Reflexive OKN with partial and full field stimulation: effects of age and light level
Author(s)
Hine, Trevor
Wallis, G
Wood, J.
Stavrou, E.
Griffith University Author(s)
Year published
2006
Metadata
Show full item recordAbstract
We recorded reflexive OKN in ten younger (32.3ᵮ98 years) and older (65.6ᶮ53) visually normal subjects under viewing conditions designed to differentiate M-pathway functioning from other pathways. Subjects were required to gaze straight ahead while viewing vertical gratings of either 0.43 or 1.08 cpd, drifting at either 5 or 20௳ec and presented at either 8 or 80% contrast. Gratings were presented as full field stimulation, central stimulation or peripheral (>15stimulation. The order of presentation of conditions was pseudo-randomised at two blocked light levels: 'mesopic' or twilight conditions (1.8 cdm-2) and 'photopic' or ...
View more >We recorded reflexive OKN in ten younger (32.3ᵮ98 years) and older (65.6ᶮ53) visually normal subjects under viewing conditions designed to differentiate M-pathway functioning from other pathways. Subjects were required to gaze straight ahead while viewing vertical gratings of either 0.43 or 1.08 cpd, drifting at either 5 or 20௳ec and presented at either 8 or 80% contrast. Gratings were presented as full field stimulation, central stimulation or peripheral (>15stimulation. The order of presentation of conditions was pseudo-randomised at two blocked light levels: 'mesopic' or twilight conditions (1.8 cdm-2) and 'photopic' or full light conditions (71.5 cdm-2). For the partial fields, central stimulation, mesopic light level, lower temporal frequencies (i.e. number of stripes passing per second) each contributed to greater OKN strength as measured by slow-phase velocity (SPV). For full field stimulation, and especially for higher temporal frequencies and low contrast, there was a significant interaction between age group נlight level (p = 0.017): SPV diminished much more among the older than the younger group for the twilight condition compared to full light. Such a clear diminution in M-pathway sensitivity revealed by OKN response has important implications for everyday situations like crash avoidance under twilight driving conditions.
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View more >We recorded reflexive OKN in ten younger (32.3ᵮ98 years) and older (65.6ᶮ53) visually normal subjects under viewing conditions designed to differentiate M-pathway functioning from other pathways. Subjects were required to gaze straight ahead while viewing vertical gratings of either 0.43 or 1.08 cpd, drifting at either 5 or 20௳ec and presented at either 8 or 80% contrast. Gratings were presented as full field stimulation, central stimulation or peripheral (>15stimulation. The order of presentation of conditions was pseudo-randomised at two blocked light levels: 'mesopic' or twilight conditions (1.8 cdm-2) and 'photopic' or full light conditions (71.5 cdm-2). For the partial fields, central stimulation, mesopic light level, lower temporal frequencies (i.e. number of stripes passing per second) each contributed to greater OKN strength as measured by slow-phase velocity (SPV). For full field stimulation, and especially for higher temporal frequencies and low contrast, there was a significant interaction between age group נlight level (p = 0.017): SPV diminished much more among the older than the younger group for the twilight condition compared to full light. Such a clear diminution in M-pathway sensitivity revealed by OKN response has important implications for everyday situations like crash avoidance under twilight driving conditions.
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Conference Title
Australian Journal of Psychology
Publisher URI
Subject
Psychology
Cognitive Sciences