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Fassihi A, Akrami A, Esmaeili V, Diamond ME (2014) Tactile perception and working memory in rats and humans. Proceedings of the National Academy of Sciences USA, 111(6):2331-2336    
Many higher cognitive functions involve working memory (WM), the storage and manipulation of information across limited time intervals. Comparing the WM capacity of different species is a key step toward understanding the underlying brain mechanisms. This study uncovers previously unknown sensory WM abilities in rats. They received two vibratory stimuli on their whiskers, separated by a variable delay, and had to compare vibration features. In analogous experiments, human subjects compared two stimuli applied to the fingertip. The acuity shown by rats in judging stimulus differences and their WM proficiency (across delays of 8 s, the longest tested) overlapped those of humans. Sensory WM now joins other cognitive functions within the rodent repertoire, setting the stage for exploration of its neuronal coding
Primates can store sensory stimulus parameters in working memory for subsequent manipulation, but until now, there has been no demonstration of this capacity in rodents. Here we report tactile working memory in rats. Each stimulus is a vibration, generated as a series of velocity values sampled from a normal distribution. To perform the task, the rat positions its whiskers to receive two such stimuli, “base” and “comparison,” separated by a variable delay. It then judges which stimulus had greater velocity SD. In analogous experiments, humans compare two vibratory stimuli on the fingertip. We demonstrate that the ability of rats to hold base stimulus information (for up to 8 s) and their acuity in assessing stimulus differences overlap the performance demonstrated by humans. This experiment highlights the ability of rats to perceive the statistical structure of vibrations and reveals their previously unknown capacity to store sensory information in working memory