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Valadares L, da Silva IB, Costa-Leonardo AM, Sandoz JC. Differentiation of workers into soldiers is associated with a size reduction of higher-order brain centers in the neotropical termite Procornitermes araujoi. Sci Rep 2023; 13:18279. [PMID: 37880273 PMCID: PMC10600217 DOI: 10.1038/s41598-023-45221-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 10/17/2023] [Indexed: 10/27/2023] Open
Abstract
Comparing the size of functionally distinct brain regions across individuals with remarkable differences in sensory processing and cognitive demands provides important insights into the selective forces shaping animal nervous systems. We took advantage of the complex system of worker-to-soldier differentiation in the termitid Procornitermes araujoi, to investigate how a profound modification of body morphology followed by an irreversible shift in task performance are translated in terms of brain structure and size. This behavioural shift is characterised by a reduction of the once wide and complex behavioural repertoire of workers to one exclusively dedicated to nest defence (soldiers). In accordance with soldier's reduced cognitive and sensory demands, we show here that differentiation of workers into soldiers is associated with a size reduction of the mushroom body (MB) compartments, higher-order brain regions responsible for multimodal processing and integration of sensory information, as well as learning, memory, and decision-making. Moreover, in soldiers, we found an apparent fusion of the medial and lateral MB calyces likely associated with its volume reduction. These results illustrate a functional neuroplasticity of the MB associated with division of labour, supporting the link between MB size and behavioural flexibility in social insect workers.
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Affiliation(s)
- Lohan Valadares
- Evolution, Genomes, Behavior, and Ecology (EGCE), Université Paris-Saclay, CNRS, IRD, Gif-Sur-Yvette, France.
| | - Iago Bueno da Silva
- Laboratório de Cupins, Departamento de Biologia Geral e Aplicada, Instituto de Biociências, Universidade Estadual Paulista (UNESP), Rio Claro, SP, Brazil
| | - Ana Maria Costa-Leonardo
- Laboratório de Cupins, Departamento de Biologia Geral e Aplicada, Instituto de Biociências, Universidade Estadual Paulista (UNESP), Rio Claro, SP, Brazil
| | - Jean-Christophe Sandoz
- Evolution, Genomes, Behavior, and Ecology (EGCE), Université Paris-Saclay, CNRS, IRD, Gif-Sur-Yvette, France
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Tuckman H, Patel M, Lei H. Effects of Mechanosensory Input on the Tracking of Pulsatile Odor Stimuli by Moth Antennal Lobe Neurons. Front Neurosci 2021; 15:739730. [PMID: 34690678 PMCID: PMC8529024 DOI: 10.3389/fnins.2021.739730] [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: 07/11/2021] [Accepted: 09/06/2021] [Indexed: 11/13/2022] Open
Abstract
Air turbulence ensures that in a natural environment insects tend to encounter odor stimuli in a pulsatile fashion. The frequency and duration of odor pulses varies with distance from the source, and hence successful mid-flight odor tracking requires resolution of spatiotemporal pulse dynamics. This requires both olfactory and mechanosensory input (from wind speed), a form of sensory integration observed within the antennal lobe (AL). In this work, we employ a model of the moth AL to study the effect of mechanosensory input on AL responses to pulsatile stimuli; in particular, we examine the ability of model neurons to: (1) encode the temporal length of a stimulus pulse; (2) resolve the temporal dynamics of a high frequency train of brief stimulus pulses. We find that AL glomeruli receiving olfactory input are adept at encoding the temporal length of a stimulus pulse but less effective at tracking the temporal dynamics of a pulse train, while glomeruli receiving mechanosensory input but little olfactory input can efficiently track the temporal dynamics of high frequency pulse delivery but poorly encode the duration of an individual pulse. Furthermore, we show that stronger intrinsic small-conductance calcium-dependent potassium (SK) currents tend to skew cells toward being better trackers of pulse frequency, while weaker SK currents tend to entail better encoding of the temporal length of individual pulses. We speculate a possible functional division of labor within the AL, wherein, for a particular odor, glomeruli receiving strong olfactory input exhibit prolonged spiking responses that facilitate detailed discrimination of odor features, while glomeruli receiving mechanosensory input (but little olfactory input) serve to resolve the temporal dynamics of brief, pulsatile odor encounters. Finally, we discuss how this hypothesis extends to explaining the functional significance of intraglomerular variability in observed phase II response patterns of AL neurons.
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Affiliation(s)
- Harrison Tuckman
- Department of Mathematics, William & Mary, Williamsburg, VA, United States
| | - Mainak Patel
- Department of Mathematics, William & Mary, Williamsburg, VA, United States
| | - Hong Lei
- School of Life Sciences, Arizona State University, Tempe, AZ, United States
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Kymre JH, Berge CN, Chu X, Ian E, Berg BG. Antennal-lobe neurons in the moth Helicoverpa armigera: Morphological features of projection neurons, local interneurons, and centrifugal neurons. J Comp Neurol 2021; 529:1516-1540. [PMID: 32949023 PMCID: PMC8048870 DOI: 10.1002/cne.25034] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 09/02/2020] [Accepted: 09/07/2020] [Indexed: 01/11/2023]
Abstract
The relatively large primary olfactory center of the insect brain, the antennal lobe (AL), contains several heterogeneous neuronal types. These include projection neurons (PNs), providing olfactory information to higher‐order neuropils via parallel pathways, and local interneurons (LNs), which provide lateral processing within the AL. In addition, various types of centrifugal neurons (CNs) offer top‐down modulation onto the other AL neurons. By performing iontophoretic intracellular staining, we collected a large number of AL neurons in the moth, Helicoverpa armigera, to examine the distinct morphological features of PNs, LNs, and CNs. We characterize 190 AL neurons. These were allocated to 25 distinct neuronal types or sub‐types, which were reconstructed and placed into a reference brain. In addition to six PN types comprising 15 sub‐types, three LN and seven CN types were identified. High‐resolution confocal images allowed us to analyze AL innervations of the various reported neurons, which demonstrated that all PNs innervating ventroposterior glomeruli contact a protocerebral neuropil rarely targeted by other PNs, that is the posteriorlateral protocerebrum. We also discuss the functional roles of the distinct CNs, which included several previously uncharacterized types, likely involved in computations spanning from multisensory processing to olfactory feedback signalization into the AL.
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Affiliation(s)
- Jonas Hansen Kymre
- Chemosensory lab, Department of Psychology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Christoffer Nerland Berge
- Chemosensory lab, Department of Psychology, Norwegian University of Science and Technology, Trondheim, Norway.,Laboratory for Neural Computation, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Xi Chu
- Chemosensory lab, Department of Psychology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Elena Ian
- Chemosensory lab, Department of Psychology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Bente G Berg
- Chemosensory lab, Department of Psychology, Norwegian University of Science and Technology, Trondheim, Norway
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Arnold T, Korek S, Massah A, Eschstruth D, Stengl M. Candidates for photic entrainment pathways to the circadian clock via optic lobe neuropils in the Madeira cockroach. J Comp Neurol 2020; 528:1754-1774. [PMID: 31860126 DOI: 10.1002/cne.24844] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 12/09/2019] [Accepted: 12/17/2019] [Indexed: 12/13/2022]
Abstract
The compound eye of cockroaches is obligatory for entrainment of the Madeira cockroach's circadian clock, but the cellular nature of its entrainment pathways is enigmatic. Employing multiple-label immunocytochemistry, histochemistry, and backfills, we searched for photic entrainment pathways to the accessory medulla (AME), the circadian clock of the Madeira cockroach. We wanted to know whether photoreceptor terminals could directly contact pigment-dispersing factor-immunoreactive (PDF-ir) circadian pacemaker neurons with somata in the lamina (PDFLAs) or somata next to the AME (PDFMEs). Short green-sensitive photoreceptor neurons of the compound eye terminated in lamina layers LA1 and LA2, adjacent to PDFLAs and PDFMEs that branched in LA3. Long UV-sensitive compound eye photoreceptor neurons terminated in medulla layer ME2 without direct contact to ipsilateral PDFMEs that arborized in ME4. Multiple neuropeptide-ir interneurons branched in ME4, connecting the AME to ME2. Before, extraocular photoreceptors of the lamina organ were suggested to send terminals to accessory laminae. There, they overlapped with PDFLAs that mostly colocalized PDF, FMRFamide, and 5-HT immunoreactivities, and with terminals of ipsi- and contralateral PDFMEs. We hypothesize that during the day cholinergic activation of the largest PDFME via lamina organ photoreceptors maintains PDF release orchestrating phases of sleep-wake cycles. As ipsilateral PDFMEs express excitatory and contralateral PDFMEs inhibitory PDF autoreceptors, diurnal PDF release keeps both PDF-dependent clock circuits in antiphase. Future experiments will test whether ipsilateral PDFMEs are sleep-promoting morning cells, while contralateral PDFMEs are activity-promoting evening cells, maintaining stable antiphase via the largest PDFME entrained by extraocular photoreceptors of the lamina organ.
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Affiliation(s)
- Thordis Arnold
- FB 10, Biology, Animal Physiology/Neuroethology, University of Kassel, Kassel, Germany
| | - Sebastian Korek
- FB 10, Biology, Animal Physiology/Neuroethology, University of Kassel, Kassel, Germany
| | - Azar Massah
- FB 10, Biology, Animal Physiology/Neuroethology, University of Kassel, Kassel, Germany
| | - David Eschstruth
- FB 10, Biology, Animal Physiology/Neuroethology, University of Kassel, Kassel, Germany
| | - Monika Stengl
- FB 10, Biology, Animal Physiology/Neuroethology, University of Kassel, Kassel, Germany
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Thevenon H, Pfuhl G. Discrepancies in the spiking threshold and frequency sensitivity of nocturnal moths explainable by biases in the canonical auditory stimulation method. ROYAL SOCIETY OPEN SCIENCE 2018; 5:172404. [PMID: 29765685 PMCID: PMC5936950 DOI: 10.1098/rsos.172404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 03/12/2018] [Indexed: 06/08/2023]
Abstract
The auditory stimulation method used in experiments on moth A cell(s) is generally believed to be adequate to characterize the encoding of bat echolocation signals. The stimulation method hosts, though, several biases. Their compounded effects can explain a range of discrepancies between the reported electrophysiological recordings and significantly alter the current interpretation. To test the hypothesis that the bias may significantly alter our current understanding of the moth's auditory transducer characteristics, papers using the same auditory stimulation method and reporting on either spiking threshold or spiking activity of the moth's A cells were analysed. The consistency of the reported data was assessed. A range of corrections issued from best practices and theoretical background were applied to the data in an attempt to re-interpret the data. We found that it is not possible to apply a posteriori corrections to all data and bias. However the corrected data indicate that the A cell's spiking may (i) be independent of the repetition rate, (ii) be maximum when detecting long and low-intensity pulses and (iii) steadily reduce as the bat closes on the moth. These observations raise the possibility that a fixed action pattern drives the moths' erratic evasive manoeuvres until the final moment. In-depth investigations of the potential bias also suggest that the auditory transducer's response may be constant for a larger frequency range than thought so far, and provide clues to explain the negative taxis in response to the searching bats' calls detection.
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Zhukovskaya MI, Polyanovsky AD. Biogenic Amines in Insect Antennae. Front Syst Neurosci 2017; 11:45. [PMID: 28701930 PMCID: PMC5487433 DOI: 10.3389/fnsys.2017.00045] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Accepted: 06/06/2017] [Indexed: 11/25/2022] Open
Abstract
Insect antenna is a multisensory organ, each modality of which can be modulated by biogenic amines. Octopamine (OA) and its metabolic precursor tyramine (TA) affect activity of antennal olfactory receptor neurons. There is some evidence that dopamine (DA) modulates gustatory neurons. Serotonin can serve as a neurotransmitter in some afferent mechanosensory neurons and both as a neurotransmitter and neurohormone in efferent fibers targeted at the antennal vessel and mechanosensory organs. As a neurohormone, serotonin affects the generation of the transepithelial potential by sensillar accessory cells. Other possible targets of biogenic amines in insect antennae are hygro- and thermosensory neurons and epithelial cells. We suggest that the insect antenna is partially autonomous in the sense that biologically active substances entering its hemolymph may exert their effects and be cleared from this compartment without affecting other body parts.
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Affiliation(s)
- Marianna I Zhukovskaya
- Laboratory of Evolution of Sense Organs, Sechenov Institute of Evolutionary Biochemistry and Physiology, Russian Academy of SciencesSaint Petersburg, Russia
| | - Andrey D Polyanovsky
- Laboratory of Evolution of Sense Organs, Sechenov Institute of Evolutionary Biochemistry and Physiology, Russian Academy of SciencesSaint Petersburg, Russia
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Antennal-lobe tracts in the noctuid moth, Heliothis virescens: new anatomical findings. Cell Tissue Res 2016; 366:23-35. [PMID: 27352608 DOI: 10.1007/s00441-016-2448-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 05/17/2016] [Indexed: 10/21/2022]
Abstract
As in other insects, three main tracts in the moth brain form parallel connections between the antennal lobe and the protocerebrum. These tracts, which consist of the antennal-lobe projection-neuron axons, target two main areas in the protocerebrum, the calyces of the mushroom bodies and the lateral horn. In spite of the solid neuroanatomical knowledge already established, there are still unresolved issues regarding the antennal-lobe tracts of the moth. One is the proportion of lateral-tract neurons targeting the calyces. In the study presented here, we have performed both retrograde and anterograde labeling of the antennal-lobe projection neurons in the brain of the moth, Heliothis virescens. The results from the retrograde staining, obtained by applying dye in the calyces, demonstrated that the direct connection between the antennal lobe and this neuropil is maintained primarily by the medial antennal-lobe tract; only a few axons confined to the lateral tract were found to innervate the calyces. In addition, these staining experiments, which allowed us to explore the arborization pattern of labeled neurons within the antennal lobe, resulted in new findings regarding anatomical arrangement of roots and cell body clusters linked to the medial tract. The results from the anterograde staining, obtained by applying dye into the antennal lobe, visualized the total assembly of axons passing along the antennal-lobe tracts. In addition to the three classical tracts, we found a transverse antennal-lobe tract not previously described in the moth. Also, these staining experiments revealed an organized neuropil in the lateral horn formed by terminals of the four antennal-lobe tracts.
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Zhao XC, Chen QY, Guo P, Xie GY, Tang QB, Guo XR, Berg BG. Glomerular identification in the antennal lobe of the male mothHelicoverpa armigera. J Comp Neurol 2016; 524:2993-3013. [DOI: 10.1002/cne.24003] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 03/16/2016] [Accepted: 03/24/2016] [Indexed: 01/02/2023]
Affiliation(s)
- Xin-Cheng Zhao
- Department of Entomology, College of Plant Protection; Henan Agricultural University; Zhengzhou 450002 China
| | - Qiu-Yan Chen
- Department of Entomology, College of Plant Protection; Henan Agricultural University; Zhengzhou 450002 China
| | - Pei Guo
- Department of Entomology, College of Plant Protection; Henan Agricultural University; Zhengzhou 450002 China
| | - Gui-Ying Xie
- Department of Entomology, College of Plant Protection; Henan Agricultural University; Zhengzhou 450002 China
| | - Qing-Bo Tang
- Department of Entomology, College of Plant Protection; Henan Agricultural University; Zhengzhou 450002 China
| | - Xian-Ru Guo
- Department of Entomology, College of Plant Protection; Henan Agricultural University; Zhengzhou 450002 China
- Collaborative Innovation Center of Henan Grain Crops; Zhengzhou 450002 China
| | - Bente G. Berg
- Department of Psychology; Norwegian University of Science and Technology; Trondheim 7489 Norway
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Berg BG, Zhao XC, Wang G. Processing of Pheromone Information in Related Species of Heliothine Moths. INSECTS 2014; 5:742-61. [PMID: 26462937 PMCID: PMC4592608 DOI: 10.3390/insects5040742] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 09/22/2014] [Accepted: 09/24/2014] [Indexed: 11/16/2022]
Abstract
In heliothine moths, the male-specific olfactory system is activated by a few odor molecules, each of which is associated with an easily identifiable glomerulus in the primary olfactory center of the brain. This arrangement is linked to two well-defined behavioral responses, one ensuring attraction and mating behavior by carrying information about pheromones released by conspecific females and the other inhibition of attraction via signal information emitted from heterospecifics. The chance of comparing the characteristic properties of pheromone receptor proteins, male-specific sensory neurons and macroglomerular complex (MGC)-units in closely-related species is especially intriguing. Here, we review studies on the male-specific olfactory system of heliothine moths with particular emphasis on five closely related species, i.e., Heliothis virescens, Heliothis subflexa, Helicoverpa zea, Helicoverpa assulta and Helicoverpa armigera.
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Affiliation(s)
- Bente G Berg
- Department of Psychology, Norwegian University of Science and Technology, Trondheim 7489, Norway.
| | - Xin-Cheng Zhao
- Department of Entomology, College of Plant Protection, Henan Agricultural University, Zhengzhou 450002, China.
| | - Guirong Wang
- State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
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Neurobiology of acoustically mediated predator detection. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2014; 201:99-109. [DOI: 10.1007/s00359-014-0948-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Revised: 09/24/2014] [Accepted: 09/28/2014] [Indexed: 12/23/2022]
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Zhemchuzhnikov MK, Pfuhl G, Berg BG. Tracing and 3-dimensional representation of the primary afferents from the moth ear. ARTHROPOD STRUCTURE & DEVELOPMENT 2014; 43:231-241. [PMID: 24732046 DOI: 10.1016/j.asd.2014.04.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 02/19/2014] [Accepted: 04/03/2014] [Indexed: 06/03/2023]
Abstract
Heliothine moths perceive acoustic information via two auditory sensory neurons only. Previous cobalt staining experiments have described the projection pattern of the two auditory neurons, called the A1 and the A2 cell, plus one additional neuron, the so-called B cell, up to the prothorax. We have obtained new and improved data about the projection pattern of the three sensory afferents by means of fluorescent staining experiments combined with scanning confocal microscopy. The present data show the fine structure of each sensory axon that arises from the moth ear and its ascending pathway relative to that of the others. In accordance with the previous data, the A2 auditory cell was found to extend projections in the pterothorax only. A novel finding is that terminal branches of the A2 cell cross the midline. The staining pattern of the two remaining neurons, the A1 and B cell, which project tightly together in the thoracic ganglia, differ somewhat from that previously described. As demonstrated here, one of these two neurons, the A1 cell, terminates in the prothoracic ganglion whereas the other, the B cell, projects further on via the cervical connectives to the subesophageal ganglion. The current data, therefore, indicate that none of the auditory afferents in the heliothine moth projects to the brain.
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Affiliation(s)
- Mikhail K Zhemchuzhnikov
- Norwegian University of Science and Technology, Department of Psychology, Neuroscience Unit, 7491 Trondheim, Norway; Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, Pr. Torez 44, 194223 Saint-Petersburg, Russia.
| | - Gerit Pfuhl
- Norwegian University of Science and Technology, Department of Psychology, Neuroscience Unit, 7491 Trondheim, Norway.
| | - Bente G Berg
- Norwegian University of Science and Technology, Department of Psychology, Neuroscience Unit, 7491 Trondheim, Norway.
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Pfuhl G, Zhao XC, Ian E, Surlykke A, Berg BG. Sound-sensitive neurons innervate the ventro-lateral protocerebrum of the heliothine moth brain. Cell Tissue Res 2013; 355:289-302. [DOI: 10.1007/s00441-013-1749-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Accepted: 10/21/2013] [Indexed: 11/29/2022]
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