Delta 7 as a bottleneck. Role of inhibition in the ring attractor ?
Gain control at the input stage is a generalized motif in the CX ?
Inputs in the NO : what are they for ?
The output channel is very narrow : possible consequences ?
Optional : network motifs ?

Material and methods

Fly stocks and crosses

For every LexA driver used, we prepared two stocks containing GCaMP6-m \cite{chen_ultrasensitive_2013} and CsChrimson \cite{klapoetke_independent_2014} under LexAop (resp. UAS) or UAS (resp. LexAop) control : XXX-LexA;13XLexAop2-IVS-p10-GCaMP6m 50.629 in VK00005, 20xUAS-CsChrimson-mCherry-trafficked in su(Hw)attP1 and XXX-LexA;20xUAS-IVS-GCaMP6m 15.629 in attP2, 13XLexAop2-CsChrimson-tdTomato in VK00005. Those stocks were then crossed to a Gal4 driver or a split-Gal4 \cite{luan_refined_2006} driver for the experiment. In the split-Gal4 case, the two split halves are inserted in attP40 and attP2 respectively. To avoid transvection between the split and the LexA driver \cite{mellert_transvection_2012}, we inserted the LexA drivers in alternative sites, either su(Hw)attP5 \cite{pfeiffer_refinement_2010} or VK22 \cite{venken_pacman:_2006}, and used the splits exclusively in combination with those lines. The list of drivers used and the corresponding cell types are given in Table  \ref{786393}. We generally follow the nomenclature proposed in \cite{wolff_neuroarchitecture_2015}.