Tactile perception and working memory in rats and humans

Abstract

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.

Transformation of Perception from Sensory to Motor Cortex

“…Inside each box is the percent correct for that stimulus pair, averaged across all subjects. For pairs distant from the diagonal, accuracy was good except for (25, 47) in rats and (14, 21) in humans, where sp1 assumed its lowest value, most likely explained by “contraction bias” [6, 7, 8]. Green rectangles enclose the stimulus set used to generate psychometric curves.(D) Average psychometric curves of rats and humans (black) and the ideal observer (gray).…”

“…To characterize working memory performance, we computed the proportion of trials in which subjects judged stimulus 2 > stimulus 1 as a function of sp2 and sp1 [6]. We fit the data with a generalized linear model in MATLAB, as follows:$percentjudged\text{stimulus}2>\text{stimulus}1=\gamma +\left(1-\gamma -\lambda \right)\frac{1}{1+exp\left(w1\left(sp1\right)+w2\left(sp2\right)+w_c\right)}.$Where w 1 is the sp1 regressor, w 2 is the sp2 regressor, and w c is the baseline regressor that captures the overall (stimulus-independent) bias of the subject in judging stimulus 2 > stimulus 1. γ and λ are the lower and upper asymptotes, respectively.…”

Requirement of Prefrontal and Midbrain Regions for Rapid Executive Control of Behavior in the Rat

“…Despite a rich rodent literature in flexible control of behavior (Durstewitz et al, 2010;Floresco et al, 2008;Jaramillo et al, 2014;Karlsson et al, 2012;Kimchi and Laubach, 2009;Rich and Shapiro, 2009;Rodgers and DeWeese, 2014), response conflict (Haddon et al, 2008;Oualian and Gisquet-Verrier, 2010), and rapid switching between fixed sensorimotor associations (Baker and Ragozzino, 2014;Leenaars et al, 2012), reports of cued, rapid remapping of the association between sensory stimuli and motor responses, occurring on the order of hundreds of milliseconds to seconds, are rare in rodents (e.g., Fassihi et al, 2014). However, such rapidity in sensorimotor remapping, indicative of the speed and flexibility with which information can be rerouted within the brain, is one of the most remarkable features of adaptive behavior.…”

Decoding vibrotactile choice independent of stimulus order and saccade selection during sequential comparisons

“…Conversely, the performance for trials with f1 in the higher range was better when f2 was higher than f1 compared with those with lower f2 (Figure 2). Such a behavioral pattern is a frequently observed phenomenon in studies using comparison tasks and is referred to as the timeorder effect or contraction bias (Ashourian & Loewenstein, 2011;Fassihi, Akrami, Esmaeili, & Diamond, 2014;Herding et al, 2016;Preuschhof, Schubert, Villringer, & Heekeren, 2009). This effect suggests a biased perception or memory trace of f1 toward the mean of the stimulus set.…”

“…Such a behavioral pattern is a frequently observed phenomenon in studies using comparison tasks and is referred to as the timeorder effect or contraction bias(Ashourian & Loewenstein, 2011;Fassihi, Akrami, Esmaeili, & Diamond, 2014;Herding et al, 2016;Preuschhof, Schubert, Villringer, & Heekeren, 2009). Such a behavioral pattern is a frequently observed phenomenon in studies using comparison tasks and is referred to as the timeorder effect or contraction bias(Ashourian & Loewenstein, 2011;Fassihi, Akrami, Esmaeili, & Diamond, 2014;Herding et al, 2016;Preuschhof, Schubert, Villringer, & Heekeren, 2009).…”