The activity of the “when” pathway during visual motion

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Abstract

Purpose

Recently, a third pathway, the “when pathway” has been described(Batteli, 2007).The when pathway is project from the Primary Visual Cortex(V1) to the inferior parietal lobe(IPL) through the middle temporal and middle superior temporal(MT+) areas. The activity of the when pathway has not been confirmed experimentally. In this study, the activity of the when pathway was examined during visual motion.

Methods

A total of 6 healthy volunteers were studied.Task 1 comprised the visual presentation of one black dot alternating with a frequency of 1 Hz. Task 2 comprised the visual presentation of two black dots alternating with a frequency of 1 Hz. Task 3 comprised the visual presentation of three black dots alternating with a frequency of 1 Hz. Electroencephalography(EEG) data were digitized from 32 electrodes, which were placed according to the extended International 10_20 system. The EEG data at rest and for each task included O2ch between 30_50 ms in the right primary visual cortex area, P8 between 170_190 ms is right MT+ areas, and P4 between 200_220 ms in the right IPL area, and the waveform extracts were performed with power spectrum analyses. The calculated power value in the range of 8_13 Hz (α frequency band) from each waveform was examined in V1, MT+, and IPL and compared between rest in each task.

Results

The α bands in V1, MT+, and IPL in each task were significantly lower than those at rest (p<0.05).

Conclusion

The crucial function of the when pathway is to keep track of multiple objects that temporally overlap or occur sequentially. In this study, the α bands in each task were significantly lower compared with those at rest. However, significant differences in the α bands were not observed in each task. We suggest that the when pathway is active in response to only one object.

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