Two types of impairments in OCD: obsessions, as problems of thought suppression; compulsions, as behavioral-executive impairment.

Impairments in executive functioning have been identified as an underlying cause of Obsessive-Compulsive Disorder (OCD). Obsessive patients attempt to suppress certain unwanted thoughts through a mechanism that Wegner referred to as 'chronic thought suppression', whereas compulsive patients are unable to inhibit their rituals. We tested 51 OCD patients using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), the White Bear Suppression Inventory (WBSI) and the Dysexecutive Questionnaire (DEX). Executive functions were tested using a cognitive test battery. We found that the total WBSI score was correlated with the Y-BOCS obsessive score but not with the Y-BOCS compulsive score. A stronger correlation was observed between the Y-BOCS obsessive score and the 'unwanted intrusive thoughts' factor based on Blumberg's 3-factor model of the WBSI. The total WBSI score was not correlated with the cognitive test results. The DEX score was significantly correlated with the Y-BOCS compulsive score; however, no correlation was found between the DEX score and the Y-BOCS obsessive score. A stronger correlation was observed between the Y-BOCS compulsive score and the 'inhibition' component of the DEX score, as defined by Burgess's 5-factor model. The DEX scores were correlated with cognitive test results measuring attention, cognitive flexibility and inhibitory processes. We conclude that obsessions indicate a failure of cognitive inhibition but do not involve significant impairment of executive functions, whereas compulsions indicate ineffective behavior inhibition and impaired executive functions.

The validation of the Hungarian version of the dimensional Yale-Brown obsessive-compulsive scale.

BACKGROUND: The Obsessive-Compulsive disorder (OCD) has a complex phenotype, which can be summarized by using a few consistent and temporally stable symptom dimensions. The dimensional approach derived from the systematic factor analytic studies of OCD symptoms. In 2006, a new psychometric scale was created by M.C. Rosario-Campos and her colleague, the Dimensional Yale-Brown Obsessive-Compulsive Scale (DY-BOCS). This scale measures the presence and severity of obsessive-compulsive (OC) symptoms within six distinct dimensions. The Hungarian translation of the test and preliminary results were published in 2009. PURPOSE: The objective of this recent study was two folded: on one hand, our goal was to validate the Hungarian version of the DY-BOCS on a larger sample size. On the other hand, we wanted to publish our results gained by the Hungarian version of the test in English. METHODS: We assessed 30 Hungarian patients diagnosed with OCD by DSM-IV. Reliability and validity of the expert and of the self-report were estimated. RESULTS: Self-report and expert ratings were highly correlated. The global DY-BOCS score was well correlated with the total Yale-Brown Obsessive-Compulsive Scale score. The internal validity of the symptom dimensions and the global severity score were high. Divergent validity was also good. CONCLUSION: These results indicate that the Hungarian version of the DY-BOCS is a reliable and valid clinical tool.

Transient cortical excitation at the onset of visual fixation.

Primates actively examine the visual world by rapidly shifting gaze (fixation) over the elements in a scene. Despite this fact, we typically study vision by presenting stimuli with gaze held constant. To better understand the dynamics of natural vision, we examined how the onset of visual fixation affects ongoing neuronal activity in the absence of visual stimulation. We used multiunit activity and current source density measurements to index neuronal firing patterns and underlying synaptic processes in macaque V1. Initial averaging of neural activity synchronized to the onset of fixation suggested that a brief period of cortical excitation follows each fixation. Subsequent single-trial analyses revealed that 1) neuronal oscillation phase transits from random to a highly organized state just after the fixation onset, 2) this phase concentration is accompanied by increased spectral power in several frequency bands, and 3) visual response amplitude is enhanced at the specific oscillatory phase associated with fixation. We hypothesize that nonvisual inputs are used by the brain to increase cortical excitability at fixation onset, thus "priming" the system for new visual inputs generated at fixation. Despite remaining mechanistic questions, it appears that analysis of fixation-related responses may be useful in studying natural vision.

Attention and arousal related modulation of spontaneous gamma-activity in the auditory cortex of the cat.

Sensory information processing in neocortex is associated with rhythmic synchronized gamma frequency firing of sensory cortical units and similar frequency oscillations of the field potentials. Different aspects of the gamma activity (20-80 Hz) have been suggested as correlates of attention, arousal and sensory binding. It is clear that attention has a modality selective influence, while arousal has a more general effect on the sensory systems. We used an experimental conditioning paradigm to separate these differential effects of attention and arousal on spontaneous neocortical gamma activity. We recorded field potentials with epidural electrodes placed above the auditory cortical areas of cats. The animals performed a simple instrumental alimentary conditioning task with different modality (visual and auditory) conditioned stimuli. When they attended to the auditory conditioned stimulus, both frequency and power increase of spontaneous gamma activity were detected. However when they attended visual, we found no power increase of gamma activity recorded above auditory areas, while the frequency increase was the same as in the "attend auditory" condition. We conclude that the power modulation of gamma activity is modality specific and thus can be attributed to selective attention, whereas the frequency modulation of gamma activity shows no modality specificity, it is influenced by the arousal level.

Effect of deviant probability and interstimulus/interdeviant interval on the auditory N1 and mismatch negativity in the cat auditory cortex.

In passive oddball paradigm the effects of changes in interstimulus/interdeviant interval (ISI; IDI) and deviant probability were investigated on mismatch negativity (MMN), auditory N1 wave and the exogenous P1 component of the auditory event-related potential in the cat. An epidural electrode matrix was chronically implanted over the auditory fields of the neocortex, and the amplitudes of the aforementioned components were measured in the location of their amplitude maxima. Dependence of the MMN both on the ISI and IDI as well as deviant probability was revealed, while the amplitude of the P1 and N1 showed dependence merely on the ISI. This method can be used for separation of the two negative, often overlapping components in the cat.