scholarly journals Robust Odor Coding via Inhalation-Coupled Transient Activity in the Mammalian Olfactory Bulb

Neuron ◽  
2010 ◽  
Vol 68 (3) ◽  
pp. 570-585 ◽  
Author(s):  
Kevin M. Cury ◽  
Naoshige Uchida
Keyword(s):  
Olfactory Bulb ◽  
Odor Coding ◽  
Transient Activity

scholarly journals Transient Activity Induces a Long-Lasting Increase in the Excitability of Olfactory Bulb Interneurons

2008 ◽  
Vol 99 (1) ◽  
pp. 187-199 ◽  
Author(s):  
Tsuyoshi Inoue ◽  
Ben W. Strowbridge
Keyword(s):  
Olfactory Bulb ◽  
Granule Cells ◽  
Receptor Activation ◽  
Brain Regions ◽  
Persistent Activity ◽  
Cellular Mechanisms ◽  
Calcium Dependent ◽  
Transient Activity ◽  
Olfactory Bulb Slices ◽  
Processing And Storage

Little is known about the cellular mechanisms that underlie the processing and storage of sensory in the mammalian olfactory system. Here we show that persistent spiking, an activity pattern associated with working memory in other brain regions, can be evoked in the olfactory bulb by stimuli that mimic physiological patterns of synaptic input. We find that brief discharges trigger persistent activity in individual interneurons that receive slow, subthreshold oscillatory input in acute rat olfactory bulb slices. A 2- to 5-Hz oscillatory input, which resembles the synaptic drive that the olfactory bulb receives during sniffing, is required to maintain persistent firing. Persistent activity depends on muscarinic receptor activation and results from interactions between calcium-dependent afterdepolarizations and low-threshold Ca spikes in granule cells. Computer simulations suggest that intrinsically generated persistent activity in granule cells can evoke correlated spiking in reciprocally connected mitral cells. The interaction between the intrinsic currents present in reciprocally connected olfactory bulb neurons constitutes a novel mechanism for synchronized firing in subpopulations of neurons during olfactory processing.

scholarly journals Recurrent cortical circuits implement concentration-invariant odor coding

Science ◽  
2018 ◽  
Vol 361 (6407) ◽  
pp. eaat6904 ◽  
Author(s):  
Kevin A. Bolding ◽  
Kevin M. Franks
Keyword(s):  
Olfactory Bulb ◽  
Concentration Dependence ◽  
Neural Circuit ◽  
Feedback Inhibition ◽  
Piriform Cortex ◽  
Cortical Activity ◽  
Cortical Circuits ◽  
Odor Coding ◽  
Recurrent Collateral ◽  
The Impact

Animals rely on olfaction to find food, attract mates, and avoid predators. To support these behaviors, they must be able to identify odors across different odorant concentrations. The neural circuit operations that implement this concentration invariance remain unclear. We found that despite concentration-dependence in the olfactory bulb (OB), representations of odor identity were preserved downstream, in the piriform cortex (PCx). The OB cells responding earliest after inhalation drove robust responses in sparse subsets of PCx neurons. Recurrent collateral connections broadcast their activation across the PCx, recruiting global feedback inhibition that rapidly truncated and suppressed cortical activity for the remainder of the sniff, discounting the impact of slower, concentration-dependent OB inputs. Eliminating recurrent collateral output amplified PCx odor responses rendered the cortex steeply concentration-dependent and abolished concentration-invariant identity decoding.

scholarly journals Cholinergic Inputs from Basal Forebrain Add an Excitatory Bias to Odor Coding in the Olfactory Bulb

2014 ◽  
Vol 34 (13) ◽  
pp. 4654-4664 ◽  
Author(s):  
M. Rothermel ◽  
R. M. Carey ◽  
A. Puche ◽  
M. T. Shipley ◽  
M. Wachowiak
Keyword(s):  
Olfactory Bulb ◽  
Basal Forebrain ◽  
Odor Coding

Odor Code Sensor and Odor Reproduction

2012 ◽  
pp. 457-470
Author(s):  
Kenshi Hayashi
Keyword(s):  
Olfactory Bulb ◽  
Odor Coding ◽  
Essential Information ◽  
Qualitative And Quantitative ◽  
Olfactory Systems ◽  
Quantitative Analyses ◽  
Molecular Information ◽  
Odor Receptors

In biological olfactory systems, odor receptors receive odor molecules by recognizing the molecular information. Humans can sense the odor by the signal from these activated receptors. The combination of the activated receptors is called “odor code,” and the odor codes are expressed as an “odor cluster map” of glomeruli on the olfactory bulb surface. The odor code is essential information for qualitative and quantitative analyses of odor sensation. In this chapter, development of odor sensors based on the odor code concept and an attempt to extract the parameters for odor coding from molecular informatics are described. Application of the obtained odor code for odor reproduction is also presented.

scholarly journals A transformation from temporal to ensemble coding in a model of piriform cortex

2017 ◽  
Author(s):  
Merav Stern ◽  
Kevin A. Bolding ◽  
L.F. Abbott ◽  
Kevin M. Franks
Keyword(s):  
Olfactory Bulb ◽  
Olfactory System ◽  
Feedback Inhibition ◽  
Piriform Cortex ◽  
Odor Coding ◽  
System A ◽  
Coding Strategies ◽  
Concentration Changes ◽  
Recurrent Collateral ◽  
The Impact

ABSTRACTDifferent coding strategies are used to represent odor information at various stages of the mammalian olfactory system. A temporal latency code represents odor identity in olfactory bulb (OB), but this temporal information is discarded in piriform cortex (PCx) where odor identity is instead encoded through ensemble membership. We developed a spiking PCx network model to understand how this transformation is implemented. In the model, the impact of OB inputs activated earliest after inhalation is amplified within PCx by diffuse recurrent collateral excitation, which then recruits strong, sustained feedback inhibition that suppresses the impact of later-responding glomeruli. Simultaneous OB-PCx recordings indicate that indeed, over a single sniff, the earliest-active OB inputs are most effective at driving PCx activity. We model increasing odor concentrations by decreasing glomerulus onset latencies while preserving their activation sequences. This produces a multiplexed cortical odor code in which activated ensembles are robust to concentration changes while concentration information is encoded through population synchrony. Our model demonstrates how PCx circuitry can implement multiplexed ensemble-identity/temporal-concentration odor coding.

scholarly journals Serotonin modulates the population activity profile of olfactory bulb external tufted cells

2012 ◽  
Vol 107 (1) ◽  
pp. 473-483 ◽  
Author(s):  
Shaolin Liu ◽  
Jason L. Aungst ◽  
Adam C. Puche ◽  
Michael T. Shipley
Keyword(s):  
Olfactory Bulb ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Inhibitory Neurons ◽  
Raphe Nuclei ◽  
Population Activity ◽  
Odor Coding ◽  
Inward Current ◽  
Tufted Cells ◽  
Raphé Nuclei

Serotonergic neurons in the raphe nuclei constitute one of the most prominent neuromodulatory systems in the brain. Projections from the dorsal and median raphe nuclei provide dense serotonergic innervation of the glomeruli of olfactory bulb. Odor information is initially processed by glomeruli, thus serotonergic modulation of glomerular circuits impacts all subsequent odor coding in the olfactory system. The present study discloses that serotonin (5-HT) produces excitatory modulation of external tufted (ET) cells, a pivotal neuron in the operation of glomerular circuits. The modulation is due to a transient receptor potential (TRP) channel-mediated inward current induced by activation of 5-HT2A receptors. This current produces membrane depolarization and increased bursting frequency in ET cells. Interestingly, the magnitude of the inward current and increased bursting inversely correlate with ET cell spontaneous (intrinsic) bursting frequency: slower bursting ET cells are more strongly modulated than faster bursting cells. Serotonin thus differentially impacts ET cells such that the mean bursting frequency of the population is increased. This centrifugal modulation could impact odor processing by: 1) increasing ET cell excitatory drive on inhibitory neurons to increase presynaptic inhibition of olfactory sensory inputs and postsynaptic inhibition of mitral/tufted cells; and/or 2) coordinating ET cell bursting with exploratory sniffing frequencies (5–8 Hz) to facilitate odor coding.

scholarly journals Dynamic Ensemble Odor Coding in the Mammalian Olfactory Bulb: Sensory Information at Different Timescales

Neuron ◽  
2008 ◽  
Vol 57 (4) ◽  
pp. 586-598 ◽  
Author(s):  
Brice Bathellier ◽  
Derek L. Buhl ◽  
Riccardo Accolla ◽  
Alan Carleton
Keyword(s):  
Olfactory Bulb ◽  
Sensory Information ◽  
Odor Coding

scholarly journals Recurrent cortical circuits implement concentration-invariant odor coding

2018 ◽  
Author(s):  
Kevin A. Bolding ◽  
Kevin M. Franks
Keyword(s):  
Olfactory Bulb ◽  
Concentration Dependence ◽  
Neural Circuit ◽  
Feedback Inhibition ◽  
Piriform Cortex ◽  
Cortical Activity ◽  
Cortical Circuits ◽  
Odor Coding ◽  
Recurrent Collateral ◽  
The Impact

Animals rely on olfaction to find food, attract mates and avoid predators. To support these behaviors, animals must reliably identify odors across different odorant concentrations. The neural circuit operations that implement this concentration invariance remain unclear. Here we demonstrate that, despite concentration-dependence in olfactory bulb (OB), representations of odor identity are preserved downstream, in piriform cortex (PCx). The OB cells responding earliest after inhalation drive robust responses in a sparse subset of PCx neurons. Recurrent collateral connections broadcast their activation across PCx, recruiting strong, global feedback inhibition that rapidly suppresses cortical activity for the remainder of the sniff, thereby discounting the impact of slower, concentration-dependent OB inputs. Eliminating recurrent collateral output dramatically amplifies PCx odor responses, renders cortex steeply concentration-dependent, and abolishes concentration-invariant identity decoding.

scholarly journals Broadly tuned and respiration-independent inhibition in the olfactory bulb of awake mice

2014 ◽  
Author(s):  
Brittany N Cazakoff ◽  
Billy Y B Lau ◽  
Kerensa L Crump ◽  
Heike Demmer ◽  
Stephen David Shea
Keyword(s):  
Olfactory Bulb ◽  
Granule Cells ◽  
Temporal Structure ◽  
Respiratory Rhythm ◽  
Brain State ◽  
Lateral Interactions ◽  
Odor Coding ◽  
State Dependent ◽  
Respiratory Synchronization ◽  
Ensemble Activity

Olfactory representations are shaped by both brain state and respiration; however, the interaction and circuit substrates of these influences are poorly understood. Granule cells (GCs) in the main olfactory bulb (MOB) are presumed to sculpt activity that reaches the olfactory cortex via inhibition of mitral/tufted cells (MTs). GCs may potentially sparsen ensemble activity by facilitating lateral inhibition among MTs, and/or they may enforce temporally-precise activity locked to breathing. Yet, the selectivity and temporal structure of GC activity during wakefulness are unknown. We recorded GCs in the MOB of anesthetized and awake mice and reveal pronounced state-dependent features of odor coding and temporal patterning. Under anesthesia, GCs exhibit sparse activity and are strongly and synchronously coupled to the respiratory cycle. Upon waking, GCs desynchronize, broaden their odor responses, and typically fire without regard for the respiratory rhythm. Thus during wakefulness, GCs exhibit stronger odor responses with less temporal structure. Based on these observations, we propose that during wakefulness GCs likely predominantly shape MT odor responses through broadened lateral interactions rather than respiratory synchronization.

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