Disclosed herein is a compound represented by the formula (I) wherein each symbol is as defined in the specification, or a salt thereof, which has an AMPA (&alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptor potentiating action. The compound of the present disclosure is useful as a prophylactic or therapeutic drug for depression, schizophrenia, Alzheimer&rsquos disease or attention deficit hyperactivity disorder (ADHD) and the like. Embodiments of the compound include the following: 9-(4-phenoxyphenyl)-3,4-dihydropyrido[2,1-c][1,2,4]thiadiazine 2,2-dioxide, and 9-[4-(cyclohexyloxy)phenyl]-3,4-dihydropyrido[2,1-c][1,2,4]thiadiazine 2,2-dioxide.
