1: J Neurosci. 2005 Jan 12;25(2):473-8. 

Adaptation to visuomotor transformations: consolidation, interference, and
forgetting.

Krakauer JW, Ghez C, Ghilardi MF.

Department of Neurology, Columbia University College of Physicians and Surgeons,
New York, New York 10032-2603, USA.

The paradigm task A-->task B-->task A, which varies the time interval between
task A and task B, has been used extensively to investigate the consolidation of
motor memory. Consolidation is defined as resistance to retrograde interference
(interference by task B on initial learning of task A). Consolidation has been
demonstrated for simple skills, motor sequencing, and learning of force fields.
In contrast, evidence to date suggests that visuomotor learning does not
consolidate. We have shown previously that adaptation to a 30 degrees
screen-cursor rotation is faster and more complete on relearning 24 hr later.
This improvement is prevented if a 30 degrees counter-rotation is learned 5 min
after the original rotation. Here, we sought to identify conditions under which
rotation learning becomes resistant to interference by a counter-rotation. In
experiment 1, we found that interference persists even when the counter-rotation
is learned 24 hr after the initial rotation. In experiment 2, we removed
potential anterograde interference (interference by task B on relearning of task
A) by introducing washout blocks before all of the learning blocks. In contrast
to experiment 1, we found resistance to interference (i.e., consolidation) when
the counter-rotation was learned after 24 hr but not after 5 min. In experiment
3, we doubled the amount of initial rotation learning and found resistance to
interference even after 5 min. Our results suggest that persistent interference
is attributable to anterograde effects on memory retrieval. When anterograde
effects are removed, rotation learning consolidates both over time and with
increased initial training.

PMID: 15647491 [PubMed - in process]