Cholinergic Modulation of Neurovascular Coupling and Neuroimaging Signals

The use of non-invasive functional neuroimaging methods to discriminate levels or patterns of brain activity between different groups, across different time points, or in response to drug treatment, depends on an understanding of neurovascular coupling relationships and how they themselves are affected by the factors of interest. For instance, Alzheimers disease (AD) features cerebral blood flow (CBF) and neurovascular unit changes as well as being characterised by a cholinergic dysfunction which impacts upon CBF regulation. The present study investigated the acute neurovascular effects of cholinergic agonist and antagonist treatment in a rat model utilising a multimodal measurement approach. Drugs were administered to rats during concurrent imaging of cortical CBF and recording of local field potential responses to somatosensory stimulation. Analysis of concurrent neuronal and vascular measures revealed a pronounced loss of neurovascular coupling following treatment with the cholinergic antagonist scopolamine. Separate analysis of CBF and neuronal responses reveal an interaction effect of stimulus input and drug treatment for both cholinergic agonist and antagonist treatment, as well as an augmentation of both neuronal and haemodynamic response magnitudes after treatment with the clinically prescribed cholinergic agonist donepezil. These findings have implications for the use and interpretation of functional neuroimaging data acquired in individuals with disease-related or pharmacological manipulations of cholinergic function.