Color distance derived from a receptor model of color vision in the honeybee (original) (raw)
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Journal of Comparative Physiology A, 1989
The spectral sensitivity of single photoreceptors of Osmia rufa was determined by a fast voltage-clamp technique. Three receptor types were found whose spectral sensitivity functions followed a rhodopsin-like photopigment absorption function with A,,,^ values at 348nm (ultraviolet receptor), 436nm (blue receptor) and 572nm (green receptor). The A max of the green receptor in Osmia rufa is shifted to much longer wavelengths compared with other insect species. Discrimination of colour signals was tested after training a bee at the entrance to its nest. The colour signals were filter discs (70 mm in diameter) with a hole (10 mm in diameter) in the centre and the bees quickly learned to use the coloured disc as a marker of the nest entrance. Tests were dual forced-choice tests with two coloured discs closely positioned next to each other. 94 different tests were each repeated 5-15 times and were performed after training to 12 different colour signals. A photoreceptor model was used to calculate the loci of the colour signals in a three-dimensional colour space and in a chromaticity diagram. The perceptual distance between the colour loci was calculated as line elements (minimum number of just noticeable difference, jnd-steps), which were based on the noise properties of the photoreceptors. The discrimination determined by the behavioural tests correlated very well with the jnd-steps. The correlation was better for the line elements in the colour plane than in the colour space. Osmia rufa was compared with the honeybee Apis mellifera and the stingless bee Melipona quadrifasciata. There is no difference in colour selection between Osmia and Apis, whereas Melipona discriminates less well in the violet-blue region. The model calculation was used to compare the chromaticity diagrams and the spectral discrimination functions of the three species. It is concluded that the receptor model used in this study predicts the discrimination behaviour of the three bee species very well. Therefore, comparative studies on colour vision in flowervisiting insects may be based on spectral measurements of the photoreceptors, and in many cases this reduces the extent of laborious behavioural studies.
Color constancy in the honeybee
The Journal of neuroscience : the official journal of the Society for Neuroscience, 1988
A multicolored display was illuminated by 3 bands of wavelengths corresponding to the maxima of the spectral sensitivities of the 3 types of photoreceptors found in the bee retina. The intensity of each band could be varied individually. The light fluxes emitted by the colored areas of the multicolored display were determined quantitatively. Free-flying honeybees were trained with sugar solution to choose one of the colored areas. The illumination was then changed in such a way that the light fluxes formerly emitted by the training area were now measured on another area. When the trained bees were tested under those conditions, they still chose the training area. The relative positions of the colored areas were changed in order to exclude learning of position. It is concluded that color vision in bees is, in a certain range, independent of the spectral content of the illumination. Model calculations show that the behavior observed in bees is consistent with the retinex theory (Land,...
Detection of coloured stimuli by honeybees: minimum visual angles and receptor specific contrasts
Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology, 1996
Honeybees Apis mellifera were trained to distinguish between the presence and the absence of a rewarded coloured spot, presented on a vertical, achromatic plane in a Y-maze. They were subsequently tested with different subtended visual angles of that spot, generated by different disk diameters and different distances from the decision point in the device. Bees were trained easily to detect bee-chromatic colours, but not an achromatic one. Chromatic contrast was not the only parameter allowing learning and, therefore, detection: α min, the subtended visual angle at which the bees detect a given stimulus with a probability P 0 = 0.6, was 5° for stimuli presenting both chromatic contrast and contrast for the green photoreceptors [i.e. excitation difference in the green photoreceptors, between target and background (green contrast)], and 15° for stimuli presenting chromatic but no green contrast. Our results suggest that green contrast can be utilized for target detection if target recognition has been established by means of the colour vision system. The green-contrast signal would be used as a far-distance signal for flower detection. This signal would always be detected before chromatic contrast during an approach flight and would be learned in compound with chromatic contrast, in a facilitation-like process.
Mechanisms, functions and ecology of colour vision in the honeybee
Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology, 2014
Research in the honeybee has laid the foundations for our understanding of insect colour vision. The trichromatic colour vision of honeybees shares fundamental properties with primate and human colour perception, such as colour constancy, colour opponency, segregation of colour and brightness coding. Laborious efforts to reconstruct the colour vision pathway in the honeybee have provided detailed descriptions of neural connectivity and the properties of photoreceptors and interneurons in the optic lobes of the bee brain. The modelling of colour perception advanced with the establishment of colour discrimination models that were based on experimental data, the Colour-Opponent Coding and Receptor Noise-Limited models, which are important tools for the quantitative assessment of bee colour vision and colour-guided behaviours. Major insights into the visual ecology of bees have been gained combining behavioural experiments and quantitative modelling, and asking how bee vision has influe...
Arthropod-Plant Interactions, 2008
It has long been assumed that bees cannot see red. However, bees visit red flowers, and the visual spectral sensitivity of bees extends into wavelengths to provide sensitivity to such flowers. We thus investigated whether bees can discriminate stimuli reflecting wavelengths above 560 nm, i.e., which appear orange and red to a human observer. Flowers do not reflect monochromatic (single wavelength) light; specifically orange and red flowers have reflectance patterns which are step functions, we thus used colored stimuli with such reflectance patterns. We first conditioned honey bees Apis mellifera to detect six stimuli reflecting light mostly above 560 nm and found that bees learned to detect only stimuli which were perceptually very different from a bee achromatic background. In a second experiment we conditioned bees to discriminate stimuli from a salient, negative (un-rewarded) yellow stimulus. In subsequent unrewarded tests we presented the bees with the trained situation and with five other tests in which the trained stimulus was presented against a novel one. We found that bees learned to discriminate the positive from the negative stimulus, and could unambiguously discriminate eight out of fifteen stimulus pairs. The performance of bees was positively correlated with differences between the trained and the novel stimulus in the receptor contrast for the long-wavelength bee photoreceptor and in the color distance (calculated using two models of the honeybee colors space). We found that the differential conditioning resulted in a concurrent inhibitory conditioning of the negative stimulus, which might have improved discrimination of stimuli which are perceptually similar. These results show that bees can detect long wavelength stimuli which appear reddish to a human observer. The mechanisms underlying discrimination of these stimuli are discussed.
Natural phototaxis and its relationship to colour vision in honeybees
Journal of Comparative Physiology A, 1985
1. Honeybees are positively phototactic when they leave a feeding place and start to fly back to the hive. The strength of this natural phototactic response in individually marked bees was measured without interfering with their foraging behaviour. 2. Absolute sensitivity of this phototactic response to a point light source is in the range of 8.3 ▪ 10 7 quanta s-1 for 537 nm. This corresponds to about 5 absorbed quanta in 28 green receptors over the integration time of 60 ms. 3. We conclude that the properties of the mono-polar cells or higher order visual interneurons rather than those of the photoreceptors control the intensity dependence of the response because the slopes (n) of the response intensity functions (R / log I) are steep (n: 1.0-2.65) and wavelength dependent. Blue light (439 nm) causes the steepest function. 4. The effect of residual light adaptation on the R / log I-function and the spectral sensitivity (S(λ)) is negligible under the experimental conditions chosen, since the time course of dark adaptation is fast (τ ≤ 1 min). 5. The blue and green receptors contribute about equally to the S(λ) of this natural phototactic response, the UV receptors somewhat less (Fig. 5). 6. Colour mixing experiments, used to test colour vision in phototaxis, reveal no significant deviation from a simple linear summation of the quantal fluxes, irrespective of the spectral mixture used. We conclude, therefore, that under the experimental conditions colour vision is very unlikely to play a role in the phototactic behaviour of the honeybee. 7. All our results (steep R/log I-functions, fast dark adaptation, S(λ) and the absence of colour vision) support to notion that the natural phototactic response is controlled by neuronal pooling, most likely in the lamina M1 monopolar cells.
Detection of bright and dim colours by honeybees. J Exp Biol
Journal of Experimental Biology
Honeybees, Apis mellifera, were trained to detect coloured disks with either a strong or a weak intensity difference against the background. Green, blue, ultraviolet-reflecting white and grey papers were reciprocally combined as targets or backgrounds, providing strong chromatic and/or achromatic cues. The behavioural performance of the honeybees was always symmetrical for both reciprocal target/background combinations of a colour pair, thus showing that target detection is independent of whether the colour is presented as a background or as a target in combination with the other colour. Bright targets against dim backgrounds and vice versa were detected more reliably than dim target/background combinations. This result favours the general assumption that the detectability of a coloured stimulus increases with increasing intensity.
Detection of coloured patterns by honeybees through chromatic and achromatic cues
Journal of Comparative Physiology A: Sensory, Neural, and Behavioral Physiology, 2001
We asked whether the detection range of twocoloured centre-surround patterns diers from that of single-coloured targets. Honeybees Apis mellifera were trained to distinguish between the presence and absence of a single-coloured disc or a coloured pattern at different visual angles. The patterns presented colours which were either dierent in chromatic and L-receptor contrasts to the background, equal in chromatic but dierent in L-receptor contrasts, or vice-versa. Patterns with colours presenting only chromatic contrast were also tested. Patterns with higher L-receptor contrast in its outer than in its inner element were better detected than patterns with a reversed L-contrast distribution. However, both were detected worse than single-coloured discs of the respective colours. When the L-receptor contrast was the same for both elements, the detection range of the two-coloured and single-coloured targets was the same. Patterns whose colours lacked L-receptor contrast were detected just as single-coloured targets of the same colours. These results demonstrate that both chromatic and L-receptor contrasts mediate the detec-tion of coloured patterns and that particular distributions of L-receptor contrast within a target are better detected than others. This ®nding is consistent with the intervention of neurons with centre-surround receptive ®elds in the detection of coloured patterns.
Animal Behaviour, 2003
Floral shape is a visual cue used by pollinators to discriminate between competing flower species. We investigated whether discrimination is possible between closed shapes presenting the same colour and lacking a centrally presented fixation point. Free-flying honeybees, Apis mellifera L., had to discriminate between a solid square and a solid triangle of the same colour presented on the back walls of a Y-maze. Different colours were used to vary chromatic contrast and receptor-specific contrasts. Discrimination was possible whenever shapes presented contrast to the long wavelength receptor but was independent of chromatic contrast, overall intensity contrast or short and middle wavelength receptor contrast. We suggest that the bees used the edges of the closed shapes to solve the task. Bees failed when shapes were rotated, showing that a single shape edge was not sufficient for recognition.