Multicompartment Simulations of NMDA Receptor Based Facilitation in an Insect Target Tracking Neuron

Bekkouche, Bo; Shoemaker, Patrick A.; Fabian, Joseph M.; Rigosi, Elisa; Wiederman, Steven D.; O’Carroll, David C.

doi:10.1007/978-3-319-68600-4_46

Cited by 4 publications

(12 citation statements)

References 17 publications

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“…Applications range from imaging neurons revealed via optogenetic techniques, to in-situ neuronal tracing in order to establish circuit level interactions between neurons (Dunbier et al, 2012;Keles and Frye, 2017). As an example, our lab has been applying biophysically realistic computational models for dendritic integration by neurons (Shoemaker, 2011;Bekkouche et al, 2017). Such models rely on high resolution 3D reconstruction of individual neuron morphologies within the brain, to establish the biophysical compartments through which neuronal signals travel.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Transparency and Shrinkage During Clearing of Insect Brains Using Media With Tunable Refractive Index

et al. 2020

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Improvement of imaging quality has the potential to visualize previously unseen building blocks of the brain and is therefore one of the great challenges in neuroscience. Rapid development of new tissue clearing techniques in recent years have attempted to solve imaging compromises in thick brain samples, particularly for high resolution optical microscopy, where the clearing medium needs to match the high refractive index of the objective immersion medium. These problems are exacerbated in insect tissue, where numerous (initially air-filled) tracheal tubes branching throughout the brain increase the scattering of light. To date, surprisingly few studies have systematically quantified the benefits of such clearing methods using objective transparency and tissue shrinkage measurements. In this study we compare a traditional and widely used insect clearing medium, methyl salicylate combined with permanent mounting in Permount (“MS/P”) with several more recently applied clearing media that offer tunable refractive index (n): 2,2′-thiodiethanol (TDE), “SeeDB2” (in variants SeeDB2S and SeeDB2G matched to oil and glycerol immersion, n = 1.52 and 1.47, respectively) and Rapiclear (also with n = 1.52 and 1.47). We measured transparency and tissue shrinkage by comparing freshly dissected brains with cleared brains from dipteran flies, with or without addition of vacuum or ethanol pre-treatments (dehydration and rehydration) to evacuate air from the tracheal system. The results show that ethanol pre-treatment is very effective for improving transparency, regardless of the subsequent clearing medium, while vacuum treatment offers little measurable benefit. Ethanol pre-treated SeeDB2G and Rapiclear brains show much less shrinkage than using the traditional MS/P method. Furthermore, at lower refractive index, closer to that of glycerol immersion, these recently developed media offer outstanding transparency compared to TDE and MS/P. Rapiclear protocols were less laborious compared to SeeDB2, but both offer sufficient transparency and refractive index tunability to permit super-resolution imaging of local volumes in whole mount brains from large insects, and even light-sheet microscopy. Although long-term permanency of Rapiclear stored samples remains to be established, our samples still showed good preservation of fluorescence after storage for more than a year at room temperature.

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Section: Introductionmentioning

confidence: 99%

Comparison of Transparency and Shrinkage During Clearing of Insect Brains Using Media With Tunable Refractive Index

et al. 2020

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“…We have reported here analysis of NMDA-mediated response facilitation using an elaborated version of a model for which we previously reported the modelling framework (Bekkouche et al, 2017). It should be noted that our preliminary version of this model suffered from mapping inaccuracies between the ESTMD inputs and the BSTMD1 model.…”

Section: Discussionmentioning

confidence: 99%

“…A low-pass temporal filter delays the signals from each partially rectified detector so that a non-linear (multiplicative) correlator within the ESTMD compares each delayed signal with the undelayed signal of opposite sign. Combination of this ‘feature template’ with fast adaptation (to reject background texture) and center-surround antagonism provides a sharp selectivity for small, moving targets within the input images (Wiederman et al, 2008; Bekkouche et al, 2017). The output of this model stage was then mapped onto the presumed input dendrites of the neurons, as projected into a 2-dimensional image ( Figure 1B ) assumed to be a retinotopic projection of the space in the visual field.…”

Section: Methodsmentioning

confidence: 99%

“…In the present study, we further developed this computational approach to investigate the possible role for NMDARs in the facilitation of dragonfly STMD neurons, as introduced in our previous work (Shoemaker, 2011; Bekkouche et al, 2017). Here we focus on the facilitation of responses to stimuli moving along long trajectories in the dragonfly BSTMD1 neuron, believed to play a key role in the dragonfly visual selective attention mechanism (Dunbier et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

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Modelling nonlinear dendritic processing of facilitation in a dragonfly target-tracking neuron

Bekkouche

Shoemaker

Fabian

et al. 2021

Preprint

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Dragonflies are highly skilled and successful aerial predators that are even capable of selectively attending to one target within a swarm. Detection and tracking prey is likely to be driven by small target motion detector (STMD) neurons identified from several insect groups. Prior work has shown that dragonfly STMD responses are facilitated by targets moving on a continuous path, enhancing the response gain at the present and predicted future location of targets. In this study, we combined detailed morphological data with computational modelling to test whether a combination of dendritic morphology combined with the nonlinear properties of NMDA receptors could explain these observations. We developed a hybrid neuronal model of neurons within the dragonfly optic lobe, which integrates numerical and morphological components. The model was able to generate potent facilitation for targets moving on continuous trajectories, including a localized spotlight of maximal sensitivity close to the last seen target location, as also measured during in vivo recordings. The model did not, however, include a mechanism capable of producing a traveling or spreading wave of facilitation. Our data support a strong role for the high dendritic density seen in the dragonfly neuron in enhancing non-linear facilitation. An alternative model based on morphology of an unrelated type of motion processing neuron from a dipteran fly required more than 3 times higher synaptic gain in order to elicit similar levels of facilitation, despite having only 20% fewer synapses. Our data supports a potential role for NMDA receptors in target tracking and also demonstrates the feasibility of combining biologically plausible dendritic computations with more abstract computational models for basic processing as used in earlier studies.

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“…Applications range from imaging neurons revealed via optogenetic techniques, to in-situ neuronal tracing in order to establish circuit level interactions between neurons (Dunbier et al, 2012; Keles and Frye, 2017). In our own lab, for example, we are interested in applying biophysically realistic computational models to improve our understanding and test hypotheses regarding how the brain works (Shoemaker, 2011; Bekkouche et al, 2017). Such models rely on high resolution microscopy, enabling 3D reconstruction of individual neuron morphologies within the brain, to establish the likely biophysical compartments through which neuronal signals travel.…”

Section: Introductionmentioning

confidence: 99%

Comparison of transparency and shrinkage of insect brains using novel and traditional clearing methods

Bekkouche

Fritz

Rigosi

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

Improvement of imaging quality has the potential to visualize previously unseen building blocks of the brain and is therefore one of the great challenges in neuroscience. Rapid development of new tissue clearing techniques in recent years have attempted to solve imaging compromises in thick brain samples, particularly for high resolution optical microscopy, where the clearing medium needs to match the refractive index of the objective immersion medium. These problems are exacerbated in insect tissue, where numerous (initially air-filled) tracheal tubes branching throughout the brain increase the scattering of light. To date, surprisingly few studies have systematically quantified the benefits of such clearing methods using objective transparency and tissue shrinkage measurements. In this study we compare a traditional and widely used insect clearing medium, methyl salicylate combined with permanent mounting in Permount (‘MS/P’) with several more recently applied clearing media that offer tunable refractive index (n): 2,2-thiodiethanol (TDE), ‘SeeDB2’ (in variants SeeDB2S & SeeDB2G matched to oil and glycerol immersion, n=1.52 & 1.47 respectively) and Rapiclear (also with n=1.52 & 1.47). We measured transparency and tissue shrinkage by comparing freshly dissected brains with cleared brains from dipteran flies, with or without addition of vacuum or ethanol pre-treatments (dehydration and rehydration) to evacuate air from the tracheal system. The results show that ethanol pre-treatment is very effective for improving transparency, regardless of the subsequent clearing medium, while vacuum treatment offers little measurable benefit. Ethanol pre-treated SeeDB2G and Rapiclear brains show much less shrinkage than using the traditional MS/P method. Furthermore, these newly developed media offer outstanding transparency compared to TDE and MS/P. Rapiclear protocols were less laborious compared to SeeDB2, but both offer sufficient transparency and refractive index tunability to permit super-resolution imaging of local volumes in whole mount brains from large insects, and even light-sheet microscopy. Although long-term permanency of Rapiclear stored samples remains to be established, our samples still showed good preservation of fluorescence after storage for more than a year at room temperature.

show abstract

Multicompartment Simulations of NMDA Receptor Based Facilitation in an Insect Target Tracking Neuron

Cited by 4 publications

References 17 publications

Comparison of Transparency and Shrinkage During Clearing of Insect Brains Using Media With Tunable Refractive Index

Comparison of Transparency and Shrinkage During Clearing of Insect Brains Using Media With Tunable Refractive Index

Modelling nonlinear dendritic processing of facilitation in a dragonfly target-tracking neuron

Comparison of transparency and shrinkage of insect brains using novel and traditional clearing methods

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