Certain pyrazolo[3,4-b]pyridine compounds which are useful for their activity in the central nervous system of warm-blooded animals, of the following formula (I) ##STR1## wherein R.sub.1 is lower alkyl;R.sub.a is hydrogen and R.sub.b is hydroxy or R.sub.a and R.sub.b combine to form a .dbd.O group;R.sub.5 is hydrogen or lower alkyl; andR.sub.6 is lower alkyl,and the pharmaceutically-acceptable salts thereof.