The Role Of Hemispheres Of The Brain In Attention And ADHD

Asymmetry and Contributions of the Hemispheres to Affective and Cognitive Processes

The Asymmetrical Scenario related to the different hemispheres of the brain has always been studied. The asymmetries in the affective, as well as the cognitive functions, have been researched. Both the cerebral hemispheres contribute to the cognitive and the affective processes but the right hemisphere dominates the aspects of emotion. The right hemisphere plays the role of the emotional side whereas the right hemisphere takes care of the emotions, attention, and arousal instincts of human beings (Elliott, Knodt & Hariri,2021). Any emotional stimuli most importantly the ones which are related to survival are prioritized in the attentional resource competition. The arousal of unpleasant emotion to stimuli are prioritized. The tasks which depend on the right hemisphere are vulnerable to interference due to the attention captured by any form of uncomfortable emotional stimulation. The right hemisphere of the brain is always actively trying to understand the uncomfortable stimuli to show the fight or flight response to the human so that they can survive. The right hemisphere is the alert part of the brain when it comes to attention.

The left hemisphere has a very important role when nonspatial attention is directed to specific stimuli such as color and frequency of the spatial distance. The left hemisphere is mainly dominant in object-based attention. The left hemisphere is dominant for the aspects of speech for right-handed people (Keren et al, 2018). For people who have a dominant left hand have the left hemisphere as dominant for speech as well. The left brain is associated with reading, writing, and analytical calculations. The left brain is the logical part of the brain and it is more calculative. The role of the left brain during attention is to have the analytical approach and calculative approach to any stimuli. The left side of the brain controls the right side of the body and the left side is the logical part of the brain.

The study of attention has always been about the aspects of selecting from among the various sensory events. This also involves the selection between the conflicting actions as well. Early evidence related to attention networks came from neurological investigations. The emergence of functional anatomy has given support to the studies of the development of attention networks. Attention is one of the most important topics functional magnetic resonance imaging is used to demonstrate that the functional connectivity inside the frontoparietal network at rest is related to attention. The dorsal attentional function was also evaluated through this FMRI test (Lurie et al, 2020).

Functional Anatomy and Functional Magnetic Resonance Imaging (fMRI) in Attention Networks

fMRI tests can tell a lot about attention networks. Human vision and eyesight are confronted with several stimuli at one time. Only some of these stimuli reach the consciousness of the brain.  fMRI scans can predict the deficit of attention in the brain of a patient with ADHD. The scan can also make the researchers understand the neurological symptoms of ADHD. Attention networks can be seen through fMRI by the 3D scanning and it can help in understanding how the three networks work together. fMRI scanning can give a first-hand picture of the functions of the brain and the networks of attention that help the right hemisphere function (Rocchi et al, 2020). The patterns of brain activation in individuals who have ADHD and healthy individuals can be compared. Attention networks can be seen through an fMRI and the intensity of the networks can also be evaluated through the 3D image. Therefore, it is essential to have an fMRI scan in order to understand the attention networks and how they work inside the brain to help the person understand stimuli. This scan can also detect the deficiencies of the networks in case the patient has had a brain injury or any form of brain trauma. Attention networks can be better understood through the fMRI scanning. 

ADHD is a neurodevelopmental disorder because the symptoms start in the developmental period. Any person with ADHD will have a persistent structure of hyperactivity or lack of attention which will interfere with life and the functioning of daily life. There are several ways in which neuropsychologists diagnose ADHD. They are given below.

1. Comprehensive assessment of cognitive as well as behavioral functions. This is used with the help of using a set of standardized procedures and tests such as questions, computer-based tests, and written tests (Zhang et al, 2020). The main strength of this diagnosis technique is that there is concrete evidence of the results which can be compared to the symptoms written in the DSM-5.
2. Rating scales for evaluating ADHD diagnosis. The neuropsychologist uses rating scales such as Barkley, BASC, Brown, and Conners to understand the self-report information from the patient. The main strength of this diagnosis is that there is a concrete scale that is being used to evaluate the symptoms. All these scales have a particular measurement which is concrete.
3. SPECT brain imaging for diagnosis. This form of imaging is a radioactive process in order to capture the 3D images of the flow of blood in certain areas of the brain. It is not painful or dangerous for the patient. SPECT imaging is beneficial for assessing the specific functioning of the brain which might have been damaged by injury or disease. It is very useful in ADHD because it only reports on how the brain of the individual functions in other scenarios such as school, outdoor activities, and interaction with other individuals. The strength of this is that it is using proper 3D proof of the brain (Pan et al, 2020).

The attention deficit that is difficult to diagnose is adult attention deficit disorder because the symptoms of ADHD become similar to anxiety in adults. 

The unilateral form of spatial neglect is very common in neurological syndromes where the right hemisphere is injured. This neglect reflects the limitations in the coding and control of spatial attention. Spatial neglect is asymmetric attention and action causing disability. It is a very common disorder of attention and it is generally the consequence of stroke in the right hemisphere of the brain (Ulke et al, 2019). It is a behavioral disorder and it is also known as a unilateral syndrome. Spatial neglect affects perceptual and behavioral deficits. There is also the presence of emotional dysfunction as evidence that supports this fact. The perceptual neglect is more than the attentional impairment because this deficit of spatial attention can make the patient have emotional dysfunction and anosognosia. Spatial neglect can occur due to stroke, traumatic injury to the brain, brain tumors, or even aneurysms. Spatial neglect can lead to visual extinction (Posner,  Rothbart & Ghassemzadeh, 2019). Neglect h=generally follows the right parietal injury and it is characterized by damage to attention or a lack of stimulus. Neglect is not as severe as extinction because neglect does not have the removal of stimuli or the capacity for attention. Blindsight is similar to amnesia which is far more severe than neglect. This is what makes neglect different from blindsight or extinction because blindsight is the complete absence of any attention or memory and neglect is not the complete absence of attention (Gammeri et al, 2020).  Blindsight is having sensation without any perception. Spatial neglect is a behavioral deficiency after the injury to the brain whereas extinction or blindsight is more biological. Blindsight makes the patient have stimuli that cannot be consciously recollected or can be identified by the patient. This is why neglect, extinction, and blindsight are very different. Extinction and blindsight are severe while neglect is behavioral and can be cured with a proper treatment. 

Diagnosis of ADHD and Related Disorders

Attention is a very important component of the cognitive and behavioral processes and it also plays a major role in the basic as well as the higher level of functioning. Posner’s model of attention has described the three main components or the networks which are present in the domain of attention (Boukrina & Chen, 2021). They are mainly, alerting, orienting, and executive control. The alerting is the one that involves very intense states of arousal to stimuli which can be dangerous. The orienting is the one that involves the selective areas of attention and the executive control pertains to cognitive functions such as memory and conflict resolution.

When it comes to ADHD, there is an impairment in the executive control system in children as compared to children who do not have ADHD. The children with ADHD had deviant brain regions for all the attentional networks. There was lesser right-side activation which is used to alert the subject, lesser re-orienting stimuli, and also less activation of stimuli control. For the alert and executive control domains, the deviant mechanism was at play. Even if children with ADHD have developed alternate strategies for the reorientation of attention, the attention networks in their brains are less powerful than the children who do not have ADHD (Prentiss et al, 2018).

Children with ADHD show significant impairment in their executive control system. The capability to maintain attention in the simplest tasks is impaired in ADHD (Posner, Rothbart & Ghassemzadeh, 2019). The underlying mechanisms at the network level are still not clear through research. The attentional networks which were mentioned above have some anomalies due to which this condition occurs. These anomalies can be due to genetic aspects and they can also be from previous stressors that the child had. The strength of the attention networks is weak in people who have ADHD and the exact reason is still not known. Children with ADHD are more impulsive and hyperactive. 

References

Boukrina, O., & Chen, P. (2021). Neural Mechanisms of Prism Adaptation in Healthy Adults and Individuals with Spatial Neglect after Unilateral Stroke: A Review of fMRI Studies. Brain sciences, 11(11), 1468.

Elliott, M. L., Knodt, A. R., & Hariri, A. R. (2021). Striving toward translation: strategies for reliable fMRI measurement. Trends in cognitive sciences, 25(9), 776-787.

Gammeri, R., Iacono, C., Ricci, R., & Salatino, A. (2020). Unilateral spatial neglect after stroke: Current insights. Neuropsychiatric disease and treatment.

Keren, H., O’Callaghan, G., Vidal-Ribas, P., Buzzell, G. A., Brotman, M. A., Leibenluft, E., … & Stringaris, A. (2018). Reward processing in depression: a conceptual and meta-analytic review across fMRI and EEG studies. American Journal of Psychiatry, 175(11), 1111-1120.

Lurie, D. J., Kessler, D., Bassett, D. S., Betzel, R. F., Breakspear, M., Kheilholz, S., … & Calhoun, V. D. (2020). Questions and controversies in the study of time-varying functional connectivity in resting fMRI. Network Neuroscience, 4(1), 30-69.

Pan, Y., Yao, T., Li, Y., & Mei, T. (2020). X-linear attention networks for image captioning. In Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition (pp. 10971-10980).

Posner, M. I., Rothbart, M. K., & Ghassemzadeh, H. (2019). Focus: Attention science: Restoring attention networks. The Yale journal of biology and medicine, 92(1), 139.

Posner, M. I., Rothbart, M. K., & Ghassemzadeh, H. (2019). Focus: Attention science: Restoring attention networks. The Yale journal of biology and medicine, 92(1), 139.

Prentiss, E. K., Schneider, C. L., Williams, Z. R., Sahin, B., & Mahon, B. Z. (2018). Spontaneous in-flight accommodation of hand orientation to unseen grasp targets: a case of action blindsight. Cognitive neuropsychology, 35(7), 343-351.

Rocchi, F., Canella, C., Noei, S., Gutierrez-Barragan, D., Coletta, L., Galbusera, A., … & Gozzi, A. (2022). Increased fMRI connectivity upon chemogenetic inhibition of the mouse prefrontal cortex. Nature communications, 13(1), 1-15.

Ulke, C., Rullmann, M., Huang, J., Luthardt, J., Becker, G. A., Patt, M., … & Strauß, M. (2019). Adult attention-deficit/hyperactivity disorder is associated with reduced norepinephrine transporter availability in right attention networks: a (S, S)-O-[11C] methylreboxetine positron emission tomography study. Translational psychiatry, 9(1), 1-10.

Zhang, H., Wu, C., Zhang, Z., Zhu, Y., Lin, H., Zhang, Z., … & Smola, A. (2020). Resnest: Split-attention networks. arXiv preprint arXiv:2004.08955.