A paper that recently appeared in the journal Neuron sets up an interesting dichotomy in describing how to view the function of the brain. One option it presents is that the brain is an input-output device: give it a stimulus, and it will process it and respond. The alternative view is that the brain is simply doing its own thing, and stimuli act to modulate its activity, rather than direct it. Since the first perspective is an easier one to approach experimentally, it has received most of the attention, but the paper presents evidence that the alternative view shouldn't be ignored.
The experiments in the paper are built around two observations. The first is that just about every measure of brain function detects spontaneous, organized activity even when the owner of the brain doesn't appear to be doing anything—in fact, this kind of activity has been detected when people are under anesthesia. The second key observation is that, even on the simplest tests, the same individual will perform differently when the test is repeated. The authors simply asked if these two were linked: is human action influenced by spontaneous brain activity?
The researchers focused on the somatomotor cortex, or SMC, as previous work has shown that the left and right SMC undergo coordinated spontaneous activity. The experiments involved a test that only required activity in the left SMC: right-handed individuals were asked to watch a symbol, and press a button with their right hand when it vanished. Due to the way the brain is wired, only the SMC on the left side will be active during this test.
