Abstracts

While children[apos]s discourse skills develop during childhood and adolescence, important developmental changes take place in language-related fronto-temporal structures and pathways (Kanemura et al, 2003; Gogtay et al, 2004; Sowell et al, 2004; Blanton et al, 2004). Cryptogenic complex partial seizures (CPS) disrupt how children organize and formulate their thoughts, particularly if they have poor seizure control, younger age, and lower Verbal IQ (Caplan et al, 2006). This study examined the integrity of neural networks underlying higher level linguistic functions, such as discourse, in children and adolescents with CPS and age-matched controls., A previously validated fMRI paradigm (Caplan & Dapretto, 2001; Dapretto et al, 2005) was used where subjects listened to short question-answer dialogues and determined if the answers made sense. Unknown to the subjects, features critical to making this decision varied so as to tap either reasoning or topic maintenance. Data were acquired on a Siemens 3T Allegra scanner in 25 CPS (age: 9.9 yrs) and 24 normal right-handed children (age: 10.3 yrs) during 2 consecutive scans (order counterbalanced across subjects). For each scan, 24 question/answer pairs were presented in 2 activation blocks. Data were preprocessed according to established procedures (Woods et al, 1999) and analyzed in SPM2 with response times and accuracy as regressors in the within-subject analyses and IQ as a covariate in the between-group contrasts., In both groups and conditions, reliable activity was observed in canonical language networks including Broca[apos]s and Wernicke[apos]s areas and their right hemisphere (RH) homologues, as well as in the anterior cingulate, medial prefrontal cortex (MPFC), and cerebellum. Within this large network, controls showed reliably stronger activity in the left inferior frontal gyrus (IFG) in the reasoning condition, and in bilateral temporal cortices and right IFG in the topic maintenance condition. CPS children also showed selective left IFG activity in the reasoning condition but failed to show any RH activity in the topic maintenance condition where they instead showed greater activity in left temporal cortex and MPFC. Group comparisons revealed reliably greater activity in controls than CPS children in the left IFG and in right temporal cortex for the reasoning and topic maintenance conditions, respectively., Abnormalities in neural circuits involved in making sense of the reasoning and topic of a conversation in the CPS group might reflect the higher-level linguistic difficulties found in these children (Caplan et al., 2006). Studies on larger CPS samples are needed to determine if these findings relate to lateralization and localization of focal epileptic activity., (Supported by NIH grants NS32070 and MH067187 (R.C.).)