Symptom Provocation of Obsessive-Compulsive Symptoms in Tourette Disorder and its Neural Correlates

It is known that Tourette Syndrome (TS) is often accompanied by obsessive-compulsive disorder (OCD) and there do exist a lot of similarities among symptoms such as tics and obsessive-compulsive symptoms (OCS; Bhikram, Crawley, Arnold, Abi-Jaoude, and Sandor, 2020).

Symptom provocation while participants underwent fMRI was used in order to identify its neural substrates (Bhikram et al., 2020). Symptom provoking pictures concerning washing, checking, and symmetry in addition to neutral and disgust pictures were used. There were three different participan groups created for comparison, These were TS with severe/moderate OCS, TS with absent/mild OCS, and healthy control participants.

The paradigm that the investigators used was found to be effective in inducing subjective anxiety of higher magnitude in TS as compared to healthy controls In the conditions with symptom provocation. Higher subjective anxiety was not found in the neutral and disgust conditions (Bhikram et al., 2020).

Within the group of TS participants, there was found a negative relationship among OCS severity and activation in brain areas such as the supramarginal gyrus, precuneus, and visual processing areas, which was found to be common in all symptom provocation conditions. Furthermore, for exept the provocation condition concerning washing, there were found negative relationships among OCS severity and activation of the precentral gyrus, SMA, and IFG to be found across all provocation conditions. 

The severity of tics was only related to activation of the anterior cingulate cortex concerning the symmetry symptom provocation condition (Bhikram et al., 2020).

Object Perception in Autism Spectrum

Perceptual organization at the ventral visual stream was investigated in participants with autism spectrum disorder ( ASD) adolescents and healthy control participants (Sapey-Triomphe, Boets, Van Eylen, Noens, Sunnaert, Steyaert, and Wagemans, 2020).

Objects were presented that did differ in perceptual organization. It was investigated if ASD participants would show diminished top-down modulation.

The results show that at the behavioral level both participant groups were comparable at identifying shapes that were embedded in random oriented Gabor pieces. Accuracy and reaction time were not affected whether the shapes were shown by only contour, only texture, or both contour and texture. Furthermore, whether the objects were recognizable or not did also not differ between the two groups.

Brain activation patterns were not very different among the groups and detection of the shapes was found to be associated with involvement of brain regions from low-level to high-level regions at the ventral visual stream. Stimuli that were meaningful, that is, objects that were recognizable, were found to be associated with larger activation in the LOC as well as in the middle occipital gyri in the participants with ASD.

Top-down modulation and functional connections among areas of the ventral visual stream was present at higher cortical hierarchy but not the lower in ASD participants as compared to healthy control participants.

Accordingly, ASD participants might get less top-down signs from brain areas at the higher level as compared to healthy control participants. The result might be that there will be diminished facilitation as well as more difficulties for the identification of objects in ASD. Global processing was found to be normal in ASD (Sapey-Triomphe et al., 2020).

Social Anxiety Disorder (SAD) and Feedback Processing

Patients with social axiety disorder (SAD) are very concerned for getting negative feedback from others (Voegler, Peterburs, Bellebaum, and Straube, 2019). SAD patients have the fear that their actions may be judged as abnormal or embarrasing. Learning from feedback is an important aspect for the succesful accomplishment of interactions with the environment, allowing contingency learning among actions and their effects and waiting for the consequences of particular behavior (Voegler et al., 2019).

The authors used a probabilistic feedback learning task while recording event related potentials and their interaction with the social context in patients with SAD and healthy control subjects. During the task feedback was given as wins or losses and were either rewarded or punished. Two conditions of the task consisted of either being obseved or as being not obseved by an observer (Voegler et al., 2019).

It was found that the patients with SAD were more unconfortable than healthy control subjects during the observation condition of the task. Furthermore, the patients with SAD did learn better from negative feedback compared to positive feedback during the no obsevation condition of the task, wheras the opposite did hold for the healthy control subjects. The ERP results showed that patients with SAD showed an enhanced feedback relativity (FRN) component amplitude during observation. The effect was more evident related to positive feedback. The results of the difference FRN and learning from negative feedback in the SAD patients was negativily associated with this component in the patients with SAD in the no obsevation condition, but not in the observation condition. In contrast, the opposite was found in healthy control subjects (Voegler et al., 2019). 

It is suggested that healthy control subjects are more relying on an avoidance-oriented strategy when they are being observed, such as social stress. The patients with SAD, however, are more implicated for negative information by default.

The results may opt for an inadequate information processing style in patients with SAD while they are being obseved with regard to the neural level. This might be due to a indefinite separation of reinforcement that is either negative or positive and as a result learning from negative feedback is impaired in these patients (Voegler et al., 2019).

Attentional Bias to Social Threat in PTSD

Post-traumatic stress disorder (PTSD) is related to hypersensitive responses to potential threat (Klein, Schindler, Neuner, Rosner, Renneberg, Steil et al., 2019). These authors investigated the ERP correlates to processing of emotional words in a group of adolescents with PTSD with childhood sexual abuse (CSA) and childhood physical abuse (CPA) compared to healthy comparison subjects. The stimuli of the task consisted of nouns from different affective categories: neutral, positive, threatening, and social threatening.

The ERP results revealed an enhanced late positive potential (LPP) response in patients with PTSD. Concerning the P3 component, both groups showed reduced amplitude for positively valenced words. Patients with PTSD exhibited a differential enhanced response to social threatening stimuli as compared to physical threatening words, neutral words, and positive words.

It is suggested that patients with PTSD show a different pattern of information processing concerning negative social stimuli (Klein et al., 2019). Furthermore, it is argued that because of their specific traumatic experiences this group has an elaborated fear network after trauma, and these negative cues might be the most relevant for the patients with PTSD. There was found a blunted cardiac response in patients with PTSD compared to healthy comparison subjects for physical stimuli that were threatening. No differences were found in healthy comparison subjects (Klein et al., 2019).

Depression and Neural Sensitivity to Self-Referential Processing

In two experiments, patients with depression and healthy control subjects were required to read self-relevant stimuli while event related potentiald were recorded (Benau, Hill, Atchley, O'Hare, Gibson, Hajcak et al., 2019).

In the first experiment the processing of emotional words in both groups was applied in order to make a separation among self-relevant effects compared to valence effects. The results showed that patients with depression had a relatively normal modulation of the late positive potential (LPP) ERP component related with affect for high-arousal self-relevant words compared to normative emotional words. This was found to be in contrast to healthy control subjects, as they showed the same enhancement of the LPP amplitude for positive, negative, and neutral stimuli, regardless of self-reliance. Patients with depression did only modulate stimuli when they were emotional and were personally relevant (Benau et al., 2019).

In the second experiment, self-evaluative linguistic processing was assessed by investigating the emotional reactivity to normative as compared to ideographic stimuli in patients with depression compared to healthy control subjects. The results of this second experiment revealed that patients suffering from depression were most likely to affirm negative self-referential statements as compared to positive self-referential statements.

Response times in the patient group were slower for both statements as compared to healthy control subjects. The response times for neutral stimuli did not differ among the groups. The ERP results revealed that the LPP was highest for self-referential sentences with a negative final word in the patients with depression. This effect was not found in the healthy control subjects (Benau et al., 2019).

Depression Symptoms and Reward and Loss Sensitivity

A dimensional approach was used in order to investigate the association among depression symptomatology and sustained reward responsiveness (Berry, Tanovic, Joormann, and Sanislow, 2019). ERPs were recorded to investigate how the early responses to rewards and losses do change over time. The doors task is a simple gambling task and was applied to elicit the reward positivity and the feedback related negativity. The subjects were given instructions for making a choice for the door that they thought was having a prize behind it. The remaining half of the doors consisted of losses.

During the gambling task, the authors found evidence of an association among depression symptomatology and responses to rewards and losses During the task. A sustained reward positivity and an increment in the feedback related negativity ERP components were found. Larger symptoms of depression were related to larger responses to both reward as well as losses.

According to the authors, higher depression symptomatology in the general population might be related to both reward and loss responses during the experimental task (Berry et al., 2019).

Risk Processing in Patients with Alcohol Use Disorder

Decision-associated versus feedback related aspects might probably contribute to decision making in patients with alcohol use disorder (Sehrig, Weiss, Miller, and Rockstroh, 2019). During the Ballon Analog Risk Task (BART) ERPs were recorded in patients and healthy comparison subjects. During the BART the participants could make a choice to inflate a visual balloon. The participants could also choose among pumping and "cash out".

Balloon pumping was revealed to be rewarding when not pumping, wheras popping the balloon resulted in a loss.

It was found that both subject groups did exhibit the same choice behavior, however, they did differ in the ERP results. Patients with alcohol use disorder showed an enhanced P3 amplitude which did not depend on the level of risk. In addition, patients showed a reduced feedback related negativity (FRN) which suggests that they have impaired responses during loss. There was found a larger N2-P3 complex in the patients, and the larger P3 in alcohol use disorder patients might be due to more heavily processing of the decision prompt related to outcome-expectancies due to learning. The reward prediction did not differ among both groups.

In the patients with alcohol use disorder, higher impulsivity was related to risk modulated decision P3, but not on the FRN. Based on these results, it is suggested that the decision as well as feedback-associated processes might have an impact on difficulties in the engagement of effective use of daily activities (Sehrig et al., 2019).