Implicit Contextual Learning in Prodromal and Early Stage Huntington's Disease Patients

Abstract

Huntington's disease (HD) is a genetic neurodegenerative disorder affecting the basal ganglia. These subcortical structures are particularly important for motor functions, response selection and implicit learning. In the current study, we have assessed prodromal and symptomatic HD participants with an implicit contextual learning task that is not based on motor learning, but on a purely visual implicit learning mechanism. We used an implicit contextual learning task in which subjects need to locate a target among several distractors. In half of the trials, the positions of the distractors and target stimuli were repeated. By memorizing this contextual information, attention can be guided faster to the target stimulus. Nine symptomatic HD participants, 16 prodromal HD participants and 22 control subjects were included. We found that the responses of the control subjects were faster for the repeated trials than for the new trials, indicating that their visual search was facilitated when repeated contextual information was present. In contrast, no difference in response times between the repeated and new trials was found for the symptomatic and prodromal HD participants. The results of the current study indicate that both prodromal and symptomatic HD participants are impaired on an implicit contextual learning task.

The Distinct Role of the Amygdala, Superior Colliculus and Pulvinar in Processing of Central and Peripheral Snakes

“…The data presented here extends previous findings that the amygdala is recruited by animal face processing during explicit evaluations [15] [52]. We had expected that snake shapes (body parts) would engage more the amygdala during peripheral presentations (LVF or RVF) which more often reflects implicit processing than central vision, because foveal vision more frequently reaches visual awareness, although not in a strict manner [63–65]. In addition, and as with other stimuli based in LSF cues, snake shapes were also predicted to be preferentially processed in areas devoted to peripheral processing (e.g., collateral sulcus) [3].…”

Scanning Patterns of Faces do not Explain Impaired Emotion Recognition in Huntington Disease: Evidence for a High Level Mechanism

“…To study overall cognitive functioning of the three groups, we used an extensive neuropsychological test battery. The results of these neuropsychological tests were also published in a recent paper on implicit learning in HD patients (Van Asselen et al, in press ). The 12-item short form of the Raven advanced progressive matrices (Raven et al, 1993 ) and the vocabulary of the WAIS-III (Wechsler, 1997 , 2008 ) were used as an indication of intelligence.…”

Relationship of Contextual Cueing and Hippocampal Volume in Amnestic Mild Cognitive Impairment Patients and Cognitively Normal Older Adults

“…However, our findings also speak to recent claims that the striatum might also be involved in contextual cueing. These claims are based on the finding that early stage Parkinson’s disease patients (van Asselen et al, 2009) and prodromal and early stage Huntington’s disease patients, conditions with primary basal ganglia pathology, fail to show contextual cueing (van Asselen et al, 2012). The lack of correlation between caudate nucleus volume and contextual cueing in our study does not support involvement of this region, at least in the population investigated here.…”