Biology subjects

Benjamin L de Bivort

Publications and source records attributed to Benjamin L de Bivort.

3 recordsLinked to original sources

bioRxiv2016

Evidence for selective attention in the insect brain

The capacity for selective attention appears to be required for any animal responding to an environment containing multiple objects, although this has been difficult to study in smaller animals such as insects. Clear operational characteristics of attention however make study of this crucial brain function accessible to any animal model. Whereas earlier approaches have relied on freely behaving paradigms placed in an ecologically relevant context, recent tethered preparations have focused on brain imaging and electrophysiology in virtual reality environments. Insight into brain activity during attention-like behavior has revealed key elements of attention in the insect brain. Surprisingly, a variety of brain structures appear to be involved, suggesting that even in the smallest brains attention might involve widespread coordination of neural activity.\n\nHighlightsO_LIInsect behavior shows attention-like filtering and allows concurrent neural recording\nC_LIO_LIRecent work finds compelling correlates of visual attention in the central complex\nC_LIO_LIPutative goal-directed stimulus-filtering is present in neuropils across the brain\nC_LI

Neuroscience↗

bioRxiv2014

Behavioral individuality reveals genetic control of phenotypic variability

Variability is ubiquitous in nature and a fundamental feature of complex systems. Few studies, however, have investigated variance itself as a trait under genetic control. By focusing primarily on trait means and ignoring the effect of alternative alleles on trait variability, we may be missing an important axis of genetic variation contributing to phenotypic differences among individuals1,2. To study genetic effects on individual-to-individual phenotypic variability (or intragenotypic variability), we used a panel of Drosophila inbred lines3 and focused on locomotor handedness4, in an assay optimized to measure variability. We discovered that some lines had consistently high levels of intragenotypic variability among individuals while others had low levels. We demonstrate that the degree of variability is itself heritable. Using a genome-wide association study (GWAS) for the degree of intragenotypic variability as the phenotype across lines, we identified several genes expressed in the brain that affect variability in handedness without affecting the mean. One of these genes, Ten-a, implicated a neuropil in the central complex5 of the fly brain as influencing the magnitude of behavioral variability, a brain region involved in sensory integration and locomotor coordination6. We have validated these results using genetic deficiencies, null alleles, and inducible RNAi transgenes. This study reveals the constellation of phenotypes that can arise from a single genotype and it shows that different genetic backgrounds differ dramatically in their propensity for phenotypic variability. Because traditional mean-focused GWASs ignore the contribution of variability to overall phenotypic variation, current methods may miss important links between genotype and phenotype.\n\nAbbreviationsDGRP: Drosophila Genome Reference Panel; ANOMV: Analysis of means for variance; QTL: quantitative trait loci, GWAS: genome wide association study, MAD: median absolute deviation. GWAS: genome wide association study, CI: confidence interval.

Genetics↗

bioRxiv2014

Neuronal control of locomotor handedness in Drosophila

Handedness in humans-better performance using either the left or right hand-is personally familiar, moderately heritable, and regulated by many genes, including those involved in general body symmetry. But behavioral handedness, i.e. lateralization, is a multifaceted phenomenon. For example, people display clockwise or counter- clockwise biases in their walking behavior that is uncorrelated to their hand dominance, and lateralized behavioral biases have been shown in species as disparate as mice (paw usage), octopi (eye usage), and tortoises (side rolled on during righting). However, the mechanisms by which asymmetries are instilled in behavior are unknown, and a system for studying behavioral handedness in a genetically tractable model system is needed. Here we show that Drosophila melanogaster flies exhibit striking variability in their left-right choice behavior during locomotion. Very strongly biased \"left-handed\" and \"right-handed\" individuals are common in every line assayed. The handedness of an individual persists for its lifetime, but is not passed on to progeny, suggesting that mechanisms other than genetics determine individual handedness. We use the Drosophila transgenic toolkit to map a specific set of neurons within the central complex that regulates the strength of behavioral handedness within a line. These findings give insights into choice behaviors and laterality in a simple model organism, and demonstrate that individuals from isogenic populations reared under experimentally identical conditions nevertheless display idiosyncratic behaviors.

Neuroscience↗