Ventral stream sensitivity in "healthy" preterm-born adolescents: psychophysical and neuropsychological evaluation

Deficits of motion processing have been reported in premature and very low birth-weight subjects during infancy, childhood and adolescence. Less is known about ventral stream functioning in preterms.

The aim of this study is to investigate ventral stream functioning in a sample of "healthy" adolescents born preterm with normal outcome and without brain damage.

We enrolled thirty preterm-born adolescents (mean age: 14.2years, mean gestational age 28.9weeks, mean birth weight 1097g), and 34 age-matched term-born controls (mean age: 14.5years). All subjects were administered a psychophysical test known as "Form Coherence Task" and a comprehensive standardized battery of neuropsychological tests suitable for investigating ventral stream functioning including Street Completion Test, Poppelreuter-Ghent Test and the first part of the Visual Object and Space Perception (VOSP) battery. Dorsal stream visual functioning was investigated by the second part of the VOSP.

Preterm (PT) subjects showed the same results in all "ventral" tasks with respect to full-term controls without any correlation to gestational age or birth weight. We found a significant negative correlation between Form Coherence Task and Letters Task (p=.014) and between Form Coherence and Silhouette Tasks (p=.017). No correlation was observed between Form Coherence Task and Street and Ghent Tests. A statistical difference was instead found between PTs and controls in two tasks of the VOSP battery that mostly involve the dorsal stream.

Preterm birth per se (in absence of evident brain lesions) is not sufficient to compromise the development of ventral pathway.