Mechanisms of action initiation and maintenance
Lead Research Organisation:
King's College London
Department Name: Neuroscience
Abstract
The vertebrate basal ganglia convey sensorimotor, limbic and associative information corresponding to action selection between behavioural modules that are competing for the control of a limited set of motor resources. Focal lesions and birth- or disease-related dysfunction of basal ganglia substructures are associated with movement disorders, such as Parkinsonism, as well as neuropsychiatric disorders including autism spectrum disorder and schizophrenia. To elucidate the neural mechanisms of action selection and decision-making, several in vivo models have been established that rely predominantly on rodents (mouse, rat) and primates (marmoset, macaque, baboon). These animal studies led to insights into the functional anatomy of basal ganglia substructures, their role in adaptive behaviour and their disease-related pathology. In addition, several neural computation models for action selection and decision-making have been developed which allow specific predictions to be tested. However, these predictions are usually tested either in rodent and primate models within a very limited area of basal ganglia activity, or they are applied to imaging studies that are at best correlative and with low cellular/circuit resolution. Thus far, the in vivo mechanisms and neural computations underlying action selection for adaptive behaviour have remained elusive. We recently resolved a highly conserved structural and functional ground pattern organization in the insect central complex (CX) and the vertebrate basal ganglia. We also showed that dysfunction of CX circuitries in Drosophila can result in synaptic and behavioural phenotypes that resemble dysfunction of basal ganglia substructures, including Parkinsonism and frontotemporal dementia with motor neuron disease. Moreover, our preliminary data identify CX circuitries that mediate the selection and maintenance of behavioural actions. These data suggest a deep homology between the basal ganglia and insect CX in action selection, and make the insect CX an ideal platform to study in vivo mechanisms and neural computations underlying action selection in health and disease. Here we propose to establish the fruitfly Drosophila as an in vivo model system to determine action selection mechanisms. Specifically we will test the hypoptheses that (i) CX circuitries mediate action selection; that (ii) reciprocal GABAergic inhibition represents an effective neural mechanism for action selection in vivo; and (iii), that dopaminergic modulation mediates action initiation. We expect that our findings will lead to fundamental insights into the mechanisms of action selection that are important to the health services, the pharmaceutical industry, as well as to veterinaries and animal welfare in general.
Technical Summary
Action selection is a central mechanism whereby behavioural repertoires compete for control of a finite set of motor resources. A central brain region involved in action selection are the basal ganglia (BG), their dysfunction being associated with movement and motivation disorders. Previous studies led to insights into the functional anatomy of BG substructures and their role in adaptive behaviour. In addition, neural computation models have been developed which allow specific predictions to be tested. However, these predictions are usually tested either in animal models within a very limited area of BG activity, or they are applied to imaging studies that are at best correlative and with low cellular/circuit resolution. Thus far, the mechanisms underlying action selection for adaptive behaviour have remained elusive. We recently resolved a highly conserved structural and functional ground pattern organization of the insect central complex (CX) and the vertebrate BG. Moreover, our preliminary data identify CX circuitries and neural computations that mediate the selection and maintenance of behavioural actions. Our data suggest a deep homology between the BG and insect CX and make the insect CX an ideal platform to study in vivo mechanisms and neural computations underlying action initiation and maintenance. Here we propose to establish the fruitfly Drosophila as an in vivo model system to investigate action initiation and maintenance. Specifically we will test the hypoptheses that (i) CX circuitries mediate action selection; that (ii) reciprocal GABAergic inhibition represents an effective mechanism for action initiation and maintenance; and (iii), that dopaminergic modulation mediates action initiation. We expect that our findings will lead to fundamental insights into the mechanisms of action selection that are important to the health services, the pharmaceutical industry, as well as to veterinaries and animal welfare in general.
Planned Impact
Research towards understanding the mechanisms and neural computations of action selection is highly relevant to the health services, the pharmaceutical industry, as well as to veterinaries and animal welfare in general. Although several in vivo animal models have been established, using predominantly rodents (mouse, rat) and non-human primates (marmoset, macaque, baboon), thus far however, the in vivo mechanisms and neural computations underlying action selection for adaptive behaviour have remained elusive. We recently resolved a highly conserved structural and functional ground pattern organization in the insect central complex (CX) and the vertebrate basal ganglia. We also showed that dysfunction of CX circuitries in Drosophila can result in synaptic and behavioural phenotypes that resemble dysfunction of basal ganglia substructures. With our proposed research we will establish the insect Drosophila and central complex circuitries as a highly relevant alternative to rodents and non-human primates in the study of action selection and decision-making, and their dysfunction in behavioural disorders. We expect to identify highly conserved neural mechanism for action selection. Moreover, we will actively advocate our novel experimental approach by presenting it at relevant scientific meetings to report our results to those engaged in animal research, health services, and the pharmaceutical industry, and by communicating our paradigm and findings to the wider public. Furthermore we will actively engage in public dissemination with radio interviews as we have done previously, and by distributing freely the large collection of tools already in our hands and those that we will generate for this project. In a wider perspective, results gained from our studies in fruitflies will not only reveal conserved mechanisms of action selection, we also expect that our insights will guide research into basal ganglia-related dysfunction, and thus ultimately inform health services and the pharmaceutical industry, as well as veterinaries and animal welfare in general.
Publications
Tziortzouda P
(2021)
Triad of TDP43 control in neurodegeneration: autoregulation, localization and aggregation.
in Nature reviews. Neuroscience
Strausfeld NJ
(2016)
Introduction to 'Homology and convergence in nervous system evolution'.
in Philosophical transactions of the Royal Society of London. Series B, Biological sciences
Strausfeld NJ
(2023)
Response to Comment on "The lower Cambrian lobopodian Cardiodictyon resolves the origin of euarthropod brains".
in Science (New York, N.Y.)
Strausfeld N
(2022)
The lower Cambrian lobopodian Cardiodictyon resolves the origin of euarthropod brains
in Science
Solomon DA
(2018)
A feedback loop between dipeptide-repeat protein, TDP-43 and karyopherin-a mediates C9orf72-related neurodegeneration.
in Brain : a journal of neurology
Shaw RE
(2018)
In vivo expansion of functionally integrated GABAergic interneurons by targeted increase in neural progenitors.
in The EMBO journal
Schuster HC
(2023)
Phylogenetic tracing of midbrain-specific regulatory sequences suggests single origin of eubilaterian brains.
in Science advances
Pasha T
(2021)
Karyopherin abnormalities in neurodegenerative proteinopathies.
in Brain : a journal of neurology
Parsons RB
(2022)
Alpha-synucleinopathy reduces NMNAT3 protein levels and neurite formation that can be rescued by targeting the NAD+ pathway.
in Human molecular genetics
Mazaud D
(2019)
Transcriptional Regulation of the Glutamate/GABA/Glutamine Cycle in Adult Glia Controls Motor Activity and Seizures in Drosophila.
in The Journal of neuroscience : the official journal of the Society for Neuroscience
Mattedi F
(2023)
Optogenetic cleavage of the Miro GTPase reveals the direct consequences of real-time loss of function in Drosophila.
in PLoS biology
Lee YB
(2017)
C9orf72 poly GA RAN-translated protein plays a key role in amyotrophic lateral sclerosis via aggregation and toxicity.
in Human molecular genetics
Kottler B
(2019)
Inverse Control of Turning Behavior by Dopamine D1 Receptor Signaling in Columnar and Ring Neurons of the Central Complex in Drosophila.
in Current biology : CB
Hirth F
(2020)
Immunostaining of the Embryonic and Larval Drosophila Brain.
in Methods in molecular biology (Clifton, N.J.)
Gonçalves-Pimentel C
(2020)
A miRNA screen procedure identifies garz as an essential factor in adult glia functions and validates Drosophila as a beneficial 3Rs model to study glial functions and GBF1 biology
in F1000Research
Fiore VG
(2017)
In silico Interrogation of Insect Central Complex Suggests Computational Roles for the Ellipsoid Body in Spatial Navigation.
in Frontiers in behavioral neuroscience
Fiore VG
(2016)
Changing pattern in the basal ganglia: motor switching under reduced dopaminergic drive.
in Scientific reports
Buhl E
(2021)
Thermoresponsive motor behavior is mediated by ring neuron circuits in the central complex of Drosophila.
in Scientific reports
Bridi JC
(2020)
Ancestral regulatory mechanisms specify conserved midbrain circuitry in arthropods and vertebrates.
in Proceedings of the National Academy of Sciences of the United States of America
Bridi JC
(2018)
Mechanisms of a-Synuclein Induced Synaptopathy in Parkinson's Disease.
in Frontiers in neuroscience
Bridi JC
(2021)
Presynaptic accumulation of a-synuclein causes synaptopathy and progressive neurodegeneration in Drosophila.
in Brain communications
Bridi JC
(2019)
Lineage-specific determination of ring neuron circuitry in the central complex of Drosophila.
in Biology open
Description | we identified circuitry essential for action selection. Our findings suggest a hierarchy among ellipsoid body (EB) ring neuron circuits, with the outer ring circuit (R2/4m) acting as input and the inner ring (R1) acting as output to the lateral accessory lobes (objectives A). We show evidence for reciprocal inhibition among R neuron circuitry (objectives B) based on computational modelling and behavioural analysis. Our genetic manipulations and neural computations identify facilitation, inhibition and disinhibition of motor activity as differential R neuron functions underlying the initiation, maintenance and termination of actions and their organisation into action sequences [1]. These findings suggest that R neuron circuitry exhibits homologies to direct and indirect pathway activities including their disease-related dysfunction (Objectives B&C). This work was under review several times (Cell, PNAS, Nature Comm, eLife) but faced fierce opposition. A key obstacle is to show paired recordings from identified EB ring neurons in order to provide further evidence for reciprocal inhibition among R neurons. Electrophysiological recordings from connected ('paired') ring neurons in the EB of Drosophila, is very difficult and time consuming and so far has been done only once (in Mark Wu's lab). Because CX research is a very competitive field, we decided to make our manuscript publicly available on bioRxiv (https://doi.org/10.1101/100420) before resolving this issue. Further to ring neuron circuitry, we identified columnar wedge neurons as part of the CX action selection circuits. We developed a novel paradigm that measures the temporal sequences of motor actions and turning behaviour of freely moving flies (please see Figs. 1&3 in new Case for Support). Using this paradigm, we show that action sequences and turning behaviour are regulated by dopamine D1 (Dop1R1) receptor signalling (objectives A-C). Dop1R1 inputs onto CX columnar-wedge and EB R2/R4m ring neuron circuits both negatively gate motor activity but inversely control turning behaviour. While flies deficient of D1 receptor signalling present normal turning behaviour despite decreased activity, restoring Dop1R1 level in R2/R4m-specific circuitry affects the temporal organisation of motor actions and turning. We also show that these EB R2/R4m neurons are in contact with columnar wedge neurons (objectives A&B) that are thought to encode body orientation and heading direction of the fly. These findings suggest that columnar-wedge and ring neuron circuits of the CX differentially modulate patterns of activity and control turning by comparative Dop1R1 signalling for goal-directed locomotion. This work [2] has been submitted and we uploaded it on bioRxiv (https://doi.org/10.1101/385674). We applied our computational model of EB action selection circuitry to spatial navigation which includes decision-making processes that can be best summarized by "you can't turn left and right at the same time". When a moving animal is facing an obstacle, a decision is necessary to avoid collision and a turn has to be executed. Therefore a selection between available alternatives needs to be made regarding the nature of the turn either by stopping and remaining inactive or by changing direction by turning left or right. Our simulations (objectives B&C) show integration of multiple sensory sources can be effectively performed in the EB. This processed information is used to trigger continuous sequences of action selections resulting in self-motion, obstacle avoidance and the navigation of simulated environments of varying complexity. The motor responses to perceived sensory stimuli can be stored in the CX to simulate navigation relying on a collective of guidance cues, akin to sensory-driven innate or habitual behaviours. By comparing behaviours under different conditions of accessible sources of input information, we show the simulated insect computes visual inputs and body posture to estimate its position in space. Finally, we tested whether the local connectome of the CX might also allow the flexibility required to recall an intentional behavioural sequence, among different courses of actions. Our simulations suggest that the central complex can encode combined representations of motor and spatial information to pursue a goal and thus successfully guide orientation behaviour. Together, the observed computational features identify CX circuitry, and especially the EB, as a key neural correlate involved in spatial navigation [3]. As a result from our experimental and computational modelling studies in Drosophila, our data provided essential input to an amended model of basal ganglia (BG) function (objectives B&C). Action selection in the BG is often described within the framework of a standard model, associating low dopaminergic drive with motor suppression. Whilst powerful, this model does not explain several clinical and experimental data, including varying therapeutic efficacy across movement disorders. We tested the predictions of this model in patients with Parkinson's disease, on and off subthalamic deep brain stimulation (DBS), focussing on adaptive sensory-motor responses to a changing environment and maintenance of an action until it is no longer suitable. Surprisingly, we observed prolonged perseverance under on-stimulation, and high inter-individual variability in terms of the motor selections performed when comparing the two conditions. To account for these data, we revised the standard model exploring its space of parameters and associated motor functions and found that, depending on effective connectivity between external and internal parts of the globus pallidus and saliency of the sensory input, a low dopaminergic drive can result in increased, dysfunctional, motor switching, besides motor suppression. This new framework provides insight into the biophysical mechanisms underlying DBS, allowing a description in terms of alteration of the signal-to-baseline ratio in the indirect pathway, which better account of known electrophysiological data in comparison with the standard model [4]. Thus our work in flies has led to new insights into the understanding of human disease and the neural computations underlying BG function (objectives B&C, academic beneficiaries and pathways to impact). In addition to the objectives stated in our grant, we furthered our understanding of CX action selection circuitry by starting to investigate its formation and the underlying developmental genetic mechanisms [5]. This work developed from our lineage analysis of EB ring neurons, which identified a pair of neural stem cells in the early embryonic brain from which all ring neurons of subtypes R1-R4 derive. We used these unprecedented insights to address a fundamental question in brain formation and evolution. A central hypothesis for brain evolution is that it might occur via expansion of progenitor cells and subsequent lineage-dependent formation of neural circuits. In Shaw et al we showed in vivo amplification and functional integration of lineage-specific circuitry in Drosophila. Levels of the cell fate determinant Prospero were attenuated in specific brain lineages within a range that expanded not only progenitors but also neuronal progeny, without tumour formation. Resulting supernumerary neural stem cells underwent normal functional transitions, progressed through the temporal patterning cascade, and generated progeny with molecular signatures matching source lineages. Fully differentiated supernumerary gamma-amino butyric acid (GABA)-ergic interneurons formed functional connections in the CX of the adult brain, as revealed by in vivo calcium imaging and open-field behavioural analysis. Our results show that quantitative control of a single transcription factor is sufficient to tune neuron numbers and clonal circuitry, and provide molecular insight into a likely mechanism of brain evolution [5]. Taken together, our studies resulting so far from grant BB/N001230/1 demonstrate pathways to impact that led to new collaborations, links to clinicians and other identified academic beneficiaries including the application to new work. Until now we trained in this field two BSc and four MSc Neuroscience students and one BBSRC LiDO rotation student, who carried out lab projects with us. The results of our studies so far are publicly disseminated in open access articles and preprints (see below), conference contributions (e.g. Neurofly) and invited plenary lectures (e.g. Janelia Farm) and in seminars and workshops at national and international institutions (e.g. Cambridge, KU Leuven, ESPCI Paris, Champalimaud Lisbon). Publications/preprints arising from this work (until September 2018): 1. Kottler B, Fiore VG, Ludlow ZN, Buhl E, Vinatier G, Faville R, Diaper DC, Stepto A, Dearlove J, Adachi Y, Brown S, Chen C, Solomon DA, White KE, Humphrey DM, Buchanan SM, Sigrist SJ, Endo K, Ito K, de Bivort B, Stanewsky R, Dolan RJ, Martin JR, Hodge JJL, Strausfeld NJ, Hirth F (2017) A lineage-related reciprocal inhibition circuitry for sensory-motor action selection. bioRxiv https://doi.org/10.1101/100420 (preprint). 2. Kottler B, Faville R, Bridi JC, Hirth F (2019) Inverse control of turning behaviour by dopamine D1 receptor signalling in columnar and ring neurons of the central complex in Drosophila. Curr Biol 29:567-577. 3. Fiore VG, Kottler B, Gu X, Hirth F (2017) In silico interrogation of insect central complex suggests computational roles for the ellipsoid body in spatial navigation. Front Behav Neurosci 11:142. doi: 10.3389/fnbeh.2017.00142. 4. Fiore VG, Rigoli F, Stenner MP, Zaehle T, Hirth F, Heinze HJ, Dolan RJ (2016) Changing pattern in the basal ganglia: motor switching under reduced dopaminergic drive. Sci Rep 6:23327. doi: 10.1038/srep23327. 5. Shaw RE, Kottler B, Ludlow ZN, Buhl E, Kim D, Morais da Silva S, Miedzik A, Coum A, Hodge JJ, Hirth F*, Sousa-Nunes R* (2018) In vivo expansion of functionally integrated GABAergic interneurons by targeted increase in neural progenitors. EMBO J 37:e98163. doi: 10.15252/embj.201798163. (*joint-senior author). |
Exploitation Route | The behavioural paradigm and software we developed has been requested by interested others (University of Queensland, Australia; UCL; University of Bristol) Our findings have led to new collaborations |
Sectors | Education,Manufacturing, including Industrial Biotechology,Other |
URL | https://www.ncbi.nlm.nih.gov/pubmed/30713106 |
Description | Project Grant |
Amount | £60,000 (GBP) |
Organisation | The Dunhill Medical Trust |
Sector | Charity/Non Profit |
Country | United Kingdom |
Start | 10/2017 |
End | 09/2018 |
Title | DART |
Description | We developed a software and behavioural paradigm using video assisted motion tracking to deconstruct and analyse motor behaviour, including parameters such as action initition and maintenance that are relevant for a large number of movement and motivation disorders |
Type Of Material | Technology assay or reagent |
Provided To Others? | No |
Impact | We have currently 2 manuscripts under review at high impact journals. We plan to publish the method in another two manuscripts in preparation. |
Description | Janelia Farm Collaboration |
Organisation | Howard Hughes Medical Institute |
Department | Janelia Research Campus |
Country | United States |
Sector | Academic/University |
PI Contribution | We established a collaboration with Dr. Albert Cardone, HHMI Janelia Research Farm. It is based on our identification of a region in the insect brain that resembles deep homology to the mammalian cerebellum/midbrain hindbrain boundary region. A high impact publication is in progress. |
Collaborator Contribution | Dr. Cardona/Janelia Farm are providing us with exceptional serial TEM data that allow the analysis of all synaptic connections in the Drosophila larva. |
Impact | Ongoing |
Start Year | 2017 |
Description | Swiss Genomics Consortium |
Organisation | University of Fribourg |
Country | Switzerland |
Sector | Academic/University |
PI Contribution | We have initiated this project and provide the conceptual framework. We also provide essential research material. |
Collaborator Contribution | Our Swiss partners have used their facility for our collaborative RNA sequencing screen and an initial bioinformatics analysis with partners from the University of Bern. |
Impact | A large dataset that will be included in future publications. |
Start Year | 2019 |
Description | VR Genome Browser |
Organisation | The Wellcome Trust Sanger Institute |
Country | United Kingdom |
Sector | Charity/Non Profit |
PI Contribution | HAmmerheadVR is developing a virtual reality genome browser with the aim to make large datasets available for navigation and interrogation. The Sanger Centre contributes bioinformatic input (genome sequences) and we at KCL provide GWAS and RNA-seq datasets. |
Collaborator Contribution | See above. |
Impact | Grant application in progress. |
Start Year | 2016 |
Description | Guest editor |
Form Of Engagement Activity | A magazine, newsletter or online publication |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | I have been invited to act as a guest editor for a special issue on "Drosophila Models for Neurodegenerative Diseases: Achievements and Prospects" in the "International Journal of Molecular Sciences" |
Year(s) Of Engagement Activity | 2020 |
URL | https://www.mdpi.com/journal/ijms/special_issues/Drosophila_Models_Neuro |
Description | Interview with Deutschlandfunk |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Media (as a channel to the public) |
Results and Impact | The radio station Deutschlandfunk interviewed me about new findings related to brain evolution. |
Year(s) Of Engagement Activity | 2016 |
URL | http://www.deutschlandfunk.de/nerven-wie-ein-wurm-der-ursprung-des-gehirns.740.de.html?dram:article_... |
Description | Interview with Science |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | I was interviewed by a senior editor (Elizabeth Pennisi) of the Journal Science to comment on recent findings in brain evolution. This was covered in a featured article in Science. |
Year(s) Of Engagement Activity | 2015 |
URL | http://www.sciencemagazinedigital.org/sciencemagazine/13_november_2015?pg=17#pg17 |
Description | Scientific adviser |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Industry/Business |
Results and Impact | I was invited to act as scientific advisor for the 5th Annual Neuroscience R&D Technologies Conference which was attended by pharmaceutical industries, small companies and academics to hear about recent technical and conceptual developments in the neurosciences. |
Year(s) Of Engagement Activity | 2019 |
URL | https://events.marketsandmarkets.com/5th-annual-marketsandmarkets-neuroscience-r-d-technologies-conf... |