"decreased activity" is correct and usable in written English.
You can use it to refer to a decrease in activity, for example: The company reported decreased activity in the second quarter of the year.
E262A eliminated activation by all compounds tested (Figure S3), but E262D decreased activity solely for 4-NP-β-mannoside and phenyl-β-glucosaminide (Fig. 3).
Depression is associated with decreased activity of important neurotransmitters like serotonin and norepinephrine.
Bioassays showed similar trends in decreased activity.
Furthermore, NOC showed decreased activity during distraction versus engagement in both angry and happy stories.
At about this time, the underlying biochemical defect, decreased activity of hepatic PAH, was identified.
In particular, the scans showed decreased activity in the subgenual prefrontal cortex, the region of interest.
This phenomenon, Dr. Carson said, is often linked to a decreased activity in the prefrontal cortex.
Furthermore, activity in the ventral striatum* was closely correlated with success, with decreased activity leading to decreased performance.
They also had decreased activity in several brain regions associated with working memory and numerical reasoning.
The areas shaded in blue highlight areas of decreased activity in the brains of meditators.
Dorsal PPC and the precuneus showed decreased activity.
