Age‐dependent mesial temporal lobe lateralization in language fMRI

Abstract

Objective FMRI activation of the mesial temporal lobe (MTL) may be important for epilepsy surgical planning. We examined MTL activation and lateralization during language fMRI in children and adults with focal epilepsy. Methods 142 controls and patients with left hemisphere focal epilepsy (Pediatric: epilepsy, n = 17, mean age = 9.9 ± 2.0; controls, n = 48; mean age = 9.1 ± 2.6; Adult: epilepsy, n = 20, mean age = 26.7 ± 5.8; controls, n = 57, mean age = 26.2 ± 7.5) underwent 3T fMRI using a language task (auditory description decision task). Image processing and analyses were conducted in SPM8; ROIs included MTL, Broca’s area, and Wernicke’s area. We assessed group and individual MTL activation, and examined degree of lateralization. Results Patients and controls (pediatric and adult) demonstrated group and individual MTL activation during language fMRI. MTL activation was left lateralized for adults but less so in children (p’s < 0.005). Patients did not differ from controls in either age group. Stronger left-lateralized MTL activation was related to older age (p = 0.02). Language lateralization (Broca’s and Wernicke’s) predicted 19% of the variance in MTL lateralization for adults (p = 0.001), but not children. Significance Language fMRI may be used to elicit group and individual MTL activation. The developmental difference in MTL lateralization and its association with language lateralization suggests a developmental shift in lateralization of MTL function, with increased left lateralization across the age span. This shift may help explain why children have better memory outcomes following resection compared to adults.

Weaker semantic language lateralization associated with better semantic language performance in healthy right‐handed children

“…Age adjustment was reached by manipulating linguistic criteria of stimuli, specifically word frequency. As task difficulty is known to modulate brain activity (Dräger et al, 2004), this is a common psycholinguistic method to achieve comparable difficulty levels across age ranges (Ambridge & Rowland, 2013;Cowan, Saults, & Elliott, 2002) and was also used previously in the original, English version of the fMRI task developed by Berl and co-workers (Berl, Mayo, et al, 2014;Sepeta et al, 2015Sepeta et al, , 2016Sun et al, 2013). However, it means that linguistic stimuli differed among age groups.…”

“…A further drawback of our study is the slice thickness of 4 mm with a 1-mm gap. While a thickness of 4 mm or more is common in studies evaluating language lateralization in children (Berl, Mayo, et al, 2014;Berl, Zimmaro, et al, 2014;Elkana, Frost, Kramer, Ben-Bashat, & Schweiger, 2013;Everts et al, 2010;Sepeta et al, 2016;Szaflarski et al, 2014;Westmacott, McAndrews, & deVeber, 2017) as it allows shorter acquisition times when covering the whole brain, thinner slices would possibly have further enhanced the detection of the BOLD signal.…”

“…It can already be found in neonates (Peña et al, 2003;Sato et al, 2012;Vannasing et al, 2016) and 3-month-old infants (Dehaene-Lambertz, Dehaene, & Hertz-Pannier, 2002) and gradually increases with age (Holland et al, 2007;Sepeta et al, 2016;Szaflarski, Holland, Schmithorst, & Byars, 2006). However, even in right-handers, the degree of language lateralization shows considerable interindividual differences (Berl, Zimmaro, et al, 2014;Springer et al, 1999).…”

Language functional MRI and direct cortical stimulation in epilepsy preoperative planning

“…During each auditory task, the control condition consisted of reverse speech where patients were instructed to push a button on hearing a tone. Task performance was evaluated by the overall accuracy for the ADDT task (true positives/sum of correct answers possible + number of commissions × 100) 10 . Data were available for six of 19 subjects: overall accuracy was 85.8% (±13.2%).…”

Advanced neuroimaging techniques for evaluating pediatric epilepsy

“…Recently, fMRI has become a promising noninvasive alternative technique to the Wada test (intracarotid amobarbital test) in the adult population to guide the resection plan by identifying critical areas of the brain near the seizure focus and minimize the risk of new deficits. 60) The patient is asked to perform a se ries of tasks during a taskbased fMRI study. Although strong preliminary evidence shows that fMRI can be used to late ralize and localize language and motor function in pediatric epilepsy surgery candidates, functional mapping via taskbased fMRI is challenging in child ren due to a lack of cooperation, developmental immaturity, and agedependent cerebral plasticity.…”