@article {68885,
	title = {A rise-to-threshold process for a relative-value decision.},
	journal = {Nature},
	volume = {619},
	year = {2023},
	month = {2023 Jul 05},
	pages = {563-571},
	abstract = {<p>Whereas progress has been made in the identification of neural signals related to rapid, cued decisions, less is known about how brains guide and terminate more ethologically relevant decisions in which an animal{\textquoteright}s own behaviour governs the options experienced over minutes. Drosophila search for many seconds to minutes for egg-laying sites with high relative value and have neurons, called oviDNs, whose activity fulfills necessity and sufficiency criteria for initiating the egg-deposition motor programme. Here we show that oviDNs express a calcium signal that (1) dips when an egg is internally prepared (ovulated), (2) drifts up and down over seconds to minutes-in a manner influenced by the relative value of substrates-as a fly determines whether to lay an egg and (3) reaches a consistent peak level just before the abdomen bend for egg deposition. This signal is apparent in the cell bodies of oviDNs in the brain and it probably reflects a behaviourally relevant rise-to-threshold process in the ventral nerve cord, where the synaptic terminals of oviDNs are located and where their output can influence behaviour. We provide perturbational evidence that the egg-deposition motor programme is initiated once this process hits a threshold and that subthreshold variation in this process regulates the time spent considering options and, ultimately, the choice taken. Finally, we identify a small recurrent circuit that feeds into oviDNs and show that activity in each of its constituent cell types is required for laying an egg. These results argue that a rise-to-threshold process regulates a relative-value, self-paced decision and provide initial insight into the underlying circuit mechanism for building this process.</p>
},
	issn = {1476-4687},
	doi = {10.1038/s41586-023-06271-6},
	author = {Vijayan, Vikram and Wang, Fei and Wang, Kaiyu and Chakravorty, Arun and Adachi, Atsuko and Akhlaghpour, Hessameddin and Dickson, Barry J and Maimon, Gaby}
}
@article {68413,
	title = {Muscles that move the retina augment compound eye vision in Drosophila.},
	journal = {Nature},
	year = {2022},
	month = {2022 Oct 26},
	abstract = {<p>Most animals have compound eyes, with tens to thousands of lenses attached rigidly to the exoskeleton. A natural assumption is that all of these species must resort to moving either their head or\&nbsp;their body to actively change their visual input. However, classic anatomy has revealed that flies have muscles poised to move their retinas under the stable lenses of each compound eye. Here we show that Drosophila use their retinal muscles to smoothly track visual motion, which helps to stabilize the retinal image, and also to perform small saccades when viewing a stationary scene. We show that when the retina moves, visual receptive fields shift accordingly, and that even the smallest retinal saccades activate visual neurons. Using a head-fixed behavioural paradigm, we find that Drosophila perform binocular, vergence movements of their retinas-which could enhance depth perception-when crossing gaps, and impairing the physiology of retinal motor neurons alters gap-crossing trajectories during free behaviour. That flies evolved an ability to actuate their retinas suggests that moving the eye independently of the head is broadly paramount for animals. The similarities of smooth and saccadic movements of the Drosophila retina and the vertebrate eye highlight a notable example of convergent evolution.</p>
},
	issn = {1476-4687},
	doi = {10.1038/s41586-022-05317-5},
	author = {Fenk, Lisa M and Avritzer, Sofia C and Weisman, Jazz L and Nair, Aditya and Randt, Lucas D and Mohren, Thomas L and Siwanowicz, Igor and Maimon, Gaby}
}
