Inferring spikes from calcium imaging in dopamine neurons

Abstract

Calcium imaging has led to discoveries about neural correlates of behavior in subcortical neurons, including dopamine (DA) neurons. However, spike inference methods have not been tested in most populations of subcortical neurons. To address this gap, we simultaneously performed calcium imaging and electrophysiology in DA neurons in brain slices, and applied a recently developed spike inference algorithm to the GCaMP fluorescence. This revealed that individual spikes can be inferred accurately in this population. Next, we inferred spikes in vivo from calcium imaging from these neurons during Pavlovian conditioning, as well as during navigation in virtual reality. In both cases, we quantitatively recapitulated previous in vivo electrophysiological observations. Our work provides a validated approach to infer spikes from calcium imaging in DA neurons, and implies that aspects of both tonic and phasic spike patterns can be recovered.

Local accumbens in vivo imaging during deep brain stimulation reveals a strategy-dependent amelioration of hedonic feeding

“…Of note, while calcium signals have been used to infer neuronal action potential rate, calcium signals are not equivalent to action potentials. The few prior studies in dopaminergic cells inferring spike activity from calcium signals (39) have been limited to ex vivo assessments using single-cell recordings, and therefore their conclusion may not apply when comparing our results with that of O'Connor (13). Further, calcium signaling is not exclusive to action potentials and may be activated by subthreshold depolarization and capture intrinsic, input, and output activity.…”

Arginine-Vasopressin Expressing Neurons in the Murine Suprachiasmatic Nucleus Exhibit a Circadian Rhythm in Network Coherence In Vivo

“…Our data indicate that most AVP neurons in the SCN exhibit slow calcium waves, approximately 20% of which show a modulatory rhythm of their frequency over a 24-hour period ( Figure 2G-I ). While increases in intracellular calcium can be indicative of neuronal firing [62], because of the slow decay time of the variant of GCaMP7 we employed, temporal discrimination of individual action potentials within bursting events was not possible. Thus, we employed SUA AVP to better characterize the firing behavior of AVP neurons within the SCN in vivo .…”