Dynamics of scientific research on mirror neuron system

doi:10.21203/rs.3.rs-3462818/v1

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Dynamics of scientific research on mirror neuron system

https://doi.org/10.21203/rs.3.rs-3462818/v1

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Over 30 years, research into the Mirror Neuron System (MNS) has flourished, but criticisms emerged in 2014 regarding its role in empathy, mind-reading, and psychiatric disorders. One would expect that these criticisms to be considered with a time lag in the field of psychiatry because they were not originally formulated in the field of psychiatry. We found no time lag in publications on the social-cognition hypothesis between the peaks of publications on psychiatric disorders and all the other publications (both peaks in June 2014). Our findings indicate an effective knowledge dissemination between psychiatric research and other research fields.

mirror neurons

psychiatry

autism.

We found a rapid decrease in the number of scientific publications on Mirror Neuron System and their implication in social cognition (empathy, mind-reading, and action understanding) after a wave of criticisms since at least 2014.
We did not find a time lag of the peaks of publication on the social-cognition hypothesis of MNS in the field of psychiatry compared to other fields.
Our findings indicate an effective knowledge dissemination between psychiatric research and other research fields.

The history of mirror neurons has already been traced in plenty of journals and books during the last decades [1]. In brief, mirror neurons were identified in 1992 by an Italian team, which initially observed in monkeys that these neurons had the property of being activated when observing and performing the execution of an action. Mirror neurons will later be identified in humans [2]. The set of regions containing mirror neurons has been further labeled “system”, thus giving rise to the famous acronym Mirror Neuron System (MNS). The fact that mirror neurons are activated while performing an action or while perceiving it in others leads to the formulation of social-perception and social-cognition hypotheses [3]. The social-perception hypothesis concern sensory perception (mainly discrimination or recognition of actions and sounds), or the coupling between perception and action during imitation. Whereas the social-cognition hypothesis is based on the idea that this coupling between perception and action would grant access to the intentions of the actor of the observed action. The social-cognition hypothesis has focused on cognitive concepts such as empathy, mind-reading, and action understanding, as well as the psychiatric disorders where these cognitive processes are suspected to be altered such as in the Autism Spectrum Disorder (ASD) and schizophrenia [4].

Several studies on the social-perception hypothesis has enlightened the functions of the MNS in humans and animals [1]. On the other hand, a series of criticisms have been published since at least 2014 concerning the social-cognition hypothesis of MNS (for instance, detailed brightly by G. Hickok [4]). One would expect that these criticisms to be considered with a time lag in the field of psychiatry for at least two reasons. First, the social-cognition hypothesis of MNS and its criticisms were not originally formulated in the field of psychiatry [4]. Second, the neuropsychological mechanisms of psychiatric disorders are insufficiently understood and the social-cognition hypothesis of MNS applied to psychiatric disorders had gained significant popularity in the media [5].

An essential characteristic of the dynamics of scientific research is to progress iteratively, by trial and error. Therefore, flexibility is expected from researchers when hypotheses, which were considered fruitful, turn out to be doubtful [6]. A bibliometric analysis of the Scopus database by Heyes et al. showed a decrease in the number of scientific publications on MNS since 2014 [1]. However, the decrease in scientific publications on the social-cognition hypothesis of MNS was not examined separately in the field of research in psychiatry. This analysis could inform us about the capability of psychiatric research to quickly take into account hypotheses that have been ruled out and also to inform on the dissemination of knowledge between distinct research fields. To address these questions, we compared the time lags between the peak of publication on MNS depending on whether the publications are related to psychiatric disorders, and more specifically in publications on the social-cognition hypothesis of MNS.

We considered all publications in the PubMed database mentioning the term “Mirror Neuron" from 1995. We set the end on the 27th of May 2023. We aim to extract the publications: (i) on MNS, (ii) MNS in the field of psychiatric disorders, and (iii) the social-cognition hypothesis of MNS in the field of psychiatric disorders.

These publications were classified in the field of research on “psychiatric disorders” using the following MeSH (Medical Subject Headings) in abstract or keywords: [“autis*”, “asd”, “schiz*”, “psychoti*”, “psychos*”, “disorder*”, “psychiatry*”]. The first five terms refer to the disorders most concerned by the research on MNS [7–9].

Publications were classified in the field of research of “social-cognition hypotheses” using the following MeSH [“empath*”, “self-*”, “theory of mind”, “mind read”, “mind-read”, “action understanding*”, “action interp*”], referring to the three main subfields of high-level hypothesis (empathy, mind-reading and action understanding) [10, 11].

We examined the number of publications per month. To determine the peak of the number of publications we estimated the maximum predicted value of a non-parametric regression model (LOESS with smoothing parameter = 0.5) [12]. Statistical analyses were conducted using R version 4.1.0 [13] with the package rentrez.

We identified 2,595 publications on “Mirror Neuron” from January 1995 until the 27^h of May 2023; 443 concerned psychiatric disorders and 2,152 were not related to psychiatric disorders. Among these publications, 550 publications concerned the social-cognition hypothesis of MNS (with 27% related to psychiatric disorders, mostly ASD and schizophrenia). We determined a time lag of 7 months between the peak of publications on psychiatric disorders (peak = Mars 2014) and all the other publications (peak = August 2013) (Fig. 1, Panel A). When we examined publications on the social-perception hypothesis of MNS, we found no time lag in the peaks of publications on psychiatric disorders and all the other publications (both peaks in June 2014) (Fig. 1, Panel B).

Based on an analysis of the publications on the social-cognition hypothesis of MNS (i.e., empathy, mind-reading, and action understanding), we did not find a time lag of the peaks of publication in the field of psychiatry compared to other fields. The reception of criticisms of the social-cognition hypothesis of MNS [4] was taken into account simultaneously inside and outside the field of psychiatric research, despite the fact that these criticisms were not originally formulated in the field of psychiatric research and despite the popularity in media of the social-cognition hypothesis of MNS applied to psychiatric disorders. Therefore, our findings indicate an effective knowledge dissemination between psychiatric research and other research fields.

Knowledge dissemination play a pivotal role in advancing scientific understanding. While the exchange of ideas and integration of knowledge between different fields of research is highly valuable, it is crucial to approach the importation of hypotheses developed in other fields with a critical perspective. It is also important to maintain a focused awareness on the relevance of these hypotheses within their original research field.

Our results must be interpreted with some limitations. First, our identification of the publications on the social-cognition hypothesis of MNS as well as the publications on psychiatric disorders based on PubMed’s MeSH should be seen more as a proxy than an actual measurement. Indeed, only 148 publications were identified on the social-cognition hypothesis of MNS in psychiatric research. Second, our method to identify the peaks of publication could vary depending on the value of the smoothing parameter of the LOESS regression model. However, when the value of the smoothing parameter of the LOESS regression was set at 0.6 (or 0.7, 0.8 and 0.9), we found on the contrary that the peak of publications on psychiatric disorders was slightly earlier (6 months for a smoothing parameter at 0.6) that the peak of the other fields of research on the social-cognition hypothesis of MNS, thus reinforcing our interpretation. Finally, our analysis of the publications on the social-cognition hypothesis of MNS indicates an effective dissemination between the field of research on psychiatric disorders and other fields. Nevertheless, it would be necessary to examine the dynamics of research on other hypotheses to further explore the dissemination of knowledge between distinct research fields.

Our results provide insights into the dynamics of scientific research. Our findings indicate an effective knowledge dissemination between psychiatric research and other research fields on the social-cognition hypothesis of MNS.

MNS: Mirror Neuron System

ASD: Autism Spectrum Disorder

Funding

The authors received no funding from an external source.

Acknowledgements

Any.

Conflict of interest

The authors declare no conflict of interest.

Author Contributions Statement

H.P. and C.G. wrote the main manuscript text. H.P. analysed the data. All authors reviewed the manuscript.

Ethical approval for human patients

Does not require ethics committee approval.

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No competing interests reported.

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Dynamics of scientific research on mirror neuron system

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