Dynamic cortical involvement in implicit and explicit motor sequence learning. A PET study

Abstract

We examined the dynamic involvement of different brain regions in implicit and explicit motor sequence learning using PET. In a serial reaction time task, subjects pressed each of four buttons with a different finger of the right hand in response to a visually presented number. Test sessions consisted of 10 cycles of the same 10-item sequence. The effects of explicit and implicit learning were assessed separately using a different behavioural parameter for each type of learning: correct recall of the test sequence for explicit learning and improvement of reaction time before the successful recall of any component of the test sequence for implicit learning. Regional cerebral blood flow was measured repeatedly during the task, and a parametric analysis was performed to identify brain regions in which activity was significantly correlated with subjects' performances: i.e. with correct recall of the test sequence or with reaction time. Explicit learning, shown as a positive correlation with the correct recall of the sequence, was associated with increased activity in the posterior parietal cortex, precuneus and premotor cortex bilaterally, also in the supplementary motor area (SMA) predominantly in the left anterior part, left thalamus, and right dorsolateral prefrontal cortex. In contrast, the reaction time showed a different pattern of correlation during different learning phases. During the implicit learning phase, when the subjects were not aware of the sequence, improvement of the reaction time was associated with increased activity in the contralateral primary sensorimotor cortex (SM1). During the explicit learning phase, the reaction time was significantly correlated with activity in a part of the frontoparietal network. During the post-learning phase, when the subjects achieved all components of the sequence explicitly, the reaction time was correlated with the activity in the ipsilateral SM1 and posterior part of the SMA. These results show that different sets of cortical regions are dynamically involved in implicit and explicit motor sequence learning.

A Blueprint for Target Motion: fMRI Reveals Perceived Sequential Complexity to Modulate Premotor Cortex

“…Most interestingly for us, all involved brain areas, but particularly premotor areas, have been reported also to underlie the planning and production of motor sequences that follow an external sequential target stimulus, as particularly evident from imaging studies using the serial reaction task paradigm (Gordon et al, 1995;Grafton et al, 1995;Hazeltine et al, 1997;Hikosaka et al, 1998Hikosaka et al, , 1996Honda et al, 1998;Sadato et al, 1996;Sakai et al, 1998;Toni et al, 1998). As expected, the present outcome indicates that an attentively observed sequential signal can be a stimulus sufficient to elicit activations within a brain network closely related to that one that participates in sequential motor behavior.…”

Disruption of Sequential Priming in Organic and Pharmacological Amnesia: A Role for the Medial Temporal Lobes in Implicit Contextual Learning

“…To the extent that they are able to distinguish between hippocampal activity on the one hand and that in entorhinal, perirhinal, and parahippocampal cortices on the other, they may shed light on the involvement of these different structures in contextual learning and priming as well as in declarative learning. Many studies have measured regional brain activation during the SRT task (eg Honda et al, 1998;Willingham et al, 2002) but these have invariably examined performance across a long block of learning trials instead of directly manipulating contextual support as in the studies reported here. Such tests are inadequate for examining contextual priming.…”

Dynamic patterns make the premotor cortex interested in objects: influence of stimulus and task revealed by fMRI

“…This finding raises and more independent from guidance by the stimulus due the question why the PMC should respond not only to to a learning process. The premotor role in this senpragmatic object properties, but also to dynamic stimulus sorimotor transformation has been indicated by a number features, such as continuously changing patterns in an of imaging studies [11,14,[19][20][21]23,26,42,51,52,67] using abstract figure sequence.…”