Title: Neural bases for producing temporal order

Speaker: Prof.Shigeru Kitazawa, Graduate School of Frontier Biosciences, Osaka University

Time: 13:00-14:30, October 30, 2018

Location: Room 1113, Wang Kezhen Building

Abstract:

McTaggart (1908) proposed that a position in time is discriminated in two ways. First, each position is either Past, Present, or Future (A series). Second, each position is either before or after another (B series).

Most previous studies addressed a question of the B series. Previous literature show that the brain can resolve the order of two stimuli that are separated in time by 30 ms. This applies to temporal order judgment of two tactile stimuli, delivered one to each hand, as long as the arms are uncrossed. However, crossing the arms caused many subjects to misreport the temporal order. When the stimuli were delivered to the tips of sticks held in each hand, the judgment was altered by crossing the sticks without crossing the hands. In combination with data from functional imaging, we proposed that a group of events are represented in space around the intraparietal cortex, and combined with the temporal directional cue provided by the motion signals in the left temporo-parietal junction. We also found that that the B series is affected by the alpha rhythm whose current source is located in the precuneus.

We have further addressed the issue of where the A-series (Past-Present-Future) is represented by using verbal stimuli that elicits clear “futureness”, “presentness”, and “pastness” in our mind. Based on data from functional imaging studies, we suggest that the A-series is represented in the medial surface of the cerebral cortex with the “present” in the precuneus. Taken together, we suggest that the precuneus and adjacent regions may play a key role in representing the A as well as the B series.

Host PI: Dr. Yuji Naya