Which EEG electrode is half the distance from O1 to T3?

Which EEG electrode is half the distance from O1 to T3?

• A. Oz
• B. T5
• C. C3
• D. P3

Answer: (B)

In the 10-20 system, electrode locations are arranged along lines around the scalp to map the underlying brain regions. On the left side, O1 sits toward the occipital region and T3 sits more toward the temporal region. Between these two along the posterior-lateral path sits T5, which is the left posterior-temporal/occipitotemporal site. Therefore, the halfway point between O1 and T3 aligns with T5. Oz is midline behind O1, C3 is more central-left, and P3 is left parietal—none of these sit between O1 and T3.

In the 10-20 system, electrode locations are arranged along lines around the scalp to map the underlying brain regions. On the left side, O1 sits toward the occipital region and T3 sits more toward the temporal region. Between these two along the posterior-lateral path sits T5, which is the left posterior-temporal/occipitotemporal site. Therefore, the halfway point between O1 and T3 aligns with T5. Oz is midline behind O1, C3 is more central-left, and P3 is left parietal—none of these sit between O1 and T3.