In "Structurno-Functionalniye, Neyrokchimicheskiye e Immunokchimicheskiye Zaconomernosty Asymmetrii e Plastichnosty Mozga" (Materials of the Scientific Center of Neurology conference), pp 336-340, Moscow, Russia.

Effect of perinatal pathology on dominant hand formation.

Nabieva T.N.

Brain Research Department, Scientific Center

of Neurology, Russian Academy of Medical Sciences,

105064, per. Obukha 5, Moscow, Russia.

During investigation of hand lateral preference usually are revealing not only strong right/left-hander's, but persons with different degree of leading hand dominance. It's not clarified yet why it can observe in population both strong right/left hander's and those who predominantly preference right ore left hand. We supposed that deviations from persistent hand lateral preference may be associated with perinatal pathology.

Method. We selected a) 20 right-handed children (5.5-6 years old) without evident neurologic pathology, but survived perinatal asphyxia (PA). All children were right-handers in writing, painting and eating. They had to perform 10 tasks, requiring bimanual activity. c) Control group included 20 right-handed children (5.5-6 years old) without perinatal pathology.

Results. c) Participants from control group used right hand as dominant and left hand as aiding in 9-10 tests from 10. a) Children with PA in anamnesis experienced some difficulties in all types of manual activity. They performed all tests slower, demonstrating some motor awkwardness, and used right hand as dominant only in 5-9 tests from 10. a) During realization some tests - knots untying, shoe lacing, - 9 children used both hands without preference. a) In 9 children lateral preference estimated as right dominance with different degree of left hand participation. Right hand dominance rate in children survived PA, appeared less as compared with control (p< 0,0001).

Consequences of endured birth trauma affect on child's physical health and nervous system formation from early childhood. Hyper-/hypotonic disturbances are usually appeared as a result of brain injury through asphyxia from first weeks of infant's life. Subsequently in those children was observed neurological complications, consisting mainly in motor deficiency. Later, relatively limited locomotor activity appeared insufficient for complex movement's realization, and children used subdominant hand more frequently than their healthy age peers.

Conclusion. Functional compensation of developing brain after the focal lesions (as a consequence of PA) in motor cortex in the area of dominant hand representation can consist in redistribution of functions between intact areas in both hemispheres. Motor activity of dominant hand can be provided not only by specific fields of both hemispheres, but adjoining cortical areas. This cerebral reorganization leads to hereto, both dominant and subdominant hands of subjects endured PA, are less lateralized as compared with healthy people. We can assume that partial hand dominance occurrence may be connected with birth trauma in anamnesis. It's possible that perinatal complications not only increase probability of left-handedness, but also delay leading hand formation; early brain injury influence not only on laterality pattern formation, but also promote partial hand dominance.