Linked Life Data

15610973

Source:http://linkedlifedata.com/resource/pubmed/id/15610973

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2004-12-21
pubmed:abstractText
The retina and optic nerve are both optically accessible parts of the central nervous system. They represent, therefore, highly valuable tissues for studies of the intrinsic physiological mechanism postulated more than 100 years ago by Roy and Sherrington, by which neural activity is coupled to blood flow and metabolism. This article describes a series of animal and human studies that explored the changes in hemodynamics and oxygenation in the retina and optic nerve in response to increased neural activity, as well as the mechanisms underlying these changes. It starts with a brief review of techniques used to assess changes in neural activity, hemodynamics, metabolism and tissue concentration of various potential mediators and modulators of the coupling. We then review: (a) the characteristics of the flicker-induced hemodynamical response in different regions of the eye, starting with the optic nerve, the region predominantly studied; (b) the effect of varying the stimulus parameters, such as modulation depth, frequency, luminance, color ratio, area of stimulation, site of measurement and others, on this response; (c) data on activity-induced intrinsic reflectance and functional magnetic resonance imaging signals from the optic nerve and retina. The data undeniably demonstrate that visual stimulation is a powerful modulator of retinal and optic nerve blood flow. Exploring the relationship between vasoactivity and metabolic changes on one side and corresponding neural activity changes on the other confirms the existence of a neurovascular/neurometabolic coupling in the neural tissue of the eye fundus and reveals that the mechanism underlying this coupling is complex and multi-factorial. The importance of fully exploiting the potential of the activity-induced vascular changes in the assessment of the pathophysiology of ocular diseases motivated studies aimed at identifying potential mediators and modulators of the functional hyperemia, as well as conditions susceptible to alter this physiological response. Altered hemodynamical responses to flicker were indeed observed during a number of physiological and pharmacological interventions and in a number of clinical conditions, such as essential systemic hypertension, diabetes, ocular hypertension and early open-angle glaucoma. The article concludes with a discussion of key questions that remain to be elucidated to increase our understanding of the physiology of ocular functional hyperemia and establish the importance of assessing the neurovascular coupling in the diagnosis and management of optic nerve and retinal diseases.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
1350-9462
pubmed:author
pubmed:issnType
Print
pubmed:volume
24
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
183-215
pubmed:dateRevised
2009-1-15
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
Visually evoked hemodynamical response and assessment of neurovascular coupling in the optic nerve and retina.
pubmed:affiliation
Institut de Recherche en Ophtalmologie, 1950 Sion, Switzerland. charles.riva@iro.vsnet.ch
pubmed:publicationType
Journal Article, Review