engleski

MEG studies on dynamic cortical networks: Integrated view on processes of perception and cognition

Magnetoencephalography (MEG) is a non-invasive neurophysiological technique that measures the magnetic fields generated by neuronal activity of the brain with milisecond temporal resolution. MEG recordings and spatio-temporal source localization were used to investigate dynamics of cortical networks activated by different tasks. Our results indicated integrated effects of perceptual and cognitive processes even during the earliest evoked activity. The goal of the first study was to determine the generators of the visual mismatch-negativity response (vMMN) to an infrequent change in a repetitive sequence of images. The peak latency of the vMMN response was between 100 and 160 ms ; neuromagnetic sources of the vMMN were localized in the occipital cortex. The aim of second study was to explore the earliest modulation of cortical activity by spatial attention in the visual modality. The results of our multi-dipole source localization analysis provided new evidence that even the earliest cortical visual neuromagnetic responses are modulated by attention. Neuromagnetic activity was also explored while subjects solved simple algebraic equations. All participants became more accurate and faster during the time course of the experiment. In addition, mathematics students noticed the patterns in the responses which helped them to improve their performance. Preliminary results suggested that early visual perception is very important in complex cognitive tasks such as equation solving.

Magnetoencephalography (MEG); electroencephalography (EEG); visual mismatch negativity (vMMN); spatio-temporal source localization; proportional reasoning; algebraic equations

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