Biology subjects

Wen, M. J.

Publications and source records attributed to Wen, M. J..

3 recordsLinked to original sources

bioRxiv2023

Comment on 'Accumbens cholinergic interneurons dynamically promote dopamine release and enable motivation'

Acetylcholine is widely believed to modulate the release of dopamine in the striatum of mammals. Experiments in brain slices clearly show that synchronous activation of striatal cholinergic interneurons is sufficient to drive dopamine release via axo-axonal stimulation of nicotinic acetylcholine receptors. However, evidence for this mechanism in vivo has been less forthcoming. A recent paper in eLife (Mohebi et al., 2023) reported that, in awake behaving rats, optogenetic activation of striatal cholinergic interneurons with blue light readily evokes dopamine release measured with the red fluorescent sensor RdLight1. Here, we show that blue light alone alters the fluorescent properties of RdLight1 in a manner that may be misconstrued as phasic dopamine release, and that this artefactual photoactivation can account for the effects attributed to cholinergic interneurons. Our findings indicate that measurements of dopamine using the red-shifted fluorescent sensor RdLight1 should be interpreted with caution when combined with optogenetics. In light of this and other publications that did not observe large acetylcholine-evoked dopamine transients in vivo, the conditions under which such release occurs in behaving animals remain unknown.

neuroscience↗

bioRxiv2023

Targeted micro-fiber arrays for measuring and manipulating localized multi-scale neural dynamics over large, deep brain volumes during behavior

Neural population dynamics relevant for behavior vary over multiple spatial and temporal scales across 3-dimensional volumes. Current optical approaches lack the spatial coverage and resolution necessary to measure and manipulate naturally occurring patterns of large-scale, distributed dynamics within and across deep brain regions such as the striatum. We designed a new micro-fiber array and imaging approach capable of chronically measuring and optogenetically manipulating local dynamics across over 100 targeted locations simultaneously in head-fixed and freely moving mice. We developed a semi-automated micro-CT based strategy to precisely localize positions of each optical fiber. This highly-customizable approach enables investigation of multi-scale spatial and temporal patterns of cell-type and neurotransmitter specific signals over arbitrary 3-D volumes at a spatial resolution and coverage previously inaccessible. We applied this method to resolve rapid dopamine release dynamics across the striatum volume which revealed distinct, modality specific spatiotemporal patterns in response to salient sensory stimuli extending over millimeters of tissue. Targeted optogenetics through our fiber arrays enabled flexible control of neural signaling on multiple spatial scales, better matching endogenous signaling patterns, and spatial localization of behavioral function across large circuits.

neuroscience↗

bioRxiv2022

Local and long-distance inputs dynamically regulate striatal acetylcholine during decision making

Within the basal ganglia, striatal dopamine (DA) and acetylcholine (Ach) are essential for the selection and reinforcement of motor actions and decision making. In vitro studies have revealed a circuit local to the striatum by which each of these two neurotransmitters directly regulates release of the other. Ach, released by a unique population of cholinergic interneurons (CINs), drives DA release via direct axonal depolarization. In turn, DA inhibits CIN activity via dopamine D2 receptors (D2R). Whether and how this circuit contributes to striatal function in vivo remains unknown. To define the in vivo role of this circuit, we monitored Ach and DA signals in the ventrolateral striatum of mice performing a reward-based decision-making task. We establish that DA and Ach exhibit multiphasic and anticorrelated transients that are modulated by decision history and reward outcome. However, CIN perturbations reveal that DA dynamics and reward-prediction error encoding do not require Ach release by CINs. On the other hand, CIN-specific deletion of D2Rs shows that DA inhibits Ach levels in a D2R-dependent manner, and loss of this regulation impairs decision-making. To determine how other inputs to striatum shape Ach signals, we assessed the contribution of projections from cortex and thalamus and found that glutamate release from both sources is required for Ach release. Altogether, we uncover a dynamic relationship between DA and Ach during decision making and reveal modes of CIN regulation by local DA signals and long-range cortical and thalamic inputs. These findings deepen our understanding of the neurochemical basis of decision making and behavior.

neuroscience↗