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Biomedical subjects

Matthew Rizzo

Publications and source records attributed to Matthew Rizzo.

7 recordsLinked to original sources
PubMed2003

Unilateral posterior parietal lobe lesions affect representation of visual space.

This study assessed accuracy of visually perceived vertical and trunk median plane orientation in 41 subjects: 17 had unilateral brain lesions including the posterior parietal lobe (PPL), 8 had lesions outside PPL, and 16 were neurologically normal. Vertical perception errors clearly increased with size of unilateral lesions to PPL and posterior superior temporal gyrus (PSTG). Median plane perception errors increased only slightly with size of unilateral lesions to frontal lobe premotor areas and supramarginal gyrus. These results are compatible with the hypothesis that accurate visual vertical perception depends critically on intact PPL and PSTG in both cerebral hemispheres while accurate median plane perception likely involves a bihemispheric network that can compensate for lesions to one hemisphere.

Adult↗
PubMed2003

Spatial attention: normal processes and their breakdown.

Although "attention" is a general term in everyday folk and psychologic use, using research from cognitive psychology allows a focus on the processes associated with attention. A process-oriented definition of attention [2] makes "attention" a concept that can be studied rigorously. Attention is necessary for eliminating unwanted sensory inputs or irrelevant behavioral tasks and is useful when some cognitive system or process receives too many inputs. Attention acts to restrict the number of inputs and allow processing to continue in an effective manner. Although there are many forms of attentional selection, spatial attention is the most studied and perhaps the best understood form of selection. Spatial attention is the variety of attention most widely studied in neuropsychologic populations. As was evident from the authors' review, different neuropsychologic syndromes can be characterized as involving different difficulties with the component processes of spatial attention. Different neural structures work in concert to produce normal spatial selection, and damage to any of these neural structures, including the parietal and frontal lobes, pulvinar, and superior colliculus, produce an attentional impairment. Attentional impairments often have been studied in cases of focal brain damage resulting from stroke, traumatic brain injury, tumor, and surgical resection. Focal or multifocal lesions caused by neurodegenerative impairments, such as PSP and AD, however, also have marked effects on neural processes of attention. Patients with AD exhibit a range of impairments in spatial attention, and these impairments have been studied relatively little. Despite the understanding of attention provided by various patient populations, gaps remain in knowledge of the mechanisms involved in attending to space. For example, most studies of neurologic patients have used a simple spatial cuing paradigm with highly predictive cues. Although this task yields robust results and can be adapted for use with many different patient groups, the spatial cuing effects produced by such tasks have multiple interpretations (e.g., allocation of resources versus reduction of decision noise). This review highlights the general point that different neural sites seem to be responsible for different forms of attentional control, such as object-based attention, attentional task switching, and the executive control of attention [8.33]. Understanding the integration of these neural sites and their relationship to cognitive processes and, ultimately, behavior, will increase understanding of normal and disordered attentional selection.

Alzheimer Disease↗
PubMed2003

The effect of wearing a restrictive neck brace on driver performance.

OBJECTIVE: Thousands of Americans are prescribed cervical orthoses each year. These orthoses restrict motion, which may influence the patient's driving performance. No legal restrictions exist that prohibit patients from wearing cervical orthoses while driving. No study addressing this issue has been published to date. Thus, we sought to assess the effects of wearing a restrictive neck brace on driver performance on the open road. METHODS: We conducted a prospective, randomized block design study in 23 volunteers. Twenty-three adult licensed drivers from the state of Iowa were recruited. Evaluation of neck motion was performed with and without the rigid cervical orthosis. On-road performance testing was conducted with the use of a state-of-the-art mobile laboratory. Drivers were randomly assigned to one of two testing groups. Each driver was evaluated during two separate drives. Volunteers in Group A (n = 11) wore a neck brace for the first drive but not during the second. Participants in Group B (n = 12) did not wear a neck brace in the first drive but did for the second. The assessment included velocity, acceleration, cervical axial rotation, and evaluation of the driver's blind spot. RESULTS: Driving performance measures were collected and analyzed for both drives. Wearing a cervical orthosis resulted in decreased velocity (P < 0.05), decreased lateral acceleration (P < 0.05), decreased axial rotation (P < 0.05), inadequate evaluation of intersection traffic, and an increase in the blind spot. CONCLUSION: A rigid cervical orthosis alters driver performance.

Adult↗
PubMed1999

Effect of Hand Posture on the Temporal and Kinematic Properties of Pointing and Drawing Movements Executed by Healthy Subjects and by a Patient With Primary Writing Tremor.

Healthy individuals (n = 6) and a patient with "pure" primary writing tremor executed pointing and drawing movements while adopting different hand postures. The control subjects and the patient exhibited similar kinematics for most conditions. The patient displayed a severe right hand 4- to 6-Hz tremor and prolonged movements only when drawing with his normal hand posture. His tremor was manifested after a ready cue, in anticipation of a go command. The premovement tremor was abolished when the authors simply eliminated the ready cue and instructed the patient to relax and not think about drawing until he heard the go cue. Thus, the patient's writing tremor depended not only upon the writing or drawing act but also upon the hand position adopted and the intent to write, even in the absence of movement. The present results suggest that (a) similar high-level control mechanisms exist for pointing and drawing in healthy subjects and (b) the patient's deficits are compatible with a higher motor defect in central nervous system structures involved in the control of pointing and drawing movements.

Journal Article↗