PKA has always been considered important in formation of a memory. In the fruit fly, reductions in expression activity of DCO (PKA catalytic subunit encoding gene) can cause severe learning disabilities, middle term memory and short term memory. Long term memory is dependent on the CREB transcription factor, regulated by PKA. A study done on drosophila reported that an increase in PKA activity can affect short term memory. However, a decrease in PKA activity by 24% inhibited learning abilities and a decrease by 16% affected both learning ability and memory retention. Formation of a normal memory is highly sensitive to PKA levels.