A team made up of HSE researchers and paediatricians of the Turner Research Institute for Children’s Orthopedics have compared the cognitive functions of children with and without arthrogryposis. The experiment revealed that children with arthrogryposis exhibit a slight delay of a few milliseconds in their brain responses to words associated with hand movements. The researchers suggest that this discovery be taken into consideration when teaching children with motor impairments and developing diagnostic tools. The paper has been published in Clinical Neurophysiology.
Arthrogryposis is a group of musculoskeletal pathologies that affect the joints, muscles, or even the spinal cord. This condition occurs in 1 in 10,000 newborns. Arthrogryposis is a condition that does not worsen over time and can be cured with treatment and rehabilitation. However, treatment for arthrogryposis can last several years and extend into adolescence.
It was previously believed that congenital muscle diseases are associated only with motion impairment and do not affect cognitive functions. A team of researchers at the HSE Centre for Cognition and Decision Making and the Turner Research Institute for Children’s Orthopedics compared the cognitive functions of healthy children to those of their peers with arthrogryposis and demonstrated a difference. The experiment involved 27 patients with arthrogryposis at the Turner Institute and 32 healthy controls.
The human brain consists of neurons that transmit electrical impulses through a network of connections. In response to external stimuli, such as sound or light, electrical impulses in the brain can either weaken or strengthen one another.
To examine how children's brains respond to specific words, the researchers utilised an electroencephalograph, which is a device that records and measures the electrical activity of neurons. The subjects took a seat in a chair and had a cap with electrodes placed on their head to record the activity of specific parts of their brain. The children were then presented with words that referred to movements of hands or feet, such as 'sculpt' or 'tread', and also with some meaningless pseudo-words. The generated potentials—electrical signals exchanged between brain neurons in response to an external signal—which were recorded. Electrodes attached to the head picked up these potentials and transmitted them to a computer to be decoded. The potentials were then displayed as waveforms on a graph.
The responses to the imperative verb 'tread' and to a similar-sounding pseudo-word were identical in both the study and control groups. However, the researchers observed a statistically significant difference in the groups' responses to the hand-related imperative verb 'sculpt'. The brains of children with arthrogryposis were found to respond differently to the word associated with hand movements, their reaction being about 1.5 times slower than that of healthy children.
The researchers emphasise that the difference in the first milliseconds after the stimulus lies in unconscious word processing, specifically in the extraction of associations with hand movement from the child's memory in response to the word 'sculpt'. The authors suggest that the slower word analysis in affected children may be due to their lack of experience with hand movements, which leads to weaker representations of these associations.
Children with arthrogryposis of the hands are born without the ability to control their hand muscles. They simply do not understand how to move their hand properly because they have never done it before. It is like asking a person who doesn't know how to move their ears to move them. A transplant of the latissimus dorsi muscle can be effective and well-tolerated, but children may require time to adjust to the changes.
The authors consider it of fundamental importance that the brains of pre-surgery children with arthrogryposis exhibited slower reactions specifically to words associated with hand movements. According to the researchers, this finding demonstrates that cognitive functions are not isolated, but rather interconnected with the body and manifested through interactions with the environment. The researchers suggest that this discovery be taken into consideration when teaching children with motor impairments and developing diagnostic tools.