|Reference code: ||PT/FB/BL-2006-073.09|
|Location: ||Arquivo PCA - Pasta 22/2006|
|Basal ganglia dysfunction caused by Huntington's disease impairs nonmotor visual learning|
|Publication year: ||2010|
Huntington's disease (HD) is a genetic neurodegenerative disorder that mainly affects the basal ganglia, although damage to cortical areas is also found. The basal ganglia are a set of subcortical structures that are particularly important for motor functions, action selection, reinforcement learning and implicit learning. However, recent studies have indicated that they might also be involved in implicit learning that does not involve motor functions and is purely based on visual learning (Castelo-Branco, et al. 2009; Van Asselen et al., 2009). To further investigate this, we have used an implicit contextual learning paradigm to test patients with HD.
This is a visual search task, in which subjects need to locate a target as quickly as possible. Importantly, in half of the trials the positions of the distractors and target stimuli are repeated and this spatial information is used as a contextual cue. By memorizing this contextual information, attention is guided to the target stimulus. Since HD is a genetic disease, patients can be diagnosed before the onset of motor and cognitive symptoms. In the current study we tested 9 symptomatic HD patients, 14 presymptomatic HD patients and 21 control subjects.
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 presymptomatic HD patients. Thus, the HD patients did not learn the repeated contextual information and improve their visual search. Together, this indicates that the basal ganglia are not only involved in implicit motor learning, but also have an important role in purely visually based implicit learning. Furthermore, this impairment is found early in the disease, before the onset of other cognitive and motor impairments.
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|Author: ||Van Asselen, M.|
|Secondary author(s): |
|Júlio, F., Almeida, I., Januário, C., Bobrowicz-Campos, E., Gonçalves, A., Castelo-Branco, M.|
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|Van Asselen, M., Júlio, F., Almeida, I., Januário, C., Bobrowicz-Campos, E., Gonçalves, A., & Castelo-Branco, M. (2010, July). Basal ganglia dysfunction caused by Huntington's disease impairs nonmotor visual learning. Poster presented at the 7th FENS Forum of European Neuroscience, Amsterdam, Netherlands. Abstract retrieved from http://fens2010.neurosciences.asso.fr/abstracts/R4/A114_50.html|
|Indexed document: ||No|
|Keywords: ||Huntington's disease / Basal ganglia dysfunction / Implicit contextual learning|