Examining procedural working memory processing in obsessive-compulsive disorder

Habitual or hyper-controlled behavior: OCD symptoms and explicit sequence learning

BACKGROUND AND OBJECTIVES

This study examined whether ritualistic behaviors characteristic of obsessive-compulsive disorder (OCD) are a product of dysfunctional goal-directed behavior leading to habitual behavior (Gillan & Robbins, 2014). We used an explicit motor sequence learning task to investigate the repetition of chunked action sequences across the OC spectrum. As sequential motor behavior is practiced, action movements appear to get bundled together, and the initial movement of the sequence activates the entire sequence, leaving it relatively insensitive to change. Therefore, compulsive behavior in OCD may be a result of failing to inhibit the full activation of an extensively learned action sequence.

METHODS

Fifty-seven participants across the range of OCD symptoms practiced one sequence and then tested on a novel sequence in which one of the middle movements was omitted. Optimal performance for the new sequence required goal-directed inhibition of the original sequence and goal-directed execution of the new sequence instead. To manipulate activation of goal-directed behavior, we added a dual-task condition with a competing auditory tonal N-Back task. Data were analyzed using mixed-effects models.

RESULTS

Although we did observe expected learning patterns during learning of the original sequence, slower reaction times for the new sequences, and higher errors in the dual-task condition, performance was not significantly related to either obsessive-compulsive symptoms or distress symptoms.

LIMITATIONS

The current study used an analog sample; replication in a treatment seeking sample is warranted.

CONCLUSIONS

These findings challenge the goal-directed dysfunction model of OCD.

Visuospatial working memory capacity moderates the relationship between anxiety and OCD related checking behaviors

BACKGROUND

Compulsive checking behavior is the most prevalent compulsive behavior in patients with obsessive-compulsive disorder (OCD). While some studies have shown that anxiety and executive function influence compulsive checking behavior, the relationship between these constructs is inconclusive. Hence, we sought to explore the interplay between executive function, anxiety and compulsive checking behavior.

MATERIALS AND METHODS

47 healthy participants (HC) and 51 patients with OCD participated in the study. Symptoms and emotional states were assessed using the Yale-Brown Obsessive Compulsive Scale, the Obsessive-Compulsive Inventory-Revised, the Beck Anxiety Inventory, and the Beck Depression Inventory. Participants also completed three tests of neuropsychological functioning: the Stop Signal Task, the Spatial working memory Task, and the Wisconsin card sorting test. We analyzed the relationships between anxiety, executive function, and compulsive checking symptoms.

RESULTS

Patients with OCD showed significantly greater anxiety (p < 0.001) and impairments in visuospatial working memory function (p = 0.030) compared to HC participants, while inhibition and set-shifting were not significantly different between the two groups. Visuospatial working memory was negatively related to compulsive checking behavior (p = 0.016). Visuospatial working memory also played a moderating role in the positive relationship between anxiety and compulsive checking behavior (β = -0.281, p = 0.022).

CONCLUSION

Anxiety symptoms play an important role in explaining compulsive checking behavior in patients with OCD who have relatively weak visuospatial working memory ability. These findings provide a foundation for further research regarding the roles of emotion and cognitive inflexibility in compulsive checking behavior in patients with OCD.

Intact capacity for implicit learning in obsessive-compulsive disorder

BACKGROUND AND OBJECTIVES

Individuals with OCD tend to rely on explicit processing when performing implicit learning tasks. However, it is unclear whether this tendency reflects impaired capacity for implicit processing or a preference toward explicit processing. We sought to use a psychometrically valid task to examine the hypothesis that individuals with OCD have intact capacity for implicit learning.

METHODS

Twenty-four participants with OCD and 24 non-psychiatric controls completed a modified artificial grammar learning task where acquisition and retrieval of the underlying grammatical rules are considered strictly implicit. In an exploratory condition designed to examine the effect of nudging participants toward controlled processing, 12 participants in each group were told that the stimuli presented at acquisition were composed according to grammatical rules and were encouraged to identify these rules.

RESULTS

As predicted, participants with OCD acquired and expressed knowledge of the grammatical rule, demonstrating intact capacity for implicit learning, with no differences found between the OCD and controls on the extent of implicit learning. The exploratory intentional learning instructions had no effect, as participants in this condition were unable to adhere to the instructions, supporting the robust implicit nature of the artificial grammar learning task.

LIMITATIONS

The relatively small sample size did not allow comparisons between OCD symptom subtypes.

CONCLUSIONS

Our results provide evidence for intact implicit learning in OCD, and challenge previous studies suggesting a general deficiency in implicit learning in OCD.

Obsessive-compulsive symptoms are related to reduced awareness of emotional valence

BACKGROUND

The Seeking Proxies for Internal States (SPIS) model of OCD asserts that obsessive-compulsive (OC) tendencies are associated with attenuated access to internal states. Here we explore the implications of this model for awareness of emotional valence.

METHODS

In Study 1, participants with high and low OC tendencies (n = 30 in each group) rated how they felt while viewing different pictures with positive, neutral, or negative valence taken from the International Affective Picture System. Study 2 replicated Study 1 among non-selected participants (n = 99) that rated positive and negative pictures chosen from the recently developed Basic-Emotions Nencki Affective Picture System. In both studies, mean deviation from norm ratings (of each picture system) served as the primary outcome measure.

RESULTS

Study 1 showed that high OC participants' mean deviation score was significantly higher, compared with low OC participants, across positive, neutral, and negative pictures (p=.01). Follow-up analyses revealed that while no group difference emerged for mean valence rating (p=.16), groups differed on the mean standard deviation of ratings within each valence category (p=.002). In Study 2, only OC tendencies, not depressive or anxiety symptoms, were positively correlated with mean deviation from norm ratings (p=.026). Dividing the sample to high and low OC groups based on an OC cutoff score yielded similar group differences to those observed in Study 1 (p<.001).

LIMITATIONS

Analog samples and a relative small sample size (Study 1).

CONCLUSIONS

This study suggests that OC symptoms are associated with reduced awareness of emotional valence, possibly emanating from a noisier emotional perception.

The effects of declaratively maintaining and proactively proceduralizing novel stimulus-response mappings

Working memory (WM) allows for the maintenance and manipulation of information when carrying out ongoing tasks. Recent models propose that representations in WM can be either in a declarative format (as content of thought) or in a procedural format (in an action-oriented state that drives the cognitive operation to be performed). Current views on the implementation of novel instructions also acknowledge this distinction, assuming these are first encoded as declarative content, and then reformatted into an action-oriented procedural representation upon task demands. Although it is widely accepted that WM has a limited capacity, little is known about the reciprocal costs of maintaining instructions in a declarative format and transforming them in an action code. In a series of three experiments, we asked participants to memorize two or four S-R mappings (i.e., declarative load), and then selected a subset of them by means of a retro-cue to trigger their reformatting into an action-oriented format (i.e., procedural load). We measured the performance in the implementation of the proceduralized mapping and in the declarative recall of the entire set of memorized mappings, to test how the increased load on one component affected the functioning of the other. Our results showed a strong influence of declarative load on the processing of the procedural component, but no effects in the opposite direction. This pattern of results suggests an asymmetry in the costs of maintenance and manipulation in WM, at least when procedural representations cannot be retrieved from long term memory and need to be reformatted online. The available resources seem to be first deployed for the maintenance of all the task-relevant declarative content, and proceduralization takes place to the extent the system can direct attention to the relevant instruction.