Specific early vulnerability of high-order executive function to focal brain lesions and long-term impact on educational persistence: Sparing of incidental episodic memory

Abstract

Mental abilities acquired through early schooling remain impaired into adulthood when early schooling is disturbed, not everyday memory which does not depend on schooling.

Evidence from unilateral lesions of early uncompensable implementation of opposed response-biases in each hemisphere of the brain

“…This can be enough in some cases, perhaps many, to subtract the equivalent of a full year of intellectually stimulating family life, daycare, or early schooling at an age where the intellect would normally be maturing at an exceptionally fast pace. A cultural explanation of the early vulnerability effect explains a number of puzzling facts: 1) early juvenile hospitalization for non-neurological medical conditions (bronchopulmonary dysplasia, cardiac malfunction, leukemia, liver failure) significantly predicts deleterious long term outcome of IQ and educational attainment [61][62][63][64]; 2) lesion volume does not modulate early vulnerability effects in large scale studies of IQ [45,50]; 3) post-lesion distortion of response-bias does not present an early vulnerability [1]; 4) neonatal brain lesions leave very few sequelae, which are common in adults such as hemiplegia or aphasiaindicating early brain resilience, not vulnerability; 5) in normal children, raw IQ doubles between the ages of 2 and 3 years of age, but shows virtually no change after six years of age [52]; 6) in rats, a potent "early housing effect" is observed: there is a strong cognitive effect of enriched/impoverished environment, which is linked to age at lesion onset. Specifically, in the long term, early lesions inhibit benefits of culture more than do lesions incurred later in life [65].…”

“…Conversely, it is now well-established that high order cognitive function is indeed modulated by age at lesion onset across the lifespan, particularly the first years of life, and that effect presents itself as an early vulnerability effect [45][46][47][48][49][50][51]. This effect has even been demonstrated with a large sample of brain lesioned children with the same task (c.f., RLAS) as the one used in the present investigation [52].…”

“…The research tool designed for the present experiment was a multitask occupational computer simula-tion called RLAS, which has been shown to be highly reflective of cognitive decline related to normal aging [53] and to brain lesions [52]. It generates normally distributed performances devoid of ceiling effects [54].…”

“…It has been argued elsewhere [46,52] that the early vulnerability effect may consist of a cultural effect or a cultural/maturational interaction, rather than a direct vulnerability of the young brain. It is possible that interruption or disturbance of early intellectually stimulating family life, daycare, or early schooling inhibits cognitive development, whether it be due to a brain lesion or to any non-neurological factor, indifferently.…”