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Higgs MJ, Webberley AE, Allan AJ, Talat M, John RM, Isles AR. The parenting hub of the hypothalamus is a focus of imprinted gene action. PLoS Genet 2023; 19:e1010961. [PMID: 37856383 PMCID: PMC10586610 DOI: 10.1371/journal.pgen.1010961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 09/07/2023] [Indexed: 10/21/2023] Open
Abstract
Imprinted genes are subject to germline epigenetic modification resulting in parental-specific allelic silencing. Although genomic imprinting is thought to be important for maternal behaviour, this idea is based on serendipitous findings from a small number of imprinted genes. Here, we undertook an unbiased systems biology approach, taking advantage of the recent delineation of specific neuronal populations responsible for controlling parental care, to test whether imprinted genes significantly converge to regulate parenting behaviour. Using single-cell RNA sequencing datasets, we identified a specific enrichment of imprinted gene expression in a recognised "parenting hub", the galanin-expressing neurons of the preoptic area. We tested the validity of linking enriched expression in these neurons to function by focusing on MAGE family member L2 (Magel2), an imprinted gene not previously linked to parenting behaviour. We confirmed expression of Magel2 in the preoptic area galanin expressing neurons. We then examined the parenting behaviour of Magel2-null(+/p) mice. Magel2-null mothers, fathers and virgin females demonstrated deficits in pup retrieval, nest building and pup-directed motivation, identifying a central role for this gene in parenting. Finally, we show that Magel2-null mothers and fathers have a significant reduction in POA galanin expressing cells, which in turn contributes to a reduced c-Fos response in the POA upon exposure to pups. Our findings identify a novel imprinted gene that impacts parenting behaviour and, moreover, demonstrates the utility of using single-cell RNA sequencing data to predict gene function from expression and in doing so here, have identified a purposeful role for genomic imprinting in mediating parental behaviour.
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Affiliation(s)
- Matthew J. Higgs
- Behavioural Genetics Group, Centre for Neuropsychiatric, Genetics and Genomics, Neuroscience and Mental Health Innovation Institute, Cardiff University, Cardiff, United Kingdom
| | - Anna E. Webberley
- Behavioural Genetics Group, Centre for Neuropsychiatric, Genetics and Genomics, Neuroscience and Mental Health Innovation Institute, Cardiff University, Cardiff, United Kingdom
| | | | - Moaz Talat
- The Mary Lyon Centre, MRC Harwell, Didcot, United Kingdom
| | - Rosalind M. John
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | - Anthony R. Isles
- Behavioural Genetics Group, Centre for Neuropsychiatric, Genetics and Genomics, Neuroscience and Mental Health Innovation Institute, Cardiff University, Cardiff, United Kingdom
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Higgs MJ, Hill MJ, John RM, Isles AR. Systematic investigation of imprinted gene expression and enrichment in the mouse brain explored at single-cell resolution. BMC Genomics 2022; 23:754. [PMID: 36384442 PMCID: PMC9670596 DOI: 10.1186/s12864-022-08986-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 11/02/2022] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Although a number of imprinted genes are known to be highly expressed in the brain, and in certain brain regions in particular, whether they are truly over-represented in the brain has never been formally tested. Using thirteen single-cell RNA sequencing datasets we systematically investigated imprinted gene over-representation at the organ, brain region, and cell-specific levels. RESULTS We established that imprinted genes are indeed over-represented in the adult brain, and in neurons particularly compared to other brain cell-types. We then examined brain-wide datasets to test enrichment within distinct brain regions and neuron subpopulations and demonstrated over-representation of imprinted genes in the hypothalamus, ventral midbrain, pons and medulla. Finally, using datasets focusing on these regions of enrichment, we identified hypothalamic neuroendocrine populations and the monoaminergic hindbrain neurons as specific hotspots of imprinted gene expression. CONCLUSIONS These analyses provide the first robust assessment of the neural systems on which imprinted genes converge. Moreover, the unbiased approach, with each analysis informed by the findings of the previous level, permits highly informed inferences about the functions on which imprinted gene expression converges. Our findings indicate the neuronal regulation of motivated behaviours such as feeding and sleep, alongside the regulation of pituitary function, as functional hotspots for imprinting. This adds statistical rigour to prior assumptions and provides testable predictions for novel neural and behavioural phenotypes associated with specific genes and imprinted gene networks. In turn, this work sheds further light on the potential evolutionary drivers of genomic imprinting in the brain.
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Affiliation(s)
- M J Higgs
- Centre for Neuropsychiatric Genetics and Genomics, Division of Psychological Medicine and Clinical Neurosciences, School of Medicine, Cardiff University, Cardiff, UK
| | - M J Hill
- School of Medicine, UK Dementia Research Institute, Cardiff University, Cardiff, UK
| | - R M John
- School of Biosciences, Cardiff University, Cardiff, UK
| | - A R Isles
- Centre for Neuropsychiatric Genetics and Genomics, Division of Psychological Medicine and Clinical Neurosciences, School of Medicine, Cardiff University, Cardiff, UK.
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Isles AR. The contribution of imprinted genes to neurodevelopmental and neuropsychiatric disorders. Transl Psychiatry 2022; 12:210. [PMID: 35597773 PMCID: PMC9124202 DOI: 10.1038/s41398-022-01972-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 04/29/2022] [Accepted: 05/04/2022] [Indexed: 11/15/2022] Open
Abstract
Imprinted genes are a subset of mammalian genes that are subject to germline parent-specific epigenetic modifications leading monoallelic expression. Imprinted gene expression is particularly prevalent in the brain and it is unsurprising that mutations affecting their expression can lead to neurodevelopmental and/or neuropsychiatric disorders in humans. Here I review the evidence for this, detailing key neurodevelopmental disorders linked to imprinted gene clusters on human chromosomes 15q11-q13 and 14q32, highlighting genes and possible regulatory links between these different syndromes. Similarly, rare copy number variant mutations at imprinted clusters also provide strong links between abnormal imprinted gene expression and the predisposition to severe psychiatric illness. In addition to direct links between brain-expressed imprinted genes and neurodevelopmental and/or neuropsychiatric disorders, I outline how imprinted genes that are expressed in another tissue hotspot, the placenta, contribute indirectly to abnormal brain and behaviour. Specifically, altered nutrient provisioning or endocrine signalling by the placenta caused by abnormal expression of imprinted genes may lead to increased prevalence of neurodevelopmental and/or neuropsychiatric problems in both the offspring and the mother.
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Affiliation(s)
- Anthony R. Isles
- grid.5600.30000 0001 0807 5670MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, CF24 4HQ UK
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Zahova SK, Humby T, Davies JR, Morgan JE, Isles AR. Comparison of mouse models reveals a molecular distinction between psychotic illness in PWS and schizophrenia. Transl Psychiatry 2021; 11:433. [PMID: 34417445 PMCID: PMC8379171 DOI: 10.1038/s41398-021-01561-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 07/13/2021] [Accepted: 07/28/2021] [Indexed: 12/25/2022] Open
Abstract
Prader-Willi Syndrome (PWS) is a neurodevelopmental disorder caused by mutations affecting paternal chromosome 15q11-q13, and characterized by hypotonia, hyperphagia, impaired cognition, and behavioural problems. Psychotic illness is a challenging problem for individuals with PWS and has different rates of prevalence in distinct PWS genotypes. Previously, we demonstrated behavioural and cognitive endophenotypes of relevance to psychiatric illness in a mouse model for one of the associated PWS genotypes, namely PWS-IC, in which deletion of the imprinting centre leads to loss of paternally imprinted gene expression and over-expression of Ube3a. Here we examine the broader gene expression changes that are specific to the psychiatric endophenotypes seen in this model. To do this we compared the brain transcriptomic profile of the PWS-IC mouse to the PWS-cr model that carries a deletion of the PWS minimal critical interval spanning the snoRNA Snord116 and Ipw. Firstly, we examined the same behavioural and cognitive endophenotypes of relevance to psychiatric illness in the PWS-cr mice. Unlike the PWS-IC mice, PWS-cr exhibit no differences in locomotor activity, sensory-motor gating, and attention. RNA-seq analysis of neonatal whole brain tissue revealed a greater number of transcriptional changes between PWS-IC and wild-type littermates than between PWS-cr and wild-type littermates. Moreover, the differentially expressed genes in the PWS-IC brain were enriched for GWAS variants of episodes of psychotic illness but, interestingly, not schizophrenia. These data illustrate the molecular pathways that may underpin psychotic illness in PWS and have implications for potential therapeutic interventions.
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Affiliation(s)
- Simona K Zahova
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, UK
| | - Trevor Humby
- School of Psychology, Cardiff University, Cardiff, UK
| | - Jennifer R Davies
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, UK
| | - Joanne E Morgan
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, UK
| | - Anthony R Isles
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, UK.
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Kummerfeld DM, Raabe CA, Brosius J, Mo D, Skryabin BV, Rozhdestvensky TS. A Comprehensive Review of Genetically Engineered Mouse Models for Prader-Willi Syndrome Research. Int J Mol Sci 2021; 22:3613. [PMID: 33807162 PMCID: PMC8037846 DOI: 10.3390/ijms22073613] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 03/26/2021] [Accepted: 03/28/2021] [Indexed: 02/05/2023] Open
Abstract
Prader-Willi syndrome (PWS) is a neurogenetic multifactorial disorder caused by the deletion or inactivation of paternally imprinted genes on human chromosome 15q11-q13. The affected homologous locus is on mouse chromosome 7C. The positional conservation and organization of genes including the imprinting pattern between mice and men implies similar physiological functions of this locus. Therefore, considerable efforts to recreate the pathogenesis of PWS have been accomplished in mouse models. We provide a summary of different mouse models that were generated for the analysis of PWS and discuss their impact on our current understanding of corresponding genes, their putative functions and the pathogenesis of PWS. Murine models of PWS unveiled the contribution of each affected gene to this multi-facetted disease, and also enabled the establishment of the minimal critical genomic region (PWScr) responsible for core symptoms, highlighting the importance of non-protein coding genes in the PWS locus. Although the underlying disease-causing mechanisms of PWS remain widely unresolved and existing mouse models do not fully capture the entire spectrum of the human PWS disorder, continuous improvements of genetically engineered mouse models have proven to be very powerful and valuable tools in PWS research.
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Affiliation(s)
- Delf-Magnus Kummerfeld
- Medical Faculty, Core Facility Transgenic Animal and Genetic Engineering Models (TRAM), University of Muenster, Von-Esmarch-Str. 56, D-48149 Muenster, Germany;
| | - Carsten A. Raabe
- Research Group Regulatory Mechanisms of Inflammation, Institute of Medical Biochemistry (ZMBE), University of Muenster, Von-Esmarch-Str. 56, D-48149 Muenster, Germany;
- Institute of Experimental Pathology (ZMBE), University of Muenster, Von-Esmarch-Str. 56, D-48149 Muenster, Germany;
| | - Juergen Brosius
- Institute of Experimental Pathology (ZMBE), University of Muenster, Von-Esmarch-Str. 56, D-48149 Muenster, Germany;
- Institutes for Systems Genetics, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Dingding Mo
- School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China;
| | - Boris V. Skryabin
- Medical Faculty, Core Facility Transgenic Animal and Genetic Engineering Models (TRAM), University of Muenster, Von-Esmarch-Str. 56, D-48149 Muenster, Germany;
| | - Timofey S. Rozhdestvensky
- Medical Faculty, Core Facility Transgenic Animal and Genetic Engineering Models (TRAM), University of Muenster, Von-Esmarch-Str. 56, D-48149 Muenster, Germany;
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6
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Salvatoni A, Nosetti L, Salvatore S, Agosti M. Benefits of multidisciplinary care in Prader-Willi syndrome. Expert Rev Endocrinol Metab 2021; 16:63-71. [PMID: 33724138 DOI: 10.1080/17446651.2021.1898375] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 03/01/2021] [Indexed: 01/25/2023]
Abstract
Introduction: Prader-Willi syndrome (PWS) is the most well-known condition of genetic obesity. Over the past 20 years, advances have been achieved in the diagnosis and treatment of PWS with a significant improvement in prognosis.Areas covered: This review focuses on the benefits of multidisciplinary approach in children and adolescents with PWS. In particular, the neonatologist and geneticist play a key role in early diagnosis and the clinical follow-up of the PWS patient must be guaranteed by a team including pediatric endocrinologist, psychologist, nutritionist/dietician, neurologist/neuropsychiatrist, sleep specialist, ears, nose and throat specialist (ENT), lung specialist, dentist, orthopedist and ophthalmologist and, eventually, gastroenterologist. We searched PubMed and critically summarized what has been reported in the last 10 years on PWS.Expert opinion: The multidisciplinary care in association with an early diagnosis and GH treatment postpones overweight development and decreases prevalence of obesity in individuals with PWS. Further prognostic improvements are expected through the selection of teams particularly experienced in the management of individuals with PWS and the discovery of new drugs.
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Affiliation(s)
| | - Luana Nosetti
- Pediatric Department, Insubria University, Varese, Italy
| | | | - Massimo Agosti
- Pediatric Department, Insubria University, Varese, Italy
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Abstract
Prader-Willi syndrome (PWS) is a neurodevelopmental disorder characterized by hyperphagia, hypotonia, learning disability, as well as a range of psychiatric conditions. The conservation of the PWS genetic interval on chromosome 15q11-q13 in human, and a cluster of genes on mouse chromosome 7, has facilitated the use of mice as animal models for PWS. Some models faithfully mimic the loss of all gene expression from the paternally inherited PWS genetic interval, whereas others target smaller regions or individual genes. Collectively, these models have provided insight into the mechanisms, many of which lead to alterations in hypothalamic function, underlying the core symptoms of PWS, including growth retardation, hyperphagia and metabolism, reproductive maturation and endophenotypes of relevance to behavioral and psychiatric problems. Here we review and summarize these studies.
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Affiliation(s)
- Simona Zahova
- Neuroscience and Mental Health Research Institute, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Anthony R Isles
- Neuroscience and Mental Health Research Institute, School of Medicine, Cardiff University, Cardiff, United Kingdom.
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8
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Wright RL, Gilmour G, Dwyer DM. Wistar Kyoto Rats Display Anhedonia In Consumption but Retain Some Sensitivity to the Anticipation of Palatable Solutions. Front Behav Neurosci 2020; 14:70. [PMID: 32581735 PMCID: PMC7283460 DOI: 10.3389/fnbeh.2020.00070] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 04/17/2020] [Indexed: 12/12/2022] Open
Abstract
The Wistar Kyoto (WKY) rat has been proposed as a model of depression-like symptoms. However, anhedonia—a reduction in the response to normatively rewarding events—as a central depression symptom has yet to be fully assessed in this model. We compared WKY rats and Wistar controls, with stress-susceptibility examined by applying mild unpredictable stress to a subset of each group. Anhedonia-like behavior was assessed using microstructural analysis of licking behavior, where mean lick cluster size reflects hedonic responses. This was combined with tests of anticipatory contrast, where the consumption of a moderately palatable solution (4% sucrose) is suppressed in anticipation of a more palatable solution (32% sucrose). WKY rats displayed greatly attenuated hedonic reactions to sucrose overall, although their reactions retained some sensitivity to differences in sucrose concentration. They displayed normal reductions in consumption in anticipatory contrast, although the effect of contrast on hedonic reactions was greatly blunted. Mild stress produced overall reductions in sucrose consumption, but this was not exacerbated in WKY rats. Moreover, mild stress did not affect hedonic reactions or the effects of contrast. These results confirm that the WKY substrain expresses a direct behavioral analog of anhedonia, which may have utility for increasing mechanistic understanding of depression symptoms.
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Affiliation(s)
- Rebecca L Wright
- School of Psychology, Cardiff University, Cardiff, United Kingdom
| | - Gary Gilmour
- Lilly Research Centre, Eli Lilly & Co. Ltd., Erl Wood Manor, United Kingdom
| | - Dominic M Dwyer
- School of Psychology, Cardiff University, Cardiff, United Kingdom
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9
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Davies JR, Wilkinson LS, Isles AR, Humby T. Prader-Willi syndrome imprinting centre deletion mice have impaired baseline and 5-HT2CR-mediated response inhibition. Hum Mol Genet 2020; 28:3013-3023. [PMID: 31087031 PMCID: PMC6737253 DOI: 10.1093/hmg/ddz100] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 05/07/2019] [Accepted: 05/10/2019] [Indexed: 12/11/2022] Open
Abstract
Prader–Willi syndrome (PWS) is a neurodevelopmental disorder caused by deletion or inactivation of paternally expressed imprinted genes on human chromosome 15q11–q13. In addition to endocrine and developmental issues, PWS presents with behavioural problems including stereotyped behaviour, impulsiveness and cognitive deficits. The PWS genetic interval contains several brain-expressed small nucleolar (sno) RNA species that are subject to genomic imprinting, including snord115 that negatively regulates post-transcriptional modification of the serotonin 2C receptor (5-HT2CR) pre-mRNA potentially leading to a reduction in 5-HT2CR function. Using the imprinting centre deletion mouse model for PWS (PWSICdel) we have previously shown impairments in a number of behaviours, some of which are abnormally sensitive to 5-HT2CR-selective drugs. In the stop-signal reaction time task test of impulsivity, PWSICdel mice showed increased impulsivity relative to wild-type (WT) littermates. Challenge with the selective 5-HT2CR agonist WAY163909 reduced impulsivity in PWSICdel mice but had no effect on WT behaviour. This behavioural dissociation in was also reflected in differential patterns of immunoreactivity of the immediate early gene c-Fos, with a blunted response to the drug in the orbitofrontal cortex of PWSICdel mice, but no difference in c-Fos activation in the nucleus accumbens. These findings suggest specific facets of response inhibition are impaired in PWSICdel mice and that abnormal 5-HT2CR function may mediate this dissociation. These data have implications for our understanding of the aetiology of PWS-related behavioural traits and translational relevance for individuals with PWS who may seek to control appetite with the new obesity treatment 5-HT2CR agonist lorcaserin.
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Affiliation(s)
- Jennifer R Davies
- Behavioural Genetics Group, MRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Schools of Medicine
| | - Lawrence S Wilkinson
- Behavioural Genetics Group, MRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Schools of Medicine.,Psychology, Cardiff University, Cardiff, UK
| | - Anthony R Isles
- Behavioural Genetics Group, MRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Schools of Medicine
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Kao KC, Hisatsune T. Differential effects of dopamine D1-like and D2-like receptor agonists on water drinking behaviour under thirsty conditions in mice with reduced dopamine secretion. Eur J Neurosci 2019; 51:584-597. [PMID: 31472080 DOI: 10.1111/ejn.14568] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 08/08/2019] [Accepted: 08/27/2019] [Indexed: 11/27/2022]
Abstract
The mesolimbic dopamine system is important for reward-oriented behaviours, such as drinking and eating. However, the precise involvement of dopaminergic neurons and dopamine receptors in water drinking behaviour remains unclear. Here, we generated triple transgenic mice harbouring Slc6a3(DAT)-icre/ERT2, Camk2a-loxP-STOP-loxP-tetracycline transactivator and tetO-tetanus toxin constructs, in which the release of dopamine is blocked by tetanus toxin. These mice, referred to as dopamine secretion interference mice, had reduced dopamine secretion in the striatum (61.4%) and the nucleus accumbens (54.5%). They showed adequate limb strength and food consumption, similarly to control mice, but exhibited motor control impairment in a challenging rotarod test. Dopamine secretion interference mice made fewer licks and had fewer bursts than control mice during a licking test under thirsty conditions. To elucidate the influence of dopamine receptors in the altered drinking behaviour, a dopamine D1 or D2/D3 receptor agonist (A68930 or ropinirole, respectively) was administered prior to the licking microstructure analysis. Treatment with the D1 agonist restored the total number of licks but not the burst number in dopamine secretion interference mice. By contrast, the D2/3 agonist impeded water drinking behaviour in both transgenic and control mice. The present findings indicate that D1 receptor activation partially ameliorates the altered drinking behaviour of the dopamine secretion interference mice and suggest that D1 receptor activity impacts drinking under thirsty conditions.
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Affiliation(s)
- Kung-Chun Kao
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Japan
| | - Tatsuhiro Hisatsune
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Japan
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Carias KV, Wevrick R. Preclinical Testing in Translational Animal Models of Prader-Willi Syndrome: Overview and Gap Analysis. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2019; 13:344-358. [PMID: 30989085 PMCID: PMC6447752 DOI: 10.1016/j.omtm.2019.03.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Prader-Willi syndrome (PWS) is a rare neurodevelopmental disorder causing endocrine, musculoskeletal, and neurological dysfunction. PWS is caused by the inactivation of contiguous genes, complicating the development of targeted therapeutics. Clinical trials are now underway in PWS, with more trials to be implemented in the next few years. PWS-like endophenotypes are recapitulated in gene-targeted mice in which the function of one or more PWS genes is disrupted. These animal models can guide priorities for clinical trials or provide information about efficacy of a compound within the context of the specific disease. We now review the current status of preclinical studies that measure the effect of therapeutics on PWS-like endophenotypes. Seven categories of therapeutics (oxytocin and related compounds, K+-ATP channel agonists, melanocortin 4 receptor agonists, incretin mimetics and/or GLP-1 receptor agonists, cannabinoids, ghrelin agents, and Caralluma fimbriata [cactus] extract) have been tested for their effect on endophenotypes in both PWS animal models and clinical trials. Many other therapeutics have been tested in clinical trials, but not preclinical models of PWS or vice versa. Fostering dialogs among investigators performing preclinical validation of animal models and those implementing clinical studies will accelerate the discovery and translation of therapies into clinical practice in PWS.
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Affiliation(s)
- K Vanessa Carias
- Department of Medical Genetics, University of Alberta, Edmonton, AB, Canada
| | - Rachel Wevrick
- Department of Medical Genetics, University of Alberta, Edmonton, AB, Canada
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Humby T, Patel Y, Carter J, Stokes LJG, Rogers RD, Wilkinson LS. Feeding behaviour, risk-sensitivity and response control: effects of 5-HT 2C receptor manipulations. Philos Trans R Soc Lond B Biol Sci 2019; 374:20180144. [PMID: 30966915 PMCID: PMC6335459 DOI: 10.1098/rstb.2018.0144] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/30/2018] [Indexed: 11/12/2022] Open
Abstract
People, like animals, tend to choose the variable option when given the choice between a fixed and variable delay to reward where, in the variable delay condition, some rewards are available immediately (Laura-Jean et al. 2019 Phil. Trans. R. Soc. B 374, 20180141. ( doi:10.1098/rstb.2018.0141 )). This bias has been suggested to reflect evolutionary pressures resulting from food scarcity in the past placing a premium on obtaining food quickly that can win out against the risks of sometimes sustaining longer delays to food. The psychologies mediating this effect may become maladaptive in the developed world where food is readily available contributing, potentially, to overeating and obesity. Here, we report our development of a novel touchscreen task in mice allowing comparisons of the impact of food delay and food magnitude across species. We show that mice exhibit the typical preference, as shown by humans, for variable over fixed delays to rewards but no preference when it comes to fixed versus variable reward amounts and further show that this bias is sensitive to manipulations of the 5-HT2C receptor, a key mediator of feeding and impulse control. We discuss the data in terms of the utility of the task to model the psychologies and underlying brain mechanisms impacting on feeding behaviours. This article is part of the theme issue 'Risk taking and impulsive behaviour: fundamental discoveries, theoretical perspectives and clinical implications'.
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Affiliation(s)
- Trevor Humby
- Behavioral Genetics Group, Cardiff University, Cardiff CF10 3AX, UK
- MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, Cardiff CF10 3AX, UK
- Division of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff CF10 3AX, UK
- Neuroscience and Mental Health Research Institute, Cardiff University, Cardiff CF10 3AX, UK
| | - Yateen Patel
- Behavioral Genetics Group, Cardiff University, Cardiff CF10 3AX, UK
- MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, Cardiff CF10 3AX, UK
- Division of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff CF10 3AX, UK
- Neuroscience and Mental Health Research Institute, Cardiff University, Cardiff CF10 3AX, UK
| | - Jenny Carter
- Behavioral Genetics Group, Cardiff University, Cardiff CF10 3AX, UK
- MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, Cardiff CF10 3AX, UK
- Division of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff CF10 3AX, UK
- Neuroscience and Mental Health Research Institute, Cardiff University, Cardiff CF10 3AX, UK
| | | | | | - Lawrence S. Wilkinson
- Behavioral Genetics Group, Cardiff University, Cardiff CF10 3AX, UK
- MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, Cardiff CF10 3AX, UK
- Division of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff CF10 3AX, UK
- Neuroscience and Mental Health Research Institute, Cardiff University, Cardiff CF10 3AX, UK
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Salminen II, Crespi BJ, Mokkonen M. Baby food and bedtime: Evidence for opposite phenotypes from different genetic and epigenetic alterations in Prader-Willi and Angelman syndromes. SAGE Open Med 2019; 7:2050312118823585. [PMID: 30728968 PMCID: PMC6350130 DOI: 10.1177/2050312118823585] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 12/14/2018] [Indexed: 12/22/2022] Open
Abstract
Prader–Willi and Angelman syndromes are often referred to as a sister pair of
neurodevelopmental disorders, resulting from different genetic and epigenetic
alterations to the same chromosomal region, 15q11-q13. Some of the primary
phenotypes of the two syndromes have been suggested to be opposite to one
another, but this hypothesis has yet to be tested comprehensively, and it
remains unclear how opposite effects could be produced by changes to different
genes in one syndrome compared to the other. We evaluated the evidence for
opposite effects on sleep and eating phenotypes in Prader–Willi syndrome and
Angelman syndrome, and developed physiological–genetic models that represent
hypothesized causes of these differences. Sleep latency shows opposite
deviations from controls in Prader–Willi and Angelman syndromes, with shorter
latency in Prader–Willi syndrome by meta-analysis and longer latency in Angelman
syndrome from previous studies. These differences can be accounted for by the
effects of variable gene dosages of UBE3A and MAGEL2, interacting with clock
genes, and leading to acceleration (in Prader–Willi syndrome) or deceleration
(in Angelman syndrome) of circadian rhythms. Prader–Willi and Angelman syndromes
also show evidence of opposite alterations in hyperphagic food selectivity, with
more paternally biased subtypes of Angelman syndrome apparently involving
increased preference for complementary foods (“baby foods”); hedonic reward from
eating may also be increased in Angelman syndrome and decreased in Prader–Willi
syndrome. These differences can be explained in part under a model whereby
hyperphagia and food selectivity are mediated by the effects of the genes
SNORD-116, UBE3A and MAGEL2, with outcomes depending upon the genotypic cause of
Angelman syndrome. The diametric variation observed in sleep and eating
phenotypes in Prader–Willi and Angelman syndromes is consistent with predictions
from the kinship theory of imprinting, reflecting extremes of higher resource
demand in Angelman syndrome and lower demand in Prader–Willi syndrome, with a
special emphasis on social–attentional demands and attachment associated with
bedtime, and feeding demands associated with mother-provided complementary foods
compared to offspring-foraged family-type foods.
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14
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Patitucci E, Nelson AJD, Dwyer DM, Honey RC. The origins of individual differences in how learning is expressed in rats: A general-process perspective. JOURNAL OF EXPERIMENTAL PSYCHOLOGY-ANIMAL LEARNING AND COGNITION 2018; 42:313-324. [PMID: 27732045 PMCID: PMC5058353 DOI: 10.1037/xan0000116] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Laboratory rats can exhibit marked, qualitative individual differences in the form of acquired behaviors. For example, when exposed to a signal-reinforcer relationship some rats show marked and consistent changes in sign-tracking (interacting with the signal; e.g., a lever) and others show marked and consistent changes in goal-tracking (interacting with the location of the predicted reinforcer; e.g., the food well). Here, stable individual differences in rats’ sign-tracking and goal-tracking emerged over the course of training, but these differences did not generalize across different signal-reinforcer relationships (Experiment 1). This selectivity suggests that individual differences in sign- and goal-tracking reflect differences in the value placed on individual reinforcers. Two findings provide direct support for this interpretation: the palatability of a reinforcer (as measured by an analysis of lick-cluster size) was positively correlated with goal-tracking (and negatively correlated with sign-tracking); and sating rats with a reinforcer affected goal-tracking but not sign-tracking (Experiment 2). These results indicate that the observed individual differences in sign- and goal-tracking behavior arise from the interaction between the palatability or value of the reinforcer and processes of association as opposed to dispositional differences (e.g., in sensory processes, “temperament,” or response repertoire).
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Affiliation(s)
- E Patitucci
- School of Psychology and Education Sciences, University of Bologna
| | | | | | - R C Honey
- School of Psychology, Cardiff University
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15
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Isles AR. Htr2c Splice Variants and 5HT 2CR-Mediated Appetite. Trends Endocrinol Metab 2017; 28:542-544. [PMID: 28499663 DOI: 10.1016/j.tem.2017.04.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 04/18/2017] [Accepted: 04/19/2017] [Indexed: 10/19/2022]
Abstract
Serotonin 2C receptor (5HT2CR) exists as different isoforms as a result of alternate splicing. A truncated variant (5HT2CR-trunc) has no canonical receptor function and yet shows robust expression levels throughout the brain. Recent work has demonstrated the biochemical role of this isoform and how altering levels of 5HT2CR-trunc leads to changes in behaviour.
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Affiliation(s)
- Anthony R Isles
- Behavioural Genetics Group, MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, Cardiff, UK.
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16
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McNamara GI, Davis BA, Dwyer DM, John RM, Isles AR. Behavioural abnormalities in a novel mouse model for Silver Russell Syndrome. Hum Mol Genet 2017; 25:5407-5417. [PMID: 27798108 PMCID: PMC5418837 DOI: 10.1093/hmg/ddw357] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 10/16/2016] [Indexed: 01/02/2023] Open
Abstract
Silver Russell Syndrome (SRS) syndrome is an imprinting disorder involving low birth weight with complex genetics and diagnostics. Some rare SRS patients carry maternally inherited microduplications spanning the imprinted genes CDKN1C, PHLDA2, SLC22A18 and KCNQ1, suggesting that overexpression of one of more of these genes contributes to the SRS phenotype. While this molecular alteration is very rare, feeding difficulties are a very common feature of this condition. Given that SRS children also have very low body mass index, understanding the underpinning biology of the eating disorder is important, as well as potential co-occurring behavioural alterations. Here, we report that a mouse model of this microduplication exhibits a number of behavioural deficits. The mice had a blunted perception of the palatability of a given foodstuff. This perception may underpin the fussiness with food. We additionally report hypoactivity, unrelated to anxiety or motoric function, and a deficit in the appropriate integration of incoming sensory information. Importantly, using a second genetic model, we were able to attribute all altered behaviours to elevated expression of a single gene, Cdkn1c. This is the first report linking elevated Cdkn1c to altered behaviour in mice. Importantly, the findings from our study may have relevance for SRS and highlight a potentially underreported aspect of this disorder.
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Affiliation(s)
- Grainne Iseult McNamara
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, UK
| | - Brittany Ann Davis
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, UK
| | | | | | - Anthony Roger Isles
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, UK
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17
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Longley M, Willis EL, Tay CX, Chen H. An open source device for operant licking in rats. PeerJ 2017; 5:e2981. [PMID: 28229020 PMCID: PMC5312574 DOI: 10.7717/peerj.2981] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Accepted: 01/11/2017] [Indexed: 11/20/2022] Open
Abstract
We created an easy-to-use device for operant licking experiments and another device that records environmental variables. Both devices use the Raspberry Pi computer to obtain data from multiple input devices (e.g., radio frequency identification tag readers, touch and motion sensors, environmental sensors) and activate output devices (e.g., LED lights, syringe pumps) as needed. Data gathered from these devices are stored locally on the computer but can be automatically transferred to a remote server via a wireless network. We tested the operant device by training rats to obtain either sucrose or water under the control of a fixed ratio, a variable ratio, or a progressive ratio reinforcement schedule. The lick data demonstrated that the device has sufficient precision and time resolution to record the fast licking behavior of rats. Data from the environment monitoring device also showed reliable measurements. By providing the source code and 3D design under an open source license, we believe these examples will stimulate innovation in behavioral studies. The source code can be found at http://github.com/chen42/openbehavior.
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Affiliation(s)
- Matthew Longley
- Undergraduate Program, University of Memphis , Memphis , TN , United States
| | - Ethan L Willis
- Maters' Program, Department of Bioinformatics, University of Memphis , Memphis , TN , United States
| | - Cindy X Tay
- Undergraduate Program, Duke University , Durham , NC , United States
| | - Hao Chen
- Department of Pharmacology, University of Tennessee Health Science Center , Memphis , TN , United States
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18
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Golding DM, Rees DJ, Davies JR, Relkovic D, Furby HV, Guschina IA, Hopkins AL, Davies JS, Resnick JL, Isles AR, Wells T. Paradoxical leanness in the imprinting-centre deletion mouse model for Prader-Willi syndrome. J Endocrinol 2017; 232:123-135. [PMID: 27799465 PMCID: PMC5118940 DOI: 10.1530/joe-16-0367] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 10/31/2016] [Indexed: 01/09/2023]
Abstract
Prader-Willi syndrome (PWS), a neurodevelopmental disorder caused by loss of paternal gene expression from 15q11-q13, is characterised by growth retardation, hyperphagia and obesity. However, as single gene mutation mouse models for this condition display an incomplete spectrum of the PWS phenotype, we have characterised the metabolic impairment in a mouse model for 'full' PWS, in which deletion of the imprinting centre (IC) abolishes paternal gene expression from the entire PWS cluster. We show that PWS-ICdel mice displayed postnatal growth retardation, with reduced body weight, hyperghrelinaemia and marked abdominal leanness; proportionate retroperitoneal, epididymal/omental and inguinal white adipose tissue (WAT) weights being reduced by 82%, 84% and 67%, respectively. PWS-ICdel mice also displayed a 48% reduction in proportionate interscapular brown adipose tissue (isBAT) weight with significant 'beiging' of abdominal WAT, and a 2°C increase in interscapular surface body temperature. Maintenance of PWS-ICdel mice under thermoneutral conditions (30°C) suppressed the thermogenic activity in PWS-ICdel males, but failed to elevate the abdominal WAT weight, possibly due to a normalisation of caloric intake. Interestingly, PWS-ICdel mice also showed exaggerated food hoarding behaviour with standard and high-fat diets, but despite becoming hyperphagic when switched to a high-fat diet, PWS-ICdel mice failed to gain weight. This evidence indicates that, unlike humans with PWS, loss of paternal gene expression from the PWS cluster in mice results in abdominal leanness. Although reduced subcutaneous insulation may lead to exaggerated heat loss and thermogenesis, abdominal leanness is likely to arise from a reduced lipid storage capacity rather than increased energy utilisation in BAT.
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Affiliation(s)
| | - Daniel J Rees
- Institute of Life SciencesCollege of Medicine, Swansea University, Swansea, UK
| | - Jennifer R Davies
- Behavioural Genetics GroupMRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Schools of Medicine & Psychology, Cardiff University, Cardiff, UK
| | - Dinko Relkovic
- Behavioural Genetics GroupMRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Schools of Medicine & Psychology, Cardiff University, Cardiff, UK
| | - Hannah V Furby
- Behavioural Genetics GroupMRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Schools of Medicine & Psychology, Cardiff University, Cardiff, UK
| | | | | | - Jeffrey S Davies
- Institute of Life SciencesCollege of Medicine, Swansea University, Swansea, UK
| | - James L Resnick
- Center for Mammalian GeneticsUniversity of Florida, College of Medicine, Gainesville, Florida, USA
| | - Anthony R Isles
- Behavioural Genetics GroupMRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Schools of Medicine & Psychology, Cardiff University, Cardiff, UK
| | - Timothy Wells
- School of BiosciencesCardiff University, Cardiff, UK
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19
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Garfield AS, Davies JR, Burke LK, Furby HV, Wilkinson LS, Heisler LK, Isles AR. Increased alternate splicing of Htr2c in a mouse model for Prader-Willi syndrome leads disruption of 5HT 2C receptor mediated appetite. Mol Brain 2016; 9:95. [PMID: 27931246 PMCID: PMC5144496 DOI: 10.1186/s13041-016-0277-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 11/30/2016] [Indexed: 12/21/2022] Open
Abstract
Alternate splicing of serotonin (5-hydroxytryptamine; 5-HT) 2C receptor (5-HT2CR) pre-RNA is negatively regulated by the small nucleolar RNA, Snord115, loss of which is observed in nearly all individuals with Prader-Willi Syndrome (PWS), a multigenic disorder characterised by hyperphagia and obesity. Given the role of the 5-HT2CR in the regulation of ingestive behaviour we investigated the pathophysiological implications of Snord115 deficiency on 5-HT2CR regulated appetite in a genotypically relevant PWS mouse model (PWS-IC). Specifically, we demonstrate that loss of Snord115 expression is associated with increased levels of hypothalamic truncated 5-HT2CR pre-mRNA. The 5-HT2CR promotes appetite suppression via engagement of the central melanocortin system. Pro-opiomelancortin (Pomc) mRNA levels within the arcuate nucleus of the hypothalamus (ARC) were reduced in PWS-IC mice. We then went on to assess the functional consequences of these molecular changes, demonstrating that PWS-IC mice are unresponsive to an anorectic doses of a 5-HT2CR agonist and that this is associated with attenuated activation of POMC neurons within the ARC. These data provide new insight into the significance of Htr2c pre-mRNA processing to the physiological regulation of appetite and potentially the pathological manifestation of hyperphagia in PWS. Furthermore, these findings have translational relevance for individuals with PWS who may seek to control appetite with another 5-HT2CR agonist, the new obesity treatment lorcaserin.
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Affiliation(s)
- Alastair S Garfield
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK.,Present address: Cardiovascular and Metabolic Disease, Pfizer, Cambridge, MA, 02139, USA
| | - Jennifer R Davies
- Behavioural Genetics Group, MRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Schools of Medicine and Pscyhology, Cardiff University, Cardiff, UK
| | - Luke K Burke
- Department of Pharmacology, University of Cambridge, Cambridge, UK
| | - Hannah V Furby
- Behavioural Genetics Group, MRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Schools of Medicine and Pscyhology, Cardiff University, Cardiff, UK
| | - Lawrence S Wilkinson
- Behavioural Genetics Group, MRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Schools of Medicine and Pscyhology, Cardiff University, Cardiff, UK
| | - Lora K Heisler
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK
| | - Anthony R Isles
- Behavioural Genetics Group, MRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Schools of Medicine and Pscyhology, Cardiff University, Cardiff, UK.
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20
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Lassi G, Maggi S, Balzani E, Cosentini I, Garcia-Garcia C, Tucci V. Working-for-Food Behaviors: A Preclinical Study in Prader-Willi Mutant Mice. Genetics 2016; 204:1129-1138. [PMID: 27672097 PMCID: PMC5105846 DOI: 10.1534/genetics.116.192286] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 08/14/2016] [Indexed: 12/31/2022] Open
Abstract
Abnormal feeding behavior is one of the main symptoms of Prader-Willi syndrome (PWS). By studying a PWS mouse mutant line, which carries a paternally inherited deletion of the small nucleolar RNA 116 (Snord116), we observed significant changes in working-for-food behavioral responses at various timescales. In particular, we report that PWS mutant mice show a significant delay compared to wild-type littermate controls in responding to both hour-scale and seconds-to-minutes-scale time intervals. This timing shift in mutant mice is associated with better performance in the working-for-food task, and results in better decision making in these mutant mice. The results of our study reveal a novel aspect of the organization of feeding behavior, and advance the understanding of the interplay between the metabolic functions and cognitive mechanisms of PWS.
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Affiliation(s)
- Glenda Lassi
- Neuroscience and Brain Technologies Department, Istituto Italiano di Tecnologia, 16163 Genova, Italy
| | - Silvia Maggi
- Neuroscience and Brain Technologies Department, Istituto Italiano di Tecnologia, 16163 Genova, Italy
| | - Edoardo Balzani
- Neuroscience and Brain Technologies Department, Istituto Italiano di Tecnologia, 16163 Genova, Italy
| | - Ilaria Cosentini
- Neuroscience and Brain Technologies Department, Istituto Italiano di Tecnologia, 16163 Genova, Italy
| | - Celina Garcia-Garcia
- Neuroscience and Brain Technologies Department, Istituto Italiano di Tecnologia, 16163 Genova, Italy
| | - Valter Tucci
- Neuroscience and Brain Technologies Department, Istituto Italiano di Tecnologia, 16163 Genova, Italy
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