Spontaneous Speech Impairments and Their Neuroanatomical Correlates in Patients with Frontal Lobe Tumors

The study was carried out in order to examine the features of spontaneous speech impairments after removal of tumors in the frontal lobe and to reveal the role of the right Frontal aslant tract (FAT) and interhemispheric connections between its cortical projections in the recovery of speech disorders in case of damage to the left FAT. As a result, two research hypotheses have been put forward. According to the null hypothesis, the volume of the left FAT was expected to correlate with the score for the spontaneous speech production task. According to the second hypothesis, we expected to obtain a significant relationship between the volumes of the right FAT and the score for spontaneous speech, as well as between the volume of interhemispheric connections and the same behavioral metric, since this could indicate a functional reorganization involving these anatomical structures. Analysis of linguistic assessment test, reconstruction of white matter tracts of the brain, and correlation analysis was used as methods in the work. We did not obtain significant results in the correlations between the tract volumes and the score for the spontaneous speech production task, as a result of which we were forced to reject both hypotheses. A possible reason for this result may be an insufficient sample size, as well as its low variability. An analysis of individual cases was also carried out, the results of which showed that when the left FAT was damaged, most of the participants showed impaired spontaneous speech in the acute postoperative period. The findings are consistent with those of previous studies that also identified impairments in spontaneous speech production in case of damage to the left FAT. However, it should be noted that these conclusions were made based on the analysis of individual cases, therefore, at this stage, we cannot draw specific conclusions about the role of FAT and interhemispheric connections in language processing and the mechanisms of functional reorganization. In the future, it is planned to continue the study on an expanded sample, taking into account the identified methodological limitations.