Influence of radiotherapy on control functions network fMRI connectivity in patients with lateralized mediobasal temporal lesions

Abstract

According to the literature, radiotherapy (RT) used for brain tumors, along with a positive effect, can be accompanied by negative consequences in the form of the development of neurocognitive deficit due to the side effects of radiation on critical brain structures. At the same time, there are indications of a possible modulation of hippocampal neurogenesis with subsequent activation of a number of cognitive functions. An important component of human cognitive activity is the so-called executive functions (EF), which include the initiation, planning, regulation and control of any purposeful activity. Their structural and functional support is currently associated with the prefrontal and parietal sections of the hemispheres, as well as with the formations of the lower temporal cortex and the hippocampus. The work is aimed at dynamic assessment of the state of the EF-network according to the analysis of resting fMRI connectivity before and after 6 months after RT. In dynamics, 14 patients with lateralized tumor lesions of the mediobasal temporal lobe were examined: 7 with the left side, 7 with the right side. The control group consisted of 9 healthy subjects. Each participant underwent fMRI at rest – with further analysis of the functional connectivity between the given regions of interest, corresponding to the topography of the EF-network. The results were compared with the MRI morphometry tumor data. It has been shown that in patients 6 months after RT, against the background of a decrease in volume or stabilization of tumor growth, the functional effects are ambiguous and depend on the lateralization of the lesion: with a right-sided lesion they tend to normalize, while with a left-sided lesion they increase.