Tonically active GABAergic neurons in the dorsal periaqueductal gray control instinctive escape in mice.

Escape behavior is a set of locomotor actions that move an animal away from threat. While these actions can be stereotyped, it is advantageous for survival that they are flexible. For example, escape probability depends on predation risk and competing motivations, and flight to safety requires continuous adjustments of trajectory and must terminate at the appropriate place and time.

A cortico-collicular circuit for orienting to shelter during escape.

When faced with predatory threats, escape towards shelter is an adaptive action that offers long-term protection against the attacker. Animals rely on knowledge of safe locations in the environment to instinctively execute rapid shelter-directed escape actions. Although previous work has identified neural mechanisms of escape initiation, it is not known how the escape circuit incorporates spatial information to execute rapid flights along the most efficient route to shelter.

Preparation of acute midbrain slices containing the superior colliculus and periaqueductal Gray for patch-clamp recordings.

This protocol is a practical guide for preparing acute coronal slices from the midbrain of young adult mice for electrophysiology experiments. It describes two different sets of solutions with their respective incubation strategies and two alternative procedures for brain extraction: decapitation under terminal isoflurane anaesthesia and intracardial perfusion with artificial cerebrospinal fluid under terminal isoflurane anaesthesia. Slices can be prepared from wild-type mice as well as from mice that have been genetically modified or transfected with viral constructs to label subsets of cells.

Ca entry through Na channels generates submillisecond axonal Ca signaling.

Calcium ions (Ca) are essential for many cellular signaling mechanisms and enter the cytosol mostly through voltage-gated calcium channels. Here, using high-speed Ca imaging up to 20 kHz in the rat layer five pyramidal neuron axon we found that activity-dependent intracellular calcium concentration ([Ca]) in the axonal initial segment was only partially dependent on voltage-gated calcium channels. Instead, [Ca] changes were sensitive to the specific voltage-gated sodium (Na) channel blocker tetrodotoxin.

The Neuropeptide Galanin Is Required for Homeostatic Rebound Sleep following Increased Neuronal Activity.

Sleep pressure increases during wake and dissipates during sleep, but the molecules and neurons that measure homeostatic sleep pressure remain poorly understood. We present a pharmacological assay in larval zebrafish that generates short-term increases in wakefulness followed by sustained rebound sleep after washout. The intensity of global neuronal activity during drug-induced wakefulness predicted the amount of subsequent rebound sleep.