Noradrenaline modulates neuronal and perceptual visual detectability via β-adrenergic receptor

Rationale Noradrenaline (NA) is a neuromodulator secreted from noradrenergic neurons in the locus coeruleus to the whole brain depending on the physiological state and behavioral context. It regulates various brain functions including vision via three major adrenergic receptor (AR) subtypes. Previous studies investigating the noradrenergic modulations on vision reported different effects, including improvement and impairment of perceptual visual sensitivity in rodents via beta-AR, an AR subtype. Therefore, it remains unknown how NA affects perceptual visual sensitivity via beta-AR and what neuronal mechanisms underlie it. Objectives The current study investigated the noradrenergic modulation of perceptual and neuronal visual sensitivity via beta-AR in the primary visual cortex (V1). Methods We performed extracellular multi-point recordings from V1 of rats performing a go/no-go visual detection task under the head-fixed condition. A beta-AR blocker, propranolol (10 mM), was topically administered onto the V1 surface, and the drug effect on behavioral and neuronal activities was quantified by comparing pre-and post-drug administration. Results The topical administration of propranolol onto the V1 surface significantly improved the task performance. An analysis of the multi-unit activity in V1 showed that propranolol significantly suppressed spontaneous activity and facilitated the visual response of the recording sites in V1. We further calculated the signal-to-noise ratio (SNR), finding that the SNR was significantly improved after propranolol administration. Conclusions Pharmacological blockade of beta-AR in V1 improves perceptual visual detectability by modifying the SNR of neuronal activity.

Automated summary

Pharmacological blockade of beta-AR in the primary visual cortex (V1) improves perceptual visual detectability by enhancing signal-to-noise ratio (SNR) of neuronal activity.