5МЕДИЦИНСКАЯ ПСИХОЛОГИЯ
RESEARCH OF A BRAIN ASYMMETRY AND ITS CORRELATION WITH A MOTHER-CHILD DYAD.
Svetlana Victorovna Grygorieva
Medical Psychology PhD USP Psychotherapist, EKPP professional Child and Adolescent Psychotherapist, Trauma Therapist
Summary. The brain asymmetry researches we have conducted with mother- adolescent pairs postural asymmetry tests (postural control tests) and have determined the highly-reliable inverse correlation with the dominant eye. Such results may indicate the dominance differences in cerebral structures of mother and child, localized in thalamus. On the base of this research, we have settled and described the structure of normal and pathological mother alpha rhythm and child alpha rhythm thalami pacemaker interaction.
Key words: mother-child dyad, asymmetry with the lateral correlation, functional hemispheric specialization, thalami, alpha rhythm, post-natal stress, development pathology, postural asymmetry.
As a practical matter, structural brain asymmetry parameters of interaction participants match and mismatch are important factors of mutual understanding between people, that was a reason why we decided to find out whether it could affect the "normal" family attachment between mother and child and investigate this through physiological indicators. We decided to learn if there is a relationship between parameters of brain structures asymmetry in mother-child dyad and how these parameters are distributed (laterality) in the mother-child pair.
Now we represent a brief overview of researches in the field of central nervous system (CNS) and in the field of relationship and attachment. John Bowlby described attachment as family emotional connectedness that occurs in childhood and is the long-lasting emotional base of human life. Mother and infant enter some self-regulating system with the mutual causality. The attachment system is a primary, genetically fixed motivation system between the baby and the caregiver, which starts immediately after the birth and provides the baby with all the necessary things for survival [1, 36].
Attachment models "mother-child" researchers pay a great attention to a mother face mimics as one of the major objects that create a brain-body system of infants. They state that the perception the mother's face emotion generates the child's resonant emotional condition. Physical closeness is caused by eye-to-eye contact with mother, but especially by the way of following the mother and establishing body contacts with her [1,37].
Parents and children CNS asymmetry researches were mainly concentrated on hereditary factors of left-handedness (D.Levy, T.Nagilaki) [2]. The phenomenon of a significant asymmetry manifestation in social life as the preference of mother to hold her child on the left side was described by Lee Saulk in 1960 [7]. He determined the important effect of a mother emotional condition on holding a child asymmetrically, it has been that women suffering from post-natal stress do not demonstrate left-hand preference [7]. Many studies are concentrated on emotion regulation via attachment in relationship. Allan Schore suggested the detail scheme of cognitive/emotional/body stage development connection with radical changes in brain. It turned out that environmental sensory information is processed by limbic systems in hierarchic order and by limbic and cortical areas of brain and this affects autonomic nervous system. He focused on amygdala, cin-gulate gyrus and orbitofrontal cortex while considering attachment of infants. Each of them is an independent system and a zone of information aggregation. There have been noticed the right brain development inhibition; hippocampus, corpus callosum and amygdala shrinkage; orbitofrontal cortex development inhibition in case of attachment disorder [5].
Brain structures functional connectivity can be monitored with the help of electroencephalogram.
We used a simple, but reliable postural asymmetry testing, by comparing lateral indices of mother and child to recognize the role of different brain structures in a pair. The term "laterality" (lateralis) is used in the meaning of as ym-metry or incomplete identity of the left and right parts of a body. It may occur at anatomic, biochemical, physiological and functional levels. [2].
We were concerned if there is a link between brain structures in a "mother-child" dyad. We suggested that the child brain functional asymmetry parameters in mother-child pair are mirror symmetrical and this may create a special type of interaction in the pair. 312 adolescents and their mothers were recruited for the testing. The age of the tested children was 14-16 years, in that period the development of brain areas functional asymmetry is mainly completed. Four parameters of lateral profile were analyzed: fingers intertwined, arms crossed, dominant eye determining (aiming) and clapping hands (the active hand determining). Our task was to find out the way of interaction in mother-child pair based on ratio of activity of different brain structures, but without emphasizing a personal lateral profile of each test participant. It is known that an eye dominancy is connected with the opposite thalamus activity as a link between the cortex from the one side and cerebellum and basal ganglia from another side. Thalamus or the opposite thalami provides filtering of information from all the receptors, it processes the information primarily and then sends it to different cortex areas. [9] Fingers intertwining, arms crossing, as any other movements, arise due to impulses from cerebral hemispheres transmitting by long nerve fibers. These are neuron axons situated in the middle part of the precentral gyrus [6]. The way of clapping is highly related to left- or right-handedness as a sign of pre-existing brain structures asymmetry not connected directly with hands manipulation ability. Laterality of
clapping is simple emotionally charged movements motor manifestation that is created in central nervous system limbic diencephalic structures and is a sign of gestational dominant functional interhemispheric asymmetry [4,150].
Here are the process and results of our research. Primarily 124 persons took part in the testing, the results were analyzed by using Pearson correlation coefficient. The significant clapping hand test and dominant eye test correlation coefficients have been observed. Mother and child dominant eye tests showed highly reliable inverse correlation r=-0,352 (rkp=0,197, p>0,05). That proves laterality difference, localized in thalamus. Also the significant inverse correlation was determined after clapping tests r=- 0,22 (rkp=0,197, p>0,05) as a result of limbic interbrain systems functionality.
Then the number of participants was increased to 312 persons (156 pairs), the results were listed in 2x2 two-way size of conjugacy tables, that has allowed to make more accurate data analyses. The following characteristics of statistical significance level were calculated:
1) chi2 - chi-square
2) phi - Pearson's contingency coefficient
3) Q - Yule's coefficient of association
4) C - Yule's coefficient of colligation
The testing results of dominant eye emphasized significant inverse correlation in mother-child pair, chi=3,88 (p < 0,05), phi=-0,17, Q=-0,34, C=-0,17, that proves the natural difference in laterality localized in thalamus. No significant correlation have not been determined in other tests (fingers intertwining, arms crossing and clapping). The significant inverse correlation in the dominant eye test proves that there is a very strong interaction, that has not disappeared when the sampling increases. (Drawing 1) Poets say that eyes are the soul mirror. Neu-ropsychologists expressed more exactly that each eye is a mirror of left or right brain hemisphere. The main source of corticipetal impulsation is thalamus, its nuclei get impulsation from the majority of sensor systems (except olfactory) as well as from basal nuclei, hippocampus and cerebellum. The peripheral information which is supplied to brain cortex concentrates and converts in thalamus. [3,386].
Drawing 1 Visual mirror symmetry of child's brain relatively to mother's brain 6
Jerre Levy with her colleagues have stated that two hemispheres differ from each other by a kind of information they retrieve from visual stimuli. [2,229] Thus, the dominance of a specific individual thalami zone defines which part of information can be retrieved from the common flow of sensory stimuli. In this context our research has proved that in case of mother and child mismatch domi-nancy in thalami zones each of them gets different information from the same sensory stimuli. Left hemisphere specializes in step-by-step information processing and is more analytical and more verbal. But the right hemisphere areas work well with processing of simultaneous kinds of information that are necessary for space patterns perception and are more non-verbal. The left hemisphere perceives and analyzes complicated visual object elements, but right hemisphere perceives the whole configuration of the object. [3,429]
That means we can formulate the assumption that in some pairs the adolescent (child) differs from mother by diametrically opposite approach of "getting" and processing information. For example, if the mother's right hemisphere is leading, she can process a lot of different information at the same time, she can estimate the problem as a whole, memorize images and faces, feel emotional issue of speech, intonation, orients in present, can dream and indulge in fantasies. Her child with the leading left hemisphere being in adolescence age can analyze data, make plans for the future, process information consequently, think inductively.
Our research proves that in sampling a mother with her child have significant inverse correlation in thalami structure. It is known that alpha rhythm is formed in the cortex under the effect of impulses from non-specific thalami nuclei that are generated by thalami alpha rhythm pacemakers. [3, 386]
The highest amplitude alpha rhythm gains in a position of being awake with the eyes closed while being in darkness. It is blocked or weakened as a result of an increased attention (especially visual) or a cognitive activity. Mother's alpha rhythm inhibits and cortex neurons desynchronize in stressful situations and hy-perarousal (a strong reaction of the cortex hyperactivity). A newborn does not have alpha rhythms until he is 3 months, only then those starts to be recognized as weak impulses [3]. Mother's alpha rhythms rhythmic sequential disorder in the first months after delivering baby can disrupt infant's thalamus synchronizing mechanism formation, as the child is not able to find mother's alpha rhythm and to tune it out. Since there is no alpha rhythm in newborn brain structures and taking into consideration the data we have received during the testing, we may suggest that the child unconsciously adjust his thalami alpha rhythm pacemaker with the mother's alpha rhythm, being compensatorily oriented to support his mother non-dominant sensory impulses. In such a way a mutual condition of mother-child pair is created. Children with vision disorder create contacts with mothers with the help of somatosensory links, which are also locked in thalamus. [6]. Thus, we can suggest that, possibly, the first three months of life may be the time of tuning of mother-child interaction and not so much through her sight and mimics, as through some resonant co-adjustment of a child's brain with his mother's brain via alpha rhythm. We could call this period "the fourth trimester of pregnancy".
Today it is known that a child's perception of emotions on his mother face creates his emotional condition [1]. Due to specific physiological features of new-borns in the first months of the development their eyes ciliary muscles are thin and weak, that is why it is hard for babies to keep their eyes on close objects. A newborn's sight can be estimated on the level of light spots and shadows perception. His eyes are able to focus only on the second or third month of life. It seems possible to achieve the resonance (in the alpha rhythm diapason) through somatic, behavioral and psychophysiological mother's reactions which the child can perceive at this age (tone of voice, intonation, mother body movement language patterns, etc ). The alpha rhythm appears under a condition of having a little doze. This is a brain electric activity type when interhemispheric interactions are better manifested in case one's attention triggers from external world to internal [1]. And, perhaps, mother's frequent immersion into her inner world is fruitful for a child's brain development in the first three months after the birth. It is possible that the postpartum depression emerges also for triggering attention to the more sensitive right brain thinking style which gives a mother better understanding of the child. But one can not think with left brain consciously. The special disconnect from external disturbing afference occurs and the child can get the maximum of mother's care and sensuality.
A woman faces in front of the great social tasks (working, social life, an active role in social networks) and sometimes she would rather start the life she was used to before giving birth to her child. Mother's postnatal realignment of emotional conditions (life when being depressed) can be successfully compensated without any harm, but for the child development these three months are morphogenous. It's very important for a mother to contact with the child calmly and to be oriented on his resonance as the right brain development is very significant, it is the basement for a reliable attachment and for harmonious personal development.
However, NICHD researches proved that the attachment is also reliable if another person, not the mother, takes care of the child in first 15 months. [1]. Apparently, caregivers (not necessary women) had a good alpha rhythm helped to create a reliable attachment. Thus, we described above the interaction structure of a mother's alpha rhythm with a child's alpha rhythm thalamic pacemaker as normal.
Now let us consider a suggested outline at the level of psychophysiological interaction in a mother-child pair, which can be created if the child has a cognitive pathology. It is a well-known fact the right brain of a child is active and develops intensively till 2 or 3 years. Schore concludes that the right brain hemisphere is responsible for the emotions and attachment with mother, it is a vital necessity for survival. It is also known that many mental and psychosomatic disorders are based on functional right brain inferiority. [5]. Mature, reasonable mother with flexible style of thinking and interbrain synchronization can sensitize on her baby right-brain style of thinking. It would be harder for her to build the communicative system with the child if she has a tendency to repress her emotional sphere. Under
the condition of the hyperarousal the adult's brain turns on the right brain managing strategy with sensory information blocking.
Being aware that mother and child are in omnipotent cohesiveness in the postpartum period, it is possible to suggest that the left-brain mother's protection systems can block her emotions processing when her leading left brain takes control of child's right brain hemisphere sensory channels. Ignoring emotions, anxiety and criticism of mother may make pressure on the infant. Probably, being under stress conditions, a mother with the leading left brain hemisphere does not feel empathy to her child and "turns off" signals (asking for help) from her child with the leading right brain hemisphere thereby trying to prevent transmitting information from the child which is conflicting with her style of thinking ("dangerous" information). This is a reason of forming deficits in the child's development. Such mother's strategy is like leaving the child in her imaginary space, limiting the child's ability to get his own experience of self -realization in reality. Not all these situations lead to mental pathologies, but they form gaps and lack of personal development. We suggest that an adult person can partially compensate this gap when consciously pay attention to sensory channels and sense of self , trying to listen to, to feel and to appreciate.
Doctor Ralph-Axel Müller who examined more than 50 children autists used functional and anatomic magnetic resonance tomography combined techniques and diffusion tensor visualization to analyze links between brain cortex and thalamus. He found out disorders in conduction paths between thalamus and brain cortex, it means that the links between those brain areas are bad [2]. We would like to remind the role of thalamus as processing, integrating and triggering center for all sensory information. This fact confirms our suggestion below about the possible block of the child's sensory channels development by the mother. In our practice, we had the circumstantial evidence when some mothers of children with cognitive disorders confirmed in their profiles the facts about psychological traumas during pregnancy and after giving birth to their babies such as severe illnesses or death of close persons.
Obviously, autism is a disease considered on a systemic level as a structural and functional problem of different brain areas involvement in information exchange. It is not caused by a damage of a special brain area and mostly the autism genesis is connected with disorders in individual child's development that have started at an embryonal stage. However, these have something in common; children with autism create looped programs by their specific games and thereby load the left brain having the right brain switched off. Probably they try to follow their mother's leading brain hemisphere in that way.
Social life requires mother to switch on beta rhythm, the neurofunctional activity arousal rhythm. A mother tries to build contacts with a child in an usual style, performing analytic tasks and working by defined algorithms. Our experience of work with autistic children mothers proves that the most of them have the left brain style of thinking and consider their own opinion as "the only right one". It's not easy for such mothers to set themselves up for the right-brain figuratively
sensual thinking, sometimes they just see no sense in that. They need to develop well-linked cerebral hemispheres by their own efforts or with the help of psychotherapy and the progress in it shows how healing are these skills that give a chance to be involved in a right brain style of thinking. From the last century women have become actively involved in the industrial relations and have demonstrated the dominant position in different fields since an average women's left brain hemisphere develops better than men's [3]. Sometimes the priority of social activity, in contrast with the mother functions, creates conditions when a mother ignores her great mission. Nevertheless, nature protects its rules and laws and breaching them is unacceptable. Importance of the right brain hemisphere in human life is great. Preparing for pregnancy should mean taking care of feelings and sensory thinking, give special consideration to different arts, painting, music, crafts, quiet dialogs about happiness and joy.
Further we examine the practical value of knowledge about the controversial (mirror-symmetrical in a pair) thalami dominance in a mother-child dyad, how it can be used in the family members relations, behavior and interaction. For example, a mother having a dominant left brain hemisphere can better deal with fast time changing situations and analyze stimuli from the perspective of details and symptoms. She can plan new things in details, acts logically without jumping to conclusions, dreams rarely, tries always find reasonable explanations of people's behavior, she is punctual, she has a good sense of time, can describe her feelings verbally and make decisions based on reality.
On the other hand, the child with the dominant right brain tendency to interact with the real world in an image-based synthetic manner and to deal with things spontaneously, to make conclusions without preliminary thinking of the all details and arguments. He can dream being awake and have bright dreams and he rarely thinks about other people actions, he can have bad feeling of time and difficulties in describing his feelings, but while having to make decisions he relies on his feelings [2,120]. But in case the child has not gained the experience of taking apprehending and his feelings mental reflection it can cause family dispute.
Thus, in a mother-child pair at a deep anatomic level, the specific cerebral structures interaction forms a relationship between them, it reflects everyday life as a systemic interaction which is often taken as a conflict. Judging by the results of described above researches we can come to the conclusion that the main function of a mother-child system is a ballance of interaction with each other and with the surroundings. The way the pair interrelation is in ballance or conflict, will depends on the maturity of a mother (her ability to perceive her child's fundamentally different manner to interact with the world). In psychological terms, the bal-lanced relationship is described as a "secure attachment".
V. E. Symonenko in his researches of married and friendship pairs have come to a conclusion that the lateral coincidence between spouses comes to 83% [4,75]. It is logical to presume that the positive function of the lateral conflict in a mother-child pair is separation alleviation during the adulthood and new relationship out of parental family creation. One of the main aspects of life philosophy
would be in providing of a ballance inside of this conflict. Indeed, the system can experience some issues if the mother-child conflict does not exists. Confluence in pairs may cause difficulties while developing of self-identity and organizing of private space are actual.
Our research conclusions are:
- Mother-child dominant eye determining tests showed significant inverse correlation confirming the difference in the lateralization, which is localized in thalami. In case of dominance mismatch in that zone each of a pair takes different information from the same sensory stimuli and have another style of thinking. A child unconsciously tunes his alpha rhythm thalami pacemaker according with the mother's alpha rhythm being compensatory oriented on supporting of non-dominant mother's sensory impulses. Probably, under the condition of tough cortex hyperactive activation reaction (hyperarousal), a mother with the dominant left brain can "switch off" signals (asking for the help) that her right brain child sends her. She tries to disconnect transmitting information she considers as controversial to her style of thinking and "dangerous". In that way she creates the child's developmental deficits. Non-coincidence in cerebral structures functional asymmetry of a mother-child pair interaction in case of mother's maturity creates a "secure attachment" through an anatomic and psychological balance.
We showed that the mother and child different thinking styles conflict is at a deep level and suggested it may be one of the conditions of human evolutional development.
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