Spiegelneuronensystem-Aktivität im fMRT : eine Altersabhängigkeitsuntersuchung

Abstract

The mirror neuron system (MNS) is a network of neurons, which are activated through execution as well as by observation of goal-directed movements. Mirror neurons seem to be involved in many processes in the field of motor learning and are used in a therapy of motor rehabilitation with stroke patients. However, to date, no study exists, which has investigated the neural activity of the MNS in age-dependent subjects.<br /><br />This question was investigated in the present study with functional magnetic resonance imaging (fMRI) with a cohort of 26 neurologically healthy volunteers ranging from 19 till 79 years old. The subjects were stimulated with video clips and pictures of transitive and intransitive movements, which they should either look at or observe and imagine this movement simultaneously. Thereby neural activity was measured as a dependent variable and was tested statistically with the subjects age dependency with regression analysis and a group comparison.<br /><br />Results showed bilateral activations in superior temporal gyrus (STG), inferior parietal lobe (IPL), premotor cortex (PM), supplementary motor area (SMA), inferior prefrontal cortex (iPFC), left precentral gyrus (corresponding M1), superior parietal lobe (SPL), medial temporal gyrus (corresponding MT, V5), visual areas (corresponding V1-V4) of occipital lobe (BA 17-19) and in cerebellum. These activations increased over the six conditions and were strongest with the presentation of videos with object-related hand movements and simultaneous imagination of the execution of this movement. The examination of age dependency of these activations showed an increased BOLD signal in occipital cortex corresponding to the prime visual area (V1) by the young and stronger activations in regions of occipital lobe, corresponding to higher visual areas V3 and V4, as well as in superior parietal lobe (SPL) by the elderly volunteers. However, there were no significant differences in activation in the areas belonging to the MNS (i.e. IPL, PM and iPFC) depending on age. Thus this study provides a paradigm for fMRI measuring reliable activity within the MNS. Further results of this study support the use of action observation therapy in elderly stroke patients.