Regional age-dependent effects of hemineodecortication upon contralateral neocortical thickness: Comparison with other measures of cortical size

This study investigated age-dependent changes in regional neocortical thick ness after hemineodecortication in cats and compared the results to previou sly reported volumetric and cross-sectional data. Subjects sustained hemine odecortication on postnatal days (P) P10, P30, P60 or in adulthood. Neocort ical thickness was quantified at 115 sites along 20 stereotaxic coronal ant erior-posterior (AP) planes using defined sites of the main cerebral sulci for the measurements. The analysis established significantly lower thicknes s values for adult-lesioned as compared to (a) P30, P60 and control groups at AP +14, (b) P30 group at 7 planes along a range of AP +9 to AP +3, and ( c) P10 and P60 groups at AP +6. Both the P10 and the P30 groups presented a significantly thicker neocortex than controls at select coronal planes clu stering behind AP +10 (parietal and temporal cortices). When analyzed by su lcus, results once again reflected significant advantages for the early-les ioned cats with a significantly thicker cortex found at 4 of the 8 sulci ex amined. Again, significant advantages were also discovered for early-lesion subjects compared with control cats (splenial, cruciate sulci). Overall, t he range of significant effects (from AP +14 to AP 0) and the direction of the means suggested that there was a significant, age-dependent (P10-P60), regional sparing of neocortical thickness with a peak effect occurring at P 30. We concluded that: (a) there was a regional sparing/increase of neocort ical thickness suggesting that discrete cortical areas are selectively invo lved in the resistance to structural atrophy following hemineodecortication in young cats (P10-P60) and (b) the global loss of neocortex volume found in our previous study was not apparent using the present thickness measurem ent. It is suggested that both of these measurements must be taken into acc ount when assessing morphological effects upon the neocortex either in huma n pathology (i.e. hemispherectomy, intractable epilepsy) or in animal model s. Copyright (C) 1999 S. Karger AG, Basal.