Alcohol consumption impairs motor coordination, attentional efforts and memory function. Alcohol-impaired driving accounted in 2013 for ~31% of all traffic accidents resulting in 10,076 fatalities and $59 billion crash-related cost. We propose to study the mechanisms how ethanol affects brain state-dependent neural signaling. Brain state-dependent signaling comprises adjustments in cellular and circuit activity to optimize how the brain processes information in a distinct behavioral context. We and others have used a locomotion paradigm to reveal that noradrenergic signaling is involved when such optimizations occur. At transitions from rest to locomotion astroglia, the support cells in the central nervous system, are norepinephrine-dependently activated simultaneously in brain regions as disparate as the cerebellum and primary visual cortex. The noradrenergic system is involved to support attentional efforts and in gating synaptic plasticity. It has long been known that alcohol can suppress the activity of locus coeruleus, the structure where noradrenergic neurons are clustered; however, it is still unclear what the consequences are for the activity of individual brain cells during active behavior. We propose to test the hypothesis that alcohol severely impairs brain state-dependent noradrenergic neuromodulation in an astroglia-dependent manner. Our approach is to combine specific mouse lines for cell type-selective genetic manipulation and expression of Ca2+ sensors with our motorized linear treadmill and two-photon microscopy to study Ca2+ dynamics and electrical activity in well-controlled behavioral states. These in vivo investigations will be complemented with acute slice Ca2+ imaging and electrophysiology experiments. We will focus our investigations on the cerebellum for its relatively straightforward circuit arrangement that facilitates mechanistic studies. The novel utilization of a specific Cre mouse line will enable us to selectively manipulate Bergmann glia, the astrocytes of the cerebellar molecular layer, but not astrocytes of the granule cell layer. We will pursue the following aims: (1) We will define extent and mechanism of the effect of acute ethanol on locomotion-induced Bergmann glia Ca2+ activation. (2) We will reveal ethanol-sensitive components of locomotion-induced Purkinje cell Ca2+ dynamics and dissect the relationship to Bergmann glia function. (3) We will investigate how locomotion- induced Purkinje cell Ca2+ dynamics regulate intrinsic and synaptic activity. Upon conclusion of our proposed studies we will have learned what components of brain state-dependent noradrenergic neural signaling are impaired by ethanol. This work will reveal how ethanol might exert its detrimental effects on attentional efforts and memory on the cellular and circuit level. These studies will further build the groundwork for future research on brain state-dependent neural signaling under neurodegenerative and neurobehavioral conditions associated with changes in noradrenergic signaling, such as Alzheimer's disease, Parkinson's disease and autism spectrum disorder.
Brain state-dependent neural signaling represents adjustments in cellular and circuit activity to optimize brain activity. The proposed studies will establish the critical foundation for understanding how alcohol impairs brain state-dependent neural signaling and might exercise its detrimental effects on attentional efforts and memory. This work will also help us predict alterations in brain activity under neurodegenerative and neurobehavioral conditions associated with changes in noradrenergic signaling, such as Alzheimer's disease, Parkinson's disease and autism.
| Ye, Liang; Haroon, Mateen A; Salinas, Angelica et al. (2017) Comparison of GCaMP3 and GCaMP6f for studying astrocyte Ca2+ dynamics in the awake mouse brain. PLoS One 12:e0181113 |
