We present here “Just Another Tool for Online Studies” (JATOS): an open source, cross-platform web application with a graphical user interface (GUI) that greatly simplifies setting up and communicating with a web server to host online studies that are written in JavaScript. JATOS is easy to install in all three major platforms (Microsoft Windows, Mac OS X, and Linux), and seamlessly pairs with a database for secure data storage. It can be installed on a server or locally, allowing researchers to try the application and feasibility of their studies within a browser environment, before engaging in setting up a server. All communication with the JATOS server takes place via a GUI (with no need to use a command line interface), making JATOS an especially accessible tool for researchers without a strong IT background. We describe JATOS’ main features and implementation and provide a detailed tutorial along with example studies to help interested researchers to set up their online studies. JATOS can be found under the Internet address: www.jatos.org.

Importance Disrupted reward processing, mainly driven by striatal dysfunction, is a key characteristic of addictive behaviors. However, functional magnetic resonance imaging (fMRI) studies have reported conflicting results, with both hypoactivations and hyperactivations during anticipation and outcome notification of monetary rewards in addiction. Objective To determine the nature and direction of reward-processing disruptions during anticipation and outcome notification of monetary rewards in individuals with addiction using image-based meta-analyses of fMRI studies. Data Sources Relevant publications were identified searching PubMed (inclusion until March 2015) using the following terms: reward, fMRI, substance use, cocaine, cannabis, opiates, alcohol, nicotine, smokers, gambling, gamblers, gaming, and gamers. Authors of included articles were contacted to obtain statistical fMRI maps. Study Selection Inclusion criteria: reward task involving monetary reward anticipation and/or outcome; participants showing addictive behaviors; and healthy control group. Exclusion criteria: participants aged younger than 18 years; recreational substance use or gambling; participants at risk for addictive behaviors; and studies using the same patient data as other included studies. Data Extraction and Synthesis Study procedures were conducted in accordance with the Meta-analysis of Observational Studies in Epidemiology guidelines. Using Seed-baseddMapping software, meta-analyses were performed using random-effect nonparametric statistics with group whole brainT-maps from individual studies as input. Analyses were performed across all addictions and for substance and gambling addictions separately. Main Outcomes and Measures Group differences (individuals with addiction vs control individuals) in reward-related brain activation during reward anticipation and outcome using fMRI (planned before data collection). Results Twenty-five studies were included in the meta-analysis, representing 643 individuals with addictive behaviors and 609 healthy control individuals. During reward anticipation, individuals with substance and gambling addictions showed decreased striatal activation compared with healthy control individuals. During reward outcome, individuals with substance addiction showed increased activation in the ventral striatum, whereas individuals with gambling addiction showed decreased activation in the dorsal striatum compared with healthy control individuals. Conclusions and Relevance Striatal hypoactivation in individuals with addiction during reward anticipation and in individuals with gambling addiction during reward outcome is in line with the reward-deficiency theory of addiction. However, the combination of hypoactivation during reward anticipation and hyperactivation during reward outcome in the striatum of individuals with substance addiction may be explained using learning-deficit theory.

Intrinsic activity of the brain during resting-state is not random and is currently discussed as a neural reflection of self-referential processing. Self-reference is typically reduced in schizophrenia as a disorder of the self while extensive self-attribution of, eg, negative thoughts is characteristic for major depression. However, a quantitative meta-analysis targeting the resting-state brain activity in both disorders is lacking. Here, we predict primarily abnormal resting-state activity in brain regions related to self-referential processing. By means of activation likelihood estimation (ALE) on functional magnetic resonance imaging and positron emission tomography studies, we investigated concurrence of hyperactivation and hypoactivation in resting-state measurements of schizophrenic and depressed patients compared with healthy controls. We found hypoactivation in ventromedial prefrontal cortex (vmPFC), left hippocampus, posterior cingulate cortex, lower precueus and the precuneus, and hyperactivation in bilateral lingual gyrus of schizophrenic patients. In major depression, we found hyperactivation in vmPFC, left ventral striatum, and left thalamus and hypoactivation in left postcentral gyrus, left fusiform gyrus, and left insula. An overall ALE analysis confirmed the proximity of hypoactivation in schizophrenia and hyperactivation in major depression in the vmPFC.The opposing resting-state activity in vmPFC for the 2 disorders is in line with the different expression of dysfunctional self-reference as core characteristics of schizophrenia and major depression. The vmPFC has previously been identified as a crucial area for self-referential processing and may represent a target to increase the diagnostic validity of resting-state activity for disorders with dysfunctions of the self.