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Studies of nervous system sensitivity in children with learning and attention disorders
Insights
Children with attention or learning disorders showed varied nervous system sensitivity. Hyperactive children were more likely to have weaker nervous systems, requiring higher medication doses, contrary to initial hypotheses.
Area of Science:
- Neuroscience
- Developmental Psychology
- Behavioral Science
Background:
- Children with learning or attention disorders exhibit a wide range of nervous system sensitivities.
- Nervous system strength, or weakness, is assessed via reaction times to varying auditory stimuli.
- Previous research suggests potential differences in nervous system sensitivity between genders and hyperactivity levels.
Purpose of the Study:
- To investigate nervous system sensitivity variations in children diagnosed with learning or attention disorders.
- To explore the relationship between nervous system sensitivity, hyperactivity, and medication response.
- To test Gray's theory regarding stimulus intensity thresholds for different nervous system types.
Main Methods:
- Assessed children's nervous system sensitivity using press and release reaction times to auditory stimuli of varying intensities (55-100 db).
- Compared reaction time gradients across intensity levels to classify nervous systems as strong or weak.
- Conducted a blind crossover study with methylphenidate in boys, adjusting dosage based on nervous system classification.
Main Results:
- Significantly more hyperactive children were classified as having weaker nervous systems.
- Contrary to expectations, no significant gender difference in nervous system sensitivity was found, though girls reported lower tolerance to intense stimuli.
- Children with weaker nervous systems (unmedicated) showed less reaction time facilitation with reward compared to those with stronger nervous systems.
Conclusions:
- Nervous system sensitivity varies significantly in children with learning/attention disorders, with hyperactivity linked to weaker systems.
- Methylphenidate dosage adjustments based on nervous system type may be a viable therapeutic strategy.
- Findings support Gray's theory on differential stimulus intensity thresholds related to nervous system strength.
Abstract:
Clinically referred children, diagnosed as having learning or attention disorders, with or without hyperactivity, were found to vary widely on a measure of nervous system sensitivity recommended by the Pavlovian investigator Vasilev. That is, the children were contrasted on their mean press and release reaction times (RIs) to four tones, ranging from soft (55 db) to very loud (100 db), with the expectation that some would be able to maintain a parallel separation of press and release RT gradients across all intensity levels (strength), whereas others would show convergence or overlap of the gradients at higher intensities (weakness). Contrary to expectation, girls did not have weaker or more sensitive nervous system than boys, although the girls rated themselves as less tolerant of intense stimuli. Significantly more of the children diagnosed as hyperactive had weaker nervous systems. The boys also participated in a blind crossover study contrasting placebo and methylphenidate effects; the prescribing physician, who was not informed of the child's nervous system classification, adjusted the dosage levels so that subjects with weaker nervous systems were titrated at higher dosage levels than those with stronger nervous systems. Gray (1964) suggested an explantation of this paradox, i.e., that a weak nervous system requires a more intense stimulus than the strong to reach the threshold of concentration (or focused attention), whereas for other thresholds the strong requires a more intense stimulus than the weak. Gray's theory was further supported by the finding that children typed as weak (unmedicated) did not show as great facilitation in RT with reward (moderate stimulus) as did those typed as strong.
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