Attractor networks and memory replay of phase coded spike patterns

We analyse the storage and retrieval capacity in a recurrent neural network of spiking integrate and fire neurons. In the model we distinguish between a learning mode, during which the synaptic connections change according to a Spike-Timing Dependent Plasticity (STDP) rule, and a recall mode, in which connections strengths are no more plastic. Our findings show the ability of the network to store and recall periodic phase coded patterns a small number of neurons has been stimulated. The self sustained dynamics selectively gives an oscillating spiking activity that matches one of the stored patterns, depending on the initialization of the network.Comment: arXiv admin note: text overlap with arXiv:1210.678

Associative memory of phase-coded spatiotemporal patterns in leaky Integrate and Fire networks

We study the collective dynamics of a Leaky Integrate and Fire network in which precise relative phase relationship of spikes among neurons are stored, as attractors of the dynamics, and selectively replayed at differentctime scales. Using an STDP-based learning process, we store in the connectivity several phase-coded spike patterns, and we find that, depending on the excitability of the network, different working regimes are possible, with transient or persistent replay activity induced by a brief signal. We introduce an order parameter to evaluate the similarity between stored and recalled phase-coded pattern, and measure the storage capacity. Modulation of spiking thresholds during replay changes the frequency of the collective oscillation or the number of spikes per cycle, keeping preserved the phases relationship. This allows a coding scheme in which phase, rate and frequency are dissociable. Robustness with respect to noise and heterogeneity of neurons parameters is studied, showing that, since dynamics is a retrieval process, neurons preserve stablecprecise phase relationship among units, keeping a unique frequency of oscillation, even in noisy conditions and with heterogeneity of internal parameters of the units

Factorial structure of the Manchester short assessment of quality of life in patients with schizophrenia-spectrum disorders

Purpose Subjective quality of life is a central patient-reported outcome in schizophrenia-spectrum disorders. The Manchester Short Assessment of Quality of Life (MANSA) is an established and widely used instrument for its assessment. The present study is a secondary analysis of large schizophrenia studies and aims to establish the factorial structure of the MANSA with a rigorous two-step methodology. Methods A sample of 3120 patients was randomly split into two datasets; the first includes two thirds of the patients and serves as the calibration sample (N = 2071) and the second includes one third of them and serves as the validation sample (N = 1049). We performed an exploratory factor analysis with the calibration sample followed by a confirmatory factor analysis with the validation sample. Results Our results for both samples revealed a model with adequate fit comprising two factors. The first factor encompasses eight items measuring satisfaction with a variety of life and health-related aspects of quality of life, whereas the second consists of four items assessing satisfaction with living environment comprising living alone or with others, accommodation, family, and safety. These two factors correlate in a different way with socio-demographic characteristics such as age and living conditions. Conclusions Future trials and service evaluation projects using the MANSA to measure quality of life should take into account that satisfaction with living environment may be distinct from satisfaction with other life and health-related aspects of quality of life

Storage of phase-coded patterns via STDP in fully-connected and sparse network: a study of the network capacity

We study the storage and retrieval of phase-coded patterns as stable dynamical attractors in recurrent neural networks, for both an analog and a integrate-and-fire spiking model. The synaptic strength is determined by a learning rule based on spike-time-dependent plasticity, with an asymmetric time window depending on the relative timing between pre- and post-synaptic activity. We store multiple patterns and study the network capacity. For the analog model, we find that the network capacity scales linearly with the network size, and that both capacity and the oscillation frequency of the retrieval state depend on the asymmetry of the learning time window. In addition to fully-connected networks, we study sparse networks, where each neuron is connected only to a small number z << N of other neurons. Connections can be short range, between neighboring neurons placed on a regular lattice, or long range, between randomly chosen pairs of neurons. We find that a small fraction of long range connections is able to amplify the capacity of the network. This imply that a small-world-network topology is optimal, as a compromise between the cost of long range connections and the capacity increase. Also in the spiking integrate and fire model the crucial result of storing and retrieval of multiple phase-coded patterns is observed. The capacity of the fully-connected spiking network is investigated, together with the relation between oscillation frequency of retrieval state and window asymmetry

“It’s a matter of building bridges…” – feasibility of a carer involvement intervention for inpatients with severe mental illness

Background Family and friends (carer) involvement in the treatment of people with mental illness is widely recommended. However, the implementation remains poor, especially during hospital treatment, where carers report being excluded from care decisions. Methods We developed structured clinical procedures to maximise carer involvement in inpatient treatment. The aim of this study was to test their feasibility across four inpatient wards in East London and explore experiences of the participants. The intervention was delivered by clinicians (social therapists, nurses and psychiatrists) who were trained by the research team. Thirty patients and thirty carers received the intervention and completed research assessments and qualitative interviews after the intervention. 80% of the patients were followed up after six weeks of admission to complete quantitative questionnaires. Six clinicians were interviewed to explore their views on the intervention. Thematic analysis was used to analyse qualitative data. Results The intervention was found to be feasible to be delivered within the first week of admission in more than a half of the patients (53%) who provided consent. The main reasons why the interventions was not delivered in the remaining 47% of patients included staff or carers not being available, withdrawal of consent from the patient or patient being discharged prior to the intervention. Two themes were identified through thematic analysis. The first captured participant experiences of the intervention as facilitating a three-way collaborative approach to treatment. The second covered how patients’ mental states and practicalities of inpatient care acted as barriers and facilitators to the intervention being implemented. Conclusions Carer involvement in hospital treatment for mental illness is more difficult to implement than is commonly thought. This study has shown that a simple structured approach can facilitate a trialogue and that patients, clinicians and carers appreciate this approach to care. Our intervention provides clear and simple manualised clinical procedures that clinicians can follow. However, even the implementation of such procedures may be challenging in the absence of wider organisational support. The involvement of senior managers and clinical leaders might play a key role in overcoming barriers and support front-line clinicians to prioritise and implement carer involvement

Symptoms and Subjective Quality of Life in Post-Traumatic Stress Disorder: A Longitudinal Study

PMCID: PMC3621668This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Implementing family involvement in the treatment of patients with psychosis: a systematic review of facilitating and hindering factors

This paper presents independent research and was partially funded by the National Institute for Health Research Collaboration for Leadership in Applied Health Research and Care (NIHR CLAHRC) North Thames at Bart's Health NHS Trust

Giving patients choices during involuntary admission : a new intervention

Background: People who receive involuntary treatment are some of the most vulnerable in psychiatric services. They are more likely to have poorer social and clinical outcomes and to be disillusioned with and disengaged from care. Research indicates that patients’ experience in the first week of involuntary treatment is a critical period: a better experience of care in the first week predicts better quality of life and reduced readmission 1 year later. Patients have identified involvement in clinical decisions as key to improving their experience of care. The aim of this study was to test the feasibility and acceptability of an intervention to facilitate involvement in decision making for involuntary inpatients called OPeNS (Options, Preferences, Negotiate, and Summarise). Methods: This was a mixed method study. The OPeNS intervention was developed based on previous research carried out by a multidisciplinary team. Clinicians were trained to deliver it to involuntary inpatients. Feasibility indices (rates of participation in the intervention and time required to deliver it) were collected. Patients (N = 14) and clinicians (N = 5) provided qualitative data on their experience of the intervention in semi-structured interviews which were analysed using thematic analysis. Results: The OPeNS intervention was found to be acceptable by both patients and clinicians and feasible to conduct within the first week of involuntary treatment. Patients’ and clinicians’ experiences of the intervention fall into two themes: ‘Enabling a different dynamic’ and ‘Clashing with usual practices and priorities’. Conclusion: The OPeNS intervention provides a structure that can be used by clinicians across disciplines to facilitate involving involuntary patients in decision making. Although challenges related to changing usual practices were identified, the intervention was received positively and was feasible to conduct in the first week of involuntary treatment

Identifying the critical time points for mental health of asylum seekers and refugees in high-income countries

Aims High heterogeneity was found in the prevalence rates of mental disorders in adult asylum seekers and refugees in high-income countries. This may be related to different problems. Among them, there is a changing exposure to risk and protective factors for mental health at different phases of these people's life before migration, and during the migratory journey and resettlement. This study aimed at identifying and distinguishing time points in which distinct risk and protective factors for the mental health of asylum seekers and refugees may occur. Methods Systematic review and narrative synthesis. A systematic search was carried out for the period January 2017–August 2019, given the existence of systematic reviews of the evidence up to January 2017. Results Two hundred and fifty-two studies were identified with our search and 31 studies were included. The critical time points identified are: (a) before the travel; (b) during the travel; (c) at initial settlement in the host country; (d) when attempting to integrate in the host country; (e) when the immigration status is challenged or revoked. Some factors such as sense of belonging in the host country can be risk factors or protective factors depending on the time point. Conclusions These five critical time points can guide the development and selection of well-timed preventive and treatment interventions. They could also be used to stratify samples in epidemiological studies and meta-analyses. At present, we know much more on risk factors than on protective factors. Knowing more about protective factors may inform the development of interventions to foster them