Perception space - The final frontier

Mapping the complex sensory behavior of animals, such as smell in bees, to relevant neural activity provides clues into how animals perceive and respond to the world through their sense

Information flow and regulation of foraging activity in bumble bees (Bombus spp.)

Publisher version: http://www.apidologie.org

Bumblebees gain fitness through learning

Despite the widespread assumption that the learning abilities of animals are adapted to the particular environments in which they operate, the quantitative effects of learning performance on fitness remain virtually unknown. Here we evaluate the learning performance of bumblebees (_Bombus terrestris_) from multiple colonies in an ecologically relevant associative learning task under laboratory conditions, before testing the foraging performance of the same colonies under the field conditions. We demonstrate that variation in learning speed among bumblebee colonies is directly correlated with foraging performance, a robust fitness measure, under natural conditions. Colonies vary in learning speed by a factor of nearly 5, with the slowest learning colonies collecting 40% less nectar than the fastest learning colonies. Such a steep fitness function suggests strong selection for higher learning speed in bumblebees. Demonstrating the adaptive value of differences in learning performance under the real conditions in which animals function represents a major step towards understanding how cognitive abilities of animals are tuned to their environment

Visual search and decision making in bees: time, speed and accuracy

An insect searching a meadow for flowers may detect several flowers from different species per second, so the task of choosing the right flowers rapidly is not trivial. Here we apply concepts from the field of visual search in human experimental psychology to the task a bee faces in searching a meadow for familiar flowers, and avoiding ‘‘distraction’’ by unknown or unrewarding flowers. Our approach highlights the importance of visual information processing for understanding the behavioral ecology of foraging. Intensity of illuminating light, target contrast with background (both chromatic and achromatic), and number of distractors are all shown to have a direct influence on decision times in behavioral choice experiments. To a considerable extent, the observed search behavior can be explained by the temporal and spatial properties of neuronal circuits underlying visual object detection. Our results also emphasize the importance of the time dimension in decision making. During visual search in humans, improved accuracy in solving discrimination tasks comes at a cost in response time, but the vast majority of studies on decision making in animals have focused on choice accuracy, not speed. We show that in behavioral choice experiments in bees, there is a tight link between the two. We demonstrate both between-individual and within- individual speed-accuracy tradeoffs, whereby bees exhibit considerable behavioral flexibility in solving visual search tasks. Motivation is an important factor in selection of behavioral strategies for a search task, and sensory discrimination capabilities may be underestimated by studies that quantify accuracy of behavioral choice but neglect the temporal dimension

Limits to the salience of ultraviolet: Lessons from colour vision in bees and birds

Publisher version: http://jeb.biologists.org/content/204/14/2571/F1.expansio

SC1/PRDM4 recruits PRMT5 to control the timing of neural precursor differentiation in developing neural stem cells

During cortical development, neural stem cells (NSCs) switch from proliferative to neuron-generating asymmetric divisions. Here we investigated the role of Schwann cell factor 1 (SC1/PRDM4), a transcriptional repressor highly expressed in the developing nervous system, during NSCs development. We found that SC1 protein levels were down-regulated in newly differentiating neurons, while remaining high in undifferentiated NSCs, suggesting an asymmetric inheritance of SC1. Knockdown of SC1 in the NSCs led to precocious differentiation of neurons and its overexpression led to an increase in Nestin-expressing precursors. We found that SC1, through its amino-terminus, recruits the chromatin modifier PRMT5, a histone arginine methyltransferase that catalyses histone H4R3 symmetric dimethylation (H4R3me2s). Mutations disrupting SC1/PRMT5 interaction resulted in loss of SC1-mediated increase in undifferentiated neural precursor cells. Our data demonstrate that SC1 and PRMT5 are components of an epigenetic regulatory complex that provides an epigenetic signature of a “stem-like” cellular state in the NSCs and which may be asymmetrically inherited during neurogenic divisions

Cognitive dimensions of predator responses to imperfect mimicry?

Many palatable insects, for example hoverflies, deter predators by mimicking well-defended insects such as wasps. However, for human observers, these flies often seem to be little better than caricatures of wasps – their visual appearance and behaviour are easily distinguishable. This imperfect mimicry baffles evolutionary biologists, because one might expect natural selection to do a more thorough job. Here we discuss two types of cognitive processes that might explain why mimics distinguishable mimics might enjoy increased protection from predation. Speed accuracy tradeoffs in predator decision making might give imperfect mimics sufficient time to escape, and predators under time constraint might avoid time-consuming discriminations between well-defended models and inaccurate edible mimics, and instead adopt a “safety first” policy of avoiding insects with similar appearance. Categorization of prey types by predators could mean that wholly dissimilar mimics may be protected, provided they share some common property with noxious prey