Trail Making Test revisited: Patterns of visual and manual trajectories as markers of executive processes

KAMIENKOWSKI JE; LINARI I; JUANTORENA G; PETRONI A

Congreso; Vision Science Society Meeting; 2020

The Trail Making Test (TMT) is a neuropsychological test widely used for decades for the diagnosis of executive dysfunctions in a set of neurological and psychiatric conditions. Briefly, the TMT has two parts: A) participants have to connect 20 consecutive numbers and B) both numbers and letters are connected in an alternate order (1-A-2-B, etc). It is a complex task involving different stages, like visual search, planning, monitoring the hand movements, and so on. These stages are also supported by distinct executive functions. Surprisingly, it is done with paper and pencil, and only the total time is quantified, resulting in a huge variability and unspecificity. In the present study, we designed a computer version of the TMT in order to study in more detail the components of the task, where we measured both hand and gaze position with high resolution in healthy participants, providing a deeper understanding of the underlying processes involved in performing a traditional test. Moreover, this task results in a very rich scenario to study the organization and architecture of cognitive processes involved in complex behavior.Firstly, we found that total time (part B vs A) was similar to the traditional version. Secondly, regarding eye movements, saccade and fixation durations were similar in A and B, but fewer fixations were needed to complete part A. Thirdly, we found a longer lag between gaze and hand in B, explained by a delay in the outgoing hand movements but not in the gaze. Fourthly, these differences were correlated with a standardized evaluation of executive functions, in order to validate the digital TMT measures. Using both hand and eye movements we are able to parse the whole task into different stages, opening the possibility of exploring them in terms of different executive functions.