Photoreceptor latency: analysis and definition.
Latency as a time difference between the stimulating light-pulse and the recorded potential response was studied with intracellular recording techniques on blowfly (Calliphora) visual receptors. Latency was shown to be a meaningful parameter in analysing the information content of the recorded receptor potential responses by comparing latency vs. amplitude functions using different intensities of stimulating light, stimulating angles of the incident light, ambient temperatures, and flies of different developmental stages. The maximum amplitude of the response is not sufficient to describe stimulus-response functions. With the help of the linear correlation analysis the most useful latency criterion among three widely used latency parameters (viz. the amplitude threshold (1 mV), the visual estimation (detectable voltage) and the maximum slope intersection with the base-line) was investigated. These were studied by correlating them with other commonly used response parameters. An arbitrarily chosen latency parameter that shows the lowest correlation coefficient is considered to contain more additional information from the photoreceptor voltage response than a latency parameter with high correlation. According to our analysis the most useful latency determination is proposed to be the time from the stimulus onset to the intersection of the maximum tangent at the base line, a criterion which also allows one to use concepts derived from systems analysis. The concept of latency is discussed and a definition proposed in the light of this and other recent findings.
D000818:Animals; D004175:Diptera / Q000502:physiology; D005260:Female; D008297:Male; D010775:Photic Stimulation; D010786:Photoreceptor Cells / Q000502:physiology*; D013696:Temperature; D013997:Time Factors