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1.
Pilot Feasibility Stud ; 9(1): 193, 2023 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-38012747

RESUMO

BACKGROUND: Child criminal exploitation is a form of child abuse that poses a serious risk to the welfare, safety, and wellbeing of young people. Multisystemic therapy (MST) is an intensive family and community-based intervention for young people with anti-social behavioral problems, many of whom will be at risk of criminal exploitation. This protocol describes a pilot feasibility study and process evaluation, designed to examine MST for children at risk of criminal exploitation. METHODS: This pilot feasibility study and process evaluation involves two phases with associated subphases: phase 1.1 involved the collaborative refinement of the logic model adapting MST for children at risk of criminal exploitation; phase 1.2 involved pre-pilot interviews with MST therapists, families, and young people; phase 2.1 is a pilot modeling study of MST for children at risk of criminal exploitation, and; Phase 2.2 is a process evaluation that will involve interviewing stakeholders, MST therapists and employees, families, and young people. The dataset for the process evaluation will include questionnaires completed by parents and young people at baseline, mid-treatment, end of treatment, and 6 months after treatment. We will supplement these data with participant-level data linkage from MST sites and services. RESULTS: Accrual to the pilot stage of this project opened on 6th August 2021 and is due to close on 31st May 2022. We aim to publish the results of this feasibility study and process evaluation in 2023. CONCLUSIONS: The results of this feasibility study and process evaluation will inform the decision as to whether it is advisable to progress to a pilot clinical trial of MST for children at risk of criminal exploitation. TRIAL REGISTRATION: Trial registration: ISRCTN registry, ISRCTN16164816 on 25th January 2021- https://doi.org/10.1186/ISRCTN16164816 .

2.
J Intellect Disabil Res ; 66(7): 642-654, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35621252

RESUMO

BACKGROUND: The Adapted Firesetting Assessment Scale was developed for use with adults with developmental disabilities targeting fire-related factors thought to be associated with deliberate firesetting behaviour (i.e. attitudes towards fire, fire interest, fire normalisation, identification with fire and fire safety awareness). However, the psychometric properties of the scale are yet to be evaluated. METHOD: The reliability, validity, comprehensibility, relevance and comprehensiveness of the Adapted Firesetting Assessment Scale were evaluated. Fifty-nine adults with developmental disabilities, some of whom had a history of firesetting, completed the Adapted Firesetting Assessment Scale on two occasions. Feedback about the questionnaire was sought from both participants and professionals. RESULTS: The AFAS has acceptable internal consistency and excellent test-retest reliability. The attitudes towards fire, fire normalisation, poor fire safety subscales and total scores discriminated firesetters from non-firesetters. Content analysis of feedback indicated items of the AFAS were understood, relevant, accessible and comprehensible. CONCLUSION: A larger study is needed to examine the factor structure of the AFAS.


Assuntos
Piromania , Adulto , Humanos , Psicometria , Reprodutibilidade dos Testes , Inquéritos e Questionários
3.
Sci Rep ; 11(1): 11807, 2021 06 03.
Artigo em Inglês | MEDLINE | ID: mdl-34083588

RESUMO

Direct evidence of ancient human occupation is typically established through archaeological excavation. Excavations are costly and destructive, and practically impossible in some lake and wetland environments. We present here an alternative approach, providing direct evidence from lake sediments using DNA metabarcoding, steroid lipid biomarkers (bile acids) and from traditional environmental analyses. Applied to an early Medieval Celtic settlement in Ireland (a crannog) this approach provides a site chronology and direct evidence of human occupation, crops, animal farming and on-site slaughtering. This is the first independently-dated, continuous molecular archive of human activity from an archeological site, demonstrating a link between animal husbandry, food resources, island use. These sites are under threat but are impossible to preserve in-situ so this approach can be used, with or without excavation, to produce a robust and full site chronology and provide direct evidence of occupation, the use of plants and animals, and activities such as butchery.


Assuntos
Arqueologia , Biomarcadores , DNA Antigo , Lagos , Lipídeos , Animais , Arqueologia/métodos , História Medieval , Humanos , Irlanda , Minerais/análise , Datação Radiométrica , Reino Unido
4.
J Intellect Disabil Res ; 59(4): 332-41, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24761788

RESUMO

BACKGROUND: The objectives were (a) to compare the general empathy abilities of men with intellectual disabilities (IDs) who had a history of sexual offending to men with IDs who had no known history of illegal behaviour; and (b) to determine whether men with IDs who had a history of sexual offending had different levels of specific victim empathy towards their own victim, in comparison with an unknown victim of sexual crime, and a victim of non-sexual crime, and make comparisons with non-offenders. METHODS: Men with mild IDs (n=35) were asked to complete a measure of general empathy and a measure of specific victim empathy. All participants completed the victim empathy measure in relation to a hypothetical victim of a sexual offence, and a non-sexual crime, while additionally, men with a history of sexual offending were asked to complete this measure in relation to their own most recent victim. RESULTS: Men with a history of sexual offending had significantly lower general empathy, and specific victim empathy towards an unknown sexual offence victim, than men with no known history of illegal behaviour. Men with a history of sexual offending had significantly lower victim empathy for their own victim than for an unknown sexual offence victim. Victim empathy towards an unknown victim of a non-sexual crime did not differ significantly between the two groups. CONCLUSIONS: The findings suggest that it is important include interventions within treatment programmes that attempt to improve empathy and perspective-taking.


Assuntos
Vítimas de Crime/psicologia , Empatia , Deficiência Intelectual/psicologia , Delitos Sexuais/psicologia , Adulto , Crime/psicologia , Humanos , Masculino , Inquéritos e Questionários
5.
Dysphagia ; 27(3): 408-17, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22207246

RESUMO

Dysphagia has previously been reported in the inflammatory myopathies (IMs): inclusion body myositis (IBM), dermatomyositis (DM), and polymyositis (PM). Patients report coughing, choking, and bolus sticking in the pharynx. Myotomy has been the treatment of choice, with variable success reported. We sought to determine underlying causes of dysphagia in IM patients using instrumental evaluation. Eighteen subjects participated in the study: four with DM, six with PM, and eight with IBM. They underwent simultaneous videofluoroscopy and manometry, yielding 214 swallows for analysis regarding function of the upper esophageal sphincter (UES), swallow initiation, hyolaryngeal excursion, and pharyngeal residue. Penetration and aspiration were also recorded. UES failed to relax in two participants. High incidence of pharyngeal dysphagia was noted; 72% of participants demonstrated abnormalities, including delayed swallow initiation (24%), decreased hyolaryngeal excursion (22%), pyriform residue (17%), and penetration (22%). Dysphagia in IM patients appears to be more due to impaired muscle contraction and reduced hyolaryngeal excursion than the often held belief of failed UES relaxation. The distinction between mechanisms causing patients' dysphagia should be examined, particularly if CP myotomy is being considered as it may be contraindicated for patients with normal UES relaxation. More studies investigating IM patients pre- and post-myotomy are needed.


Assuntos
Transtornos de Deglutição/fisiopatologia , Dermatomiosite/fisiopatologia , Miosite de Corpos de Inclusão/fisiopatologia , Músculos do Pescoço/fisiopatologia , Polimiosite/fisiopatologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Transtornos de Deglutição/etiologia , Transtornos de Deglutição/cirurgia , Dermatomiosite/complicações , Esfíncter Esofágico Superior/fisiopatologia , Esfíncter Esofágico Superior/cirurgia , Feminino , Fluoroscopia , Humanos , Masculino , Manometria , Pessoa de Meia-Idade , Miosite de Corpos de Inclusão/complicações , Polimiosite/complicações , Pressão
6.
J Intellect Disabil Res ; 53(9): 807-15, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19627428

RESUMO

BACKGROUND: Staff working within secure services for people with intellectual disabilities (ID) are likely to work with sexual offenders, but very little attention has been paid to how they think about this sexual offending behaviour. METHOD: Forty-eight staff working within secure services for people with ID were recruited and completed the Attribution Style Questionnaire in relation to the sexual offending behaviour and challenging behaviour of men with mild ID. Attributions towards challenging behaviour and sexual offending were compared and relationships between level of ID and seriousness of the sexual offence were explored. RESULTS: The results indicated that staff attributed sexual offending as more external to the staff group than they did for challenging behaviour. Sexual offending behaviour was also seen as more stable, and less controllable by people with ID than was challenging behaviour. Sexual offending was also attributed as more uncontrollable by the staff group than challenging behaviour. There was a significant negative correlation between general intellectual functioning and several attributional dimensions regarding sexual offending, but not challenging behaviour. Sexual offending that was coded as more serious was attributed as universal and uncontrollable by the staff group. CONCLUSIONS: The differences between staff attributions regarding challenging behaviour and sexual offending potentially relate to the decision-making processes involved in deciding whether or not to involve criminal justice agencies when someone with ID commits a sexual offence. Further research within this area is warranted.


Assuntos
Atitude do Pessoal de Saúde , Deficiência Intelectual/epidemiologia , Controle Interno-Externo , Transtornos Mentais/epidemiologia , Delitos Sexuais/estatística & dados numéricos , Estudos Transversais , Inglaterra/epidemiologia , Feminino , Humanos , Masculino , Inquéritos e Questionários
7.
Neuroepidemiology ; 32(2): 107-13, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19039243

RESUMO

BACKGROUND: Respiratory infections are common in acute stroke. Previous studies have found dysphagia is associated with respiratory infections. Of interest is whether patients who are 'Nil by Mouth' (NBM) and tube fed have higher risk of developing infections due to aspiration of bacteria-laden saliva or refluxed material than stroke patients who are fed orally. METHODS: Prospective cohort of 330 ischemic stroke survivors were followed for 30 days and infections recorded. RESULTS: 115 infections were treated with antibiotics; these included 51 respiratory infections. Incidence of infection in NBM tube-fed stroke patients (n = 74) was 69%, with 30 respiratory infections occurring in 74 patients who received enteral feeding after stroke. Logistic regression analysis showed tube feeding during admission was a significant risk for respiratory infection. We also saw a significant time-to-event effect with 73% (22/30) respiratory infections in tube-fed survivors diagnosed on days 2-4 after stroke, and 76% (39/51) of infections in all tube-fed survivors occurring by day 7 after stroke. Relevance to a theory of critical period of susceptibility to infection in acute stroke is discussed. CONCLUSIONS: NBM tube-fed survivors were unlikely to have aspirated anything other than saliva/secretions or reflux, yet experienced significantly higher rates of respiratory infections than survivors fed orally. Stringent oral care and measures to prevent reflux are potentially modifiable aspects of stroke management.


Assuntos
Isquemia Encefálica/epidemiologia , Nutrição Enteral/efeitos adversos , Infecções Respiratórias/epidemiologia , Infecções Respiratórias/etiologia , Acidente Vascular Cerebral/epidemiologia , Idoso , Idoso de 80 Anos ou mais , Isquemia Encefálica/complicações , Isquemia Encefálica/terapia , Estudos de Coortes , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Boca , Estudos Prospectivos , Acidente Vascular Cerebral/complicações , Acidente Vascular Cerebral/terapia
8.
J Clin Neurosci ; 14(7): 630-4, 2007 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-17434310

RESUMO

Dysphagia in stroke is linked with increased risk of pneumonia, increased length of stay and poorer outcomes. This study followed a cohort of 88 acute ischaemic stroke patients admitted to hospitals in Perth, Western Australia, over 30 days. There were 8/88 deaths (9%). Infections were treated in 25/80 survivors (31%). Presence and severity of dysphagia were measured at 2 and 7 days post-stroke. Respiratory tract infections occurred at significantly higher rates for dysphagics (p<0.05). At 2 days post-stroke, the odds ratio (OR) of chest infection for dysphagics was 1.45 (95% CI=1.07-1.98). Survivors who were "nil by mouth" 2 days post-stroke were significantly more likely to develop pneumonia (p=0.01). At 7 days post-stroke, dysphagics were again more likely to develop pneumonia (p=0.014) with OR=1.77 (95% CI=1.26-2.49). The total anterior circulation infarcts demonstrated more severe and prolonged dysphagia than other stroke subtypes.


Assuntos
Transtornos de Deglutição/etiologia , Acidente Vascular Cerebral/classificação , Acidente Vascular Cerebral/complicações , Idoso , Estudos de Coortes , Transtornos de Deglutição/mortalidade , Transtornos de Deglutição/patologia , Transtornos de Deglutição/fisiopatologia , Demografia , Feminino , Humanos , Masculino , Razão de Chances , Recuperação de Função Fisiológica , Fatores de Risco , Índice de Gravidade de Doença , Acidente Vascular Cerebral/epidemiologia , Fatores de Tempo , Austrália Ocidental/epidemiologia
9.
J Intellect Disabil Res ; 50(Pt 11): 828-36, 2006 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16999782

RESUMO

BACKGROUND: The social climate of inpatient facilities is thought to be an important contributor to treatment outcome. However, little research has focused on this construct within secure forensic services for people with intellectual disabilities (ID). Therefore, the objective of this study was to investigate the social climate of two different types of secure units ('low' secure vs. 'medium' secure) contained within the same facility for offenders with ID. Two hypotheses were generated: (1) residents would rate the social climate of the whole facility in a more negative direction than staff, and (2) residents and staff would rate the social climate of the 'low' secure unit in a more positive direction than that of the 'medium' secure unit. METHOD: Using a 2 (factor 'Participant' = Staff or Resident) x 2 (factor 'Unit' = 'Low' or 'Medium' Secure Unit) between-subjects design, 18 residents and 37 staff members were recruited and completed the Correctional Institutions Environment Scale (CIES), a measure of social climate. RESULTS: Residents tended to rate the units in a more positive direction than staff on some sub-scales. Participants rated the 'low' secure unit in a more positive direction than the 'medium' secure unit on two sub-scales of the CIES. However, on selected sub-scales there were differences. The findings of this study suggest that the CIES may be a valid instrument for use within forensic services for people with ID, and further suggests that residents and staff have different perceptions of the shared social climate, which may have implications for service development.


Assuntos
Deficiência Intelectual/terapia , Serviços de Saúde Mental/normas , Prisões/organização & administração , Medidas de Segurança/classificação , Meio Social , Adulto , Atitude do Pessoal de Saúde , Atitude Frente a Saúde , Psiquiatria Legal , Humanos , Masculino , Prisões/classificação , Reino Unido
10.
J Intellect Disabil Res ; 50(Pt 7): 523-31, 2006 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-16774637

RESUMO

BACKGROUND: The aim of the current study was to update an existing short measure of sexual knowledge and generate some initial reliability and normative data. Comparisons of sexual knowledge across several groups were made to examine whether or not a lack of sexual knowledge is related to sexual offending. METHODS: The Bender Sexual Knowledge Questionnaire (BSKQ) was revised, and a new questionnaire, the General Sexual Knowledge Questionnaire (GSKQ), was created and administered to four groups of participants: (1) sex offenders with an intellectual disability (ID) and a history of engagement in treatment (n = 12); (2) sex offenders with an ID and no history of treatment (n = 13); (3) non-offenders with an ID (n = 28); and (4) non-offenders without an ID (n = 10). Between-group comparisons were made; internal consistency, split-half reliability and correlations were examined. RESULTS: The internal consistency and the split-half reliability of the entire questionnaire was good. Non-offenders without an ID scored significantly higher than non-offenders with an ID on all sections of the GSKQ. Sex offenders who had undergone treatment scored significantly higher than non-offenders with an ID on several sections of this questionnaire. CONCLUSIONS: The initial findings from this study suggest that the psychometric properties of the GSKQ are promising. The assumption that lower sexual knowledge may be related to the risk of committing a sexual offence by people with IDs is possibly erroneous, and further research is required to clarify this possibility.


Assuntos
Deficiência Intelectual/epidemiologia , Educação Sexual , Delitos Sexuais/estatística & dados numéricos , Inquéritos e Questionários , Adulto , Feminino , Humanos , Deficiência Intelectual/psicologia , Masculino , Pessoa de Meia-Idade , Pedofilia/epidemiologia , Pedofilia/psicologia , Pedofilia/terapia , Psicometria/estatística & dados numéricos , Psicoterapia , Reprodutibilidade dos Testes , Delitos Sexuais/prevenção & controle , Delitos Sexuais/psicologia
11.
J Immunol ; 166(8): 5145-54, 2001 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-11290797

RESUMO

STRL33/BONZO/TYMSTR is an orphan chemokine and HIV/SIV coreceptor receptor that is expressed on activated T lymphocytes. We describe an expression cloning strategy whereby we isolated a novel chemokine, which we name CXCL16. CXCL16 is an alpha (CXC) chemokine but also has characteristics of CC chemokines and a structure similar to fractalkine (neurotactin) in having a transmembrane region and a chemokine domain suspended by a mucin-like stalk. A recombinant version of CXCL16 fails to mediate chemotaxis to all known chemokine receptor transfectants tested but does mediate robust chemotaxis, high affinity binding, and calcium mobilization to Bonzo receptor transfectants, indicating that this is a unique receptor ligand interaction. In vitro polarized T cell subsets including Th1, Th2, and Tr1 cells express functional Bonzo, suggesting expression of this receptor in chronic inflammation, which we further verified by demonstration of CXCL16-mediated migration of tonsil-derived CD4(+) T lymphocytes. CXCL16 is expressed on the surface of APCs including subsets of CD19(+) B cells and CD14(+) monocyte/macrophages, and functional CXCL16 is also shed from macrophages. The combination of unique structural features of both Bonzo and CXCL16 suggest that this interaction may represent a new class of ligands for this receptor family. Additionally, this chemokine might play a unique dual role of attracting activated lymphocyte subsets during inflammation as well as facilitating immune responses via cell-cell contact.


Assuntos
Quimiocinas CC/química , Quimiocinas CX3C/química , Quimiocinas CXC/química , Quimiocinas CXC/genética , Clonagem Molecular/métodos , Proteínas de Membrana/química , Proteínas de Membrana/genética , Receptores de Citocinas/metabolismo , Receptores Acoplados a Proteínas G , Receptores Imunológicos , Receptores Virais , Sequência de Aminoácidos , Southern Blotting , Linhagem Celular , Membrana Celular/genética , Membrana Celular/imunologia , Membrana Celular/metabolismo , Quimiocina CXCL16 , Quimiocinas CXC/biossíntese , Quimiocinas CXC/fisiologia , DNA Complementar/isolamento & purificação , Glicosilação , Humanos , Leucócitos/imunologia , Leucócitos/metabolismo , Ligantes , Ativação Linfocitária , Macrófagos/imunologia , Macrófagos/metabolismo , Proteínas de Membrana/biossíntese , Proteínas de Membrana/fisiologia , Dados de Sequência Molecular , RNA/biossíntese , Receptores CXCR6 , Receptores de Quimiocinas , Receptores Depuradores , Proteínas Recombinantes de Fusão/metabolismo , Análise de Sequência de Proteína , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Transfecção
12.
J Immunol ; 165(6): 2943-9, 2000 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-10975800

RESUMO

Mucosae-associated epithelial chemokine (MEC) is a novel chemokine whose mRNA is most abundant in salivary gland, with strong expression in other mucosal sites, including colon, trachea, and mammary gland. MEC is constitutively expressed by epithelial cells; MEC mRNA is detected in cultured bronchial and mammary gland epithelial cell lines and in epithelia isolated from salivary gland and colon using laser capture microdissection, but not in the endothelial, hemolymphoid, or fibroblastic cell lines tested. Although MEC is poorly expressed in skin, its closest homologue is the keratinocyte-expressed cutaneous T cell-attracting chemokine (CTACK; CCL27), and MEC supports chemotaxis of transfected lymphoid cells expressing CCR10, a known CTACK receptor. In contrast to CTACK, however, MEC also supports migration through CCR3. Consistent with this, MEC attracts eosinophils in addition to memory lymphocyte subsets. These results suggest an important role for MEC in the physiology of extracutaneous epithelial tissues, including diverse mucosal organs.


Assuntos
Quimiocinas/biossíntese , Células Epiteliais/imunologia , Células Epiteliais/metabolismo , Imunidade nas Mucosas , Receptores de Quimiocinas/metabolismo , Sequência de Aminoácidos , Animais , Sequência de Bases , Mama/imunologia , Mama/metabolismo , Linhagem Celular , Quimiocinas/genética , Quimiocinas/isolamento & purificação , Quimiocinas/metabolismo , Quimiocinas CC , Feminino , Humanos , Imunidade nas Mucosas/genética , Mucosa Intestinal/imunologia , Mucosa Intestinal/metabolismo , Ligantes , Camundongos , Dados de Sequência Molecular , Mucosa Bucal/imunologia , Mucosa Bucal/metabolismo , Especificidade de Órgãos/imunologia , Receptores CCR10 , Receptores CCR3 , Mucosa Respiratória/imunologia , Mucosa Respiratória/metabolismo , Células Tumorais Cultivadas
13.
Brain Res Dev Brain Res ; 102(2): 291-3, 1997 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-9352112

RESUMO

It was hypothesized that 5-HT2 receptors in the olfactory bulb prime the bulbar response to a beta adrenoceptor mediated unconditioned stimulus (UCS) during odor preference learning in 1-week-old rat pups. The ability of 4 mg/kg of isoproterenol + stroking and 6 mg/kg of isoproterenol + no stroking to induce normal odor preference learning in pups depleted of bulbar 5-HT in the present study supports the hypothesis. The inverted-U curve relation between UCS strength and learning also appears to occur within the bulb.


Assuntos
Condicionamento Clássico/efeitos dos fármacos , Deficiências da Aprendizagem/fisiopatologia , Odorantes , Bulbo Olfatório/fisiologia , Receptores Adrenérgicos beta/fisiologia , Serotonina/deficiência , Agonistas Adrenérgicos beta/farmacologia , Análise de Variância , Animais , Comportamento de Escolha/efeitos dos fármacos , Isoproterenol/farmacologia , Ratos , Ratos Sprague-Dawley
15.
J Paediatr Child Health ; 32(1): 42-7, 1996 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-8652213

RESUMO

OBJECTIVE: To describe survival patterns, use of health services and related costs for Australian children with perinatally acquired human immunodeficiency virus (HIV) infection. METHODOLOGY: A retrospective cross-sectional survey was made of 20 children with HIV infection (91% of those diagnosed) and 13 children with maternal antibodies who subsequently seroreverted, treated at 10 medical centres. Details of disease progression and use of health services were obtained from hospital medical records. Monthly costs for three phases of infection were estimated by linking service usage rates with estimates of the unit cost of each service. The average lifetime cost was estimated by combining monthly costs and phase duration estimates from the literature. RESULTS: Patterns of disease progression were similar to those reported internationally, with a median survival of 8 years. Use of health services increased with severity of illness. Mean monthly costs were $120 per month (1992 Australian dollars) for children with maternal antibodies who subsequently seroreverted, $320 per month for children with HIV infection but no acquired immunodeficiency syndrome (AIDS)-defining illness, and $1830 per month for children with AIDS. The present value of total lifetime cost for a child with HIV infection was $48174, 46% of which was for treatment of AIDS. DISCUSSION: The mean lifetime cost for a perinatally infected child was just over half that for a man with HIV in Australia. Health service usage and costs were lower for Australian than American children with HIV.


Assuntos
Infecções por HIV/congênito , Infecções por HIV/economia , Soropositividade para HIV/congênito , Custos de Cuidados de Saúde , Austrália , Estudos Transversais , Custos de Medicamentos , Feminino , Infecções por HIV/tratamento farmacológico , Soropositividade para HIV/tratamento farmacológico , Soropositividade para HIV/economia , Humanos , Recém-Nascido , Masculino , Admissão do Paciente , Estudos Retrospectivos , Taxa de Sobrevida
16.
J Cogn Neurosci ; 6(2): 117-38, 1994.
Artigo em Inglês | MEDLINE | ID: mdl-23962365

RESUMO

Abstract Saccadic accuracy requires that the control signal sent to the motor neurons must be the right size to bring the fovea to the target, whatever the initial position of the eyes (and corresponding state of the eye muscles). Clinical and experimental evidence indicates that the basic machinery for generating saccadic eye movements, located in the brainstem, is not accurate: learning to make accurate saccades requires cerebellar circuitry located in the posterior vermis and fastigial nucleus. How do these two circuits interact to achieve adaptive control of saccades? A model of this interaction is described, based on Kawato's principle of feedback-error-learning. Its three components were (1) a simple controller with no knowledge of initial eye position, corresponding to the superior colliculus; (2) Robinson's internal feedback model of the saccadic burst generator, corresponding to preoculomotor areas in the brain-stem; and (3) Albus's Cerebellar Model Arithmetic Computer (CMK), a neural net model of the cerebellum. The connections between these components were (I) the simple feedback controller passed a (usually inaccurate) command to the pulse generator, and (2) a copy of this command to the CMAC; (3) the CMAC combined the copy with information about initial eye position to (4) alter the gain on the pulse generator's internal feedback loop, thereby adjusting the size of burst sent to the motor neurons. (5) If the saccade were inaccurate, an error signal from the feedback controller adjusted the weights in the CMAC. It was proposed that connection (2) corresponds to the mossy fiber projection from superior colliculus to oculomotor vermis via the nucleus reticularis tegmenti pontis, and connection (5) to the climbing fiber projection from superior colliculus to the oculomotor vermis via the inferior olive. Plausible initialization values were chosen so that the system produced hypometric saccades (as do human infants) at the start of learning, and position-dependent hypermetric saccades when the cerebellum was removed. Simulations for horizontal eye movements showed that accurate saccades from any starting position could be learned rapidly, even if the error signal conveyed only whether the initial saccade were too large or too small. In subsequent tests the model adapted realistically both to simulated weakening of the eye muscles, and to intrasaccadic displacement of the target, thereby mimicking saccadic plasticity in adults. The architecture of the model may therefore offer a functional explanation of hitherto mysterious tectocerebellar projections, and a framework for investigating in greater detail how the cerebellum adaptively controls saccadic accuracy.

17.
J Acquir Immune Defic Syndr (1988) ; 6 Suppl 1: S20-3, 1993.
Artigo em Inglês | MEDLINE | ID: mdl-8426297

RESUMO

Pediatric infection with human immunodeficiency virus (HIV) in Australia, as elsewhere, now reflects HIV seroprevalence in women of childbearing age although numbers remain small. A perinatal transmission rate of approximately 30% has been observed. The rate appears to be higher for breast-fed babies; exclusively bottle-fed babies of HIV-infected mothers appear to have a risk of < 20% of acquiring HIV perinatally. Although the seroprevalence rate in women of childbearing age in Australia remains low, routine antenatal screening will not be cost-effective. Although passively acquired maternal antibody may confound serodiagnosis for up to 18 months, in practice, HIV infection, when present, can be detected clinically or with use of other laboratory parameters (p24, polymerase chain reaction, viral culture, hyperglobulinemia) during the first 6 months of life. Zidovudine appears to be relatively nontoxic in children and effective in producing weight gain and preventing opportunistic infection. Although experience with didanosine is limited, this drug appears to have a very acceptable toxicity profile and the advantage of twice-daily dosing. However, the bioavailability and penetration into the cerebrospinal fluid are poor. Neurological disease can improve when absorption is adequate. Residential family camps may help to reduce isolation for families and provide them with an opportunity for improving their understanding of HIV through interaction with peers and professionals.


Assuntos
Infecções por HIV , Adulto , Austrália/epidemiologia , Didanosina/uso terapêutico , Feminino , Infecções por HIV/tratamento farmacológico , Infecções por HIV/epidemiologia , Infecções por HIV/etiologia , Infecções por HIV/transmissão , Humanos , Lactente , Recém-Nascido , Masculino , Apoio Social
20.
Biol Cybern ; 66(1): 27-36, 1991.
Artigo em Inglês | MEDLINE | ID: mdl-1768710

RESUMO

The high speed of saccades means that they cannot be guided by visual feedback, so that any saccadic control system must know in advance the correct output signals to fixate a particular retinal position. To investigate neural-net architectures for learning this inverse-kinematics problem we simulated a 4 deg-of-freedom robot camera-head system, in which the head could pan and tilt and the cameras pan and verge. The main findings were: (1) Linear nets, multilayer perceptrons (MLPs) trained by backpropagation, and cerebellar model arithmetic computers (CMACs) all learnt rapidly to 5-10% accuracy when given perfect error feedback. (2) For additional accuracy (down to 2%) two-layer nets learnt much faster than a single MLP or CMAC: the best combination tried was to have a CMAC learn the errors of a trained linear net. (3) Imperfect error signals were provided by a crude controller whose output was simply proportional to retinal input in the relevant axis, thereby providing a mechanism for (a) controlling the camera-head system when the feedforward neural net controller was wrong or inoperative, and (b) converting sensory error signals into motor error signals as required in supervised learning. It proved possible to train neural-net controllers using these imperfect error signals over a range of learning rates and crude-controller gains. These results suggest that appropriate neural-net architectures can provide practical, accurate and robust adaptive control for saccadic movements. In addition, the arrangement of a crude controller teaching a sophisticated one may be similar to that used by the primate saccadic system, with brainstem circuitry teaching the cerebellum.


Assuntos
Tronco Encefálico/fisiologia , Cerebelo/fisiologia , Aprendizagem , Modelos Neurológicos , Rede Nervosa/fisiologia , Robótica , Movimentos Sacádicos/fisiologia , Humanos , Lactente , Fotografação
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