Putative neurochemical and cell type contributions to hemodynamic activity in the rodent caudate putamen

Abstract

Functional magnetic resonance imaging (fMRI) is widely used by researchers to noninvasively monitor brain-wide activity. The traditional assumption of a uniform relationship between neuronal and hemodynamic activity throughout the brain has been increasingly challenged. This relationship is now believed to be impacted by heterogeneously distributed cell types and neurochemical signaling. To date, most cell-type- and neurotransmitter-specific influences on hemodynamics have been examined within the cortex and hippocampus of rodent models, where glutamatergic signaling is prominent. However, neurochemical influences on hemodynamics are relatively unknown in largely GABAergic brain regions such as the rodent caudate putamen (CPu). Given the extensive contribution of CPu function and dysfunction to behavior, and the increasing focus on this region in fMRI studies, improved understanding of CPu hemodynamics could have broad impacts. Here we discuss existing findings on neurochemical contributions to hemodynamics as they may relate to the CPu with special consideration for how these contributions could originate from various cell types and circuits. We hope this review can help inform the direction of future studies as well as interpretation of fMRI findings in the CPu.

Acute alcohol induces greater dose-dependent increase in the lateral cortical network functional connectivity in adult than adolescent rats

“…Glucose is essential for the synthesis of the glutamate-precursor glutamine [ 97 ], and alcohol misuse has been linked to a deficit in extracellular glutamate levels and an altered balance between the glutamate-dependent excitatory and GABA-dependent inhibitory neurotransmission systems [ 98 , 99 ]. Nevertheless, it should be noted that decrease in neuronal activity or glucose metabolism does not necessarily come with a decrease in FC (i.e., enhanced synchronization can occur at lower amplitude of activity), and involvement of vasoactive neurotransmission can lead to decoupling between neuronal activity and flow [ 60 , 100 , 101 ]. In a recent study, Ochi and colleagues (2022) reported an inverted correlation between alcohol-induced increase in cortical FC and somatostatin cortical gene expression in human brain, suggesting that alcohol-induced inhibition of GABAergic interneurons might underly the change in connectivity [ 83 ].…”