scholarly journals Functional relevance of dual olfactory bulb in olfactory coding

2019 ◽  
Author(s):  
Praveen Kuruppath ◽  
Li Bai ◽  
Leonardo Belluscio
Keyword(s):  
Olfactory Bulb ◽  
Receptive Fields ◽  
Behavioral Experiments ◽  
Olfactory Bulbs ◽  
Olfactory Coding ◽  
Olfactory Information ◽  
Functional Relevance ◽  
Stimulus Localization ◽  
External Stimuli ◽  
First Time

AbstractBilateral convergence of external stimuli is a common feature of vertebrate sensory systems. This convergence of inputs from the bilateral receptive fields allows higher order sensory perception, such as depth perception in the vertebrate visual system and stimulus localization in the auditory system. The functional role of such bilateral convergence in the olfactory system is mostly unknown. To test whether each olfactory bulb contributes a separate piece of olfactory information, and whether information from the bilateral olfactory bulb is integrated, we synchronized the activation of olfactory bulbs with blue light in mice expressing channelrhodopsin in the olfactory sensory neurons and behaviorally assessed the relevance of dual olfactory bulb in olfactory perception. Our findings suggest that each olfactory bulb contributes separate components of olfactory information and mice integrate the olfactory information from each olfactory bulb to identify an olfactory stimulus.Significance statementIdentifying an odor is the first step in olfactory coding, as it is critical for the survival of most animals. Previous studies have shown that bilateral olfactory bulbs help rodents to localize the odor source and navigate accordingly. But It is still unclear whether the bilateral olfactory information plays any role in determining odor identity. Here for the first time, using optogenetics and behavioral experiments, we demonstrate that each olfactory bulb provides distinct olfactory information, and rodents integrate information from the two bulbs to identify an odor.

scholarly journals Functional relevance of dual olfactory bulbs in olfactory coding

eNeuro ◽  
2021 ◽  
pp. ENEURO.0070-21.2021
Author(s):  
Praveen Kuruppath ◽  
Li Bai ◽  
Leonardo Belluscio
Keyword(s):  
Olfactory Bulbs ◽  
Olfactory Coding ◽  
Functional Relevance

scholarly journals NMDA spikes mediate amplification of inputs in the rat piriform cortex

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Amit Kumar ◽  
Oded Schiff ◽  
Edi Barkai ◽  
Bartlett W Mel ◽  
Alon Poleg-Polsky ◽  
...  
Keyword(s):  
Olfactory Bulb ◽  
Pyramidal Neurons ◽  
Piriform Cortex ◽  
Receptive Fields ◽  
Odor Recognition ◽  
Olfactory Glomeruli ◽  
Direct Input ◽  
Main Station ◽  
First Time ◽  
Prevailing View

The piriform cortex (PCx) receives direct input from the olfactory bulb (OB) and is the brain's main station for odor recognition and memory. The transformation of the odor code from OB to PCx is profound: mitral and tufted cells in olfactory glomeruli respond to individual odorant molecules, whereas pyramidal neurons (PNs) in the PCx responds to multiple, apparently random combinations of activated glomeruli. How these ‘discontinuous’ receptive fields are formed from OB inputs remains unknown. Counter to the prevailing view that olfactory PNs sum their inputs passively, we show for the first time that NMDA spikes within individual dendrites can both amplify OB inputs and impose combination selectivity upon them, while their ability to compartmentalize voltage signals allows different dendrites to represent different odorant combinations. Thus, the 2-layer integrative behavior of olfactory PN dendrites provides a parsimonious account for the nonlinear remapping of the odor code from bulb to cortex.

scholarly journals NMDA spikes mediate amplification of odor pathway information in the piriform cortex

2018 ◽  
Author(s):  
Amit Kumar ◽  
Oded Schiff ◽  
Edi Barkai ◽  
Bartlett W. Mel ◽  
Alon Poleg-Polsky ◽  
...  
Keyword(s):  
Olfactory Bulb ◽  
Pyramidal Neurons ◽  
Piriform Cortex ◽  
Receptive Fields ◽  
Odor Recognition ◽  
Olfactory Glomeruli ◽  
Direct Input ◽  
Main Station ◽  
First Time ◽  
Prevailing View

AbstractThe piriform cortex (PCx) receives direct input from the olfactory bulb (OB) and is the brain’s main station for odor recognition and memory. The transformation of the odor code from OB to PCx is profound: mitral and tufted cells in olfactory glomeruli respond to individual odorant molecules, whereas pyramidal neurons (PNs) in the PCx responds to multiple, apparently random combinations of activated glomeruli. How these “discontinuous” receptive fields are formed from OB inputs remains unknown. Counter to the prevailing view that olfactory PNs sum their inputs passively, we show for the first time that NMDA spikes within individual dendrites can both amplify OB inputs and impose combination selectivity upon them, while their ability to compartmentalize voltage signals allows different dendrites to represent different odorant combinations. Thus, the 2-layer integrative behavior of olfactory PN dendrites provides a parsimonious account for the nonlinear remapping of the odor code from bulb to cortex.

scholarly journals Olfactory acuity in theropods: palaeobiological and evolutionary implications

2008 ◽  
Vol 276 (1657) ◽  
pp. 667-673 ◽  
Author(s):  
Darla K Zelenitsky ◽  
François Therrien ◽  
Yoshitsugu Kobayashi
Keyword(s):  
Olfactory Bulb ◽  
Cerebral Hemisphere ◽  
Home Ranges ◽  
Light Conditions ◽  
Low Light ◽  
Olfactory Bulbs ◽  
Theropod Dinosaurs ◽  
Olfactory Acuity ◽  
Predicted Values ◽  
Omnivorous Diet

This research presents the first quantitative evaluation of the olfactory acuity in extinct theropod dinosaurs. Olfactory ratios (i.e. the ratio of the greatest diameter of the olfactory bulb to the greatest diameter of the cerebral hemisphere) are analysed in order to infer the olfactory acuity and behavioural traits in theropods, as well as to identify phylogenetic trends in olfaction within Theropoda. A phylogenetically corrected regression of olfactory ratio to body mass reveals that, relative to predicted values, the olfactory bulbs of (i) tyrannosaurids and dromaeosaurids are significantly larger, (ii) ornithomimosaurs and oviraptorids are significantly smaller, and (iii) ceratosaurians, allosauroids, basal tyrannosauroids, troodontids and basal birds are within the 95% CI. Relative to other theropods, olfactory acuity was high in tyrannosaurids and dromaeosaurids and therefore olfaction would have played an important role in their ecology, possibly for activities in low-light conditions, locating food, or for navigation within large home ranges. Olfactory acuity was the lowest in ornithomimosaurs and oviraptorids, suggesting a reduced reliance on olfaction and perhaps an omnivorous diet in these theropods. Phylogenetic trends in olfaction among theropods reveal that olfactory acuity did not decrease in the ancestry of birds, as troodontids, dromaeosaurids and primitive birds possessed typical or high olfactory acuity. Thus, the sense of smell must have remained important in primitive birds and its presumed decrease associated with the increased importance of sight did not occur until later among more derived birds.

scholarly journals Adaptation of Orientation Vectors of Otolith-Related Central Vestibular Neurons to Gravity

2008 ◽  
Vol 100 (3) ◽  
pp. 1686-1690 ◽  
Author(s):  
Julia N. Eron ◽  
Bernard Cohen ◽  
Theodore Raphan ◽  
Sergei B. Yakushin
Keyword(s):  
Polarization Vector ◽  
Vestibular Nuclei ◽  
Perceptual Information ◽  
Behavioral Experiments ◽  
Adaptive Capabilities ◽  
Before And After ◽  
Vector Orientation ◽  
First Time ◽  
Specific Orientation ◽  
Response Vector

Behavioral experiments indicate that central pathways that process otolith-ocular and perceptual information have adaptive capabilities. Because polarization vectors of otolith afferents are directly related to the electro-mechanical properties of the hair cell bundle, it is unlikely that they change their direction of excitation. This indicates that the adaptation must take place in central pathways. Here we demonstrate for the first time that otolith polarization vectors of canal-otolith convergent neurons in the vestibular nuclei have adaptive capability. A total of 10 vestibular-only and vestibular-plus-saccade neurons were recorded extracellularly in two monkeys before and after they were in side-down positions for 2 h. The spatial characteristics of the otolith input were determined from the response vector orientation (RVO), which is the projection of the otolith polarization vector, onto the head horizontal plane. The RVOs had no specific orientation before animals were in side-down positions but moved toward the gravitational axis after the animals were tilted for extended periods. Vector reorientations varied from 0 to 109° and were linearly related to the original deviation of the RVOs from gravity in the position of adaptation. Such reorientation of central polarization vectors could provide the basis for changes in perception and eye movements related to prolonged head tilts relative to gravity or in microgravity.

Olfactory coding in the mammalian olfactory bulb

2003 ◽  
Vol 42 (1) ◽  
pp. 23-32 ◽  
Author(s):  
Michael Leon ◽  
Brett A. Johnson
Keyword(s):  
Olfactory Bulb ◽  
Olfactory Coding

Odd Sound Processing in the Sleeping Brain

2008 ◽  
Vol 20 (2) ◽  
pp. 296-311 ◽  
Author(s):  
Perrine Ruby ◽  
Anne Caclin ◽  
Sabrina Boulet ◽  
Claude Delpuech ◽  
Dominique Morlet
Keyword(s):  
Paradoxical Sleep ◽  
Sleep Stage ◽  
Sleep Stages ◽  
Oddball Paradigm ◽  
External Stimulation ◽  
Memory Processing ◽  
Stage 4 ◽  
Stage 1 ◽  
External Stimuli ◽  
First Time

How does the sleeping brain process external stimuli, and in particular, up to which extent does the sleeping brain detect and process modifications in its sensory environment? In order to address this issue, we investigated brain reactivity to simple auditory stimulations during sleep in young healthy subjects. Electroencephalogram signal was acquired continuously during a whole night of sleep while a classical oddball paradigm with duration deviance was applied. In all sleep stages, except Sleep Stage 4, a mismatch negativity (MMN) was unquestionably found in response to deviant tones, revealing for the first time preserved sensory memory processing during almost the whole night. Surprisingly, during Sleep Stage 2 and paradoxical sleep, both P3a-like and P3b-like components were identified after the MMN, whereas a P3a alone followed the MMN in wakefulness and in Sleep Stage 1. This totally new result suggests elaborated processing of external stimulation during sleep. We propose that the P3b-like response could be associated to an active processing of the deviant tone in the dream's consciousness.

Stimulus-Dependent Synchronization of Neuronal Assemblies

1993 ◽  
Vol 5 (4) ◽  
pp. 550-569 ◽  
Author(s):  
E. R. Grannan ◽  
D. Kleinfeld ◽  
H. Sompolinsky
Keyword(s):  
Receptive Fields ◽  
Spatial Variations ◽  
Neuronal Oscillations ◽  
Neuronal Assemblies ◽  
Neuronal Interactions ◽  
Cooperative Dynamics ◽  
Neuronal Oscillators ◽  
External Stimuli ◽  
Activity Dependent

We study theoretically how an interaction between assemblies of neuronal oscillators can be modulated by the pattern of external stimuli. It is shown that spatial variations in the stimuli can control the magnitude and phase of the synchronization between the output of neurons with different receptive fields. This modulation emerges from cooperative dynamics in the network, without the need for specialized, activity-dependent synapses. Our results further suggest that the modulation of neuronal interactions by extended features of a stimulus may give rise to complex spatiotemporal fluctuations in the phases of neuronal oscillations.

scholarly journals Input connectivity reveals additional heterogeneity of dopaminergic reinforcement in Drosophila

2020 ◽  
Author(s):  
Nils Otto ◽  
Markus W. Pleijzier ◽  
Isabel C. Morgan ◽  
Amelia J. Edmondson-Stait ◽  
Konrad J. Heinz ◽  
...  
Keyword(s):  
Dopaminergic Neurons ◽  
Mushroom Body ◽  
List Type ◽  
Behavioral Experiments ◽  
State Dependent ◽  
Memory Extinction ◽  
Level Function ◽  
Output Neurons ◽  
Functional Relevance ◽  
Dendritic Branches

SummaryDifferent types of Drosophila dopaminergic neurons (DANs) reinforce memories of unique valence and provide state-dependent motivational control [1]. Prior studies suggest that the compartment architecture of the mushroom body (MB) is the relevant resolution for distinct DAN functions [2, 3]. Here we used a recent electron microscope volume of the fly brain [4] to reconstruct the fine anatomy of individual DANs within three MB compartments. We find the 20 DANs of the γ5 compartment, at least some of which provide reward teaching signals, can be clustered into 5 anatomical subtypes that innervate different regions within γ5. Reconstructing 821 upstream neurons reveals input selectivity, supporting the functional relevance of DAN sub-classification. Only one PAM-γ5 DAN subtype γ5(fb) receives direct recurrent input from γ5β’2a mushroom body output neurons (MBONs) and behavioral experiments distinguish a role for these DANs in memory revaluation from those reinforcing sugar memory. Other DAN subtypes receive major, and potentially reinforcing, inputs from putative gustatory interneurons or lateral horn neurons, which can also relay indirect feedback from MBONs. We similarly reconstructed the single aversively reinforcing PPL1-γ1pedc DAN. The γ1pedc DAN inputs mostly differ from those of γ5 DANs and they cluster onto distinct dendritic branches, presumably separating its established roles in aversive reinforcement and appetitive motivation [5, 6]. Tracing also identified neurons that provide broad input to γ5, β’2a and γ1pedc DANs suggesting that distributed DAN populations can be coordinately regulated. These connectomic and behavioral analyses therefore reveal further complexity of dopaminergic reinforcement circuits between and within MB compartments.HighlightsNanoscale anatomy reveals additional subtypes of rewarding dopaminergic neurons.Connectomics reveals extensive input specificity to subtypes of dopaminergic neurons.Axon morphology implies dopaminergic neurons provide subcompartment-level function.Unique dopaminergic subtypes serve aversive memory extinction and sugar learning.

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