Introduction
Highly skilled surgeons have the ability to monitor and rapidly adapt to changes in the environment, appropriately tune into relevant information variables, select from a large repertoire of possible sensorimotor commands and execute with a smoothness that belies their many years of training.1 2 While the majority of research on surgical performance has examined the overt behavioral characteristics of such expertise (e.g., time to task completion3 4) and subjective measures of mental workload (largely examined through post hoc surveys5), there have been very few investigations into the underlying cognitive mechanisms that mediate the ability to carry out the complex sequences of action selection and execution required for surgical practice (see ref 6 for a review).
In cognitive neuroscience, the processes involved in goal-directed attention, outcome monitoring, executing motor commands and suppressing irrelevant motor responses are clustered under the label of ‘cognitive control’ (also referred to as ‘executive function’7). One putative neural correlate of cognitive control is a pattern of oscillatory brain activity known as ‘frontal theta’—a signal that can be observed on the scalp through electroencephalography (EEG) recordings and quantified by calculating signal power in the 4–7 Hz range.8
Frontal theta is considered to be critical in performance monitoring9 10 and core to error detection10 11—the key to triggering selection and prioritization of information processing12 13 and subsequent action.14 15 The recruitment of these ‘top down’ control processes is heightened in scenarios where automatic processes are insufficient for successful adaptation to the current environment,7 with the prefrontal cortex responsible for engaging a broad network of systems involved in goal-directed actions.16–20 To our knowledge, there has been no examination into the relationship between this neural signal and surgical performance to date.
Extant theories of skill acquisition often describe a shift from deliberate to automatic action selection and execution, with requisite reductions in the working memory requirements during the performance of a highly practiced action.21 A recent unifying framework for theories of cognition and action—known as the ‘Free Energy Principle’—proposes that the neocortex (involved in higher order functions, such as sensory perception and spatial reasoning) constantly makes inferences about the world and learns from experiences through the violation of its predictions.22 Viewed in this framework, frontal theta activity could serve as both a teaching signal for the system to learn that it needs to refine its prediction for the future and simultaneously, trigger the cognitive resources required to produce adaptive control.23 A more accurate world model would require fewer behavioral adjustments and thus, a reduction in the need to recruit cognitive control.
Predicated on this theory and evidence from neuroscience, we examined whether frontal theta activity could be used to distinguish between experienced and novice dental surgery trainees on a simulated drilling task carried out on a high-fidelity virtual reality simulator. We predicted that overall, novice participants would exhibit greater task-related theta activity, reflecting greater top-down engagement of cognitive control processes relative to their more experienced counterparts. Second, given that behavioral adaptation following prediction error is a hallmark of learning, we expected a relationship between performance errors and frontal theta activity.