scholarly journals State-dependent changes in olfactory cortical networks via cholinergic modulation

2018 ◽  
Author(s):  
Donald A. Wilson ◽  
Maxime Juventin ◽  
Maria Ilina ◽  
Alessandro Pizzo ◽  
Catia Teixeira
Keyword(s):  
Olfactory Bulb ◽  
Entorhinal Cortex ◽  
Synaptic Input ◽  
Piriform Cortex ◽  
Receptor Activation ◽  
Relative Strength ◽  
Top Down ◽  
Cortical Networks ◽  
Bottom Up ◽  
State Dependent

AbstractActivity in sensory cortical networks reflects both peripheral sensory input and intra‐ and inter-cortical network input. How sensory cortices balance these diverse inputs to provide relatively stable, accurate representations of the external world is not well understood. Furthermore, neuromodulation could alter the balance of these inputs in a state‐ and behavior-dependent manner. Here, we used optogenetic stimulation to directly assay the relative strength of bottom-up (olfactory bulb) and top-down (lateral entorhinal cortex) synaptic inputs to piriform cortex in freely moving rats. Optotrodes in the piriform cortex were used to test the relative strength of these two inputs, in separate animals, with extracellular, monosynaptic evoked potentials. The results suggest a rapid state-dependent shift in the balance of bottom-up and top-down inputs to PCX, with enhancement in the strength of lateral entorhinal cortex synaptic input and stability or depression of olfactory bulb synaptic input during slow-wave sleep compared to waking. The shift is in part due to a state-dependent change in cholinergic tone as assessed with fiber photometry of GCaMP6 fluorescence in basal forebrain ChAT+ neurons, and blockade of the state-dependent synaptic shift with cholinergic muscarinic receptor activation.

scholarly journals State-dependent linearisation of mixture representations by the olfactory bulb

2021 ◽  
Author(s):  
Aliya Mari Adefuin ◽  
Janine K Reinert ◽  
Sannder Lindeman ◽  
Izumi Fukunaga
Keyword(s):  
Olfactory Bulb ◽  
Sensory Processing ◽  
Piriform Cortex ◽  
Brain State ◽  
Complex Signals ◽  
Two Photon ◽  
State Dependent ◽  
The Difference ◽  
Apical Dendrites ◽  
The Brain

Sensory systems are often tasked to analyse complex signals from the environment, to separate relevant from irrelevant parts. This process of decomposing signals is challenging when component signals interfere with each other. For example, when a mixture of signals does not equal the sum of its parts, this leads to an unpredictable corruption of signal patterns, making the target recognition harder. In olfaction, nonlinear summation is prevalent at various stages of sensory processing, from stimulus transduction in the nasal epithelium to higher areas, including the olfactory bulb (OB) and the piriform cortex. Here, we investigate how the olfactory system deals with binary mixtures of odours, using two-photon imaging with several behavioural paradigms. Unlike previous studies using anaesthetised animals, we found the mixture summation to be substantially more linear when using awake, head-fixed mice performing an odour detection task. This linearisation was also observed in awake, untrained mice, in both engaged and disengaged states, revealing that the bulk of the difference in mixture summation is explained by the brain state. However, in the apical dendrites of M/T cells, mixture representation is dominated by sublinear summation. Altogether, our results demonstrate that the property of mixture representation in the primary olfactory area likely reflects state-dependent differences in sensory processing.

PREDATION RISK AFFECTS RELATIVE STRENGTH OF TOP-DOWN AND BOTTOM-UP IMPACTS ON INSECT HERBIVORES

Ecology ◽  
2003 ◽  
Vol 84 (4) ◽  
pp. 1032-1044 ◽  
Author(s):  
Robert F. Denno ◽  
Claudio Gratton ◽  
Hartmut Döbel ◽  
Deborah L. Finke
Keyword(s):  
Predation Risk ◽  
Relative Strength ◽  
Insect Herbivores ◽  
Top Down ◽  
Bottom Up

The Dynamics and Relative Strength of Bottom-Up vs Top-Down Impacts in a Community of Subtropical Lake Plankton

Oikos ◽  
1995 ◽  
Vol 73 (1) ◽  
pp. 104 ◽  
Author(s):  
Vladimir Matveev
Keyword(s):  
Relative Strength ◽  
Top Down ◽  
Bottom Up ◽  
Subtropical Lake

scholarly journals Does management of a top carnivore influence the response of mesopredators and prey to rainfall in arid ecosystems? Evidence for a Baseline Density theory

2021 ◽  
Author(s):  
Renee L. Brawata
Keyword(s):  
Primary Productivity ◽  
Relative Strength ◽  
Trophic Levels ◽  
Arid Ecosystems ◽  
Top Down ◽  
Down Regulation ◽  
Bottom Up ◽  
Rate Of Increase ◽  
Abundance And Diversity

ABSTRACT The removal of apex carnivores from ecosystems can impact the abundance and diversity of species in lower trophic levels. In arid ecosystems, where “bottom up” forces of primary productivity and resource availability strongly affect trophic interactions, the role of “top down” effects is still much debated. This study explored the potential role of an apex predator, the dingo, as a “top down” trophic regulator in Australian arid ecosystems under different levels of primary productivity and dingo management regimes. Consistent with the theory of top down regulation, strong relationships were found between dingo management, dingo activity and fox activity. Dingoes appeared to suppress fox activity where dingoes were uncontrolled or only opportunistically controlled. At sites where dingoes were absent or in low numbers, fox activity was higher, and this inverse relationship persisted regardless of rainfall. The activity of rabbits and small mammals was lower where dingoes were absent and fox activity was high, while the activity of macropods was higher in the absence of dingoes. Feral cat activity did not differ significantly between sites under different dingo management or between years. These results suggest that management of dingoes is a key determinant of fox activity and the activity of some prey under varying levels of productivity. Evidence from this research showed that while the strength of trophic regulation by dingoes may fluctuate, top down effects occurred both prior to and post significant rainfall events. Following this, top down regulation of fox populations during dry periods at sites where dingoes are retained may enable higher and more stable “baseline” densities of small vertebrates, from which a larger and more rapid rate of increase of these prey during the “boom” periods can occur. Understanding the relative strength and interactions of top down and bottom up forces in regulating populations, and under what ecological states the importance of each changes, is important for the long-term conservation of biodiversity in arid regions.

scholarly journals Tuning of ventral tenia tecta neurons of the olfactory cortex to distinct scenes of feeding behavior

2018 ◽  
Author(s):  
Kazuki Shiotani ◽  
Hiroyuki Manabe ◽  
Yuta Tanisumi ◽  
Koshi Murata ◽  
Junya Hirokawa ◽  
...  
Keyword(s):  
Prefrontal Cortex ◽  
Olfactory Bulb ◽  
Drinking Behavior ◽  
Piriform Cortex ◽  
Sensory Information ◽  
Afferent Input ◽  
Olfactory Cortex ◽  
Top Down ◽  
Behavioral Correlates ◽  
Drinking Behaviors

AbstractVentral tenia tecta (vTT) is a part of the olfactory cortex that receives both olfactory sensory signals from the olfactory bulb and top-down signals from the prefrontal cortex. To address the question whether and how the neuronal activity of the vTT is modulated by prefrontal cognitive processes such as attention, expectation and working memory that occurs during goal-directed behaviors, we recorded individual neuronal responses in the vTT of freely moving awake mice that performed learned odor-guided feeding and drinking behaviors. We found that the firing pattern of individual vTT cells had repeatable behavioral correlates such that the environmental and behavioral scene the mouse encountered during the learned behavior was the major determinant of when individual vTT neurons fired maximally. Furthermore, spiking activity of these scene cells was modulated not only by the present scene but also by the future scene that the mouse predicted. We show that vTT receives afferent input from the olfactory bulb and top-down inputs from the medial prefrontal cortex and piriform cortex.These results indicate that different groups of vTT cells are activated at different scenes and suggest that processing of olfactory sensory information is handled by different scene cells during distinct scenes of learned feeding and drinking behaviors. In other words, during the feeding and drinking behavior, vTT changes its working mode moment by moment in accord with the scene change by selectively biasing specific scene cells. The scene effect on olfactory sensory processing in the vTT has implications for the neuronal circuit mechanisms of top-down attention and scene-dependent encoding and recall of olfactory memory.

RELATIVE STRENGTH OF TOP-DOWN, BOTTOM-UP, AND CONSUMER SPECIES RICHNESS EFFECTS ON POND ECOSYSTEMS

2005 ◽  
Vol 75 (4) ◽  
pp. 489-504 ◽  
Author(s):  
Jeremy M. Wojdak
Keyword(s):  
Species Richness ◽  
Relative Strength ◽  
Top Down ◽  
Bottom Up ◽  
Pond Ecosystems

Entorhinal cortex stimulation modulates amygdala and piriform cortex responses to olfactory bulb inputs in the rat

Neuroscience ◽  
2006 ◽  
Vol 137 (4) ◽  
pp. 1131-1141 ◽  
Author(s):  
A.-M. Mouly ◽  
G. Di Scala
Keyword(s):  
Olfactory Bulb ◽  
Entorhinal Cortex ◽  
Piriform Cortex

scholarly journals Top-down inputs drive neuronal network rewiring and context-enhanced sensory processing in olfaction

2018 ◽  
Author(s):  
Wayne Adams ◽  
James N. Graham ◽  
Xuchen Han ◽  
Hermann Riecke
Keyword(s):  
Information Processing ◽  
Olfactory Bulb ◽  
Sensory Processing ◽  
Olfactory System ◽  
Sensory Input ◽  
Granule Cells ◽  
Top Down ◽  
Brain Areas ◽  
Bottom Up ◽  
Cluttered Environments

AbstractMuch of the computational power of the mammalian brain arises from its extensive top-down projections. To enable neuron-specific information processing these projections have to be precisely targeted. How such a specific connectivity emerges and what functions it supports is still poorly understood. We addressed these questions in silico in the context of the profound structural plasticity of the olfactory system. At the core of this plasticity are the granule cells of the olfactory bulb, which integrate bottom-up sensory inputs and top-down inputs delivered by vast top-down projections from cortical and other brain areas. We developed a biophysically supported computational model for the rewiring of the top-down projections and the intra-bulbar network via adult neurogenesis. The model captures various previous physiological and behavioral observations and makes specific predictions for the cortico-bulbar network connectivity that is learned by odor exposure and environmental contexts. Specifically, it predicts that after learning the granule-cell receptive fields with respect to sensory and with respect to cortical inputs are highly correlated. This enables cortical cells that respond to a learned odor to enact disynaptic inhibitory control specifically of bulbar principal cells that respond to that odor. Functionally, the model predicts context-enhanced stimulus discrimination in cluttered environments (‘olfactory cocktail parties’) and the ability of the system to adapt to its tasks by rapidly switching between different odor-processing modes. These predictions are experimentally testable. At the same time they provide guidance for future experiments aimed at unraveling the cortico-bulbar connectivity.Author summaryIn mammalian sensory processing, extensive top-down feedback from higher brain areas reshapes the feedforward, bottom-up information processing. The structure of the top-down connectivity, the mechanisms leading to its specificity, and the functions it supports are still poorly understood. Using computational modeling, we investigated these issues in the olfactory system. There, the granule cells of the olfactory bulb, which is the first brain area to receive sensory input from the nose, are the key players of extensive structural changes to the network through the addition and also the removal of granule cells as well as through the formation and removal of their connections. This structural plasticity allows the system to learn and to adapt its sensory processing to its odor environment. Crucially, the granule cells combine bottom-up sensory input from the nose with top-down input from higher brain areas, including cortex. Our biophysically supported computational model predicts that, after learning, the granule cells enable cortical neurons that respond to a learned odor to gain inhibitory control of principal neurons of the olfactory bulb, specifically of those that respond to the learned odor. Functionally, this allows top-down input to enhance odor discrimination in cluttered environments and to quickly switch between odor tasks.

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