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An Introduction to EEG Phenotypes (Part 2)

brainmap_orginal_2In Part 1 of this series, I provided an introduction to and overview of the candidate EEG phenotypes as proposed by Johnstone, Gunkelman, & Lunt (2005). Readers may want to first view Part 1 to better understand the current discussion. Part 2 provides a detailed description of 5 of the 11 candidate EEG phenotypes along with their implications for neurofeedback treatment planning as described by Johnston, Gunkelman, & Lunt (2005), Gunkelman (2006), and Arns, Gunkelman, Breteler, & Spronk (prepublication). All references to scalp locations are based on the International 10/20 System. Fisher & Cordova (2006) provide an excellent descriptive overview of the International 10/20 System complete with magnetic resonance imaging (MRI) pictures of corresponding physical locations.

Here are the first 5 of 11 candidate EEG phenotypes in no particular order:

“Diffuse Slow Activity” (with or without low alpha frequency) (DSA) requires the presence of excessive frontal slow activity (i.e., often delta and/or theta), particularly in the 1-7 Hertz (Hz) range. DSA is often referred to as “frontal slow.” Persons with DSA respond best to neurofeedback that inhibits the excessive frontal activity and rewards appropriate levels of beta activity (Johnstone, Gunkelman, & Lunt, 2005).

“Focal Abnormalities, Not Epileptiform” (FAN) is evident in persons with discrete areas of excessive slowing or a lack of activity.  FAN can be suggestive of cerebral dysfunction and/or physical damage to an area of the brain (Fisher & Cordova, 2006) .  Recommendations for neurofeedback include inhibiting the slow wave activity and rewarding beta frequencies (i.e., greater than 12 Hz) (Johnstone, Gunkelman, & Lunt, 2005).

The “Mixed Fast and Slow” (MFS) phenotype presents with increased activity in the 1-7 Hz range, reduced alpha (8-13 Hz), and excessive higher beta (i.e., greater than 20 Hz). Often the overall activity in MFS is seen in frontal areas; however, MFS sometimes can be found within posterior or widespread regions. MFS activity can also be the results of medication effects or to encephalopathy.  Implications for neurofeedback include inhibiting excessive slowing and rewarding alpha (8-13 Hz) and SMR along the sensorimotor strip (Johnstone, Gunkelman, & Lunt, 2005).

The “Frontal Lobe Disturbances” (FLD) phenotype is characterized by excessive theta and/or alpha in the frontal region (Johnstone, Gunkelman, & Lunt, 2005).  The frontal lobes, especially the pre-frontal areas, are known to regulate attention and concentration, inhibit impulsive behaviors, and play a role in some mental disorders, such as depression (Thompson & Thompson, 2003).  Not surprisingly, persons with the FLD often have complaints associated with Attention Deficit/Hyperactivity Disorder (ADHD).  With focal abnormalities in the anterior cingulate gyrus, expect reports of Obsessive Compulsive Disorder (OCD), Oppositional Defiant Disorder (ODD), Generalized Anxiety Disorder, or even Reactive Attachment Disorder (RAD). Neurotherapy should remediate excessive frontal or midline slow activity. Concurrent cognitive beta frequency rewards may benefit persons without excessive beta.  Some patients may find it difficult to reduce frontal alpha, in which case, it is recommended to enhance 11-14 Hz at Pz.  Parietal alpha enhancement in combination with frontal beta suppression helps reduce excessive frontal beta if present.  Low Resolution Brain Electromagnetic Tomography (LORETA) may be required to better isolate the exact location of the excessive activity for neurofeedback (Johnstone, Gunkelman, & Lunt, 2005).

The “Frontal Asymmetries” (FAS) consists of disproportionate amounts of alpha or beta in one hemisphere. Comparisons are often made at F3/F4. When classifying as a clinically significant FAS, one must take into account naturally occurring asymmetries (Johnstone, Gunkelman, & Lunt, 2005). Demos (2005) advocates his BAT (i.e., beta, alpha, theta) triad of hemispheric symmetry.  BAT states that for the majority of persons the left hemisphere beta is greater than right hemisphere beta, right hemisphere alpha is greater than left hemisphere alpha, and theta is roughly equal between the two hemispheres. Neurofeedback treatment of FAS focuses on the restoration of hemispheric symmetry of alpha and/or beta through appropriate rewards and inhibits.  Normative databases are particularly helpful in providing asymmetry estimates based on age appropriate normative data. Additionally, asymmetry protocols are available within some neurofeedback software.

Part 3 will cover the remaining 6 EEG Phenotypes and an overall summary to wrap up this series.

Enjoy.

CFisher

References:
Arns, M., Gunkelman, J., Breteler, M., & Spronk, D. (unpublished manuscript). EEG phenotypes predict treatment outcome to stimulants in children with ADHD.

Demos, J. (2005). Getting Started with Neurofeedback. New York: W. W. Norton & Company.

Fisher, R., & Cordova, S. (2006) EEG for beginners. In G.L. Krauss & R.S. Fisher (Eds.), The Johns Hopkins Atlas of Digital EEG: An Interactive Training Guide (pp. 11-74). Baltimore: The Johns Hopkins University Press.

Gunkelman, J., (2006). Transcend the DSM using phenotypes. Biofeedback, 34(3), 95-98.

Gunkelman, J., Crocket, C.A., & Cripe, C. (unpublished manuscript). Clinical outcomes in addiction: A large neurofeedback case series.

Johnstone, J., Gunkelman, J., & Lunt, J. (2005). Clinical database development: Characterization of EEG phenotypes. Clinical EEG and Neuroscience, 36(2), 99-107.

Thompson, M., & Thompson, L. (2003). The Neurofeedback Book. Warwick: Association for Applied Psychophysiology And Biofeedback.

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