Practice induces function-specific changes in brain activity

Background

Practice can have a profound effect on performance and brain activity, especially if a task can be automated. Tasks that allow for automatization typically involve repeated encoding of information that is paired with a constant response. Much remains unknown about the effects of practice on encoding and response selection in an automated task.

Methodology

To investigate function-specific effects of automatization we employed a variant of a Sternberg task with optimized separation of activity associated with encoding and response selection by means of m-sequences. This optimized randomized event-related design allows for model free measurement of BOLD signals over the course of practice. Brain activity was measured at six consecutive runs of practice and compared to brain activity in a novel task.

Principal Findings

Prompt reductions were found in the entire cortical network involved in encoding after a single run of practice. Changes in the network associated with response selection were less robust and were present only after the third run of practice.

Conclusions/Significance

This study shows that automatization causes heterogeneous decreases in brain activity across functional regions that do not strictly track performance improvement. This suggests that cognitive performance is supported by a dynamic allocation of multiple resources in a distributed network. Our findings may bear importance in understanding the role of automatization in complex cognitive performance, as increased encoding efficiency in early stages of practice possibly increases the capacity to otherwise interfering information.     

Age-dependent changes in activity of mallard plasma cholinesterases

Plasma acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activity was measured repeatedly in 27 mallard (Anas platyrhynchos) ducklings between 7 and 85 days of age to determine age-dependent changes in enzyme activity. Plasma AChE, BChE, and total cholinesterase (ChE) activity decreased significantly with age. The relative proportion of AChE in total ChE activity also decreased slightly with age. Since some anti-ChE chemicals can selectively inhibit AChE or BChE activity, characterization of age-dependent changes in the activity of each enzyme may be necessary to accurately identify the occurrence of pesticide exposure.