Gradients of thalamic connectivity in the macaque lateral prefrontal cortex

Area of Science:

• Neuroscience
• Primate Brain Anatomy
• Cognitive Neuroscience

Background:

• The primate lateral prefrontal cortex (LPF) is crucial for cognitive control.
• Previous studies in macaques revealed distinct connectivity patterns within the LPF.
• Understanding thalamic input to the LPF is key to deciphering its functional organization.

Purpose of the Study:

• To investigate the topographical organization of thalamic projections to the primate LPF.
• To determine if fine-grained cortical connectivity gradients are reflected in thalamo-LPF projections.
• To map the specific thalamic nuclei projecting to different LPF sectors.

Main Methods:

• Utilized tracer injections at various dorsoventral and rostrocaudal levels of the primate cortex.
• Examined the projections from the nucleus medialis dorsalis (MD) to the LPF.
• Analyzed projections from the nucleus pulvinaris medialis and nucleus anterior medialis to the LPF.

Main Results:

• The nucleus medialis dorsalis (MD) is the primary source of thalamic input to the LPF.
• MD projections to the LPF exhibit a rostral-to-caudal organization, with more rostral MD zones targeting caudal LPF sectors.
• Specific MD sectors project to distinct LPF regions, including those involved in oculomotor control and ventral/dorsal LPF areas.

Conclusions:

• Thalamo-LPF projections, particularly from MD, are not organized by simple topological rules.
• The topography of these projections is primarily dictated by functional criteria.
• This study provides insights into the functional architecture of the primate prefrontal cortex and its thalamic connections.