Segregation of the human basal forebrain using resting state functional MRI

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Neuroimaging

Background:

• The basal forebrain (BF) is crucial for cognition due to its widespread projections and complex neurochemistry.
• While BF function is studied in animals, in vivo human BF research is limited.
• Understanding human BF in vivo function is key to understanding its role in cognition.

Purpose of the Study:

• To investigate the functional segregation of human basal forebrain (BF) nuclei in vivo.
• To map the distinct projection patterns of BF nuclei using resting-state functional magnetic resonance imaging (rs-fMRI).
• To explore the neuromodulatory role of the human BF in orchestrating brain network dynamics.

Main Methods:

• Utilized multi-echo resting-state functional magnetic resonance imaging (rs-fMRI) in 100 young adults (18-34 years).
• Applied multi-echo processing for enhanced signal-to-noise ratio (SNR), particularly in the BF.
• Employed bottom-up clustering of voxel-wise BF functional connectivity maps.

Main Results:

• Identified distinct functional clusters within the BF, aligning with the nucleus basalis of Meynert (NBM) and medial septum/diagonal band of Broca (MS/DB).
• Observed unique projection patterns for NBM (widespread cortical and amygdala coupling) and MS/DB (orbitofrontal cortex and hippocampal complex coupling).
• Demonstrated conserved, nuclei-specific functional connectivity in humans compared to known anatomical projections.

Conclusions:

• Human BF nuclei (NBM and MS/DB) support distinct resting-state functional networks.
• The human BF functions as a neuromodulatory hub, orchestrating brain network dynamics.
• These findings highlight the in vivo functional segregation of the human BF.