“School of Cognitive Sciences”
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| Paper IPM / Cognitive Sciences / 14564 |
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Understanding the neural mechanism for coordination of brain networks is an important unmet purpose in neuroscience. How do distributed populations of neurons coordinate their activity across a diversity of spatial and temporal dimensions? Unfortunately a complete understanding of dynamic coordination mechanism remains elusive but evidence suggests that oscillations may have a critical role in this process. Several groups have suggested that brain rhythms have a key role in the dynamic coordination of functional brain networks. Attention, which is a mechanism that deals with information overloaded by selecting a stimulus over other existing stimuli in the visual scene, is one of those functions. Columnar organization of neurons in Primary Visual Cortex (V1) has an important role in this process. Generally, each column of V1 has a preferred orientation and direction. There is a hypothesis that columns with the same preferred direction are connected and they enhance each other. Our main purpose of this study is to investigate the connectivity of columns with preferred direction by neural synchrony and oscillations across feature based attention. Data were recorded from an awake behaving macaque monkey. The monkey was trained to do a feature based attention task. After the monkey fixated at a central point on the screen, a cue which was a static stimulus appeared. Then, after a short delay (270 ms), the stimuli were presented on the screen for 1.33- 3 s. The stimuli were two moving random dot patterns with 180 degree direction difference; one of them was inside of the receptive field of the recorded neurons and the other outside of the receptive fields. In each session the direction of movement was varied and there were totally 12 different directions. The monkey should respond to a direction change of the cued stimulus while ignore the direction changes in the un-cued stimulus. A 96-electrode Utah array was implanted in the primary visual cortex and it was used for recoding. The stimulus was selected large enough to include receptive fields of all the electrodes.
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