Growth Rules for the Repair of Asynchronous Irregular Neuronal Networks after Peripheral Lesions

© 2021 Sinha et al. This is an open access article distributed under the terms of the Creative Commons Attribution License. https://creativecommons.org/licenses/by/4.0/Several homeostatic mechanisms enable the brain to maintain desired levels of neuronal activity. One of these, homeostatic structural plasticity, has been reported to restore activity in networks disrupted by peripheral lesions by altering their neuronal connectivity. While multiple lesion experiments have studied the changes in neurite morphology that underlie modifications of synapses in these networks, the underlying mechanisms that drive these changes are yet to be explained. Evidence suggests that neuronal activity modulates neurite morphology and may stimulate neurites to selective sprout or retract to restore network activity levels. We developed a new spiking network model of peripheral lesioning and accurately reproduced the characteristics of network repair after deafferentation that are reported in experiments to study the activity dependent growth regimes of neurites. To ensure that our simulations closely resemble the behaviour of networks in the brain, we model deafferentation in a biologically realistic balanced network model that exhibits low frequency Asynchronous Irregular (AI) activity as observed in cerebral cortex. Our simulation results indicate that the re-establishment of activity in neurons both within and outside the deprived region, the Lesion Projection Zone (LPZ), requires opposite activity dependent growth rules for excitatory and inhibitory post-synaptic elements. Analysis of these growth regimes indicates that they also contribute to the maintenance of activity levels in individual neurons. Furthermore, in our model, the directional formation of synapses that is observed in experiments requires that pre-synaptic excitatory and inhibitory elements also follow opposite growth rules. Lastly, we observe that our proposed structural plasticity growth rules and the inhibitory synaptic plasticity mechanism that also balances our AI network both contribute to the restoration of the network to pre-deafferentation stable activity levels.Peer reviewe

The role of insight, social rank, mindfulness and self-compassion in depression following first episode psychosis

Gaining awareness of psychosis (i.e., insight) is linked to depression, particularly in the post-acute phase of psychosis. Informed by social rank theory, we examined whether the insight-depression relationship is explained by reduced social rank related to psychosis and whether self-compassion (including uncompassionate self-responding [UCS] and compassionate self-responding [CSR]) and mindfulness buffered the relationship between social rank and depression in individuals with first episode psychosis during the post-acute phase. Participants were 145 young people (Mage  = 20.81; female = 66) with first episode psychosis approaching discharge from an early psychosis intervention centre. Questionnaires and interviews assessed insight, depressive symptoms, perceived social rank, self-compassion, mindfulness and illness severity. Results showed that insight was not significantly associated to depression and thus no mediation analysis was conducted. However, lower perceived social rank was related to higher depression, and this relationship was moderated by self-compassion and, more specifically, UCS. Mindfulness was related to depression but had no moderating effect on social rank and depression. Results supported previous findings that depressive symptoms are common during the post-acute phase. The role of insight in depression for this sample is unclear and may be less important during the post-acute phase than previously considered. Supporting social rank theory, the results suggest that low perceived social rank contributes to depression, and reducing UCS may ameliorate this effect. UCS, social rank and possibly mindfulness may be valuable intervention targets for depression intervention and prevention efforts in the recovery of psychosis

Experiences of a Digital Mental Health Intervention from the Perspectives of Young People Recovering from First-Episode Psychosis: A Focus Group Study.

UNLABELLED: Horyzons is a digital health intervention designed to support recovery in young people receiving specialized early intervention services for first-episode psychosis (FEP). Horyzons was developed in Australia and adapted for implementation in Canada based on input from clinicians and patients (Horyzons-Canada Phase 1) and subsequently pilot-tested with 20 young people with FEP (Horyzons-Canada Phase 2). OBJECTIVE: To understand the experiences of young adults with FEP who participated in the pilot study based on focus group data. METHODS: Among the twenty individuals that accessed the intervention, nine participated across four focus groups. Three team members were involved in data management and analysis, informed by a thematic analysis approach. A coding framework was created by adapting the Phase 1 framework to current study objectives, then revised iteratively by applying it to the current data. Once the coding framework was finalized, it was systematically applied to the entire dataset. RESULTS: Four themes were identified: (1) Perceiving Horyzons-Canada as helpful for recovery; (2) Appreciating core intervention components (i.e., peer networking; therapeutic content; moderation) and ease of use; (3) Being unaware of its features; and (4) Expressing concerns, suggestions, and future directions. CONCLUSIONS: Horyzons-Canada was well received, with participants wanting it to grow in scale, accessibility, and functionality

A Pilot Digital Intervention Targeting Loneliness in Youth Mental Health

Background: Loneliness is an emerging issue for young people, but yet many interventions to address loneliness in this group focus on providing social opportunities. While these sorts of interventions may appear to increase social connections, loneliness is more related to quality rather than quantity of social relationships. Thus, interventions addressing loneliness should focus on maximizing the quality of current relationships. Together with youth consumers both with mental ill health and those without, we developed a digital smartphone application (app) called +Connect. The 6-week program delivers positive psychology content designed to improve relationship quality. We tested the acceptability, feasibility, and safety of the program in lonely young people with or without a mental health diagnosis of social anxiety disorder. We used a mixed method study design to triangulate pilot quantitative and qualitative data in young people with and without social anxiety disorder (SAD). Method: Nine participants with a diagnosis of social anxiety disorder (Mage = 21.00; SD = 1.41) and 11 participants with no mental health conditions (Mage = 20.36; SD = 2.16) completed the +Connect digital intervention. Results: Those with social anxiety disorder reported less acceptable ratings on outcomes. Feasibility ratings, measured by uptake and app completion, met a priori threshold criteria in both groups. Those with social anxiety disorder yielded more attrition, with almost double the attrition rate compared with those without the disorder. There were no safety issues elicited during the pilot study. In terms of outcomes, exploratory analyses indicated that the app itself is likely to be beneficial rather than cause harm. Our qualitative data indicated both groups reported no negative outcomes and noted that positive outcomes were driven by three processes: reflection, learning, and real-life application. Further exploratory data on usability indicated room for improvement in terms of giving more support for different components of the app (i.e., challenges). Conclusion: The pilot findings of this proof-of-concept app indicates some promise in terms of a second iterative version of +Connect