FoxP influences the speed and accuracy of a perceptual decision in Drosophila

Abstract

Decisions take time if information gradually accumulates to a response threshold, but the neural mechanisms of integration and thresholding are unknown. We characterized a decision process in Drosophila that bears the behavioral signature of evidence accumulation. As stimulus contrast in trained odor discriminations decreased, reaction times increased and perceptual accuracy declined, in quantitative agreement with a drift-diffusion model. FoxP mutants took longer than wild-type flies to form decisions of similar or reduced accuracy, especially in difficult, low-contrast tasks. RNAi knock-down of FoxP in αβ core Kenyon cells, or the overexpression of a potassium conductance in these neurons, recapitulated the FoxP mutant phenotype. A mushroom body subdomain whose development or function require the transcription factor FoxP thus supports the progression of a decision towards commitment.

Next stop: Language. The ‘FOXP2’ gene’s journey through time

“…Using green fluorescent protein to report FoxP promotor activity, Lawton et al (2014) saw expression in the so called central complex, that has been hypothesized (Strausfeld & Hirth, 2013) to be functionally analogous to the vertebrate basal ganglia. In contrast, using a slightly different promoter sequence, DasGupta et al (2014) did not find FoxP expression in the central complex at all but in the core region of the mushroom bodies instead, a multimodal integration site in the fly brain that is important for learning and memory. These differences might also account for the fact that in one study motor behavior (walking) was reported to be normal (DasGupta et al, 2014) whereas in other studies (Lawton et al, 2014) motor behavior was impaired.…”

“…In contrast, using a slightly different promoter sequence, DasGupta et al (2014) did not find FoxP expression in the central complex at all but in the core region of the mushroom bodies instead, a multimodal integration site in the fly brain that is important for learning and memory. These differences might also account for the fact that in one study motor behavior (walking) was reported to be normal (DasGupta et al, 2014) whereas in other studies (Lawton et al, 2014) motor behavior was impaired. Needless to say, the devil with experimental conditions lies in the details and follow up studies using more approaches to determine where FoxP mRNA and protein is expressed in the nervous system of developing and adult flies as well as honey bees will refine the currently still confusingly complex results of the compare and contrast approach.…”

“…On the agreement side, all FoxP mutant flies show interesting behavioral deficits that are at first sight not incompatible with each other and could also be conceptually related to the behavioral deficits observed in vertebrates with reduced FoxP2 dosage. The authors of one study observed reduced courtship behavior (Lawton et al, 2014), in another study the flies were able to use visual cues to avoid punishment but were unable to use somatosensory information for the same task (Mendoza et al, 2014) and in a third study the mutant flies had trouble with decision making using olfactory cues in different concentrations and punishment as an incentive to learn (DasGupta et al, 2014). In this last experiment, the phenotype could be traced to a particular small set of neurons that had previously been described to be important for decision making and were now shown to also express FoxP.…”

“…In the mouse lung, FoxP1 and FoxP4 are involved in the development of the lung epithelium (Li et al, 2012 (Santos, Athanasiadis, Leitão, DuPasquier, & Sucena, 2011). Turning to insects to pursue the idea that FoxP may fulfill similar functions in invertebrates and vertebrates, we and other groups have started to study the expression pattern and function in fruit flies and honeybees (Apis mellifera) (DasGupta, Ferreira, & Miesenböck, 2014;Kiya, Itoh, & Kubo, 2008;Lawton, Wassmer, & Deitcher, 2014;Mendoza et al, 2014) (Figure 6). As is often the case in the initial stages of scientific discovery of a new subject, some findings agree while other diverge.…”

The use of computational modeling to link sensory processing with behavior in Drosophila

“…This approach has been applied successfully to study the behavioral evaluation of courtship songs (Clemens and Hennig 2013;Clemens et al 2015a). When extended with a behavioral threshold, such models resemble so-called "drift diffusion models", which integrate sensory information -in this case the output of the LN model -to a decision boundary, the crossing of which corresponds to decision making (Brunton et al 2013;DasGupta et al 2014;Clemens et al 2014).…”