Basal forebrain subcortical projections

• Published in: Brain Structure and Function Vol. 224; no. 3; pp. 1097 - 1117
• Main Authors: Agostinelli, Lindsay J., Geerling, Joel C., Scammell, Thomas E.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.04.2019; Springer Nature B.V
• Subjects: Animals; Arousal; Basal forebrain; Basal Forebrain - anatomy & histology; Basal Forebrain - metabolism; Biomedical and Life Sciences; Biomedicine; Brain Mapping; Cell Biology; Choline O-Acetyltransferase - genetics; Choline O-Acetyltransferase - metabolism; Cre recombinase; Dynorphins - metabolism; Female; Forebrain; Glutamatergic transmission; Glutamic Acid - metabolism; Luminescent Proteins - genetics; Luminescent Proteins - metabolism; Mice; Mice, Transgenic; Motivation; Nerve Net - physiology; Neural Pathways - physiology; Neurology; Neurons; Neurons - classification; Neurons - physiology; Neurosciences; Original Article; Preoptic area; Red Fluorescent Protein; Septum; Substantia innominata; Transduction, Genetic; Vesicular Glutamate Transport Protein 2 - genetics; Vesicular Glutamate Transport Protein 2 - metabolism; Vesicular Inhibitory Amino Acid Transport Proteins - genetics; Vesicular Inhibitory Amino Acid Transport Proteins - metabolism; γ-Aminobutyric acid; GABA; Mice; Acetylcholine; Tracing; Substantia innominata; Anterograde
• ISSN: 1863-2653; 1863-2661; 1863-2661; 0340-2061
• DOI: 10.1007/s00429-018-01820-6

The basal forebrain (BF) contains at least three distinct populations of neurons (cholinergic, glutamatergic, and GABA-ergic) across its different regions (medial septum, diagonal band, magnocellular preoptic area, and substantia innominata). Much attention has focused on the BF’s ascending projections to cortex, but less is known about descending projections to subcortical regions. Given the neurochemical and anatomical heterogeneity of the BF, we used conditional anterograde tracing to map the patterns of subcortical projections from multiple BF regions and neurochemical cell types using mice that express Cre recombinase only in cholinergic, glutamatergic, or GABAergic neurons. We confirmed that different BF regions innervate distinct subcortical targets, with more subcortical projections arising from neurons in the caudal and lateral BF (substantia innominata and magnocellular preoptic area). Additionally, glutamatergic and GABAergic BF neurons have distinct patterns of descending projections, while cholinergic descending projections are sparse. Considering the intensity of glutamatergic and GABAergic descending projections, the BF likely acts through subcortical targets to promote arousal, motivation, and other behaviors.