Biology subjects

Ishida, I. G.

Publications and source records attributed to Ishida, I. G..

3 recordsLinked to original sources

bioRxiv2023

Neuronal calcium spikes enable vector inversion in the Drosophila brain

A typical neuron signals to downstream cells when it is depolarized and firing sodium spikes. Some neurons, however, also fire calcium spikes when hyperpolarized. The function of such bidirectional signaling remains unclear in most circuits. Here we show how a neuron class that participates in vector computation in the fly central complex employs hyperpolarization-elicited calcium spikes to invert two-dimensional mathematical vectors. By switching from firing sodium to calcium spikes, these neurons implement a [~]180{degrees} realignment between the vector encoded in the neuronal population and the flys internal compass signal, thus inverting the vector. We show that the calcium spikes rely on the T-type calcium channel Ca-1T, and argue, via analytical and experimental approaches, that these spikes enable vector computations in portions of angular space that would otherwise be inaccessible. These results reveal a seamless interaction between molecular, cellular and circuit properties for implementing vector mathematics in the brain.

neuroscience↗

bioRxiv2019

SPARC: a method to genetically manipulate precise proportions of cells.

Many experimental approaches rely on controlling gene expression in select subsets of cells within an individual animal. However, reproducibly targeting transgene expression to specific fractions of a genetically-defined cell-type is challenging. We developed Sparse Predictive Activity through Recombinase Competition (SPARC), a generalizable toolkit that can express any effector in precise proportions of post-mitotic cells in Drosophila. Using this approach, we demonstrate targeted expression of many effectors and apply these tools to calcium imaging of individual neurons and optogenetic manipulation of sparse cell populations in vivo.

neuroscience↗

bioRxiv2019

KV1.2 channels inactivate through a mechanism similar to C-type inactivation

C-type inactivation has been described in multiple voltage-gated K+ channels and in great detail in the Drosophila Shaker channel. As channels have moved into the structural era, atomic details of this and other gating mechanisms have started to be better understood. To date, the only voltage-gated channels whose structure has been solved are KvAP (X-ray diffraction), the KV1.2- KV2.1 \"paddle\" chimera (X-ray diffraction), KV1.2 (Cryo-EM); and ether-a-go-go (Cryo-EM) (Wang and MacKinnon, 2017), however, the characteristics and mechanisms of slow inactivation in these channels are unknown or poorly characterized. Here we present a detailed study of slow inactivation in the rat KV1.2 and show that it has some properties consistent with the C-type inactivation described in Shaker. We also study the effects of some mutations that are known to modulate C-type inactivation in Shaker and show that qualitative and quantitative differences exist in their functional effects, possibly underscoring subtle but important structural differences between the C-inactivated states in Shaker and KV1.2.

biophysics↗