Biomedical subjects

Alek H Pogosyan

Publications and source records attributed to Alek H Pogosyan.

3 recordsLinked to original sources

PubMed2004

Cortico-cortical coupling patterns during dual task performance.

We investigated the neural correlates of dual task performance using EEG coherence as a measure of the functional coupling between cortical regions. Nine healthy participants performed a rhythmical movement with the right hand and an isometric contraction with the left hand, either initiated simultaneously or successively. EEG data revealed that dual task performance was associated with stronger coherence in left hemispheric and mesial areas than the sum of the tasks performed separately in the beta (>12-30 Hz), but not alpha (8-12 Hz), band. This effect was more pronounced when the two assignments were initiated simultaneously, as opposed to successively. The data demonstrate that the pattern of cortico-cortical coupling during bimanual actions is not just the sum of that associated with its component parts, but is increased according to coordinative demands and processing load.

Arm↗

PubMed2003

Influence of working memory on patterns of motor related cortico-cortical coupling.

Working memory is implicated in various higher-order cognitive operations. We hypothesized that the availability of a temporal representation in working memory would limit the extent of cortico-cortical coupling necessary to undertake a self-paced rhythmic movement. To this end we examined modulations in cortico-cortical interactions as determined by EEG coherence during a delay interval and subsequent movement reproduction. Right hand movement was initially paced by a metronome beat every 0.9 s, followed by a delay interval, after which hand movement was repeated in an unpaced manner. Movement reproduction after a long (22.5 s, corresponding to 25 movement cycles) compared to a short (5.4 s, corresponding to 6 movement cycles) delay interval was associated with an increased degree of functional coupling in the beta frequency band (12-30 Hz) of the left (movement-driving) hemisphere (F3-FC3, F3-C3 and F3-P3 connections) as well as mesial regions (FCz-FC3, FCz-C3 and Cz-FC3 connections) even though overall behavioral characteristics were not influenced. In addition, analysis of the EEG coherence in the delay period revealed a bilateral frontal network (F3-F4, F3-FC4, F4-FC3 and FC3-FC4 connections). Activity in the latter tended to be synchronized in the theta band (4-8 Hz) and was significantly less strong at 22.5 s than 5.4 s. These data suggest that working memory may be partly subserved by synchronization in a bilateral frontal network and may provide an intrinsic contextual influence that shapes the pattern of cortico-cortical interaction during a given task.

Biomechanical Phenomena↗

PubMed2003

Anticipatory cortico-cortical interactions: switching the task configuration between effectors.

Cognitive regulation enables a subject to plan actions according to context and to respond in a flexible manner to environmental conditions. This implies that foreknowledge about a change in system configuration will trigger preparatory activity in anticipation of the impending transformation. In the present study, we evaluate a unimanual task under two performance conditions that affected the cognitive context, and examine modulations in cortico-cortical interactions as determined by EEG coherence. The right hand movement was performed in an experimental paradigm that necessitated in some trials a voluntary and predictable switch towards a left hand movement, whereas in other trials no switch was required and movement of the right hand continued. The data showed that execution of the right hand movement was associated with an increased degree of task-related coherence in the alpha frequency band (8-12 Hz) in the switching as compared to the no switching condition, and this was most apparent for fronto-parietal connections of the movement-driving (left) as well as for the primed (right) hemisphere. For the primed hemisphere, we observed that the information flow was driven from the F4 electrode overlying the prefrontal area, which suggests that anticipatory preplanning occurred. These data indicate that higher-order cognitive operations bias cortico-cortical interactions in respect of an upcoming switch of the task settings between effectors by recruiting neural resources proactively. Dynamic adjustments in the alpha band suggest that low frequency activity is a characteristic of distributed information processing related to movement planning.

Adult↗