Most brain imaging experiments tend to follow a similar pattern - instruct the participant to perform some task, or show them a picture, or play them a sound, and then see which areas of their brain light up. This approach has propagated a misconception that the brain has to be prodded into action. But the reality is that the brain constantly beavers away and guzzles just as much energy when we're resting doing nothing, as when we're engaged in an externally focused task. In fact, there's a default network that actually ramps up its activity levels during rest compared with when we're outwardly engaged. Such findings have prompted speculation about what all this resting brain activity is for. Possibilities include preparing for the future and mind-wandering. A new study, however, provides evidence that resting brain activity is involved in motor learning.
Neil Albert and colleagues scanned the brains of 24 participants twice: when they were resting before a joystick task and then again resting afterwards. Crucially, half the participants performed the tracking task with a dodgy joystick that became progressively disconnected from its cursor. These participants had to adapt continuously to the changing de-synchronisation between joystick and cursor. The remaining control participants used a normal joystick. All participants also performed an irrelevant four-minute visual task prior to the final resting brain scan. This was to rule out any effects on the second resting scan that may have been caused by the participants still thinking about that dodgy joystick.
The initial scan of the participants at rest revealed a number of resting state networks: suites of inter-connected brain regions pulsing away in unison. In the brains of the participants who had to adapt to the dodgy joystick, but not the control participants, the strength of one of these - a fronto-parietal network - was greater in the second resting scan, as if it was still particularly busy consolidating the earlier motor learning. A second resting network, incorporating the cauliflower-like cerebellum at the back of the brain, also grew in strength in the brains of the participants who had to adapt to the dodgy joystick, whereas this network wasn't even present in the control participants.
These findings suggest that it was specifically learning to control the dodgy joystick, not joystick use per se, that led to increased activity in two resting state networks. "We have shown that motor learning, but not motor performance, can modulate particular resting state networks," the researchers said. "Our results add a new dimension to our understanding of the resting brain and potentially provide a powerful new technique to examine the neuronal machinery of off-line processing," they concluded.
Albert, N., Robertson, E., & Miall, R. (2009). The Resting Human Brain and Motor Learning. Current Biology, 19 (12), 1023-1027 DOI: 10.1016/j.cub.2009.04.028
Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.