Precise Detection of Direct Glomerular Input Duration by the Olfactory Bulb

Abstract

Sensory neuron input to the olfactory bulb (OB) was activated precisely for different durations with blue light in mice expressing channelrhodopsin-2 in olfactory sensory neurons. Behaviorally the mice discriminated differences of 10 ms in duration of direct glomerular activation. In addition, a subset of mitral/tufted cells in the OB of awake mice responded tonically therefore conveying information on stimulus duration. Our study provides evidence that duration of the input to glomeruli not synchronized to sniffing is detected. This potent cue may be used to obtain information on puffs in odor plumes.

Optogenetic Activation of Accessory Olfactory Bulb Input to the Forebrain Differentially Modulates Investigation of Opposite versus Same-Sex Urinary Chemosignals and Stimulates Mating in Male Mice

“…From the electrophysiological recordings of anesthetized mice that received laser stimulation, we saw that spiking occurred in the medial amygdala even without odors present, suggesting that medial amygdala activation alone is not sufficient to alter investigation of an irrelevant stimulus. The absence of any behavioral effect of optogenetic AOB activation in the absence of a pheromonal odor context contrasts with results of previous experiments showing that optogenetic activation of dopaminergic neurons in the ventral tegmental area (Tsai et al, 2009) as well as serotonergic neurons in the dorsal raphe nucleus (Li et al, 2014) caused mice to investigate stimulation-linked spatial areas.…”

“…Optogenetic methods in transgenic animals offer the possibility of precisely timed stimulation of AOB neurons while subjects engage in olfactory-dependent behaviors. Such methods have been applied to manipulate activity in the MOB of behaving subjects (Smear et al, 2013; Li et al, 2014; Kermen et al, 2016). These studies indicate that optogenetic activation of the MOB yields a signal that can be detected and acted on by awake behaving animals, suggesting that an optogenetic approach may be a useful way to study the dynamics of chemosignal processing in the olfactory system.…”

Illuminating odors: when optogenetics brings to light unexpected olfactory abilities

“…In the same vein as explored in insects, Li et al (2014) used mice in which ChR2 was expressed as a transgene under the control of an ORN-specific promoter. They addressed whether mice could detect different delays between two deliveries of the same odor.…”

“…For example, one could slice and photostimulate the ex vivo brain while recording neural activity. This is the option chosen by Li et al (2014): they used the patch-clamp technique to verify that they could initiate MT responses to the stimulation of ORN projections. However, one might argue that brain slices are not ideal for understating neural process involved in behavioral responses.…”

Miniaturized fiber-coupled confocal fluorescence microscope with an electrowetting variable focus lens using no moving parts

“…To demonstrate imaging in tissue with our FCM, we imaged intact mouse olfactory nerve fibers expressing yellow-fluorescent protein in olfactory neurons [29]. The mouse was sacrificed by CO 2 inhalation and the head was bisected sagittally to expose the olfactory epithelium and nerve.…”