set out to test the hypothesis that enhanced(More)
Event-related potentials (ERPs) were recorded during auditory and visual "oddball" tasks from a patient with a severe verbal memory deficit due to a low grade infiltrating glioma which involved the full extent of the left medial temporal lobe. In both sensory modalities, the patient's oddball-evoked P300s were symmetrical and of normal amplitude. These(More)