Neuroscience highlights: The mirror inside our brain
KRABÓTH Zoltán1,2, KÁLMÁN Bernadette1,2
JANUARY 30, 2021
Clinical Neuroscience - 2021;74(01-02)
KRABÓTH Zoltán1,2, KÁLMÁN Bernadette1,2
JANUARY 30, 2021
Clinical Neuroscience - 2021;74(01-02)
Over the second half of the 19th century, numerous theories arose concerning mechanisms involved in understanding of action, imitative learning, language development and theory of mind. These explorations gained new momentum with the discovery of the so called “mirror neurons”. Rizzolatti’s work inspired large groups of scientists seeking explanation in a new and hitherto unexplored area of how we perceive and understand the actions and intentions of others, how we learn through imitation to help our own survival, and what mechanisms have helped us to develop a unique human trait, language. Numerous studies have addressed these questions over the years, gathering information about mirror neurons themselves, their subtypes, the different brain areas involved in the mirror neuron system, their role in the above mentioned mechanisms, and the varying consequences of their dysfunction in human life. In this short review, we summarize the most important theories and discoveries that argue for the existence of the mirror neuron system, and its essential function in normal human life or some pathological conditions.
Autism spectrum disorder is a neurodevelopmental disorder with a heterogeneous presentation, the etiology of which is not clearly elucidated. In recent years, comorbidity has become more evident with the increase in the frequency of autism and diagnostic possibilities of inborn errors of metabolism. One hundred and seventy-nine patients with diagnosis of autism spectrum disorder who presented to the Pediatric Metabolism outpatient clinic between 01/September/2018-29/February/2020 constituted the study population. The personal information, routine and specific metabolic tests of the patients were analyzed retrospectively. Out of the 3261 patients who presented to our outpatient clinic, 179 (5.48%) were diagnosed with autism spectrum disorder and were included in the study. As a result of specific metabolic examinations performed, 6 (3.3%) patients were diagnosed with inborn errors of metabolism. Two of our patients were diagnosed with classical phenylketonuria, two with classical homocystinuria, one with mucopolysaccharidosis type 3D (Sanfilippo syndrome) and one with 3-methylchrotonyl Co-A carboxylase deficiency. Inborn errors of metabolism may rarely present with autism spectrum disorder symptoms. Careful evaluation of the history, physical examination and additional findings in patients diagnosed with autism spectrum disorder will guide the clinician in the decision-making process and chose the appropriate specific metabolic investigation. An underlying inborn errors of metabolism may be a treatable cause of autism.
Far lateral lumbar disc herniations (FLDH) consist approximately 0.7-12% of all lumbar disc herniations. Compared to the more common central and paramedian lumbar disc herniations, they cause more severe and persistent radicular pain due to direct compression of the nerve root and dorsal root ganglion. In patients who do not respond to conservative treatments such as medical treatment and physical therapy, and have not developed neurological deficits, it is difficult to decide on surgical treatment because of the nerve root damage and spinal instability risk due to disruption of facet joint integrity. In this study, we aimed to evaluate the effect of transforaminal epidural steroid injection (TFESI) on the improvement of both pain control and functional capacity in patients with FLDH. A total of 37 patients who had radicular pain caused by far lateral disc herniation which is visible in their lumbar magnetic resonance imaging (MRI) scan, had no neurological deficit and did not respond to conservative treatment, were included the study. TFESI was applied to patients by preganglionic approach. Pre-treatment Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI) scores of the patients were compared with the 3rd week, 3rd month and 6th month scores after the procedure. The mean initial VAS score was 8.63 ± 0.55, while it was 3.84 ± 1.66, 5.09 ± 0.85, 4.56 ± 1.66 at the 3rd week, 3rd month and 6th month controls, respectively. This decrease in the VAS score was found statistically significant (p = 0.001). ODI score with baseline mean value of 52.38 ± 6.84 was found to be 18.56 ± 4.95 at the 3rd week, 37.41 ± 14.1 at the 3rd month and 34.88 ± 14.33 at the 6th month. This downtrend of patient’s ODI scores was found statistically significant (p = 0.001). This study has demonstrated that TFESI is an effective method for gaining increased functional capacity and pain control in the treatment of patients who are not suitable for surgical treatment with radicular complaints due to far lateral lumbar disc hernia.
Myasthenia gravis (MG) is an autoimmune disorder of neuromuscular transmission. Autonomic dysfunction is not a commonly known association with MG. We conducted this study to evaluate autonomic functions in MG & subgroups and to investigate the effects of acetylcholinesterase inhibitors. This study comprised 30 autoimmune MG patients and 30 healthy volunteers. Autonomic tests including sympathetic skin response (SSR) and R-R interval variation analysis (RRIV) was carried out. The tests were performed two times for patients who were under acetylcholinesterase inhibitors during the current assessment. The RRIV rise during hyperventilation was better (p=0.006) and Valsalva ratio (p=0.039) was lower in control group. The SSR amplitudes were lower thereafter drug intake (p=0.030). As much as time went by after drug administration prolonged SSR latencies were obtained (p=0.043).Valsalva ratio was lower in the AchR antibody negative group (p=0.033). The findings showed that both ocular/generalized MG patients have a subclinical parasympathetic abnormality prominent in the AchR antibody negative group and pyridostigmine has a peripheral sympathetic cholinergic noncumulative effect.
Matrix metalloproteinases (MMPs), which are synthesized by many cell groups and responsible for the destruction of matrix proteins, and endogen tissue inhibitors of MMPs (TIMPs) have a role in the pathogenesis of Multiple Sclerosis (MS) by affecting the blood-brain barrier. We aimed to investigate the role of MMPs and TIMPs in the immunopathogenesis and in the course of multiple sclerosis (MS). We enrolled 25 relapsing remitting MS patients, who had a definite MS diagnosis according to McDonald criteria and 25 healthy subjects similar for age and gender as control group. MMP-9- and TIMP-1 levels were measured twice in patient group (one time during an attack and one in remission) and once in healthy subjects. MMP-9- and TIMP-levels of patients during attack and remission period and MMP-9/TIMP-1 ratio were found significantly higher than in the control subjects. In patient group MMP-9 and TIMP-1 levels and MMP-9/TIMP-1 ratio during attacks were not significantly different than during remission period. However, when subdivided according to their number of attacks, patients with 2 attacks had significantly higher levels during attack period comparing to remission period (p<0.05); in case of patients with more than 2 attacks did not have a statistically significant difference in attack and remission periods. Matrix metalloproteinases are important actors in MS immunopathogenesis, particularly in the early period and inhibitor agents for these enzymes can be used as a treatment option.
Transcranial magnetic stimulation is a non-invasive procedure that uses robust magnetic fields to create an electrical current in the cerebral cortex. Dual stimulation consists of administering subthreshold conditioning stimulation (CS), then suprathreshold test stimulation (TS). When the interstimulus interval (ISI) is 1-6 msec, the motor evoked potential (MEP) decreases in amplitude; this decrease is termed “short interval intracortical inhibition” (SICI); when the ISI is 7-30 msec, an increase in MEP amplitude occurs, termed “short interval intracortical facilitation” (SICF). Continuous theta burst stimulation (cTBS), often applied at a frequency of 50 Hz, has been shown to decrease cortical excitability. The primary objective is to determine which duration of cTBS achieves better inhibition or excitation. The secondary objective is to compare 50 Hz cTBS to 30 Hz and 100 Hz cTBS. The resting motor threshold (rMT), MEP, SICI, and SICF were studied in 30 healthy volunteers. CS and TS were administered at 80%-120% and 70%-140% of rMT at 2 and 3-millisecond (msec) intervals for SICI, and 10- and 12-msec intervals for SICF. Ten individuals in each group received 30, 50, or 100 Hz, followed by administration of rMT, MT-MEP, SICI, SICF immediately and at 30 minutes. Greater inhibition was achieved with 3 msec than 2 msec in SICI, whereas better facilitation occurred at 12 msec than 10 msec in SICF. At 30 Hz, cTBS augmented inhibition and suppressed facilitation, while 50 Hz yielded less inhibition and greater inter-individual variability. At 100 Hz, cTBS provided slight facilitation in MEP amplitudes with less interindividual variability. SICI and SICF did not differ significantly between 50 Hz and 100 Hz cTBS. Our results suggest that performing SICI and SICF for 3 and 12 msec, respectively, and CS and TS at 80%-120% of rMT, demonstrate safer inhibition and facilitation. Recently, TBS has been used in the treatment of various neurological diseases, and we recommend preferentially 30 Hz over 50 Hz cTBS for better inhibition with greater safety and less inter-individual variability.
[Mentalization or theory of mind as an aspect of our social cognition, is our ability to infer mental states of others (intentions, desires, thoughts, emotions) and to predict their behavior accordingly. This function significantly affects our participation and orientation in the social world and plays an important role in conversational situations, social interactions, social integration and adaptation. The brain regions that serve as the basis for mind-reading function can be damaged as a consequence of traumatic brain injury, which frequently occurs among the younger population. Traumatic brain injury can cause focal or diffuse cerebral injuries, often leading to theory of mind deficit. In this topic such publications were researched that compared theory of mind ability between traumatic brain injury patients and control subjects (comparative case-control studies). We searched for the studies in the following internet based/online databases: PubMed, Web of Science, ScienceDirect, Google Scholar, APA PsycNET (PsycARTICLES) and EBSCO Host. The search was performed using the following key word combinations: theory of mind or mentalizing or social cognition AND traumatic brain injury or head/brain injury or diffuse axonal injury. Based on the results of the included and processed studies (21 pc), traumatic brain injury often leads to mentalization deficit with different severity. With this present review we aim to draw attention to the fact that the appearance and severity of mind reading dysfunction can considerably affect the outcome of the disease, the length of rehabilitation time and the prognosis of traumatic brain injury patients. Besides this, with this review, we aim to take sides in whether theory of mind ability is domain-specific or domian-general based on studies including traumatic brain injury patients.]
Lege Artis Medicinae
[In this paper, our aim is to scrutinise the psychology and phenomenology of interpersonal relationships from an interdisciplinary viewpoint. This multi-perspectival examination has a key concept: we critically discuss the interdisciplinary dialogues and philosophical appraisals regarding the issue of mirror neurons. Empathy and resonance phenomena have philosophical, psychological, and biomedical importance. Our paper, by applying certain philosophical and empirical results of the overarching paradigm of embodiment, attempts to shed light on several semantic problems, which could come up with respect to the function of mirror-neurons. In conclusion, we would like to attempt to utilise the results of contemporary phenomenology in order to clear some semantic problems, considering the features of mirroring and resonant behaviour.]
[Introduction – Mentalization is the ability to attribute mental states (intentions, desires, thoughts, emotions) to others, and hence to predict their behaviour. This ability fundamentally determines our participation in social relationships and adaptation to society. A significant proportion of the disorders of the central nervous system (CNS) affects those brain structures and neurotransmitter systems that play a role in the mentalizing processes. Accordingly, a number of CNS disorders may be associated with mentalizing deficits, which may affect the outcome of these diseases. Here, we review recent research on mentalizing abilities in neurological diseases. Methods – An internet database search was performed to identify publications on the subject. Results – Sixty-two publications in English corresponded to the search criteria. These publications reported impaired mentalization in several neurological disorders (e.g. epilepsy, Parkinson’s disease, multiple sclerosis, dementias, traumatic brain injury). Discussion – The results indicate that a number of neurological disorders associate with mentalizing deficit. This deficit is often present in the early stages of the diseases and has a prognostic value, which in turn emphasizes the importance of the early detection and adequate rehabilitation.]
The link between the hippocampus and declarative memory dysfunctions following the removal of the medial temporal lobe opened unexplored fields in neuroscience. In the first part of our review, we summarized current theoretical frameworks discussing the role of hippocampus in learning and memory. Several theories are highlighted suggesting that the hippocampus is responsible for assembling stimulus elements into a unitary representation that later can be utilized to simulate future events. The hippocampal formation has been implicated in a growing number of disorders, from neurodegenerative diseases to atypical cognitive ageing and depression. Recent neuroimaging studies provided new opportunities to study in detail the hippocampal formation’s role in higher levels of the nervous system. We will present data regarding the regional specialization of the hippocampus in experimental models developed for healthy and neurological conditions with a special focus on Parkinson’s disease. Combined evidence from neuroimaging studies suggested that hippocampal volume is reduced in non-demented, newly diagnosed patients with Parkinson’s disease, which is associated with impaired memory performance. These findings proposed that, beyond the well-known striatal dopamine loss, impaired hippocampal synaptic plasticity may contribute to cognitive and affective impairments in early Parkinson’s disease.
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[BACKGROUND - Nowadays it is an understood fact, that theory of mind has a great psychological significance. Deficits of theory of mind skills are observed in schizophrenia such as depression, dementia, autism and some personality disorders as well. Conceptions of theory of mind and emotion recognition ability have been coming in front at the expanse of the older empathy also in the present-day research in connection with helper connections and their effects. It is probably due to popular approach of cognitive neuroscience exact methods. METHODS - We intended to demonstrate, that the ability of emotion recognition can be developed, or partially restored, even in case of patients suffering from schizophrenia. We compiled an 8-seat training. Our method was a bibliotherapy training, each of chosen novels expressed one of basic emotions (by Ekman). After a common reading we projected validated portraits expressing also those emotions. Participants had to choose reflecting the emotional state of the characters photos. Then they shared stories from their own lives experiencing similar emotions. We measured the effectiveness of our method by the Reading the Mind in the Eyes measured (RMET) test. RESULTS - Comparing data before and after the training in t-test we detected significant difference (p=0.000608 <0.05). Verifying that the observed changes are not only the common effects of the other types of treatment, the same tests were performed on a similar in-patient treated control group. There was no significant difference between the RMET first time and two weeks later values of the control group (p=0.467). The rate of changes in the test and control group (RMET) was compared in a paired-sample t-test, and we also found a significant difference: p=0.000786 <0.005. CONCLUSIONS - The deficit of theory of mind in schizophrenia can be reduced, which indirectly can improve our patients' communication and adaptation skills, or worse, their deterioration can be reduced.]
Clinical NeuroscienceCases of inborn errors of metabolism diagnosed in children with autism
Clinical NeuroscienceEvaluation of the effectiveness of transforaminal epidural steroid injection in far lateral lumbar disc herniations
Clinical NeuroscienceElectrophysiological investigation for autonomic dysfunction in patients with myasthenia gravis: A prospective study
Lege Artis Medicinae[LAM 30: 1990–2020. Facing the mirror: Three decades of LAM, the Hungarian medicine and health care system]
Lege Artis Medicinae[Dear Reader! Greetings to the 30th anniversary of founding the LAM]