Biology subjects

Bracey, E. F.

Publications and source records attributed to Bracey, E. F..

3 recordsLinked to original sources

bioRxiv2022

Control and coding of pupil size by hypothalamic orexin neurons

Brain orexin (hypocretin) neurons are implicated in sleep-wake switching and reward-seeking, but their roles in rapid arousal dynamics and reward perception remain unclear. Here, cellspecific stimulation, deletion, and in vivo recordings revealed strong correlative and causal links between pupil dilation - a quantitative arousal marker - and orexin cell activity. Coding of arousal and reward was distributed across orexin cells, indicating that they specialize in rapid, multiplexed communication of momentary arousal and reward states.

neuroscience↗

bioRxiv2021

The retrosplenial cortex combines internal and external cues to encode head velocity during navigation

The extent to which we successfully navigate the environment depends on our ability to continuously track our heading direction and speed. Angular head velocity (AHV) cells, which encode the speed and direction of head turns during navigation, are fundamental to this process, yet the mechanisms that determine their function remain unknown. By performing chronic single-unit recordings in the retrosplenial cortex (RSP) of the mouse and tracking the activity of individual AHV neurons between freely moving and head-restrained conditions, we find that vestibular inputs dominate AHV signalling. In addition, we discover that self-generated optic flow input onto these neurons increases the gain and signal-to-noise ratio of angular velocity coding during free exploration. Psychophysical experiments and neural decoding further reveal that vestibular-visual integration increases the perceptual accuracy of egocentric angular velocity and the fidelity of its representation by RSP ensembles. We propose that while AHV coding is dependent on vestibular input, it also uses vision to maximise navigation accuracy in nocturnal and diurnal environments.

neuroscience↗

bioRxiv2019

Rapid sensory integration in orexin neurons governs probability of future movements

Internally and externally triggered movement is crucial for survival and is controlled by multiple interconnected neuronal populations spanning many brain areas. Lateral hypothalamic orexin/hypocretin neurons are thought to play a slow, modulatory part in this scheme through their key role in promoting metabolism and wakefulness. However, it is unknown whether orexin/hypocretin neurons participate in rapid neural processing, leading to immediate movement. Furthermore, their role in sensorimotor transformations remains unknown. Here we use cellular-resolution Ca2+ imaging and optogenetics to show that orexin/hypocretin cells are instantaneous regulators of self-generated and sensory-evoked movement. They are activated before and during movement, preventing this activation reduces self-generated locomotion, and optogenetic mimicry of this transient activation rapidly initiates locomotion. We find that the same orexin neurons whose activity predicts movement initiation are rapidly controllable by external sensory stimuli, and silencing orexin cells during sensation prevents normal motor performance. These findings place orexin neurons in a physiological position of unexpectedly rapid and strong sensorimotor control.

neuroscience↗