Figure 3: Measures of object detectability thresholds for single photoreceptors.
From: Visual acuity of the honey bee retina and the limits for feature detection
(a) Left Peak responses (in mV, mean ± 95% confidential intervals, CI) for increasing object areas in both frontal (N = 10, black line) and lateral photoreceptors (N = 8, green line). Horizontal dashed lines represent σ and 2σ for the averaged photoreceptor noise (see experimental procedures and Fig. 2). Right Mean ± 95% CI SNR estimated in the frequency domain for frontal (black line) and lateral (green lines) photoreceptors. Horizontal dotted line represents 0 dB. Vertical lines are drawn to identify the corresponding object size at 2σ noise and for an SNR of 0 dB respectively. (b) Photoreceptor gain obtained as slope from the linear regression of responses to objects <1° (as in the right panel) correlate with both the horizontal and vertical measures of Δρ. (c) Zoomed in view of the data in (a), for object areas ≤0.8 deg2. Black lines are the linear regression for responses to objects <1° while data in red are for the signal to noise ratio (SNR) calculated as described in ‘Temporal analysis of SNR’. Dotted and unbroken lines represent average lateral and frontal photoreceptor responses, respectively. Horizontal dotted lines represent σ and 2σ of the averaged photoreceptor noise. Means ± 95% CI are indicated by shading.
