1,535 research outputs found
Recommended from our members
Public value in public values
No full textPF speaks with Steven Parker of The Open University and Joyce Liddle of Durham University about how to apply public values at different delivery levels
Motivational incentives and methylphenidate enhance electrophysiological correlates of error monitoring in children with attention deficit/hyperactivity disorder
No full textBackground
Children with attention deficit hyperactivity disorder (ADHD) are characterised by developmentally inappropriate levels of hyperactivity, impulsivity and/or inattention and are particularly impaired when performing tasks that require a high level of cognitive control. Methylphenidate (MPH) and motivational incentives may help improve cognitive control by enhancing the ability to monitor response accuracy and regulate performance accordingly.
Methods
Twenty-eight children with DSM-IV ADHD (combined type) aged 9–15 years and pairwise-matched typically developing children (CTRL) performed a go/no-go task in which the incentives attached to performance on no-go trials were manipulated. The ADHD group performed the task off and on their usual dose of MPH. CTRL children performed the task twice but were never medicated. EEG data were recorded simultaneously and two electrophysiological indices of error monitoring, the error-related negativity (ERN) and error positivity (Pe) were measured. Amplitudes of each ERP were compared between diagnostic groups (CTRL, ADHD), medication days (Off MPH, On MPH) and motivational conditions (baseline – low incentive, reward, response cost).
Results
Error rates were lower in the reward and response cost conditions compared with baseline across diagnostic groups and medication days. ERN and Pe amplitudes were significantly reduced in ADHD compared with CTRL, and were significantly enhanced by MPH. Incentives significantly increased ERN and Pe amplitudes in the ADHD group but had no effect in CTRL. The effects of incentives did not interact with the effects of MPH on either ERP. Effect sizes were computed and revealed larger effects of MPH than incentives on ERN and Pe amplitudes.
Conclusions
The findings reveal independent effects of motivational incentives and MPH on two electrophysiological markers of error monitoring in children with ADHD, suggesting that each may be important tools for enhancing or restoring cognitive control in these children
Contextual metrical invisibility
No full textIn some languages, certain vowels are invisible to syllable-sensitive processes, but only in certain contexts. This paper argues that metrically invisible vowels are undominated by a syllable node in prosodic structure. Considering mainly Mohawk and Passamaquoddy, the behavior of these "weak vowels" is derived from pressure to avoid using weak vowels as syllable nuclei, countered by pressure to realize underlying segments in well-formed syllables. Because not only epenthetic vowels can be weak vowels, their unsuitability as syllable nuclei is derived representationally, through amount of underlying prosodic structure. Existing analyses of the data are critiqued, and the theoretical implications and potential extensions are discussed.The definitive version of this paper was published in PF: Papers at the Interface (1997) and is available at http://mitwpl.mit.edu/catalog/mwpl30/Hagstrom, P. (1997). Contextual metrical invisibility. In B. Bruening, Y. Kang, & M. McGinnis (Eds.) PF: Papers at the interface (pp. 113-181). Cambridge, MA: Department of Linguistics and Philosophy, Massachusetts Institute of Technology
Brileyetal2018_FigS2.tif
No full textFigure S2 associated with Briley PM, Liddle EB, Groom MJ, Smith HJF, Morris PG, Colclough GL, Brookes MJ, Liddle PF (2018). The development of human electrophysiological brain networks. Journal of Neurophysiology.The differences in beta band connectivity between adults and adolescents (A) and between adolescents and children (B). Connectivities are averaged across the pairs of ROIs within each of the four networks. See also Figure 3D, which shows the differences between adults and children. Asterisks show uncorrected p-values: * p</div
Task-related default mode network modulation and inhibitory control in ADHD: effects of motivation and methylphenidate
No full textBackground: Deficits characteristic of Attention Deficit/Hyperactivity Disorder (ADHD), including poor attention and inhibitory control, are at least partially alleviated by factors that increase engagement of attention, suggesting a hypodopaminergic reward deficit. Lapses of attention are associated with attenuated deactivation of the Default Mode Network (DMN), a distributed brain system normally deactivated during tasks requiring attention to the external world. Task-related DMN deactivation has been shown to be attenuated in ADHD relative to controls. We hypothesised that motivational incentives to balance speed against restraint would increase task engagement during an inhibitory control task, enhancing DMN deactivation in ADHD. We also hypothesised that methylphenidate, an indirect dopamine agonist, would tend to normalise abnormal patterns of DMN deactivation.
Method: We obtained functional magnetic resonance images from eighteen methylphenidate-responsive children with ADHD (DSM-IV combined subtype) and 18 pairwise-matched typically developing children aged 9-15 years while they performed a paced Go/No-go task. We manipulated motivational incentive to balance response speed against inhibitory control, and tested children with ADHD both on and off methylphenidate.
Results: When children with ADHD were off-methylphenidate and task incentive was low, event-related DMN deactivation was significantly attenuated compared to controls, but the two groups did not differ under high motivational incentives. The modulation of DMN deactivation by incentive in the children with ADHD, off- methylphenidate, was statistically significant, and significantly greater than in typically developing children. When children with ADHD were on-methylphenidate, motivational modulation of event-related DMN deactivation was abolished, and no attenuation relative to their typically developing peers was apparent in either motivational condition.
Conclusions: During an inhibitory control task, children with ADHD exhibit a raised motivational threshold at which task-relevant stimuli become sufficiently salient to deactivate the DMN. Treatment with methylphenidate normalises this threshold, rendering their pattern of task-related DMN deactivation indistinguishable from that of typically developing children
Street slang and schizophrenia
No full textWe report the case of a 26 year old streetwise young postman who presented with a six month history of reduced occupational and social function, low mood, and lack of motivation. He complained of feeling less sociable and less interested in his friends and of being clumsy and finding it harder to think. He was otherwise fit and healthy, with no physical abnormalities, neurological signs, or objective cognitive impairments. There was no history of a recent stressor that might have precipitated his symptoms. He was referred to a specialist service for patients in the prodromal phase of psychotic illness for further assessment after he had seen his general practitioner and the local community mental health team. The differential diagnosis at this stage was depression, the prodrome of schizophrenia, or no formal clinical disorder.
His premorbid occupational and social function had been good. There was no history of abnormal . social, language, and motor development and he left school with two A levels. After three years of service at the post office he had been promoted to a supervisory role. He had a good relationship with his family and had six or so good friends. There has been a number of previous heterosexual relationships, although none in the past year. Aside from smoking cannabis on two occasions when he was 19, there was no history of illicit substance use.
Detailed and repeated assessment of his mental state found a normal affect, no delusions, hallucinations, or catatonia, and no cognitive dysfunction. His speech, however, was peppered with what seemed (to his middle class and older psychiatrist) to be an unusual use of words, although he said they were street slang (table).Go It was thus unclear whether he was displaying subtle signs of formal thought disorder (manifest as disorganised speech, including the use of unusual words or phrases, and neologisms) or using a "street" argot. This was a crucial diagnostic distinction as thought disorder is a feature of psychotic illnesses and can indicate a diagnosis of schizophrenia.
We sought to verify his explanations using an online dictionary of slang (urbandictionary.com). To our surprise, many of the words he used were listed and the definitions accorded with those he gave (see table). We further investigated whether his speech showed evidence of thought disorder by examining recordings of his speech as he described a series of ambiguous pictures from the thematic apperception test, a procedure that elicits thought disordered speech. His speech was transcribed and rated with the thought and language index, a standardised scale for assessing thought disorder. Slang used in a linguistically appropriate way is not scored as abnormal on this scale. His score was 5.25, primarily reflecting a mild loosening of associations. For example, he described a picture of a boat on a lake thus: "There’s a boat and a tree. There seems to be a reflection. There are no beds, and I wonder why there are no beds. There’s a breeze going through the branches of the tree."
His score was outside the normal range (mean for normal controls 0.88, SD 1.15) and indicates subtle thought disorder, equivalent to that evident in remitted patients with schizophrenia (mean in remitted patients 3.89, SD 2.56) but lower than that in patients with formal thought disorder (mean 27.4, SD 8.3).
Over the following year his social and occupational functioning deteriorated further, and he developed frank formal thought disorder as well as grandiose and persecutory delusions to the extent that he met DSM-IV criteria for schizophrenia. His speech was assessed as before, and the thought and language index score had increased to 11.75. This mainly reflected abnormalities on items comprising "positive" thought disorder, particularly the use of neologisms such as "chronocolising" and non-sequiturs.
To our knowledge this is the first case report to describe difficulties in distinguishing "street" argots from formal thought disorder. It is perhaps not surprising that slang can complicate the assessment of disorganised speech as psychotic illnesses usually develop in young adults, whereas the assessing clinician is often from an older generation (and different sociocultural background) less familiar with contemporary urban slang. Online resources offer a means of distinguishing street argot from neologisms or a peculiar use of words, and linguistic rating scales may be a useful adjunct to clinical assessment when thought disorder is subtle. Differentiating thought disorder from slang can be especially difficult in the context of "prodromal" signs of psychosis, when speech abnormalities, if present, are usually subtle. Nevertheless, accurate speech assessment is important as subtle thought disorder can, as in this case, predate the subsequent onset of schizophrenia, and early detection and treatment of psychosis might be associated with a better long term clinical outcome
The portraits of the female author: the case of Ángela Figuera Aymerich
No full textEste artículo se enmarca en el Programa Severo Ochoa (referencia PA-17-PF-BP16126) de Ayudas predoctorales para la investigación y la docencia del Gobierno del Principado de Asturias
Brileyetal2018_FigS1.tif
No full textFigure S1 associated with Briley PM, Liddle EB, Groom MJ, Smith HJF, Morris PG, Colclough GL, Brookes MJ, Liddle PF (2018). The development of human electrophysiological brain networks. Journal of Neurophysiology.The within-network beta band connectivity for the DMN as a function of age, before (grey diamonds, dashed line) and after (blue squares, solid line) adjustment for variation in head size and shape across participants. Symbols show individual participants and lines show model fits. Fitted values of the parameter governing the initial rate of increase of connectivity with age (α3, which has units years-1) are given in the legend. </div
The prosodic structure of Serbo-Croatian function words: An argument for tied constraints
No full textThe question of the proper treatment of clitics has received considerable attention in literature on the syntax-morphology and morphology-phonology interfaces. Selkirk (1996) proposes an elegant theory of the prosodification of clitic function words crosslinguistically, demonstrating that variation in the behavior of function words both within a language (English) and across dialects of a language (Serbo-Croatian) follows straightforwardly from re-rankings of universal constraints in an Optimality Theory. In this paper I argue that, in addition to strict re-rankings of constraints, tied constraints are also needed within such a system, in order to capture the Serbo-Croatian facts. I discuss three empirical shortcomings of Selkirk¹s analysis, all involving optionality, and show how they can be remedied by appealing to a particular notion of what it means for constraints to be tied in rank. To the extent that Selkirk¹s basic insights are correct, this supports the conclusion that tied constraints play an important role in OT accounts of the ways in which dependent and independent morphemes are combined into larger prosodic units. It adds to the growing evidence for "crucial nonranking", whereby separate tableaux are computed for each ordering of the relevant constraints and the output of each is a valid possibility in the language.The definitive version of this paper was published in MITWPL 30: PF: Papers at the Interface (1997) and is available at http://mitwpl.mit.edu/catalog/mwpl30/Schütze, C.T. (1997). The Prosodic Structure of Serbo-Croatian Function Words: An Argument for Tied Constraints. In B. Bruening, Y. Kang, & M. McGinnis (Eds.) PF: Papers at the Interface. Cambridge, MA : MIT Dept. of Linguistics
Stochastic Nodal Analysis: EnKF and PF applied to petroleum production systems
No full textA petroleum production system is generally modelled based on the concept of nodal analysis, where the entire system is broken down into discrete elements such as near-well bore, tubing, surface choke and flow line. Operating flow rates and pressures can be estimated with a nodal analysis procedure by calculation of the intersection of performance curves. Input parameters in nodal analysis of production systems are considered deterministic, however, some of these parameters are better represented as distributions. In this report, the ensemble-based data assimilation methods “ensemble Kalman filter” (EnKF) and “particle filter” (PF) are applied to steady-state models of a production system for tuning of uncertain model parameters during the test separator phase. The performance of the EnKF and the PF is tested with the use of twin experiments. The calibrated model parameters of the choke, tubing and the near-well bore elements with EnKF and PF can be used to create an ensemble of performance curves leading to an ensemble of operating flow rates and pressures. The foreseen next step is to use the posterior distributions of model parameters as inputs for soft sensing of flow rates during semi-steady-state production for a single phase oil reservoir, where the oil rate and reservoir pressure are considered as unknown parameters. In the twin experiments as used in this thesis, a total number of three steady-state pressure drop measurements was used to estimate a total of six independent parameters which constitutes an ill-posed problem, resulting in non-unique parameter estimates. It is recommended to alleviate this issue by either reducing the number of parameters or by using multiple separator tests at different flow rates.Petroleum Engineering and Geo-science
- …
