## 5 Discussion  
Our study demonstrated that a paralimbic-related subcortical-based semi-quantitative BDS has proven to be sensitive to dysmaturational differences between CHD and control infants. We also show secondarily in a subset of these patients that this BDS score can predict neurodevelopmental outcomes within CHD infants, including associations with early language, clinical, and feeding outcomes. Most conventional semi-quantitative  
Figure 6: Mouse RNA Sequencing Analysis Shows Significant Difference in Gene Expression. (**A**) Genes associated with learning and memory showed lesser expression in control mice compared to _Ohia_ mutant mice. (**B**) Genes associated with feeding behavior showed an abnormal pattern in _Ohia_ mice. _Ohia_ mice showed a pattern of expression that was opposite compared control mice at both time points. (**C**) Genes associated with neuronal differentiation showed an opposite pattern of expression in _Ohia_ mutant mice compared to controls. (**D**) Genes associated with synaptic transmission had a different expression pattern in _Ohia_ mutant mice compared to controls. MRI scoring systems in CHD patients have exclusively focused on either acquired brain injury or cortical maturation assessment, particularly in the neonatal period [26; 27; 28; 29; 30; 31; 32; 33]. In this study, we demonstrated that not only is it possible to generate a paralimbic-related subcortically informed scoring system, but that such a scoring system holds important information regarding outcomes for CHD infants at risk for atypical neurodevelopment. The key subcortical components of our scoring system included subcortical structures that are known to be part of paralimbic neural networks including the olfactory bulb, the hippocampus, the cerebellum, and the deep grey structures like the striatum. Furthermore, we showed that there is a distinct similarity between findings seen in CHD infants when compared to a preclinical mouse model of CHD suggesting similar mechanisms of brain dysmaturation. Interestingly, the subcortical abnormalities identified in our CHD patients (olfactory, cerebellar, and hippocampal abnormalities) have been described in non-CHD pediatric disorders like autism and attention deficit hyperactivity disorder. In our study, we found a high incidence of paralimbic-related subcortical abnormalities including olfactory, cerebellar, hippocampal, and brainstem abnormalities in infants with CHD compared to controls. We found similar olfactory bulb defects in the preclinical mouse model that we also see in our human CHD population. These abnormalities were used to derive a semi-quantitative subcortical abnormality or brain dysplasia score (BDS). We found that this BDS correlated with reduced cortical maturation (measured with the classic TMS), increased CSF volume and increased deep grey volume (striatum/thalamus). In contrast, the BDS did not correlate with GA, preterm status, cardiac lesion subtype, birth factors, intraoperative factors, or different vendor MRI/field strength. There was no correlation between acquired brain injury patterns and BDS. BDS did correlate with developmental delay and poor expressive language development. There was no correlation between preoperative or postoperative status and BDS score. The BDS also correlated with age at surgery, increased length of hospitalization, and need for G-tube placement. A more detailed evaluation of factors surrounding feeding and individual brain dysplasia parameters found correlations between lack oral feeding prior to neonatal hospital discharge and dysplasia of multiple brain areas as well as the BDS, and additionally with hospital length of stay, which is likely the sequala of feeding dysfunction. Interestingly, swallowing dysfunction was associated with dysplasia of the brain stem. Of note, there are other possible confounding factors like anesthetic exposure and other clinical factors related to the hospital stay that we did not examine in our study, that could potentially impact brain neurogenesis and hence the BDS score.