Dear Colleagues,

The Obsessive Compulsive Disorder (OCD) is the main disorder of a spectrum of related conditions identified as obsessive-compulsive spectrum disorders (OCSDs) sharing obsessions and compulsive behaviors as their defining characteristics. Lifetime prevalence of OCD is 2.3%, however, more than 25% of the general population have reported obsessions or compulsions at some point in their lives, suggesting that the OCSDs, including subclinical OCD, may be more prevalent than previously expected. From a functional point of view, different prefrontal cortical regions serve different neurocognitive functions. The orbitofrontal cortex (OFC) is implied in decision making, behavioral planning and extinction recall, integrating affective implications and warning some types of reward. The anterior cingulate cortex (ACC), and its connections with the limbic system, is involved in motivation, attention, error detection, fear conditioning, inhibitory control and action planning. The dorsolateral prefrontal cortex (dlPFC) is believed to mediate executive functions and working memory. The striatums function is to perform an information processing, contributing to higher-order cognitive functions such as thought inhibition and memory retrieval. By integrating inputs arriving from the cortex and sending efferences to the thalamus through direct and indirect pathways, subcortical structures can reduce “sparse cortical information” reinforcing learning rules and signals.

Recently, Gillian and colleagues formed the opinion that compulsions are a manifestation of a disarray in the neurobiological balance between goal directed action and automatic habits, and that excessive habit learning and deficits in goal-directed control systems are an adequate model for compulsive behavior. Compulsive-like habits in OCD appear to be valence independent and obsession independent, therefore compulsions are not epiphenomenal but rather a core component of OCD.

This special issue is focused on original researches and narrative reviews regarding pathophysiological and neurobiological basis of OCD.

Prof. Dr. Massimo Pasquini
Guest Editor