Parallel Processing

Students in the spotlight

The Processing of Ryan Phillips: Getting past the default

That moment when you realize you’ve been intently staring at your boss for the last five minutes -watching his or her mouth move, you’ve even been nodding intently -and suddenly you’re acutely aware that you have no idea what has been said that whole time.  It’s an experience we all have had, perhaps more often than we’d like to admit. It’s a reaction that is unpredictable, hard to control, and generally inexplicable.

Ryan Philips wants to change all that.

During his time in the Carter Lab, Ryan has become interested in the functions of the Default Mode Network (DMN). Comprised of functionally correlated brain regions including the ventromedial prefrontal cortex (PFC), posterior cingulate cortex, and inferior parietal sulcus, the DMN was originally defined by its tendency to decrease in activation during focused tasks, and has been generally thought to represent the brain at rest.  The DMN is also referred to as the “task-negative” network, distinguishing it from other “task-positive” brain areas that tend to be engaged during tasks.  Ryan, however has kept his eye on recent research suggesting that the DMN may be more than just “task-negative.” He thinks the DMN may subserve a set of processes that interfere with task performance, including self-reflective thought and mind-wandering.

Coming from a philosophical background (he holds a Bachelor of Arts in cognitive science with a minor in philosophy from Occidental College in Los Angeles), Ryan spends a lot of  his time wondering about neurological processes that may be difficult to define, but which affect our day-to-day lives. His interest in everyday mind-wandering, which he describes as short and involuntary shifts in attention away from a task, has motivated his current study.

“I’m interested in the interaction of logic and thinking intentionally with emotion or passions (like those that might arise during self-reflective ruminations) which are not as formal and rigid but which still compel us to do things,” he says.  “Especially when that interaction causes attention to fail and break down.”

Ryan has designed a task which he hopes will allow him to investigate the relationship between lapses in attention induced by self-reflective processes and activity in the DMN. He will attempt to induce such processes through the presentation of self-referential words while asking subjects to complete the AX Continuous Performance Task (AXCPT), an attention and cognitive control task. The AXCPT requires impulsivity control and context management. Subjects must suppress indication of the wrong target following an invalid cue and must only indicate the correct target when it is preceded by the appropriate probe. Ryan expects that presenting words with high emotional significance, such as “lazy,” will influence activation of the DMN differently than words with low emotional significance, such as “relaxed.” He also predicts that he will see poorer performance, indicating more lapses, when the words are particularly relevant to the subject.

Ryan is currently conducting a behavioral pilot study with undergraduate student participants to validate his task. He expects to see an effect of high significance words on reaction time and error frequency. If so, he hopes to begin incorporating functional imaging by winter. At that point he will be able to test his hypothesis that DMN activity will be positively  correlated with errors and long reaction times, which in turn will be correlated with high significance self-referential words. He is also curious to see how regions subserving executive control might play in.

“My main prediction is that the dorsolateral PFC might be incorporated into the processing of the DMN,” he explained. “The other prediction I would make is that as it increases in connectivity with the DMN regions, it may decrease in connectivity with other task positive regions. The ultimate idea being that the resources of the dorsolateral PFC are not available for task positive activities any longer.”

Ryan hopes that research in this area will eventually allow us to be able to describe mind-wandering as more than just some random, unpredictable phenomenon.

“I think we will find that it’s not just spontaneous activity in the DMN, but something important related to the self that is occurring.”


To learn more about Ryan’s research you can visit his poster entitled “Disentangling the Roles of the Default Mode Network in Attention Lapses” at the Northern California Consciousness meeting on Friday, October 17, 2014 at the UC Davis Center for Mind and Brain.