Pupil-linked arousal modulates behavior in rats performing a whisker deflection direction discrimination task

Area of Science:

• Neuroscience
• Animal Behavior
• Sensory Processing

Background:

• Non-luminance-mediated pupil size changes are established arousal indicators.
• Previous research linked pupil dynamics to sensory processing in animals.
• The relationship between pupil-linked arousal and perceptual task performance in animals remains unclear.

Purpose of the Study:

• To investigate the link between pupil dynamics, arousal, and perceptual performance in head-fixed rats performing a whisker direction discrimination task.
• To determine if baseline pupil size can predict behavioral outcomes in a cognitive task.

Main Methods:

• Head-fixed rats were trained on a Go/No-Go whisker movement direction discrimination task.
• Pupil size was continuously imaged during task performance.
• Behavioral data (reaction time, accuracy) and pupil dynamics were analyzed.
• A Bayesian decoder was used to predict behavioral outcomes from baseline pupil size.

Main Results:

• Reaction times were slower in the discrimination task compared to detection tasks, suggesting higher cognitive load.
• Pupil dilation occurred in all trials post-stimulus presentation.
• In correct rejection trials, pupil dilation was greater for more difficult stimuli.
• Baseline pupil size strongly correlated with perceptual sensitivity and reaction time.
• A Bayesian decoder accurately predicted behavioral outcomes from baseline pupil size.
• Previous trial outcomes influenced current trial behavior (faster responses after hits, higher sensitivity after correct rejections).

Conclusions:

• Pupil dynamics, perceptual performance, and reaction time are tightly correlated in behaving rats.
• Fluctuating arousal states, as indicated by pupil dynamics, modulate cognitive and perceptual performance.
• This study demonstrates a novel whisker discrimination task in rats and highlights the predictive power of baseline pupil size for behavior.