Biomedical subjects

Elizabeth Coulthard

Publications and source records attributed to Elizabeth Coulthard.

4 recordsLinked to original sources

PubMed2006

Hemispatial neglect, balance and eye-movement control.

PURPOSE OF REVIEW: Disorders of spatial awareness and balance following stroke are common but often under-diagnosed. They lead to poor outcome and frequently coexist. Here we focus on recent progress in the understanding of the mechanisms underlying these disorders and potential therapeutic advances. RECENT FINDINGS: Right-hemisphere networks are important for both spatial attention and postural awareness. Neglect patients show multiple oculomotor impairments including reduced saccade amplitude and difficulty retaining spatial locations across saccades. There has been controversy regarding the brain regions associated with neglect, although most studies show the right inferior parietal lobe to be crucial and new imaging modalities have provided insight into neglect caused by subcortical stroke. The 'pusher syndrome' is a poorly understood balance disorder where patients push towards their paretic side, resulting in falls. It may involve impairment of subjective verticality but experimental studies have reported diverse findings. Advances in treatment for neglect include the successful use of prism adaptation and pilot data suggesting noradrenergic stimulation may improve search in selected patients. SUMMARY: New experimental techniques have provided insight into the debilitating disorders of spatial and postural awareness that often follow stroke. There are currently no widely used therapies for neglect but both new behavioural techniques and pharmacological methods are promising.

Animals↗

PubMed2006

Treatment of attention deficits in neurological disorders.

PURPOSE OF REVIEW: Recent work has revealed the impact of deficits of attention on patients with neurological disorders. Here we discuss therapeutic interventions that have been used across a range of conditions, highlighting common themes both in the nature of the attention deficits and the strategies employed to treat them. RECENT FINDINGS: Cholinesterase inhibitors improve attention, as well as memory, in several conditions including cortical Lewy body disease, Parkinson's disease dementia, traumatic brain injury and Alzheimer's disease. Recent studies suggest that cholinergic stimulation may boost attention further if more specific nicotinic cholinergic agonists are used, or if cholinesterase inhibitors are combined with other agents. Monoaminergic drugs have been shown to improve attention in traumatic brain injury, attention-deficit hyperactivity disorder and hemispatial neglect following right-hemisphere stroke. New compounds targeting other neurotransmitter systems are currently being tested, while several types of behavioural intervention have shown promise, particularly in stroke patients. SUMMARY: Pharmacological and behavioural interventions can improve attention in neurological patients. In the future, optimum therapy may depend on careful delineation of the components of attention that are impaired as well as assessment of the potential for surviving brain regions to compensate for attention deficits.

Attention↗

PubMed2005

Action control in visual neglect.

Patients with unilateral neglect show a variety of impairments when reaching towards objects in contralesional space. The basis of these deficits could be perceptual, motor or at one of the intermediate stages linking these processes. Here, we review studies of visually guided reaching in neglect and integrate these results with findings from normal human and monkey action control. We consider evidence which shows that neglect patients can be slow to initiate or execute reaches particularly to a contralesional target. We discuss the directional and spatial deficits that may interact to contribute to such reaching abnormalities and highlight the importance of effective target selection and on-line guidance, exploring the idea that deficits in these mechanisms underlie increased susceptibility to ipsilesional visual distraction in neglect. We also examine the relationship between optic ataxia and neglect by considering two illustrative cases, one with pure optic ataxia and the other with optic ataxia plus neglect, which reveal differences in the anatomical substrates of the two syndromes. We conclude that many patients with neglect make abnormal visually guided reaches, but the pattern of reaching deficits is highly variable, most likely reflecting heterogeneity of lesion location across subjects. Rather than being specific to the neglect syndrome, abnormalities of reaching in these patients may correspond to the extent of damage to the visuomotor control system which involves critical regions in both the parietal and frontal cortex, the white matter tracts connecting them and subcortical regions. Thus, the action control deficits in neglect may be conceptualised as a range of impairments affecting multiple stages in the visuomotor control process.

Attention↗

PubMed2005

Neuropharmacological modulation of cognitive deficits after brain damage.

PURPOSE OF REVIEW: This review discusses recent studies that have implications for potential neuropharmacological interventions which target cognitive deficits resulting from traumatic brain injury or stroke. RECENT FINDINGS: An important new study concerning the activity of N-methyl-D-aspartate (NMDA) receptors after brain injury reveals that previous influential hypotheses about an increase in glutamate triggering neuronal death may need to be revised. Furthermore, the study suggests that cognitive function may be best preserved by stimulation of NMDA receptors with agonists rather than by the use of antagonists, as previously believed. Investigations of animal models of stroke and traumatic brain injury have further demonstrated the possibility of intervening in the acute and sub-acute stages to protect specific brain systems, such as preservation of the cholinergic system (via cholinesterase inhibitors) and hippocampal neurons (via a D2 agonist). Clinical trials in humans indicate it is also possible to target these neurotransmitter systems to enhance cognitive performance in patients with chronic deficits. In particular, recent studies demonstrated that it is possible to ameliorate the effects of two common cognitive syndromes, visual neglect and aphasia. SUMMARY: Cognitive deficits are an extremely common consequence of either traumatic brain injury or stroke. Recent studies demonstrate the potential for using neuropharmacological intervention after acquired brain injury to prevent or ameliorate the effects of cognitive impairments. These treatments, however, are still in their preliminary stages and further research is required to identify the most effective compounds.

Animals↗