Frontal lobe dysfunction underlies the differential word retrieval impairment in adolescents with high‐functioning autism

Abstract

There is substantial evidence of word retrieval impairment as indicated by poor performance on the category fluency test in autism spectrum disorder (ASD). However, little is known about the neural mechanisms underlying this impairment. Functional neuroimaging studies have shown that the lateral frontal cortex plays a key role in flexible word retrieval. Thus, we examined whether individuals with ASD exhibited altered frontal processing during the category fluency test using functional near‐infrared spectroscopy (fNIRS). Twenty‐two adolescents with high‐functioning ASD (20 males) and 22 typically developing (TD) adolescents (16 males) aged 11–18 years were recruited. All underwent a category fluency paradigm, which required production of animal or means of transportation words for 1 min each although their frontal hemodynamic changes were recorded with fNIRS. We found that adolescents with ASD produced fewer animal but not transportation words (group‐by‐category interaction: P = 0.003), suggesting differential word retrieval impairment. In addition, unlike TD adolescents who exhibited activation primarily in lateral frontal regions during word production, adolescents with ASD had comparable activation across lateral and medial frontal regions. More importantly, this lack of lateral–medial distinction of activation, which was associated with poor word retrieval, differed significantly between groups only in the animal category (group‐by‐category interaction: P = 0.018). Thus, our findings implicate frontal lobe dysfunction in the impairment of differential word retrieval in adolescents with ASD. The relatively greater involvement of the medial frontopolar cortex might reflect the use of nonspecialized brain regions to compensate for the category‐dependent difficulties with word retrieval in ASD. Autism Res 2019, 12: 600–613. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. Lay Summary Using an optical imaging tool, we found that adolescents with autism had difficulties with producing semantically related words and exhibited frontal lobe dysfunction. Nonetheless, poor word production and altered brain processing was only seen when these adolescents were asked to produce words from a category of living things but not nonliving things (i.e., animals but not means of transportation). Category‐dependent word retrieval problems and frontal lobe dysfunction might be two features of this disorder.

Neurophysiological and behavioral effects of multisession prefrontal tDCS and concurrent cognitive remediation training in patients with autism spectrum disorder (ASD): A double-blind, randomized controlled fNIRS study

“…The arrangements of channels, near-infrared emitters and detectors, as well as the channel groupings, are illustrated in Figure 2. The channels were grouped to represent the medial and lateral PFC in the left and right hemispheres to increase the signal-to-noise ratio [51]. A resting fNIRS measurement was collected in the eyes-open condition for five minutes, with the participants asked to focus on an image (i.e., a house) displayed on a computer screen [52].…”

Cerebral Functional Manipulation of Repetitive Transcranial Magnetic Stimulation in Cognitive Impairment Patients After Stroke: An fMRI Study

“…It mainly works for integrating the afferent information from other brain regions and organizing efferent impulses timely, to ensure the overall synergy between the nervous system and psychosocial processes. It involves in a variety of higher functioning processing, including memory, abstract thinking, judgment, emotion, personality and impulsive behavior, etc (55)(56)(57)(58)(59). Hence, the enhancement of functional connections in frontal lobe with the LDPFC, such as MFG and IFG, has a strong connection with the improvement of cognitive function.…”

Application of functional near-infrared spectroscopy in the healthcare industry: A review

“…28 In addition to the lateral frontopolar cortex activation that is observed in healthy persons, the medial frontopolar cortex of highfunctioning ASD patients also exhibited activation, thereby demonstrating the compensation mechanism of an impaired brain. 29…”

“…96,97,109 The headgears/caps are also provided by the system manufacturers, therefore, in most cases, these headgears/caps are used to place and hold the optodes at a¯xed distance of 3 cm. [28][29][30][31][32][33][34]121,[194][195][196][197][198][199]224,241,242 It is recommended to use a channel separation of 2 cm for children and infants due to smaller head size and the resulting reduced width between super¯cial layers. 23,42,167,294…”