Cytoarchitecture: What the Brodmann Analysis Can Tell Us

On July 4, 2009, in Highly Accessed, QEEG, submitted by Barry Sterman, Ph.D.

Brain imaging and analysis continues to evolve and provide us with more information upon which to base our clinical decisions. Brodmann mapped the cortex according to types of neurons and their density in different cortical layers. The areas he numbered (1 to 52 in each hemisphere) followed the variations in the cellular architectures he observed. The Brodmann area information has been employed for more than a century. Recently the SKIL database has provided the capability to subject the raw EEG to an analysis that employs the Brodmann areas as the focus of inquiry. Following is a QEEG analysis of a client in which the Brodmann analysis was the major factor in locating the abnormalities.

The client is a 65 year-old female who was referred by her physician. She evidenced no cognitive or gross motor abnormalities upon presentation. The client is currently in severe, unremitting sciatic pain which she reports to be worse in the right leg. She has a history of failed back syndrome and back surgery. The client’s family history includes maternal arthritis and fibromyalgia. Her three brothers also have back problems. At 17 years old, the client was in a car accident in which she experienced whiplash and possible rotational injuries. The client is an accomplished dancer, attorney, and film producer. She has consulted many physicians regarding her treatment and is considering the implantation of a morphine pump. The client is currently taking the following medications: Oxycontin, Dilaudid, Zanoflex, Neurontin and Keppra.

Findings:

Figure 1 (click to enlarge). Brodmann maps with eyes open based on cortical cell type and focused on sensorimotor and dorsal temporal regions. Pink color in areas 4 & 6 indicate significantly elevated fast 15-18 Hz activity bilaterally. These include secondary and opercular motor areas.

EEG data were effectively cleared of artifact and viewed using several different referencing montages. Reliability of findings was confirmed with multiple independent recordings. Because of the distorting effect of the many medications currently on board in this client, a distortion which raised slow frequencies at all sites, attention was directed primarily to the Laplacian reconfigurations, which negate common features and emphasize unique characteristics where they occur. The program utilized here provides for three different perspectives on functionality. These include amplitude characteristics, temporal coordination, or timing characteristics, and anatomical characteristics based on the cytoarchitecture of cell types provided by the Brodmann classification system.

Figure 2 (click to enlarge). Brodmann maps as above but with eyes closed. Elevated fast activity is limited to left hemisphere here and extended to include Broca’s speech area.

A different functional disturbance was revealed through analysis based on specific cortical cell types as classified in the Brodmann cytoarchitectural classification. This analysis showed that activity in the faster frequency range was uniquely increased in supplemental motor areas, extending into a region buried beneath the anterior temporal lobe, called the operculum (Corresponds approximately to the opercular part of the inferior frontal gyrus) (figs. 1 & 2). This effect was restricted to the left hemisphere with eyes closed but became bilateral (but still greatest on the left) when the eyes were open. When the EEG was configured according to the Brodmann area system fast and sharp activity was revealed in the signal from these areas (figs. 3a & 3b).

Figure 3a (click to enlarge). Sample of EEG with eyes open (10 seconds) derived from Brodmann Laplacian montage and showing EEG characteristics in each anatomically defined region. Note sharp waves, fast (beta) bursts, and trains of slow activity in supplemental motor (including operculum) region in top 2 channels. This disturbance was seen in all states.

Conclusions:
It is important to point out at the outset that the various medications (5) prescribed and used by this client have clearly altered the EEG and made interpretation of findings a true challenge. However, reliance on multiple recordings across a series of functional states, together with a battery of varied and unique quantitative measurement tools, made it possible to identify valid and reliable disturbances in her Central Nervous System.

Figure 3b (click to enlarge). Samples of EEG during reading (7 seconds) derived from Brodmann Laplacian montage and showing EEG characteristics in each anatomically defined region. Note sharp waves, fast (beta) bursts and trains of slow activity in supplemental motor (including operculum) region in top 2 channels (as seen in Figure 3a). This disturbance was seen in all states.

The most significant of these is the evidence of hyper-excitability in the operculum (and associated supplemental motor areas) as seen clearly in both EEG tracings and quantitative maps when data were configured using Brodmann area Laplacian analysis (figures 1-3). Characteristic sharp, fast, and slow waves were seen here in all test recordings, often most evident in the left hemisphere. This is a highly significant finding for this case, as a body of recent evidence has indicated that this area may be the projection target of afferent pain fibers reaching the cerebral cortex. Thus, as noted above, we can propose that this cortical reception area for pain is in a state of chronic hyper-excitability, a condition which may be the root cause of her unrelenting pain, particularly in her right leg. It is unclear how this important finding may relate to the evidence for elevated slow activity at 4-5 Hz in temporal and left centro-parietal areas, as well as disturbed coordination at 10 Hz in the left centro-parietal area. Suffice it to say that disregulation in pain centers likely also disturbs cognitive and perceptual functions in ways that are not clearly understood at present but can be exposed with sensitive analytic methods.

M. Barry Sterman, Ph.D.

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