Why canʼt you tickle yourself?

Abstract

It is well known that you cannot tickle yourself. Here, we discuss the proposal that such attenuation of self-produced tactile stimulation is due to the sensory predictions made by an internal forward model of the motor system. A forward model predicts the sensory consequences of a movement based on the motor command. When a movement is self-produced, its sensory consequences can be accurately predicted, and this prediction can be used to attenuate the sensory effects of the movement. Studies are reviewed that demonstrate that as the discrepancy between predicted and actual sensory feedback increases during self-produced tactile stimulation there is a concomitant decrease in the level of sensory attenuation and an increase in tickliness. Functional neuroimaging studies have demonstrated that this sensory attenuation might be mediated by somatosensory cortex and anterior cingulate cortex: these areas are activated less by a self-produced tactile stimulus than by the same stimulus when it is externally produced. Furthermore, evidence suggests that the cerebellum might be involved in generating the prediction of the sensory consequences of movement. Finally, recent evidence suggests that this predictive mechanism is abnormal in patients with auditory hallucinations and/or passivity experiences.

Implicit Agency in Observed Actions: Evidence for N1 Suppression of Tones Caused by Self-made and Observed Actions

“…This comparison is thought to occur through efference copies or corollary discharges of the movement (von Holst, 1954;Sperry, 1950). These two aspects of predictive forward models, the prediction about an action (Wolpert et al, 1995) and the comparison of the predicted effects to the actual effect (Blakemore, Wolpert, & Frith, 2000), are thought to contribute to the causal associations we make between our actions and their sensory consequences (David et al, 2008). Recently it has been suggested that a similar predictive process is involved when we observe othersʼ goal-directed actions; that is, we predict the goals, intentions, and consequences of othersʼ actions through an internal representation of the observed action (Kilner, Friston, & Frith, 2007).…”

A Self-Organized Internal Models Architecture for Coding Sensory–Motor Schemes

“…While the IM is mainly required for motor control, the FM has been proposed as a possible model for a number of important issues, among which are sensory cancelation (Blakemore et al, 2000), state estimation (Wolpert et al, 1995), and body map acquisition (Schillaci et al, 2012a).…”

“…Based on extensive empirical evidence of its putative functionality in the Central Nervous System (Kawato, 1999;Blakemore et al, 2000;Wolpert et al, 2001), Forward and Inverse Models provide arguably a sound epistemological basis to understand cognitive processes at a certain level of description under the embodied cognition framework.…”

Spectral Subtraction of Robot Motion Noise for Improved Event Detection in Tactile Acceleration Signals

“…First, we gathered the data set necessary to compute the velocity-dependent ego-vibration magnitude spectrum estimates |N (f,Θ i )| defined in Equation (5). Joint velocities were obtained from the ROS Diamondback pr2 mechanism model class, which reports velocities using firstorder differentiation of encoder readings.…”

“…The human central nervous system is believed to use the motor commands sent to the muscles to predict the sensory consequences of movement. These predictions allow one to distinguish self-produced sensations from those arising from external events [5].…”