# Different Brain Network Connectomic Relationships Subserve Hand Dexterity During Task Versus Resting States in People with Brain Tumors

## TL;DR

This study shows that brain network connections related to hand dexterity differ when patients with brain tumors are at rest versus performing tasks.

## Contribution

The study reveals distinct connectomic relationships for dexterity in task and resting states in brain tumor patients.

## Key findings

- Low somatomotor-basal ganglia connectivity at rest and high during tasks correlates with poor dexterity.
- Resting somatomotor-salience connectivity is higher in poor dexterity performers, similar to healthy controls.
- Connectomic measures predict dexterity better than tumor size, grade, or location.

## Abstract

The purpose of this study was to explore different brain network connectomic relationships subserving hand dexterity in patients with contrast‐enhancing brain tumors during task and resting states.

We measured hand dexterity, resting state functional connectivity, and task‐based functional connectivity in 21 participants with newly diagnosed brain tumors. Hand dexterity was measured using the 9‐hole peg test (9HPT), and patient‐reported outcomes were assessed with the Duroz Hand Index (DHI).

We discovered the following: (1) The inability to complete dexterous tasks is most associated with low somatomotor‐basal ganglia network connectivity during rest but high somatomotor‐basal ganglia network connectivity during tasks; (2) in the subgroup of better dexterous performers, resting somatomotor‐salience connectivity is higher in people with poor dexterity—a relationship that holds true in healthy adult subjects from the Human Connectome Project (HCP), suggesting it has fundamental importance; and (3) connectomic measurements were stronger predictors of dexterous performance than classical variables of tumor (i.e., size, grade, or anatomical location).

These data suggest that connectomic correlates of dexterity are different in resting and task‐based states. Additionally, our data suggest a threshold level of somatomotor‐to‐basal ganglia connectivity is required to accomplish dexterous movements, and, in the cases of appropriately preserved somatomotor‐to‐basal ganglia connectivity, salience‐somatomotor connectivity then becomes the dominant connection facilitating performance in a hierarchical fashion. These findings have fundamental implications for both surgical planning and neuromodulation‐based rehabilitation.

Key findings of this study include that poor dexterity in patients with brain tumors is related to reduced somatomotor connectivity to the basal ganglia and increased connectivity with the salience networks. Lesions in the anterior hand knob are most associated with such reduced dexterity and connectivity.