Delay-dependent cholinergic modulation of visual short-term memory in rhesus macaques

Area of Science:

• Neuroscience
• Cognitive Science
• Pharmacology

Background:

• Cholinergic neuromodulation significantly impacts visual working memory (VWM).
• Evidence on cholinergic effects during VWM delay periods in primates is mixed.
• Understanding VWM decay and cholinergic influence is crucial for cognitive research.

Purpose of the Study:

• To characterize VWM maintenance across varying delay durations in rhesus macaques.
• To investigate the influence of cholinergic neuromodulation on VWM maintenance.
• To examine the effects of scopolamine and donepezil on VWM performance.

Main Methods:

• Utilized a delayed matching to sample task in rhesus macaques (N=6).
• Administered scopolamine (muscarinic antagonist) and donepezil (acetylcholinesterase inhibitor).
• Assessed VWM performance across delay durations from 1 to 76 seconds.

Main Results:

• Scopolamine-induced VWM impairments were delay-dependent, most prominent between 15-33 seconds.
• Scopolamine exacerbated the natural decay of VWM over time.
• Donepezil partially mitigated the VWM deficits caused by scopolamine.

Conclusions:

• Cholinergic tone, particularly via muscarinic receptors, is critical for VWM maintenance beyond a few seconds.
• Findings support the role of cholinergic system in sustaining neural activity during VWM delays.
• This study provides behavioral evidence for cholinergic neuromodulation in VWM maintenance.