scholarly journals Interhemispheric connections between olfactory bulbs improve odor detection

2019 ◽  
Author(s):  
Florence Kermen ◽  
Emre Yaksi
Keyword(s):  
Olfactory System ◽  
Spatial Organization ◽  
Sensory Information ◽  
Granule Cell Layer ◽  
Top Down ◽  
Olfactory Bulbs ◽  
Brain Hemispheres ◽  
Fine Grained ◽  
Olfactory Glomeruli ◽  
Interhemispheric Connection

SUMMARYInterhemispheric connections enable interaction and integration of sensory information in bilaterian nervous systems and are thought to optimize sensory computations. However, the cellular and spatial organization of interhemispheric networks as well as the computational properties they mediate in vertebrates are still poorly understood. Thus, it remains unclear to which extent the connectivity between left and right brain hemispheres participates in sensory processing. Here, we show that the zebrafish olfactory bulbs (OBs) receive direct interhemispheric projections from their contralateral counterparts in addition to top-down inputs from the contralateral zebrafish homolog of olfactory cortex. The direct interhemispheric projections between the OBs reach peripheral layers of the contralateral OB and retain a fine-grained topographic organization, which directly connects similarly tuned olfactory glomeruli across hemispheres. In contrast, interhemispheric top-down inputs consist of diffuse projections that broadly innervate the inhibitory granule cell layer. Jointly, these interhemispheric connections elicit a balance of topographically organized excitation and non-topographic inhibition on the contralateral OB and modulate odor responses. We show that the interhemispheric connections in the olfactory system enable the modulation of odor response and improve the detection of a reproductive pheromone, when presented together with competing complex olfactory cues, by boosting the response of the pheromone selective neurons. Taken together, our data shows a previously unknown function for an interhemispheric connection between chemosensory maps of the olfactory system.

scholarly journals The influence of stimulus duration on olfactory identity

2020 ◽  
Author(s):  
Praveen Kuruppath ◽  
Leonardo Belluscio
Keyword(s):  
Blue Light ◽  
Auditory System ◽  
Stimulus Duration ◽  
Olfactory System ◽  
Sensory Information ◽  
Olfactory Bulbs ◽  
Olfactory Information

AbstractDuration of a stimulus plays an important role in coding of sensory information. The role of stimulus duration is extensively studied in tactile, visual and auditory system. In the olfactory system, how the stimulus duration influences the identity of an olfactory information is not well understood. To test this, we activated the olfactory bulbs with blue light in mice expressing channelrhodopsin and behaviorally assessed the relevance of stimulus duration on olfactory identity. Our behavior data demonstrate that stimulus duration changes the olfactory information and the associated behavior.

Ultrastructural analysis of unique glycoconjugates in the rat olfactory system

1992 ◽  
Vol 50 (1) ◽  
pp. 890-891
Author(s):  
James E. Crandall ◽  
Linda C. Hassinger ◽  
Gerald A. Schwarting
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Monoclonal Antibodies ◽  
Olfactory System ◽  
Olfactory Bulbs ◽  
Temporal And Spatial Patterns ◽  
Carbohydrate Epitopes ◽  
Olfactory Systems ◽  
Temporal And Spatial ◽  
Cell Surface Glycoconjugates

Cell surface glycoconjugates are considered to play important roles in cell-cell interactions in the developing central nervous system. We have previously described a group of monoclonal antibodies that recognize defined carbohydrate epitopes and reveal unique temporal and spatial patterns of immunoreactivity in the developing main and accessory olfactory systems in rats. Antibody CC2 reacts with complex α-galactosyl and α-fucosyl glycoproteins and glycolipids. Antibody CC1 reacts with terminal N-acetyl galactosamine residues of globoside-like glycolipids. Antibody 1B2 reacts with β-galactosyl glycolipids and glycoproteins. Our light microscopic data suggest that these antigens may be located on the surfaces of axons of the vomeronasal and olfactory nerves as well as on some of their target neurons in the main and accessory olfactory bulbs.

Histological Properties of Main and Accessory Olfactory Bulbs in the Common Hippopotamus

2017 ◽  
Vol 90 (3) ◽  
pp. 224-231 ◽  
Author(s):  
Daisuke Kondoh ◽  
Kenichi Watanabe ◽  
Kaori Nishihara ◽  
Yurie S. Ono ◽  
Kentaro G. Nakamura ◽  
...  
Keyword(s):  
Granule Cell ◽  
Olfactory System ◽  
Olfactory Nerve ◽  
Mitral Cell ◽  
Vomeronasal System ◽  
Olfactory Bulbs ◽  
Hippopotamus Amphibius ◽  
Cell Layers ◽  
The Common ◽  
Tufted Cells

The olfactory system of mammals comprises a main olfactory system that detects hundreds of odorants and a vomeronasal system that detects specific chemicals such as pheromones. The main (MOB) and accessory (AOB) olfactory bulbs are the respective primary centers of the main olfactory and vomeronasal systems. Most mammals including artiodactyls possess a large MOB and a comparatively small AOB, whereas most cetaceans lack olfactory bulbs. The common hippopotamus (Hippopotamus amphibius) is semiaquatic and belongs to the order Cetartiodactyla, family Hippopotamidae, which seems to be the closest extant family to cetaceans. The present study evaluates the significance of the olfactory system in the hippopotamus by histologically analyzing the MOB and AOB of a male common hippopotamus. The MOB comprised six layers (olfactory nerve, glomerular, external plexiform, mitral cell, internal plexiform, and granule cell), and the AOB comprised vomeronasal nerve, glomerular, plexiform, and granule cell layers. The MOB contained mitral cells and tufted cells, and the AOB possessed mitral/tufted cells. These histological features of the MOB and the AOB were similar to those in most artiodactyls. All glomeruli in the AOB were positive for anti-Gαi2, but weakly positive for anti-Gαo, suggesting that the hippopotamus vomeronasal system expresses vomeronasal type 1 receptors with a high affinity for volatile compounds. These findings suggest that the olfactory system of the hippopotamus is as well developed as that of other artiodactyl species and that the hippopotamus might depend on its olfactory system for terrestrial social communication.

scholarly journals A supragranular nexus for the effects of neocortical beta events on human tactile perception

2019 ◽  
Author(s):  
Robert G. Law ◽  
Sarah Pugliese ◽  
Hyeyoung Shin ◽  
Danielle Sliva ◽  
Shane Lee ◽  
...  
Keyword(s):  
Somatosensory Cortex ◽  
Spectral Power ◽  
Sensory Information ◽  
Sensory Perception ◽  
Higher Order ◽  
Beta Band ◽  
Top Down ◽  
Sensory Suppression ◽  
Neuronal Mechanisms ◽  
Event Rates

AbstractTransient neocortical events with high spectral power in the 15–29Hz beta band are among the most reliable predictors of sensory perception: High prestimulus beta event rates in primary somatosensory lead to sensory suppression, most effective at 100–300ms prestimulus latency. However, the synaptic and neuronal mechanisms inducing beta’s perceptual effects have not been completely localized. We combined human MEG with neural modeling designed to account for these macroscale signals to interpret the cellular and circuit mechanisms that underlie the influence of beta on tactile detection. Extending prior studies, we modeled the hypothesis that higher-order thalamic bursts, sufficient for beta event generation in cortex, recruit supragranular GABAB inhibition acting on a 300ms time scale to suppress sensory information. Consistency between model and MEG data supported this hypothesis and led to a further prediction, validated in our data, that stimuli are perceived when beta events occur simultaneously with tactile stimulation. The post-event suppressive mechanism explains an array of studies that associate beta with decreased processing, while the during-event mechanism may demand a reinterpretation of the role of beta events in the context of coincident timing.Significance statementSomatosensory beta events – transient 15-29Hz oscillations in electromagnetic recordings – are thought to be generated when “top-down” bursts of spikes presumably originating in higher-order thalamus arrive in upper layers of somatosensory cortex. Physiological evidence had shown that the immediate action of these top-down projections should be excitatory; however, after a beta event, sensory perception is noticeably inhibited for approximately 300ms. The source of this post-event sensory suppression, in particular, had been unresolved. Using a detailed computational model of somatosensory cortex, we find evidence for the hypothesis that these bursts couple indirectly to GABAB inhibition in upper layers of cortex, and that beta events first briefly disinhibit sensory relay before a longer period of inhibition.

Counting on Carrington Road: Street Numbers as Metonyms of the Urban

2018 ◽  
Vol 17 (4) ◽  
pp. 433-450 ◽  
Author(s):  
Alexandra Crosby ◽  
Kirsten Seale
Keyword(s):  
Visual Presentation ◽  
Creative Industries ◽  
Creative Economy ◽  
Top Down ◽  
Fine Grained ◽  
Creative City ◽  
Starting Point ◽  
Urban Futures ◽  
Post Industrial ◽  
The City

As urban renewal agendas are fortified in cities globally, ‘creativity’ – as contained within discourses of the creative industries, the Creative City and the creative economy – is circulated as the currency of secure post-industrial urban futures. Using the nexus between creativity and the urban as a starting point, the authors investigate how local enterprises visually communicate the urban in a neighbourhood that is characterized by the interface between manufacturing and creative industries. This research takes a fine-grained approach to the notion of creativity through an audit and qualitative analysis of the visual presentation, material attributes and semiotic meaning of street numbers. The authors do this by collecting data on and analysing how street numbers have been made, selected, used, replaced and layered in a contested industrial precinct in Australia’s largest city, Sydney. They contend that street numbers, as a ubiquitous technology within the city that is both operational and creative, are metonyms for what they understand to be urban. In arguing for vernacular readings of the city, they make use of a top-down, governmental mode of reading the city – the operational legibility of street numbering – as an intervention in current discourses of the urban and of creativity in the city.

scholarly journals Top-down attention selection is fine grained

2006 ◽  
Vol 6 (11) ◽  
pp. 4-4 ◽  
Author(s):  
V. Navalpakkam ◽  
L. Itti
Keyword(s):  
Top Down ◽  
Fine Grained ◽  
Attention Selection

scholarly journals Behavioral responses across a mosaic of ecosystem states restructure a sea otter–urchin trophic cascade

2021 ◽  
Vol 118 (11) ◽  
pp. e2012493118 ◽  
Author(s):  
Joshua G. Smith ◽  
Joseph Tomoleoni ◽  
Michelle Staedler ◽  
Sophia Lyon ◽  
Jessica Fujii ◽  
...  
Keyword(s):  
Foraging Behavior ◽  
Sea Urchin ◽  
Spatial Organization ◽  
Scale Up ◽  
Population Level ◽  
Kelp Forests ◽  
Sea Otter ◽  
Natural Ecosystems ◽  
Top Down ◽  
Relative Contribution

Consumer and predator foraging behavior can impart profound trait-mediated constraints on community regulation that scale up to influence the structure and stability of ecosystems. Here, we demonstrate how the behavioral response of an apex predator to changes in prey behavior and condition can dramatically alter the role and relative contribution of top-down forcing, depending on the spatial organization of ecosystem states. In 2014, a rapid and dramatic decline in the abundance of a mesopredator (Pycnopodia helianthoides) and primary producer (Macrocystis pyrifera) coincided with a fundamental change in purple sea urchin (Strongylocentrotus purpuratus) foraging behavior and condition, resulting in a spatial mosaic of kelp forests interspersed with patches of sea urchin barrens. We show that this mosaic of adjacent alternative ecosystem states led to an increase in the number of sea otters (Enhydra lutris nereis) specializing on urchin prey, a population-level increase in urchin consumption, and an increase in sea otter survivorship. We further show that the spatial distribution of sea otter foraging efforts for urchin prey was not directly linked to high prey density but rather was predicted by the distribution of energetically profitable prey. Therefore, we infer that spatially explicit sea otter foraging enhances the resistance of remnant forests to overgrazing but does not directly contribute to the resilience (recovery) of forests. These results highlight the role of consumer and predator trait-mediated responses to resource mosaics that are common throughout natural ecosystems and enhance understanding of reciprocal feedbacks between top-down and bottom-up forcing on the regional stability of ecosystems.

scholarly journals Nonlinear Dendritic Coincidence Detection for Supervised Learning

2021 ◽  
Vol 15 ◽  
Author(s):  
Fabian Schubert ◽  
Claudius Gros
Keyword(s):  
Pyramidal Neurons ◽  
Hebbian Learning ◽  
Sensory Information ◽  
Dendritic Tree ◽  
Compartment Model ◽  
Active Role ◽  
Research Field ◽  
Coincidence Detection ◽  
Top Down ◽  
Feed Forward

Cortical pyramidal neurons have a complex dendritic anatomy, whose function is an active research field. In particular, the segregation between its soma and the apical dendritic tree is believed to play an active role in processing feed-forward sensory information and top-down or feedback signals. In this work, we use a simple two-compartment model accounting for the nonlinear interactions between basal and apical input streams and show that standard unsupervised Hebbian learning rules in the basal compartment allow the neuron to align the feed-forward basal input with the top-down target signal received by the apical compartment. We show that this learning process, termed coincidence detection, is robust against strong distractions in the basal input space and demonstrate its effectiveness in a linear classification task.

scholarly journals Plume Dynamics Structure the Spatiotemporal Activity of Mitral/Tufted Cell Networks in the Mouse Olfactory Bulb

2021 ◽  
Vol 15 ◽  
Author(s):  
Suzanne M. Lewis ◽  
Lai Xu ◽  
Nicola Rigolli ◽  
Mohammad F. Tariq ◽  
Lucas M. Suarez ◽  
...  
Keyword(s):  
Olfactory Bulb ◽  
Olfactory System ◽  
Large Scale ◽  
Early Stage ◽  
Wide Field ◽  
Flow Conditions ◽  
Population Activity ◽  
Plume Dynamics ◽  
Olfactory Glomeruli ◽  
Odor Plumes

Although mice locate resources using turbulent airborne odor plumes, the stochasticity and intermittency of fluctuating plumes create challenges for interpreting odor cues in natural environments. Population activity within the olfactory bulb (OB) is thought to process this complex spatial and temporal information, but how plume dynamics impact odor representation in this early stage of the mouse olfactory system is unknown. Limitations in odor detection technology have made it difficult to measure plume fluctuations while simultaneously recording from the mouse's brain. Thus, previous studies have measured OB activity following controlled odor pulses of varying profiles or frequencies, but this approach only captures a subset of features found within olfactory plumes. Adequately sampling this feature space is difficult given a lack of knowledge regarding which features the brain extracts during exposure to natural olfactory scenes. Here we measured OB responses to naturally fluctuating odor plumes using a miniature, adapted odor sensor combined with wide-field GCaMP6f signaling from the dendrites of mitral and tufted (MT) cells imaged in olfactory glomeruli of head-fixed mice. We precisely tracked plume dynamics and imaged glomerular responses to this fluctuating input, while varying flow conditions across a range of ethologically-relevant values. We found that a consistent portion of MT activity in glomeruli follows odor concentration dynamics, and the strongest responding glomeruli are the best at following fluctuations within odor plumes. Further, the reliability and average response magnitude of glomerular populations of MT cells are affected by the flow condition in which the animal samples the plume, with the fidelity of plume following by MT cells increasing in conditions of higher flow velocity where odor dynamics result in intermittent whiffs of stronger concentration. Thus, the flow environment in which an animal encounters an odor has a large-scale impact on the temporal representation of an odor plume in the OB. Additionally, across flow conditions odor dynamics are a major driver of activity in many glomerular networks. Taken together, these data demonstrate that plume dynamics structure olfactory representations in the first stage of odor processing in the mouse olfactory system.

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