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Kohn JR, Portes JP, Christenson MP, Abbott LF, Behnia R. Flexible filtering by neural inputs supports motion computation across states and stimuli. Curr Biol 2021; 31:5249-5260.e5. [PMID: 34670114 DOI: 10.1016/j.cub.2021.09.061] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Revised: 08/10/2021] [Accepted: 09/22/2021] [Indexed: 01/05/2023]
Abstract
Sensory systems flexibly adapt their processing properties across a wide range of environmental and behavioral conditions. Such variable processing complicates attempts to extract a mechanistic understanding of sensory computations. This is evident in the highly constrained, canonical Drosophila motion detection circuit, where the core computation underlying direction selectivity is still debated despite extensive studies. Here we measured the filtering properties of neural inputs to the OFF motion-detecting T5 cell in Drosophila. We report state- and stimulus-dependent changes in the shape of these signals, which become more biphasic under specific conditions. Summing these inputs within the framework of a connectomic-constrained model of the circuit demonstrates that these shapes are sufficient to explain T5 responses to various motion stimuli. Thus, our stimulus- and state-dependent measurements reconcile motion computation with the anatomy of the circuit. These findings provide a clear example of how a basic circuit supports flexible sensory computation.
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Affiliation(s)
- Jessica R Kohn
- The Mortimer B. Zuckerman Mind Brain Behavior Institute, Department of Neuroscience, Columbia University, New York, NY 10027, USA
| | - Jacob P Portes
- The Mortimer B. Zuckerman Mind Brain Behavior Institute, Department of Neuroscience, Columbia University, New York, NY 10027, USA; Center for Theoretical Neuroscience, Columbia University, New York, NY, USA
| | - Matthias P Christenson
- The Mortimer B. Zuckerman Mind Brain Behavior Institute, Department of Neuroscience, Columbia University, New York, NY 10027, USA; Center for Theoretical Neuroscience, Columbia University, New York, NY, USA
| | - L F Abbott
- The Mortimer B. Zuckerman Mind Brain Behavior Institute, Department of Neuroscience, Columbia University, New York, NY 10027, USA; Center for Theoretical Neuroscience, Columbia University, New York, NY, USA
| | - Rudy Behnia
- The Mortimer B. Zuckerman Mind Brain Behavior Institute, Department of Neuroscience, Columbia University, New York, NY 10027, USA; Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA.
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Neveu ML, Kohn JR, Frost AS, Borahay MA, Simpson K, Wang KC, Wu HY, Patzkowsky KE. Unexpected Adenomyosis Among Hysterectomy for Benign Indications: A Review of Preoperative Characteristics and Imaging. J Minim Invasive Gynecol 2021. [DOI: 10.1016/j.jmig.2021.09.481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Heath SL, Christenson MP, Oriol E, Saavedra-Weisenhaus M, Kohn JR, Behnia R. Circuit Mechanisms Underlying Chromatic Encoding in Drosophila Photoreceptors. Curr Biol 2020; 30:264-275.e8. [PMID: 31928878 DOI: 10.1016/j.cub.2019.11.075] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 11/22/2019] [Accepted: 11/26/2019] [Indexed: 10/25/2022]
Abstract
Spectral information is commonly processed in the brain through generation of antagonistic responses to different wavelengths. In many species, these color opponent signals arise as early as photoreceptor terminals. Here, we measure the spectral tuning of photoreceptors in Drosophila. In addition to a previously described pathway comparing wavelengths at each point in space, we find a horizontal-cell-mediated pathway similar to that found in mammals. This pathway enables additional spectral comparisons through lateral inhibition, expanding the range of chromatic encoding in the fly. Together, these two pathways enable efficient decorrelation and dimensionality reduction of photoreceptor signals while retaining maximal chromatic information. A biologically constrained model accounts for our findings and predicts a spatio-chromatic receptive field for fly photoreceptor outputs, with a color opponent center and broadband surround. This dual mechanism combines motifs of both an insect-specific visual circuit and an evolutionarily convergent circuit architecture, endowing flies with the ability to extract chromatic information at distinct spatial resolutions.
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Affiliation(s)
- Sarah L Heath
- Department of Neuroscience, Mortimer Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Matthias P Christenson
- Department of Neuroscience, Mortimer Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Elie Oriol
- Department of Neuroscience, Mortimer Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Maia Saavedra-Weisenhaus
- Department of Neuroscience, Mortimer Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Jessica R Kohn
- Department of Neuroscience, Mortimer Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Rudy Behnia
- Department of Neuroscience, Mortimer Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA; Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA.
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Kohn JR, Frost AS, Wilson C, Borahay M. Cost Drivers for Benign Hysterectomy in a Healthcare System, 2013-2019. J Minim Invasive Gynecol 2019. [DOI: 10.1016/j.jmig.2019.09.659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Kohn JR, Heath SL, Behnia R. Eyes Matched to the Prize: The State of Matched Filters in Insect Visual Circuits. Front Neural Circuits 2018; 12:26. [PMID: 29670512 PMCID: PMC5893817 DOI: 10.3389/fncir.2018.00026] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 03/13/2018] [Indexed: 12/16/2022] Open
Abstract
Confronted with an ever-changing visual landscape, animals must be able to detect relevant stimuli and translate this information into behavioral output. A visual scene contains an abundance of information: to interpret the entirety of it would be uneconomical. To optimally perform this task, neural mechanisms exist to enhance the detection of important features of the sensory environment while simultaneously filtering out irrelevant information. This can be accomplished by using a circuit design that implements specific "matched filters" that are tuned to relevant stimuli. Following this rule, the well-characterized visual systems of insects have evolved to streamline feature extraction on both a structural and functional level. Here, we review examples of specialized visual microcircuits for vital behaviors across insect species, including feature detection, escape, and estimation of self-motion. Additionally, we discuss how these microcircuits are modulated to weigh relevant input with respect to different internal and behavioral states.
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Affiliation(s)
- Jessica R Kohn
- Department of Neuroscience, Columbia University, New York, NY, United States
| | - Sarah L Heath
- Department of Neuroscience, Columbia University, New York, NY, United States
| | - Rudy Behnia
- Department of Neuroscience, Columbia University, New York, NY, United States
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Kohn JR, Shamshirsaz AA, Popek E, Guan X, Belfort MA, Fox KA. Pregnancy after endometrial ablation: a systematic review. BJOG 2017; 125:43-53. [DOI: 10.1111/1471-0528.14854] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/03/2017] [Indexed: 01/10/2023]
Affiliation(s)
- JR Kohn
- Baylor College of Medicine; Houston TX USA
| | - AA Shamshirsaz
- Department of Obstetrics and Gynecology; Division of Maternal-Fetal Medicine; Baylor College of Medicine; Houston TX USA
| | - E Popek
- Department of Pathology; Division of Perinatal & Placental Pathology; Baylor College of Medicine; Houston TX USA
| | - X Guan
- Department of Obstetrics and Gynaecology; Section of Minimally Invasive Gynaecologic Surgery; Baylor College of Medicine; Houston TX USA
| | - MA Belfort
- Department of Obstetrics and Gynecology; Division of Maternal-Fetal Medicine; Baylor College of Medicine; Houston TX USA
| | - KA Fox
- Department of Obstetrics and Gynecology; Division of Maternal-Fetal Medicine; Baylor College of Medicine; Houston TX USA
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Igic B, Smith WA, Robertson KA, Schaal BA, Kohn JR. Studies of self-incompatibility in wild tomatoes: I. S-allele diversity in Solanum chilense (Dun.) Reiche [corrected] (Solanaceae). Heredity (Edinb) 2007; 99:553-61. [PMID: 17700636 DOI: 10.1038/sj.hdy.6801035] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
We characterized the molecular allelic variation of RNases at the self-incompatibility (SI) locus of Solanum chilense Dun. We recovered 30 S-RNase allele sequences from 34 plants representing a broad geographic sample. This yielded a species-wide estimate of 35 (95% likelihood interval 31-40) S-alleles. We performed crosses to confirm the association with SI function of 10 of the putative S-RNase allele sequences. Results in all cases were consistent with the expectation that these sequences represent functional alleles under single-locus gametophytic SI. We used the allele sequences to conduct an analysis of selection, as measured by the excess of nonsynonymous changes per site, and found evidence for adaptive changes both within the traditionally defined hypervariable regions and downstream, near the 3'-end of the molecule.
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Affiliation(s)
- B Igic
- Department of Biological Sciences, University of Illinois-Chicago, Chicago, IL 60607, USA.
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Abstract
We tested whether selection by pollinators could explain the parapatric distribution of coastal red- and inland yellow-flowered races of Mimulus aurantiacus (Phrymaceae) by examining visitation to natural and experimental populations. As a first step in evaluating whether indirect selection might explain floral divergence, we also tested for local adaptation in early life stages using a reciprocal transplant experiment. Hummingbirds visited flowers of each race at similar rates in natural populations but showed strong (>95%) preference for red flowers in all habitats in experimental arrays. Hawkmoths demonstrated nearly exclusive (>99% of visits) preference for yellow flowers and only visited in inland regions. Strong preferences for alternative floral forms support a direct role for pollinators in floral divergence. Despite these preferences, measures of plant performance across environments showed that red-flowered plants consistently survived better, grew larger and received more overall pollinator visits than yellow-flowered plants. Unmeasured components of fitness may favour the yellow race in inland habitats. Alternatively, we document a marked recent increase in inland hummingbird density that may have caused a change in the selective environment, favouring the eastward advance of red-flowered plants.
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Affiliation(s)
- M A Streisfeld
- Section of Ecology, Behavior and Evolution, Division of Biological Sciences, University of California San Diego, La Jolla, CA , USA.
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9
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Abstract
RT-PCR was used to obtain the first estimates from natural populations of allelic diversity at the RNase-based gametophytic self-incompatibility locus in the Rosaceae. A total of 20 alleles were retrieved from 20 Sorbus aucuparia individuals, whereas 17 alleles were found in 13 Crataegus monogyna samples. Estimates of population-level allele numbers fall within the range observed in the Solanaceae, the only other family with RNase-based incompatibility for which estimates are available. The nucleotide diversity of S-allele sequences was found to be much lower in the two Rosaceae species as compared with the Solanaceae. This was not due to a lower sequence divergence among most closely related alleles. Rather, it is the depth of the entire genealogy that differs markedly in the two families, with Rosaceae S-alleles exhibiting more recent apparent coalescence. We also investigated patterns of selection at the molecular level by comparing nucleotide diversity at synonymous and nonsynonymous sites. Stabilizing selection was inferred for the 5' region of the molecule, while evidence of diversifying selection was present elsewhere.
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Affiliation(s)
- O Raspé
- University of California at San Diego, Section of Ecology, Behavior, and Evolution, Division of Biology, 9500 Gilman Drive, La Jolla, CA 92093-0116, USA.
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Abstract
T2-type RNases are responsible for self-pollen recognition and rejection in three distantly related families of flowering plants-the Solanaceae, Scrophulariaceae, and Rosaceae. We used phylogenetic analyses of 67 T2-type RNases together with information on intron number and position to determine whether the use of RNases for self-incompatibility in these families is homologous or convergent. All methods of phylogenetic reconstruction as well as patterns of variation in intron structure find that all self-incompatibility RNases along with non-S genes from only two taxa form a monophyletic clade. Several lines of evidence suggest that the best interpretation of this pattern is homology of self-incompatibility RNases from the Scrophulariaceae, Solanaceae, and Rosaceae. Because the most recent common ancestor of these three families is the ancestor of approximately 75% of dicot families, our results indicate that RNase-based self-incompatibility was the ancestral state in the majority of dicots.
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Affiliation(s)
- B Igic
- Section of Ecology, Behavior, and Evolution, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
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Abstract
The bilobed stigma of many species in the order Scrophulariales closes in response to touch by an animal pollinator. In hummingbird-pollinated bush monkey flower, Mimulus aurantiacus (Scrophulariaceae), closure is rapid, occurring within seconds of tactile stimulus. We investigated the proximate causes of stigma closure and subsequent reopening in M. aurantiacus, as well as potential costs and benefits of stigma closure for female fitness. Stigma closure is elicited by both touch and pollen, but closure in response to pollen is much slower, requiring 0.5-1.5 h. Stigmata reopen within 2.5-4.5 h if touch, but no pollen, is applied. Upon receipt of pollen, most stigmata remain closed for the remaining lifetime of the flower, even if less pollen is received than is needed for full seed set. Those stigmata that do reopen after pollination generally require between 20 and 28 h to do so, much longer than for unpollinated stigmata. Reopening after pollination appears to be a response to low seed set rather than to low pollen load. Natural pollination of stigmata manipulated to prevent closure shows that closure does not increase capture of pollen or seed set. In fact, closure reduces the average pollen load received by flowers. Despite this, there is no evidence that stigma closure has any negative effect on female fitness in terms of seed set or germinability. Hypotheses for the adaptive significance of stigma closure are discussed. Understanding proximate causes of stigma closure and reopening is essential in the evaluation of these hypotheses.
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Affiliation(s)
- A E Fetscher
- Department of Biology, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0116
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Richman AD, Kohn JR. Self-incompatibility alleles from Physalis: implications for historical inference from balanced genetic polymorphisms. Proc Natl Acad Sci U S A 1999; 96:168-72. [PMID: 9874790 PMCID: PMC15111 DOI: 10.1073/pnas.96.1.168] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Balanced genetic polymorphism has been proposed as a source from which to infer population history complementary to that of neutral genetic polymorphism, because genetic polymorphism maintained by balancing selection permits inferences about population size over much longer spans of time. However, empirical data for both S genes and major histocompatibility complex genes do not fit expectations of coalescent theory. Species-specific gene genealogies have longer terminal branches than expected, indicating an apparent slowdown in the origination of new alleles. Here, we present evidence that divergent S alleles were selectively maintained in Physalis cinerascens during a reduction in population size, generating longer terminal branches in the S gene genealogy relative to the congener Physalis crassifolia. Retention of divergent alleles during reduction in the number of alleles violates assumptions of the coalescent model used to estimate effective population size. Recent theoretical and empirical results are consistent with the proposition that nonrandom sorting is a general property of balanced genetic polymorphisms, suggesting that studies of balanced polymorphism that infer the absence of population bottlenecks may overestimate effective population size.
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Affiliation(s)
- A D Richman
- Biology Department, Montana State University, Bozeman, MT 59717-0346, USA.
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Graham SW, Kohn JR, Morton BR, Eckenwalder JE, Barrett SC. Phylogenetic congruence and discordance among one morphological and three molecular data sets from Pontederiaceae. Syst Biol 1998; 47:545-67. [PMID: 12066301 DOI: 10.1080/106351598260572] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
Abstract
A morphological data set and three sources of data from the chloroplast genome (two genes and a restriction site survey) were used to reconstruct the phylogenetic history of the pickerelweed family Pontederiaceae. The chloroplast data converged towards a single tree, presumably the true chloroplast phylogeny of the family. Unrooted trees estimated from each of the three chloroplast data sets were identical or extremely similar in shape to each other and mostly robustly supported. There was no evidence of significant heterogeneity among the data sets, and the few topological differences seen among unrooted trees from each chloroplast data set are probably artifacts of sampling error on short branches. Despite well-documented differences in rates of evolution for different characters in individual data sets, equally weighted parsimony permits accurate reconstructions of chloroplast relationships in Pontederiaceae. A separate morphology-based data set yielded trees that were very different from the chloroplast trees. Although there was substantial support from the morphological evidence for several major clades supported by chloroplast trees, most of the conflicting phylogenetic structure on the morphology trees was not robust. Nonetheless, several statistical tests of incongruence indicate significant heterogeneity between molecules and morphology. The source of this apparent incongruence appears to be a low ratio of phylogenetic signal to noise in the morphological data.
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Affiliation(s)
- S W Graham
- Department of Botany, Box 355325, University of Washington, Seattle, Washington 98195-5325, USA
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Abstract
The self-incompatibility (S) locus of flowering plants offers an example of extreme polymorphism maintained by balancing selection. Estimates of recent and long-term effective population size (Ne) were determined for two solanaceous species by examination of S-allele diversity. Estimates of recent Ne in two solanaceous species differed by an order of magnitude, consistent with differences in the species' ecology. In one species, the evidence was consistent with historical population restriction despite a large recent Ne. In the other, no severe bottleneck was indicated over millions of years. Bottlenecks are integral to founder-event speciation, and loci that are subject to balancing selection can be used to evaluate the frequency of this mode of speciation.
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Affiliation(s)
- A D Richman
- Department of Biology, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0116, USA
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Richman AD, Uyenoyama MK, Kohn JR. S-allele diversity in a natural population of Physalis crassifolia (Solanaceae) (ground cherry) assessed by RT-PCR. Heredity (Edinb) 1996; 76 ( Pt 5):497-505. [PMID: 8666546 DOI: 10.1038/hdy.1996.72] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Allelic diversity at the self-incompatibility (S-) locus in the ground cherry, Physalis crassifolia (Solanaceae), was surveyed in a natural population occurring in Deep Canyon, CA, using a molecular assay to determine the genotype of individual plants. A total of 28 different S-alleles were identified and sequenced from a sample of 22 plants. All plants examined were heterozygous, as expected under gametophytic self-incompatibility (GSI). The estimated number of alleles in this population is 43-44, comparable to allelic diversity reported for other species, as determined by the standard diallel crossing method. Allele frequencies in the sample deviated from the expectation of equal frequency under GSI; it is suggested that this deviation may result from sampling of related individuals. Molecular analysis of genotypes within single pollen donor families indicates that, for all alleles examined, segregation is consistent with predictions for single-locus GSI. The implications of a reliable and efficient molecular assay for determining the S-genotype of plants are discussed.
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Affiliation(s)
- A D Richman
- Department of Biology 0116, University of California at San Diego, La Jolla 92093-0116, USA
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