These brainwave patterns may be the key to treating mental illness

In the cerebral cortex, neurons are arranged in six distinct layers that can be easily seen under a microscope. A team of scientists from the Massachusetts Institute of Technology Vanderbilt University found that these sections also show distinct patterns of electrical activity.

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In the upper layers, neuronal activity is dominated by rapid oscillations called gamma waves. In the deeper layers, slower oscillations called alpha and beta waves dominate. The universality of these patterns suggests that these oscillations likely play an important role throughout the brain. An imbalance in the interaction between these oscillations may be related to brain disorders such as ADHD. Details are described in the magazine Normal neuroscience.

Dr. Diego Mendoza Halliday of MIT explains:

Whether we look at mice, humans, or any type of mammal, the cortex is anatomically organized into six layers, and this pattern is present in all areas of the cortex in every species. Unfortunately, many studies of brain activity have ignored these layers because when recording neuronal activity, it is difficult to understand where they are in the context of these layers.

Brainwave patterns will help get to the roots of mental disorders

The human brain contains billions of neurons, each with its own patterns of electrical activity. Groups of neurons with similar patterns generate oscillations in electrical activity, or brain waves, that can have different frequencies. Researchers from MIT have previously shown that high-frequency gamma rhythms are associated with the encoding and retrieval of sensory information, while low-frequency beta rhythms serve as a control mechanism that determines what information will be read from working memory.

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The researchers also found that in some parts of the prefrontal cortex, different layers of the brain show distinct oscillation patterns – faster on the surface and slower in the deeper layers. While the animals performed working memory tasks, low-frequency rhythms generated in the deep layers down-regulated the high-frequency gamma rhythms found in the superficial layers.

Now the researchers wanted to test whether the pattern of layered oscillations observed in the prefrontal cortex was more widespread in different parts of the cortex and in different species. So they analyzed 14 different areas of the cerebral cortex of four species of mammals. Recording from individual cortical layers was difficult in the past, because each layer was less than a millimeter thick, so it was difficult to know which area the signal was coming from. In this study, electrical activity was recorded using special electrodes that record data from all layers simultaneously and then feed the data into a new computational algorithm called FLIP. This algorithm can determine which layer each signal comes from.

In all species and in every region studied, scientists found the same multi-layered pattern of activity.

Dr. Diego Mendoza Halliday adds:

We performed a group analysis of all the data to see if we could find the same pattern across all areas of the cerebral cortex, and lo and behold, it is everywhere. This was a real indication that what had been previously observed in several regions represents a basic mechanism in the cerebral cortex.

The results support a previously developed neural model that posits that the brain's spatial organization helps it integrate new information carried by high-frequency oscillations into existing memories and brain processes maintained by low-frequency oscillations. An imbalance between high and low frequency oscillations can lead to attention deficits such as ADHD (too much information) or delusional disorders such as schizophrenia (too little information).