Table 1.

Key elements emerging from the studies in theme 1.

Systematic Review	Highlights
[62]	The study emphasizes speech and language delays in young autistic children, utilizing neuroimaging, especially fMRI, to explore early neurobiological indicators. Key findings encompass atypical neural lateralization, connectivity alterations, and varied neural sensitivities, with an early detection potential of as early as 6 weeks. These results underscore fMRIs ability to reveal early signs of delays before behavioral manifestations, highlighting the importance of standardized paradigms.
[63]	The study reported different neuroimaging techniques to identify brain abnormalities associated with psychiatric conditions, emphasizing the intricate interplay of physiology and anatomy in these disorders. The meta-analysis strongly advocates for the utilization of neuroimaging techniques, particularly emphasizing the physiological and anatomical insights provided by fMRI, in the accurate detection of psychiatric disorders, including autism.
[65]	The study delves into the neural intricacies of brain structure and function in children with co-occurring neurodevelopmental disorders, using structural MRI, diffusion tensor imaging, and resting-state fMRI. It emphasizes the uniqueness of neural correlates for each disorder, shedding light on their distinct characteristics despite common co-occurrence.
[68]	The study highlights significant neural effects and behavioral improvements resulting from interventions based on motion activity, with chronic interventions showing greater efficacy. The review calls for more extensive research with larger sample sizes and standardized neuroimaging tools to better comprehend the underlying neural mechanisms that benefit individuals with developmental disabilities, emphasizing the crucial interplay of anatomy and physiology in this context.
[70]	The study stresses the need to prioritize females in ASD research due to their distinct phenotypic trajectories and age-related brain differences. It underscores the influence of sex-related biological factors, proposing a comprehensive approach to understanding brain-based sex differences in ASD, focusing on anatomy and physiology. The review of neuroimaging studies identifies consistent sex differences in brain regions, suggesting unique neurodevelopmental patterns in females with ASD. The concept of a ‘female protective effect’ gains support, emphasizing genetic and endocrine influences on brain development.
[72]	The study focused on near-infrared spectroscopy (fNIRS), highlighting its potential advantages in exploring the neural connections to speech and language issues across diverse conditions, including autism spectrum disorders. The findings suggest that fNIRS holds promise for early diagnosis, assessment of treatment responses, and applications in neuroprosthetics and neurofeedback.
[73]	The study identifies practicality, portability, and reduced sensitivity to movement artifacts as advantages of fNIRS as a functional neuroimaging technique. However, it notes variations in study quality and a lack of large, randomized controlled trials. Although some studies suggest the feasibility of modulating brain function in autism, conclusions remain premature. The study highlights the potential for clinical translation and emphasizes the need for improved research practices and reporting for further methodological advancements in fNIRS-neurofeedback.
[74]	The study reveals distinct structural and functional brain irregularities in attention-deficit/hyperactivity disorder (ADHD) and ASD during cognitive control tasks. Specifically, ADHD is associated with reduced gray matter volume in the ventromedial orbitofrontal area, whereas ASD is characterized by increased gray matter volume in regions like the bilateral temporal and right dorsolateral prefrontal areas. Functional differences emerge as underactivation in the medial prefrontal region and overactivation in the bilateral ventrolateral prefrontal cortices and precuneus in ASD. Conversely, individuals with ADHD demonstrate right inferior fronto-striatal underactivation, particularly during motor response inhibition.
[76]	The study investigates how individuals with ASD process rewarding stimuli, particularly if these differences extend beyond social rewards. Utilizing fMRI, the research uncovers distinct patterns of reward processing in ASD individuals, encompassing both social and nonsocial rewards, with atypical brain activation in specific striatal regions. Notably, heightened brain activation occurs when individuals with ASD are exposed to their restricted interests, challenging traditional notions of the social motivation hypothesis.
[78]	The study in [58] revisits the attention-grabbing potential link between dysfunction in the mirror neuron system and challenges in social interaction and communication in individuals with ASD. Various neuroscience methods, including EEG, MEG, TMS, eyetracking, EMG, and fMRI, were used to assess the integrity of the mirror system in autism. Notably, fMRI emerges as the most effective measure of mirror system function. In fMRI studies, those using emotional stimuli reveal group differences, while those employing non-emotional hand action stimuli do not show similar distinctions.
[79]	The work analyzes studies using functional fMRI and diffusion tensor imaging (DTI) data to evaluate their alignment with the proposed social communication and behavioral symptom dyad in individuals diagnosed with ASD according to the DSM-5. The results reveal abnormalities in brain function and structure within various networks, such as fronto-temporal and limbic networks linked to social and pragmatic language deficits, temporo-parieto-occipital networks associated with syntactic-semantic language deficits, and fronto-striato-cerebellar networks related to repetitive behaviors and restricted interests in individuals with ASD.
[80]	In the study, one of the most consistently observed findings is a disruption in the function of brain regions associated with social interactions in ASD. These differences in activation within the social brain may stem from a diminished preference for social stimuli rather than a fundamental malfunction of these brain areas. Accumulating evidence suggests challenges in effectively integrating various functional brain regions and difficulties in finely adjusting brain function based on changing task demands in individuals with ASD.
[81]	The study investigates the brain regions associated with social cognition deficits in ASD and Schizophrenia (SZ). The results show that both ASD and SZ exhibit reduced activation in certain brain areas linked to social cognition, particularly in the medial prefrontal region. However, there are specific differences in brain activation patterns and engagement with stimuli between the two disorders. These findings offer valuable insights for future research and understanding of these conditions.