The Mirror Neurons Network in Aging, Mild Cognitive Impairment, and Alzheimer Disease: A functional MRI Study

Abstract

The aim of the current study is to investigate the integrity of the Mirror Neurons (MN) network in normal aging, Mild Cognitive Impairment (MCI), and Alzheimer disease (AD). Although AD and MCI are considered “cognitive” diseases, there has been increasing recognition of a link between motor function and AD. More recently the embodied cognition hypothesis has also been developed: it postulates that a part of cognition results from the coupling between action and perception representations. MN represent a neuronal population which links perception, action, and cognition, therefore we decided to characterize MN functioning in neurodegenerative cognitive decline. Three matched groups of 16 subjects (normal elderly-NE, amnesic MCI with hippocampal atrophy and AD) were evaluated with a focused neuropsychological battery and an fMRI task specifically created to test MN: that comprised of an observation run, where subjects were shown movies of a right hand grasping different objects, and of a motor run, where subjects observed visual pictures of objects oriented to be grasped with the right hand. In NE subjects, the conjunction analysis (comparing fMRI activation during observation and execution), showed the activation of a bilateral fronto-parietal network in “classical” MN areas, and of the superior temporal gyrus (STG). The MCI group showed the activation of areas belonging to the same network, however, parietal areas were activated to a lesser extent and the STG was not activated, while the opposite was true for the right Broca's area. We did not observe any activation of the fronto-parietal network in AD participants. They did not perform as well as the NE subjects in all the neuropsychological tests (including tests of functions attributed to MN) whereas the MCI subjects were significantly different from the NE subjects only in episodic memory and semantic fluency. Here we show that the MN network is largely preserved in aging, while it appears involved following an anterior-posterior gradient in neurodegenerative decline. In AD, task performance decays and the MN network appears clearly deficient. The preservation of the anterior part of the MN network in MCI could possibly supplement the initial decay of the posterior part, preserving cognitive performance.

Anti‑inflammatory effects of bone marrow mesenchymal stem cells on mice with Alzheimer's disease

“…Some studies have pointed out that if stem cells are induced into neural stem cells in vitro , the direct injection of neural stem cells into the hippocampus of the brain will be more effective in the treatment of AD, but the difficulty lies in how to inject neural stem cells into a designated place and avoid trauma to the brain ( 19 ). It was found in the study of Farina et al ( 20 ) that BMSCs can attenuate the memory impairment of Aβ deposits and stimulate the signal pathways of the primary tumor, change the expression levels of relevant genes, and inhibit apoptosis of nerve cells. Other studies have revealed that the occurrence process of AD is accompanied by inflammation, which can cause inflammation responses, resulting in changes in the in vivo contents of some factors associated with the verification.…”

Mirror neurons and their relationship with neurodegenerative disorders

“…It is interesting to note that an fMRI study focusing on mindreading (or theory of mind; Baglio et al, ) similarly found a preserved performance at RME in people with MCI, despite a reduced activation of some posterior regions of the mind reading network. In the study of Farina et al () an increased activation of the left Broca area (B44), thought to be a node of the MN system, was observed. This result suggests that the preservation and maybe hyperactivation of MN prefrontal areas could play a compensatory role.…”

“…However, recently an intervention focused on MN in AD patients showed negative results (Caffarra et al, , oral communication at XI Sindem National Congress, Florence, Italy). If the MN network is already disturbed in the pre‐dementia phase, as suggested by Moretti’s () and Farina et al's () studies, AOT would result ineffective as a rehabilitation technique in moderate AD, and it should be rather performed in the MCI or at least in the early phase to achieve positive results.…”

“…Recently, another study investigated the MN network functioning in people with MCI and AD, alongside with its relationship to cognitive performance (Farina et al, ). In this study, three matched groups of 16 subjects each (normal elderly, amnesic MCI with hippocampal atrophy, and AD) were assessed with a fMRI task specifically created to test MN and a focused neuropsychological battery.…”

Artificial Intelligence and brain

“…This may complement posterior mirror neurons during their initial decline in Mild Cognitive Impairment. In normal aging, mirror neurons are generally conserved [ 20 ]. Using fMRI studies in autism and normal individuals, when participants match brain activity of other individuals; mirror neurons are identified as responsible for emotions, empathy, intention recognition, and complex cognition [ 21 ].…”