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Weger AA, Rittschof CC. The diverse roles of insulin signaling in insect behavior. FRONTIERS IN INSECT SCIENCE 2024; 4:1360320. [PMID: 38638680 PMCID: PMC11024295 DOI: 10.3389/finsc.2024.1360320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 03/21/2024] [Indexed: 04/20/2024]
Abstract
In insects and other animals, nutrition-mediated behaviors are modulated by communication between the brain and peripheral systems, a process that relies heavily on the insulin/insulin-like growth factor signaling pathway (IIS). Previous studies have focused on the mechanistic and physiological functions of insulin-like peptides (ILPs) in critical developmental and adult milestones like pupation or vitellogenesis. Less work has detailed the mechanisms connecting ILPs to adult nutrient-mediated behaviors related to survival and reproductive success. Here we briefly review the range of behaviors linked to IIS in insects, from conserved regulation of feeding behavior to evolutionarily derived polyphenisms. Where possible, we incorporate information from Drosophila melanogaster and other model species to describe molecular and neural mechanisms that connect nutritional status to behavioral expression via IIS. We identify knowledge gaps which include the diverse functional roles of peripheral ILPs, how ILPs modulate neural function and behavior across the lifespan, and the lack of detailed mechanistic research in a broad range of taxa. Addressing these gaps would enable a better understanding of the evolution of this conserved and widely deployed tool kit pathway.
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Affiliation(s)
| | - Clare C. Rittschof
- Department of Entomology, University of Kentucky, Lexington, KY, United States
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2
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Jin P, Zhu B, Jia Y, Zhang Y, Wang W, Shen Y, Zhong Y, Zheng Y, Wang Y, Tong Y, Zhang W, Li S. Single-cell transcriptomics reveals the brain evolution of web-building spiders. Nat Ecol Evol 2023; 7:2125-2142. [PMID: 37919396 PMCID: PMC10697844 DOI: 10.1038/s41559-023-02238-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 09/29/2023] [Indexed: 11/04/2023]
Abstract
Spiders are renowned for their efficient capture of flying insects using intricate aerial webs. How the spider nervous systems evolved to cope with this specialized hunting strategy and various environmental clues in an aerial space remains unknown. Here we report a brain-cell atlas of >30,000 single-cell transcriptomes from a web-building spider (Hylyphantes graminicola). Our analysis revealed the preservation of ancestral neuron types in spiders, including the potential coexistence of noradrenergic and octopaminergic neurons, and many peptidergic neuronal types that are lost in insects. By comparing the genome of two newly sequenced plesiomorphic burrowing spiders with three aerial web-building spiders, we found that the positively selected genes in the ancestral branch of web-building spiders were preferentially expressed (42%) in the brain, especially in the three mushroom body-like neuronal types. By gene enrichment analysis and RNAi experiments, these genes were suggested to be involved in the learning and memory pathway and may influence the spiders' web-building and hunting behaviour. Our results provide key sources for understanding the evolution of behaviour in spiders and reveal how molecular evolution drives neuron innovation and the diversification of associated complex behaviours.
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Affiliation(s)
- Pengyu Jin
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Bingyue Zhu
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yinjun Jia
- School of Life Sciences, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing, China
- Tsinghua-Peking Center for Life Sciences, Beijing, China
| | - Yiming Zhang
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Wei Wang
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- Guangxi Normal University, Guilin, China
| | - Yunxiao Shen
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yu Zhong
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yami Zheng
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yang Wang
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yan Tong
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Wei Zhang
- School of Life Sciences, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing, China
- Tsinghua-Peking Center for Life Sciences, Beijing, China
| | - Shuqiang Li
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
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3
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Fischer EK, Hauber ME, Bell AM. Back to the basics? Transcriptomics offers integrative insights into the role of space, time and the environment for gene expression and behaviour. Biol Lett 2021; 17:20210293. [PMID: 34520681 DOI: 10.1098/rsbl.2021.0293] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Fuelled by the ongoing genomic revolution, broadscale RNA expression surveys are fast replacing studies targeting one or a few genes to understand the molecular basis of behaviour. Yet, the timescale of RNA-sequencing experiments and the dynamics of neural gene activation are insufficient to drive real-time switches between behavioural states. Moreover, the spatial, functional and transcriptional complexity of the brain (the most commonly targeted tissue in studies of behaviour) further complicates inference. We argue that a Central Dogma-like 'back-to-basics' assumption that gene expression changes cause behaviour leaves some of the most important aspects of gene-behaviour relationships unexplored, including the roles of environmental influences, timing and feedback from behaviour-and the environmental shifts it causes-to neural gene expression. No perfect experimental solutions exist but we advocate that explicit consideration, exploration and discussion of these factors will pave the way toward a richer understanding of the complicated relationships between genes, environments, brain gene expression and behaviour over developmental and evolutionary timescales.
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Affiliation(s)
- Eva K Fischer
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois, Urbana-Champaign, IL 61801, USA.,Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana-Champaign, IL 61801, USA
| | - Mark E Hauber
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois, Urbana-Champaign, IL 61801, USA.,Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana-Champaign, IL 61801, USA
| | - Alison M Bell
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois, Urbana-Champaign, IL 61801, USA.,Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana-Champaign, IL 61801, USA
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4
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Uy FMK, Jernigan CM, Zaba NC, Mehrotra E, Miller SE, Sheehan MJ. Dynamic neurogenomic responses to social interactions and dominance outcomes in female paper wasps. PLoS Genet 2021; 17:e1009474. [PMID: 34478434 PMCID: PMC8415593 DOI: 10.1371/journal.pgen.1009474] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 08/03/2021] [Indexed: 11/19/2022] Open
Abstract
Social interactions have large effects on individual physiology and fitness. In the immediate sense, social stimuli are often highly salient and engaging. Over longer time scales, competitive interactions often lead to distinct social ranks and differences in physiology and behavior. Understanding how initial responses lead to longer-term effects of social interactions requires examining the changes in responses over time. Here we examined the effects of social interactions on transcriptomic signatures at two times, at the end of a 45-minute interaction and 4 hours later, in female Polistes fuscatus paper wasp foundresses. Female P. fuscatus have variable facial patterns that are used for visual individual recognition, so we separately examined the transcriptional dynamics in the optic lobe and the non-visual brain. Results demonstrate much stronger transcriptional responses to social interactions in the non-visual brain compared to the optic lobe. Differentially regulated genes in response to social interactions are enriched for memory-related transcripts. Comparisons between winners and losers of the encounters revealed similar overall transcriptional profiles at the end of an interaction, which significantly diverged over the course of 4 hours, with losers showing changes in expression levels of genes associated with aggression and reproduction in paper wasps. On nests, subordinate foundresses are less aggressive, do more foraging and lay fewer eggs compared to dominant foundresses and we find losers shift expression of many genes in the non-visual brain, including vitellogenin, related to aggression, worker behavior, and reproduction within hours of losing an encounter. These results highlight the early neurogenomic changes that likely contribute to behavioral and physiological effects of social status changes in a social insect.
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Affiliation(s)
- Floria M. K. Uy
- Laboratory for Animal Social Evolution and Recognition, Department of Neurobiology and Behavior, Cornell University, Ithaca, New York, United States of America
| | - Christopher M. Jernigan
- Laboratory for Animal Social Evolution and Recognition, Department of Neurobiology and Behavior, Cornell University, Ithaca, New York, United States of America
| | - Natalie C. Zaba
- Laboratory for Animal Social Evolution and Recognition, Department of Neurobiology and Behavior, Cornell University, Ithaca, New York, United States of America
| | - Eshan Mehrotra
- Laboratory for Animal Social Evolution and Recognition, Department of Neurobiology and Behavior, Cornell University, Ithaca, New York, United States of America
| | - Sara E. Miller
- Laboratory for Animal Social Evolution and Recognition, Department of Neurobiology and Behavior, Cornell University, Ithaca, New York, United States of America
| | - Michael J. Sheehan
- Laboratory for Animal Social Evolution and Recognition, Department of Neurobiology and Behavior, Cornell University, Ithaca, New York, United States of America
- * E-mail:
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5
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Mukherjee D, Gonzales BJ, Ashwal-Fluss R, Turm H, Groysman M, Citri A. Egr2 induction in spiny projection neurons of the ventrolateral striatum contributes to cocaine place preference in mice. eLife 2021; 10:65228. [PMID: 33724178 PMCID: PMC8057818 DOI: 10.7554/elife.65228] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 03/15/2021] [Indexed: 12/16/2022] Open
Abstract
Drug addiction develops due to brain-wide plasticity within neuronal ensembles, mediated by dynamic gene expression. Though the most common approach to identify such ensembles relies on immediate early gene expression, little is known of how the activity of these genes is linked to modified behavior observed following repeated drug exposure. To address this gap, we present a broad-to-specific approach, beginning with a comprehensive investigation of brain-wide cocaine-driven gene expression, through the description of dynamic spatial patterns of gene induction in subregions of the striatum, and finally address functionality of region-specific gene induction in the development of cocaine preference. Our findings reveal differential cell-type specific dynamic transcriptional recruitment patterns within two subdomains of the dorsal striatum following repeated cocaine exposure. Furthermore, we demonstrate that induction of the IEG Egr2 in the ventrolateral striatum, as well as the cells within which it is expressed, are required for the development of cocaine seeking. The human brain is ever changing, constantly rewiring itself in response to new experiences, knowledge or information from the environment. Addictive drugs such as cocaine can hijack the genetic mechanisms responsible for this plasticity, creating dangerous, obsessive drug-seeking and consuming behaviors. Cocaine-induced plasticity is difficult to apprehend, however, as brain regions or even cell populations can react differently to the compound. For instance, sub-regions in the striatum – the brain area that responds to rewards and helps to plan movement – show distinct responses during progressive exposure to cocaine. And while researchers know that the drug immediately changes how neurons switch certain genes on and off, it is still unclear how these genetic modifications later affect behavior. Mukherjee, Gonzales et al. explored these questions at different scales, first focusing on how progressive cocaine exposure changed the way various gene programs were activated across the entire brain. This revealed that programs in the striatum were the most affected by the drug. Examining this region more closely showed that cocaine switches on genes in specific ‘spiny projection’ neuron populations, depending on where these cells are located and the drug history of the mouse. Finally, Mukherjee, Gonzales et al. used genetically modified mice to piece together cocaine exposure, genetic changes and modifications in behavior. These experiments revealed that the drive to seek cocaine depended on activation of the Egr2 gene in populations of spiny projection neurons in a specific sub-region of the striatum. The gene, which codes for a protein that regulates how genes are switched on and off, was itself strongly activated by cocaine intake. Cocaine addiction can have devastating consequences for individuals. Grasping how this drug alters the brain could pave the way for new treatments, while also providing information on the basic mechanisms underlying brain plasticity.
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Affiliation(s)
- Diptendu Mukherjee
- The Edmond and Lily Safra Center for Brain Sciences, Jerusalem, Israel.,Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Ben Jerry Gonzales
- The Edmond and Lily Safra Center for Brain Sciences, Jerusalem, Israel.,Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Reut Ashwal-Fluss
- The Edmond and Lily Safra Center for Brain Sciences, Jerusalem, Israel
| | - Hagit Turm
- The Edmond and Lily Safra Center for Brain Sciences, Jerusalem, Israel.,Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Maya Groysman
- The Edmond and Lily Safra Center for Brain Sciences, Jerusalem, Israel
| | - Ami Citri
- The Edmond and Lily Safra Center for Brain Sciences, Jerusalem, Israel.,Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel.,Program in Child and Brain Development, Canadian Institute for Advanced Research, MaRS Centre, Toronto, Canada
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6
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Abstract
A now substantial body of science implicates a dynamic interplay between genetic and environmental variation in the development of individual differences in behavior and health. Such outcomes are affected by molecular, often epigenetic, processes involving gene-environment (G-E) interplay that can influence gene expression. Early environments with exposures to poverty, chronic adversities, and acutely stressful events have been linked to maladaptive development and compromised health and behavior. Genetic differences can impart either enhanced or blunted susceptibility to the effects of such pathogenic environments. However, largely missing from present discourse regarding G-E interplay is the role of time, a "third factor" guiding the emergence of complex developmental endpoints across different scales of time. Trajectories of development increasingly appear best accounted for by a complex, dynamic interchange among the highly linked elements of genes, contexts, and time at multiple scales, including neurobiological (minutes to milliseconds), genomic (hours to minutes), developmental (years and months), and evolutionary (centuries and millennia) time. This special issue of PNAS thus explores time and timing among G-E transactions: The importance of timing and timescales in plasticity and critical periods of brain development; epigenetics and the molecular underpinnings of biologically embedded experience; the encoding of experience across time and biological levels of organization; and gene-regulatory networks in behavior and development and their linkages to neuronal networks. Taken together, the collection of papers offers perspectives on how G-E interplay operates contingently within and against a backdrop of time and timescales.
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7
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Honey bee aggression: evaluating causal links to disease-resistance traits and infection. Behav Ecol Sociobiol 2020. [DOI: 10.1007/s00265-020-02887-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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8
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Honey bee colony aggression and indirect genetic effects. Proc Natl Acad Sci U S A 2020; 117:18148-18150. [PMID: 32690713 DOI: 10.1073/pnas.2012366117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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9
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Forebrain Transcriptional Response to Transient Changes in Circulating Androgens in a Cichlid Fish. G3-GENES GENOMES GENETICS 2020; 10:1971-1982. [PMID: 32276961 PMCID: PMC7263668 DOI: 10.1534/g3.119.400947] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
It has been hypothesized that androgens respond to the social interactions as a way to adjust the behavior of individuals to the challenges of the social environment in an adaptive manner. Therefore, it is expected that transient changes in circulating androgen levels within physiological scope should impact the state of the brain network that regulates social behavior, which should translate into adaptive behavioral changes. Here, we examined the effect that a transient peak in androgen circulating levels, which mimics socially driven changes in androgen levels, has on the forebrain state, which harbors most nuclei of the social decision-making network. For this purpose, we successfully induced transient changes in circulating androgen levels in an African cichlid fish (Mozambique tilapia, Oreochromis mossambicus) commonly used as a model in behavioral neuroendocrinology by injecting 11-ketotestosterone or testosterone, and compared the forebrain transcriptome of these individuals to control fish injected with vehicle. Forebrain samples were collected 30 min and 60 min after injection and analyzed using RNAseq. Our results showed that a transient peak in 11-ketotestosterone drives more accentuated changes in forebrain transcriptome than testosterone, and that transcriptomic impact was greater at the 30 min than at the 60 min post-androgen administration. Several genes involved in the regulation of translation, steroid metabolism, ion channel membrane receptors, and genes involved in epigenetic mechanisms were differentially expressed after 11-ketotestosterone or testosterone injection. In summary, this study identified specific candidate genes that may regulate socially driven changes in behavioral flexibility mediated by androgens.
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10
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Cunningham CB. Functional genomics of parental care of insects. Horm Behav 2020; 122:104756. [PMID: 32353447 DOI: 10.1016/j.yhbeh.2020.104756] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 04/01/2020] [Accepted: 04/06/2020] [Indexed: 12/19/2022]
Abstract
Parental care was likely the first step most lineages made towards sociality. However, the molecular mechanisms that generate parental care are not broadly characterized. Insects are important as an evolutionary independent group from classic models of parental care, such as, house mice. They provide an opportunity to test the generality of our understanding. With this review, I survey the functional genomics of parental care of insects, summarize several recent advances in the broader framework for studying and understanding parental care, and finish with suggested priorities for further research. Although there are too few studies to draw definitive conclusions, I argue that natural selection appears to be rewiring existing gene networks to produce parental care, that the epigenetic mechanisms influencing parental care are not well understood, and, as an interesting early consensus, that genes strongly associated with carer/offspring interactions appear biased towards proteins that are secreted. I summarize the studies that have functionally validate candidate genes and highlight the increasing need to perform this work. I finish with arguments for both conceptual and practical changes moving forward. I argue that future work can increase the use of predictive frameworks, broaden its definition of conservation of mechanism to gene networks rather than single genes, and increase the use of more established comparative methods. I further highlight the practical considerations of standardizing analyses and reporting, increasing the sampling of both carers and offspring, better characterizing gene regulatory networks, better characterizing taxonomically restricted genes and any consistent role they have underpinning parental care, and using factorial designs to disentangle the influence of multiple variables on the expression of parental care.
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11
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Rittschof CC, Rubin BER, Palmer JH. The transcriptomic signature of low aggression in honey bees resembles a response to infection. BMC Genomics 2019; 20:1029. [PMID: 31888487 PMCID: PMC6937707 DOI: 10.1186/s12864-019-6417-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 12/19/2019] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Behavior reflects an organism's health status. Many organisms display a generalized suite of behaviors that indicate infection or predict infection susceptibility. We apply this concept to honey bee aggression, a behavior that has been associated with positive health outcomes in previous studies. We sequenced the transcriptomes of the brain, fat body, and midgut of adult sibling worker bees who developed as pre-adults in relatively high versus low aggression colonies. Previous studies showed that this pre-adult experience impacts both aggressive behavior and resilience to pesticides. We performed enrichment analyses on differentially expressed genes to determine whether variation in aggression resembles the molecular response to infection. We further assessed whether the transcriptomic signature of aggression in the brain is similar to the neuromolecular response to acute predator threat, exposure to a high-aggression environment as an adult, or adult behavioral maturation. RESULTS Across all three tissues assessed, genes that are differentially expressed as a function of aggression significantly overlap with genes whose expression is modulated by a variety of pathogens and parasitic feeding. In the fat body, and to some degree the midgut, our data specifically support the hypothesis that low aggression resembles a diseased or parasitized state. However, we find little evidence of active infection in individuals from the low aggression group. We also find little evidence that the brain molecular signature of aggression is enriched for genes modulated by social cues that induce aggression in adults. However, we do find evidence that genes associated with adult behavioral maturation are enriched in our brain samples. CONCLUSIONS Results support the hypothesis that low aggression resembles a molecular state of infection. This pattern is most robust in the peripheral fat body, an immune responsive tissue in the honey bee. We find no evidence of acute infection in bees from the low aggression group, suggesting the physiological state characterizing low aggression may instead predispose bees to negative health outcomes when they are exposed to additional stressors. The similarity of molecular signatures associated with the seemingly disparate traits of aggression and disease suggests that these characteristics may, in fact, be intimately tied.
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Affiliation(s)
- Clare C Rittschof
- University of Kentucky, S-225 Agricultural Science Center North, Lexington, KY, 40546, USA.
| | - Benjamin E R Rubin
- Department of Ecology and Evolutionary Biology; Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, 08544, USA
| | - Joseph H Palmer
- Kentucky State University, 400 E. Main St., Frankfort, KY, 40601, USA
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12
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Badcock PB, Friston KJ, Ramstead MJD, Ploeger A, Hohwy J. The hierarchically mechanistic mind: an evolutionary systems theory of the human brain, cognition, and behavior. COGNITIVE, AFFECTIVE & BEHAVIORAL NEUROSCIENCE 2019; 19:1319-1351. [PMID: 31115833 PMCID: PMC6861365 DOI: 10.3758/s13415-019-00721-3] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The purpose of this review was to integrate leading paradigms in psychology and neuroscience with a theory of the embodied, situated human brain, called the Hierarchically Mechanistic Mind (HMM). The HMM describes the brain as a complex adaptive system that functions to minimize the entropy of our sensory and physical states via action-perception cycles generated by hierarchical neural dynamics. First, we review the extant literature on the hierarchical structure of the brain. Next, we derive the HMM from a broader evolutionary systems theory that explains neural structure and function in terms of dynamic interactions across four nested levels of biological causation (i.e., adaptation, phylogeny, ontogeny, and mechanism). We then describe how the HMM aligns with a global brain theory in neuroscience called the free-energy principle, leveraging this theory to mathematically formulate neural dynamics across hierarchical spatiotemporal scales. We conclude by exploring the implications of the HMM for psychological inquiry.
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Affiliation(s)
- Paul B Badcock
- Centre for Youth Mental Health, The University of Melbourne, Melbourne, Australia.
- Melbourne School of Psychological Sciences, The University of Melbourne, Melbourne, Australia.
- Orygen, The National Centre of Excellence in Youth Mental Health, Melbourne, Australia.
| | - Karl J Friston
- Wellcome Trust Centre for Neuroimaging, University College London, London, UK
| | - Maxwell J D Ramstead
- Wellcome Trust Centre for Neuroimaging, University College London, London, UK
- Department of Philosophy, McGill University, Montreal, QC, Canada
- Division of Social and Transcultural Psychiatry, Department of Psychiatry, McGill University, Montreal, QC, Canada
| | - Annemie Ploeger
- Department of Psychology, University of Amsterdam, Amsterdam, The Netherlands
| | - Jakob Hohwy
- Cognition & Philosophy Lab, Monash University, Clayton, VIC, Australia
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Harrison JW, Palmer JH, Rittschof CC. Altering social cue perception impacts honey bee aggression with minimal impacts on aggression-related brain gene expression. Sci Rep 2019; 9:14642. [PMID: 31601943 PMCID: PMC6787081 DOI: 10.1038/s41598-019-51223-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 09/24/2019] [Indexed: 02/01/2023] Open
Abstract
Gene expression changes resulting from social interactions may give rise to long term behavioral change, or simply reflect the activity of neural circuitry associated with behavioral expression. In honey bees, social cues broadly modulate aggressive behavior and brain gene expression. Previous studies suggest that expression changes are limited to contexts in which social cues give rise to stable, relatively long-term changes in behavior. Here we use a traditional beekeeping approach that inhibits aggression, smoke exposure, to deprive individuals of aggression-inducing olfactory cues and evaluate whether behavioral changes occur in absence of expression variation in a set of four biomarker genes (drat, cyp6g1/2, GB53860, inos) associated with aggression in previous studies. We also evaluate two markers of a brain hypoxic response (hif1α, hsf) to determine whether smoke induces molecular changes at all. We find that bees with blocked sensory perception as a result of smoke exposure show a strong, temporary inhibition of aggression relative to bees allowed to perceive normal social cues. However, blocking sensory perception had minimal impacts on aggression-relevant gene expression, althought it did induce a hypoxic molecular response in the brain. Results suggest that certain genes differentiate social cue-induced changes in aggression from long-term modulation of this phenotype.
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Affiliation(s)
- James W Harrison
- Department of Entomology, University of Kentucky, S-225 Agricultural Science Center North, Lexington, KY, 40546, USA
| | - Joseph H Palmer
- Department of Entomology, University of Kentucky, S-225 Agricultural Science Center North, Lexington, KY, 40546, USA
- College of Agriculture, Communities, and the Environment, Kentucky State University, 400 E. Main St., Frankfort, KY, 40601, USA
| | - Clare C Rittschof
- Department of Entomology, University of Kentucky, S-225 Agricultural Science Center North, Lexington, KY, 40546, USA.
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14
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Ma R, Rangel J, Grozinger CM. Honey bee (Apis mellifera) larval pheromones may regulate gene expression related to foraging task specialization. BMC Genomics 2019; 20:592. [PMID: 31324147 PMCID: PMC6642498 DOI: 10.1186/s12864-019-5923-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Accepted: 06/21/2019] [Indexed: 12/22/2022] Open
Abstract
Background Foraging behavior in honey bees (Apis mellifera) is a complex phenotype that is regulated by physiological state and social signals. How these factors are integrated at the molecular level to modulate foraging behavior has not been well characterized. The transition of worker bees from nursing to foraging behaviors is mediated by large-scale changes in brain gene expression, which are influenced by pheromones produced by the queen and larvae. Larval pheromones can also stimulate foragers to leave the colony to collect pollen. However, the mechanisms underpinning this rapid behavioral plasticity in foragers that specialize in collecting pollen over nectar, and how larval pheromones impact these different behavioral states, remains to be determined. Here, we investigated the patterns of gene expression related to rapid behavioral plasticity and task allocation among honey bee foragers exposed to two larval pheromones, brood pheromone (BP) and (E)-beta-ocimene (EBO). We hypothesized that both pheromones would alter expression of genes in the brain related to foraging and would differentially impact brain gene expression depending on foraging specialization. Results Combining data reduction, clustering, and network analysis methods, we found that foraging preference (nectar vs. pollen) and pheromone exposure are each associated with specific brain gene expression profiles. Furthermore, pheromone exposure has a strong transcriptional effect on genes that are preferentially expressed in nectar foragers. Representation factor analysis between our study and previous landmark honey bee transcriptome studies revealed significant overlaps for both pheromone communication and foraging task specialization. Conclusions Our results suggest that, as social signals, pheromones alter expression patterns of foraging-related genes in the bee’s brain to increase pollen foraging at both long and short time scales. These results provide new insights into how social signals and task specialization are potentially integrated at the molecular level, and highlights the possible role that brain gene expression may play in honey bee behavioral plasticity across time scales. Electronic supplementary material The online version of this article (10.1186/s12864-019-5923-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Rong Ma
- Department of Entomology, Center for Pollinator Research, Center for Chemical Ecology, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, USA.
| | - Juliana Rangel
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | - Christina M Grozinger
- Department of Entomology, Center for Pollinator Research, Center for Chemical Ecology, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, USA
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The role of the genome in experience-dependent plasticity: Extending the analogy of the genomic action potential. Proc Natl Acad Sci U S A 2019; 117:23252-23260. [PMID: 31127037 DOI: 10.1073/pnas.1820837116] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Our past experiences shape our current and future behavior. These experiences must leave some enduring imprint on our brains, altering neural circuits that mediate behavior and contributing to our individual differences. As a framework for understanding how experiences might produce lasting changes in neural circuits, Clayton [D. F. Clayton, Neurobiol. Learn. Mem. 74, 185-216 (2000)] introduced the concept of the genomic action potential (gAP)-a structured genomic response in the brain to acute experience. Similar to the familiar electrophysiological action potential (eAP), the gAP also provides a means for integrating afferent patterns of activity but on a slower timescale and with longer-lasting effects. We revisit this concept in light of contemporary work on experience-dependent modification of neural circuits. We review the "Immediate Early Gene" (IEG) response, the starting point for understanding the gAP. We discuss evidence for its involvement in the encoding of experience to long-term memory across time and biological levels of organization ranging from individual cells to cell ensembles and whole organisms. We explore distinctions between memory encoding and homeostatic functions and consider the potential for perpetuation of the imprint of experience through epigenetic mechanisms. We describe a specific example of a gAP in humans linked to individual differences in the response to stress. Finally, we identify key objectives and new tools for continuing research in this area.
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Rittschof CC, Vekaria HJ, Palmer JH, Sullivan PG. Biogenic amines and activity levels alter the neural energetic response to aggressive social cues in the honey bee Apis mellifera. J Neurosci Res 2019; 97:991-1003. [PMID: 31090236 DOI: 10.1002/jnr.24443] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 04/24/2019] [Accepted: 04/24/2019] [Indexed: 01/18/2023]
Abstract
Mitochondrial activity is highly dynamic in the healthy brain, and it can reflect both the signaling potential and the signaling history of neural circuits. Recent studies spanning invertebrates to mammals have highlighted a role for neural mitochondrial dynamics in learning and memory processes as well as behavior. In the current study, we investigate the interplay between biogenic amine signaling and neural energetics in the honey bee, Apis mellifera. In this species, aggressive behaviors are regulated by neural energetic state and biogenic amine titers, but it is unclear how these mechanisms are linked to impact behavioral expression. We show that brain mitochondrial number is highest in aggression-relevant brain regions and in individual bees that are most responsive to aggressive cues, emphasizing the importance of energetics in modulating this phenotype. We also show that the neural energetic response to alarm pheromone, an aggression inducing social cue, is activity dependent, modulated by the "fight or flight" insect neurotransmitter octopamine. Two other neuroactive compounds known to cause variation in aggression, dopamine, and serotonin, also modulate neural energetic state in aggression-relevant regions of the brain. However, the effects of these compounds on respiration at baseline and following alarm pheromone exposure are distinct, suggesting unique mechanisms underlying variation in mitochondrial respiration in these circuits. These results motivate new explanations for the ways in which biogenic amines alter sensory perception in the context of aggression. Considering neural energetics improves predictions about the regulation of complex and context-dependent behavioral phenotypes.
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Affiliation(s)
- Clare C Rittschof
- Department of Entomology, University of Kentucky, Lexington, Kentucky
| | - Hemendra J Vekaria
- Department of Neuroscience, Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, Kentucky
| | - Joseph H Palmer
- Department of Entomology, University of Kentucky, Lexington, Kentucky
| | - Patrick G Sullivan
- Department of Neuroscience, Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, Kentucky
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Hou L, Li B, Ding D, Kang L, Wang X. CREB-B acts as a key mediator of NPF/NO pathway involved in phase-related locomotor plasticity in locusts. PLoS Genet 2019; 15:e1008176. [PMID: 31150381 PMCID: PMC6561586 DOI: 10.1371/journal.pgen.1008176] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 06/12/2019] [Accepted: 05/07/2019] [Indexed: 12/14/2022] Open
Abstract
Gene expression changes in neural systems are essential for environment-induced behavioral plasticity in animals; however, neuronal signaling pathways mediating the effect of external stimuli on transcriptional changes are largely unknown. Recently, we have demonstrated that the neuropeptide F (NPF)/nitric oxide (NO) signaling pathway plays a regulatory role in phase-related locomotor plasticity in the migratory locust, Locusta migratoria. Here, we report that a conserved transcription factor, cAMP response element-binding protein B (CREB-B), is a key mediator involved in the signaling pathway from NPF2 to NOS in the migratory locust, triggering locomotor activity shift between solitarious and gregarious phases. We find that CREB-B directly activates brain NOS expression by interacting with NOS promoter region. The phosphorylation at serine 110 site of CREB-B dynamically changes in response to population density variation and is negatively controlled by NPF2. The involvement of CREB-B in NPF2-regulated locomotor plasticity is further validated by RNAi experiment and behavioral assay. Furthermore, we reveal that protein kinase A mediates the regulatory effects of NPF2 on CREB-B phosphorylation and NOS transcription. These findings highlight a precise signal cascade underlying environment-induced behavioral plasticity.
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Affiliation(s)
- Li Hou
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Beibei Li
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Ding Ding
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Le Kang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, China
| | - Xianhui Wang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
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Westneat DF, Potts LJ, Sasser KL, Shaffer JD. Causes and Consequences of Phenotypic Plasticity in Complex Environments. Trends Ecol Evol 2019; 34:555-568. [PMID: 30871734 DOI: 10.1016/j.tree.2019.02.010] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 02/11/2019] [Accepted: 02/18/2019] [Indexed: 10/27/2022]
Abstract
Phenotypic plasticity is a ubiquitous and necessary adaptation of organisms to variable environments, but most environments have multiple dimensions that vary. Many studies have documented plasticity of a trait with respect to variation in multiple environmental factors. Such multidimensional phenotypic plasticity (MDPP) exists at all levels of organismal organization, from the whole organism to within cells. This complexity in plasticity cannot be explained solely by scaling up ideas from models of unidimensional plasticity. MDPP generates new questions about the mechanism and function of plasticity and its role in speciation and population persistence. Here we review empirical and theoretical approaches to plasticity in response to multidimensional environments and we outline new opportunities along with some difficulties facing future research.
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Affiliation(s)
- David F Westneat
- Department of Biology, 101 T.H. Morgan Building, University of Kentucky, Lexington, KY 40506-0225, USA.
| | - Leslie J Potts
- Department of Entomology, S-225 Agricultural Science Center North, University of Kentucky, Lexington, KY 40546-0091, USA
| | - Katherine L Sasser
- Department of Biology, 101 T.H. Morgan Building, University of Kentucky, Lexington, KY 40506-0225, USA
| | - James D Shaffer
- Department of Biology, 101 T.H. Morgan Building, University of Kentucky, Lexington, KY 40506-0225, USA
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Rittschof CC, Vekaria HJ, Palmer JH, Sullivan PG. Brain mitochondrial bioenergetics change with rapid and prolonged shifts in aggression in the honey bee, Apis mellifera. J Exp Biol 2018; 221:jeb.176917. [DOI: 10.1242/jeb.176917] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 02/26/2018] [Indexed: 12/12/2022]
Abstract
Neuronal function demands high-level energy production, and as such, a decline in mitochondrial respiration characterizes brain injury and disease. A growing number of studies, however, link brain mitochondrial function to behavioral modulation in non-diseased contexts. In the honey bee, we show for the first time that an acute social interaction, which invokes an aggressive response, may also cause a rapid decline in brain mitochondrial bioenergetics. The degree and speed of this decline has only been previously observed in the context of brain injury. Furthermore, in the honey bee, age-related increases in aggressive tendency are associated with increased baseline brain mitochondrial respiration, as well as increased plasticity in response to metabolic fuel type in vitro. Similarly, diet restriction and ketone body feeding, which commonly enhance mammalian brain mitochondrial function in vivo, cause increased aggression. Thus, even in normal behavioral contexts, brain mitochondria show a surprising degree of variation in function over both rapid and prolonged timescales, with age predicting both baseline function and plasticity in function. These results suggest that mitochondrial function is integral to modulating aggression-related neuronal signaling. We hypothesize that variation in function reflects mitochondrial calcium buffering activity, and that shifts in mitochondrial function signal to the neuronal soma to regulate gene expression and neural energetic state. Modulating brain energetic state is emerging as a critical component of the regulation of behavior in non-diseased contexts.
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Affiliation(s)
- Clare C. Rittschof
- Department of Entomology, University of Kentucky, S-225 Ag. Science Center North, Lexington, KY, 40546, USA
| | - Hemendra J. Vekaria
- Spinal Cord and Brain Injury Research Center and the Department of Neuroscience, University of Kentucky, 741 South Limestone Street, 475 BBSRB, Lexington, KY 40536-0509, USA
| | - Joseph H. Palmer
- Department of Entomology, University of Kentucky, S-225 Ag. Science Center North, Lexington, KY, 40546, USA
| | - Patrick G. Sullivan
- Spinal Cord and Brain Injury Research Center and the Department of Neuroscience, University of Kentucky, 741 South Limestone Street, 475 BBSRB, Lexington, KY 40536-0509, USA
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