To visualize odorant representations by receptor neuron input to the mouse olfactory bulb, we loaded receptor neurons with calcium-sensitive dye and imaged odorant-evoked responses from their axon terminals. Fluorescence increases reflected activation of receptor neuron populations converging onto individual glomeruli. We report several findings. First, five glomeruli were identifiable across a...

Spike synchronization across neurons can be selective for the situation where neurons are driven at similar firing rates, a "many are equal" computation. This can be achieved in the absence of synaptic interactions between neurons, through phase locking to a common underlying oscillatory potential. Based on this principle, we instantiate an algorithm for robust odor recognition into a model net...

Glomeruli in the olfactory bulb are anatomically discrete modules receiving input from idiotypic olfactory sensory neurons. To examine the functional organization of sensory inputs to individual glomeruli, we loaded olfactory sensory neurons with a Ca(2+) indicator and measured odorant-evoked presynaptic Ca(2+) signals within single glomeruli by using two-photon microscopy in anaesthetized mice...

An odorant stimulus given to a bee elicits a characteristic combinatorial pattern of activity in neuronal units called glomeruli. These patterns can be measured by optical imaging, however detecting and identifying the glomeruli is a laborious task and prone to errors. Here, we present an image analysis pipeline for the automatic detection and identification of glomeruli. It involves Independen...

Odor elicits a well-organized pattern of glomerular activation in the olfactory bulb. However, the mechanisms by which this spatial map is transformed into an odor code remain unclear. We examined this question in rat olfactory bulb slices in recordings from output mitral cells. Electrical stimulation of incoming afferents elicited slow ( approximately 2 Hz) oscillations that originated in glom...

The glomerular layer of the olfactory bulb constitutes the first stage where information from olfactory receptor neurons (ORNs) is organized and processed. The projection from ORNs to glomeruli is extremely convergent with on average several thousands ORNs converging onto each glomerulus of the mammalian olfactory bulb. Each of the several thousand of ORNs expressing the same odor receptor conv...

Odors synchronize the activity of olfactory bulb mitral cells that project to the same glomerulus. In vitro, a slow rhythmic excitation intrinsic to the glomerular network persists, even in the absence of afferent input. We show here that a subpopulation of juxtaglomerular cells, external tufted (ET) cells, may trigger this rhythmic activity. We used paired whole-cell recording and Ca(2+) imagi...

Each odorant receptor gene defines a unique type of olfactory receptor neuron (ORN) and a corresponding type of second-order neuron. Because each odor can activate multiple ORN types, information must ultimately be integrated across these processing channels to form a unified percept. Here, we show that, in Drosophila, integration begins at the level of second-order projection neurons (PNs). We...