Fiber pathways connecting cortical areas relevant for spatial orienting and exploration

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Neuroimaging

Background:

• Spatial neglect, a deficit in spatial awareness, is often studied in stroke patients.
• Previous research identified cortical areas activated during spatial tasks that, when lesioned, cause spatial neglect.

Purpose of the Study:

• To investigate direct cortico-cortical connections between brain regions activated during a spatial neglect-like task in healthy subjects.
• To empirically validate the postulated perisylvian network for spatial orienting and attention in healthy individuals.

Main Methods:

• Probabilistic fiber-tracking was used in 52 healthy subjects.
• Functional activation data from a spatial neglect-like task (Himmelbach et al.) were used to define target regions.

Main Results:

• Direct connections were found between prefrontal cortex clusters and the superior temporal cortex and temporo-parietal junction (TPJ) via the extreme capsule (EmC) and middle longitudinal fascicle (MdLF).
• The TPJ activation peak was further connected to the inferior frontal cortex through the arcuate fascicle and superior longitudinal fascicle (SLF II) in the right hemisphere.

Conclusions:

• This study provides the first empirical evidence of the complete perisylvian network connecting key areas for spatial orienting and attention in healthy subjects.
• The findings complement patient studies by detailing the anatomical underpinnings of spatial attention networks.