چكيده به لاتين
Investigation of the relationship between neural activities and behavioral responses is an important issue in behavioral neuroscience. It helps neuroscientists to quantify connection between the neural activity and cognition. One crucial parameter that represents the time period between cortical processing till to behavioral action is behavioral reaction time (RT). Different parts of brain are taking apart in processing behavioral actions, including visual cortex. However, it is not clear how neurons in associative visual areas are processing the relevant information and shaping a behavioral action. To answer, we examined the neural activities from visual area MT of macaque monkeys during a change detection task. Previous investigations in visual cortex have shown that attention can shorten RT and enhance the correlation between neural activity and behavioral responses. So, it is important to be considered visual attention as an important factor that influences neural-behavioral correlation. Our results show that visually evoked activity in macaque MT area can predict the speed of behavioral responses. Furthermore, we found that synchronization in high-gamma frequencies (180-220 Hz) is significantly enhanced among MT neurons (an area within dorsal visual pathway) preceding to fast behavioral responses. Given a similar observation, but in gamma frequency band (40-70 Hz) in area V4 (an area within ventral visual pathway), we proposed that downstream association area may use these frequency bands to distinguish the source of information (spikes) receives from two visual pathway. Investigation of nested oscillations in MT area reveals that the beta oscillation (10-26 Hz) may facilitate communication of the high-gamma information between upstream and downstream associated areas. Accordingly, our results propose that visual attention influences information processing and shorten RT via two independent ways; (1) by improving neural coding (discriminability) in sensory areas and (2) by facilitating the communication with downstream areas for routing the most relevant behavioral information. Moreover, the data suggests that non-linear cortical process may play functional role in processing and controlling the speed of behavioral responses.
