Association fibers are axons (nerve fibers) that connect cortical areas within the same cerebral hemisphere.

The association fibers unite different parts of the same cerebral hemisphere, and are of two kinds: (1) short association fibers that connect adjacent gyri; (2) long association fibers that make connections between more distant parts.

Many of the short association fibers (also called arcuate or "U"-fibers) lie in the superficial white matter immediately beneath the gray matter of the cerebral cortex, and connect together adjacent gyri.

[3] The long association fibers connect the more widely separated gyri and are grouped into bundles.

[3] They include the following: Diffusion tensor imaging is a non-invasive method to study the course of association fibers.