The development of a brief Functional Magnetic Resonance Imaging test battery for neurofunctional investigation of language, memory encoding and motor function in normal children

Abstract

Several patient groups (e.g., intractable epilepsy, intracerebral tumours) require neurosurgical treatment. The goals of neurosurgery are to resect affected tissue, and to avoid morbidity of function. Previous studies have validated the ability of single fMRI tasks for the preoperative investigation of the localization and lateralization of functions such as language, memory and motor functioning, with a notable paucity of fMRI studies conducted in children. The limitations of using single-tasks for preoperative evaluations have been identified, including discrepancies with ‘gold-standard’ techniques such as the Wada Test and Cortical Stimulation Mapping in terms of lateralization of functions, particularly for language. However, few studies have attempted to use a battery of tasks to combat these issues. Of the few existing studies employing fMRI task batteries, most have been conducted in adults, and have tended to focus on language functions. The current study developed and evaluated the use of a brief fMRI task battery for neurofunctional investigation of language, memory encoding and motor functioning in a sample of 22 healthy children (aged 6.4-16.6 years); that can be used with children of various ages and abilities, and thus it is envisaged that the task battery can be applied to clinical paediatric populations for the purposes of preoperative localization and lateralization of these functions. The study employed two tasks well-reported in existing adult and paediatric fMRI literature (noun-verb generation, NVG; and finger opposition, FO), and two ‘novel’ tasks for use in children (an auditory word presentation task of parametric design, WA; and a picture encoding task, PE). As hypothesized, the tasks showed robust activation in the predicted regions (inferior and middle frontal regions for NVG; M1, S1, SMA and cerebellum for the FO task; superior temporal gyrus and primary auditory association cortex for the WA task; and anterior medial temporal lobe for the PE task). Lateralization indices were also conducted for the NVG, WA and PE tasks. The limitations and considerations of use of fMRI in clinical paediatric populations are also discussed, including the use of mock scanners with paediatric fMRI studies, and the lack of a paediatric atlas equivalent to existing adult atlases for analysis of fMRI data. This study concludes that the proposed fMRI battery provides a brief, valid means for neurofunctional investigation of language, memory encoding and motor functioning in healthy children; which has potential for use in preoperative investigation of these functions in children with neuropathology, in conjunction with other assessment methods such as the Wada Test, Cortical Stimulation Mapping, and neuropsychological assessment