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Based on recent insight into the thalamocortical system and its role in perception and conscious experience, a unified pathophysiological framework for hallucinations in neurological and psychiatric conditions is proposed, which integrates previously unrelated neurobiological and psychological findings. Gamma-frequency rhythms of discharge activity from thalamic and cortical neurons are facilitated by cholinergic arousal and resonate in networks of thalamocortical circuits, thereby transiently forming assemblies of coherent gamma oscillations under constraints of afferent sensory input and prefrontal attentional mechanisms. If perception is based on synchronisation of intrinsic gamma activity in the thalamocortical system, then sensory input to specific thalamic nuclei may merely play a constraining role. Hallucinations can be regarded as underconstrained perceptions that arise when the impact of sensory input on activation of thalamocortical circuits and synchronisation of thalamocortical gamma activity is reduced. In conditions that are accompanied by hallucinations, factors such as cortical hyperexcitability, cortical attentional mechanisms, hyperarousal, increased noise in specific thalamic nuclei, and random sensory input to specific thalamic nuclei may, to a varying degree, contribute to underconstrained activation of thalamocortical circuits. The reticular thalamic nucleus plays an important role in suppressing random activity of relay cells in specific thalamic nuclei, and its dysfunction may be implicated in the biological vulnerability to hallucinations in schizophrenia. Combined with general activation during cholinergic arousal, this leads to excessive disinhibition in specific thalamic nuclei, which may allow cortical attentional mechanisms to recruit thalamic relay cells into resonant assemblies of gamma oscillations, regardless of their actual sensory input, thereby producing an underconstrained perceptual experience.

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Background/Aims: Visuospatial impairments are known to occur in Alzheimer’s disease (AD). We hypothesised that functional magnetic resonance imaging (fMRI) response in task-related brain regions would be impaired in patients with AD during the task and that treatment with acetyl cholinesterase inhibitors would enhance activations in brain regions concerned with this visual perceptual processing. Method: Ten AD subjects were neuropsychologically assessed and underwent fMRI imaging whilst performing a series of visuospatial perception tasks, before and after treatment with acetyl cholinesterase inhibitors. Eleven healthy elderly comparison subjects were also scanned twice. Results: Regions of increased brain activation in AD included the left precuneus, left cuneus, left supramarginal gyrus, right parieto-temporal cortex and right inferior parietal lobule. Further, increased activation in the left precuneus was found to correlate significantly with improved functioning of activities of daily living. Conclusions: We believe this to be the first fMRI study that, after controlling for the confound of repeat scanning, demonstrates altered patterns of brain activation associated with visuospatial processing following treatment in patients with AD. The treatment-related improvement of visual perception in AD may rely on enhanced attentional mechanisms, thereby possibly supporting independent living through improvement on activities of daily living.

The results of this review highlight the potential of online lifestyle interventions as adjunctive treatments for depression, and the possibility of achieving significant improvements in depressive symptoms when targeting lifestyle behaviour change.

Background Online interventions can be a cost-effective and efficient way to deliver programs to large numbers of people regardless of geographic location. However, attrition in web-based interventions is often an issue. Developing ways to keep participants engaged is important for ensuring validity and limiting potential biases. We developed a web-based dietary intervention as part of The My Food & Mood study which aimed to optimize ways to engage participants with low mood or depressive symptoms to promote dietary behavior change. Different versions of the My Food & Mood program were tested during optimization. Iterations were developed based on user feedback and usage analysis. Objective The purpose of this study was to compare engagement and nonusage attrition across 4 program iterations—which differed by platform format, delivery mode, and activity type—to create an optimized version. Methods Each program version contained modular videos with key activities with respect to implementing behavior change techniques of equivalent levels of required participation and length: version 1.0, desktop program and smartphone app; version 2.1, desktop or smartphone program; version 2.2, desktop program; and version 3.0, smartphone app. Adults with PHQ-8 scores of 5 or greater were recruited online and assigned to 1 of the 4 versions. Participants were asked to use the program for 8 weeks and complete measures at weeks 4 and 8. Engagement data were collected from the web-based platform system logs and customized reports. Cox regression survival analysis examined nonusage attrition and Kruskal-Wallis tests compared engagement across each cohort. Results A total of 614 adults participated. Kruskal-Wallis tests showed significant differences across the 4 cohorts in all engagement measures. The smartphone app (version 3.0) had the greatest engagement as measured by weeks engaged, total usage time, total time key activities, number of active sessions, percentage of activities completed against protocol, goals completed, and percentage of videos watched. Cox regression multivariate survival analysis showed referral from a health practitioner (hazard ratio [HR] 0.344, P=.001) and greater proficiency with computers (HR 0.796, P=.049) reduced the risk of nonusage attrition. Computer confidence was associated with an increased risk of nonusage attrition. Conclusions My Food & Mood version 3.0, a dietary intervention delivered via smartphone app with self-monitoring tools for diet quality and mood monitoring, was the version with greatest engagement in a population with low mood or depression. The iterative design techniques employed and analysis of feedback from participants resulted in a program that achieved lower rates of nonusage attrition and higher rates of intensity of use.

Recent randomized controlled trials have shown that improving diet quality reduces symptoms in those with depression. The provision of digital health interventions that can support dietary change in those with depression has important benefits with respect to reach, accessibility convenience and cost. The My Food & Mood study used single arm cohort design to test the feasibility of such an intervention. Participants with current depressive symptoms were recruited and enrolled online to use the My Food & Mood m-Health (smartphone delivered) program for 8 weeks. Participants completed depression (PHQ-8) and dietary questionnaires (MEDAS) at baseline, week 4 and week 8. Metrics of use and intensity of use engagement measures were calculated from system logs and data entries. There was a significant change in both MEDAS score (t ¼ 8.147, df ¼ 44, p < 0.001) and PHQ-8 score (t ¼ À7.199, df ¼ 44, p < 0.001) throughout the study. There was a moderate positive association between change in MEDAS score and activities completed, goals and weeks engaged, and a strong inverse association between change in MEDAS score and change in PHQ-8 score. An m-Health program targeting dietary intervention in those with depression was feasible. Dietary change was associated with higher engagement and reduced depressive symptoms.

The intrahypophysial mechanisms involved in the control of gonadotrophin secretion remain unclear. In the horse, a divergent pattern of gonadotrophins is observed at different stages of the reproductive cycle in response to a single secretagogue (gonadotrophin-releasing hormone), and dramatic changes in fertility take place throughout the year in response to photoperiod. This species thus provides a useful model to investigate the regulation of fertility directly at the level of the hypophysis. A series of studies were undertaken to examine the cytological arrangements and heterogeneity of gonadotrophin storage in the pars distalis (PD) and pars tuberalis (PT) of the hypophysis of male and female horses. Specifically, the seasonal and gonadal effects on distribution, density and hormonal identity of gonadotrophs, the existence of gonadotroph-lactotroph associations and the expression of prolactin receptors (PRL-R) as possible morphological bases for the differential control of gonadotrophin secretion were investigated. It became apparent that both isolated and clustered gonadotrophs are normally distributed around the pars intermedia and surrounding capillaries in the PD, and in the caudal ventral region of the PT. In the PD, no effects of season or of reproductive state on the density or number of gonadotrophs could be detected in either male or female animals. In contrast, a fivefold increase in gonadotroph density was observed in the PT during the sexually active stage. In males, robust gonadal effects were detected on the gonadotroph population; orchidectomy significantly reduced both the number and proportion of gonadotrophs, in relation to other hypophysial cell types, in both the PD and PT regions. Luteinizing hormone (LH) monohormonal, follicle-stimulating hormone (FSH) monohormonal and bihormonal gonadotrophs were identified in the PD and PT of male and female horses. Interestingly, in males, the relative proportions of gonadotroph subtypes and the LH/FSH monohormonal gonadotroph ratio were not affected by either season or the presence of the gonads. In contrast, a larger proportion of monohormonal gonadotrophs was clearly observed in sexually active females. Specific gonadotroph-lactotroph associations and expression of PRL-R in cells other than gonadotrophs were detected in the PD throughout the annual reproductive cycle. In addition to a stimulatory gonadal effect on lactotroph density, a substantial gonadal-independent effect of season was apparent on this variable. The findings have revealed important seasonal and gonadal effects on the cytological configuration of the equine hypophysis, which may provide the morphological basis for the intrahypophysial control of fertility.