Study Reveals Brain Effects Of DMT

Psychedelic substances have been used for millennia in various cultural and spiritual contexts for their mind-altering and medicinal effects.

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Recent scientific studies have demonstrated that these compounds, such as psilocybin (the active ingredient in magic mushrooms), LSD, and N, N-Dimethyltryptamine (DMT), can have profound effects on the brain. Despite these advances, the acute effects of psychedelics on brain function remain poorly understood.

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A recent placebo-controlled multimodal neuroimaging study, led by Dr. Christopher Timmermann of the Centre for Psychedelic Research, Imperial College London, has shed new light on this topic by assessing the effects of DMT, a potent and fast-acting psychedelic, on brain activity.

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This study by Timmermann and colleagues is the first significant functional neuroimaging study on DMT. The group's previous publications on psilocybin and LSD have also provided valuable and innovative insights into the brain's workings when exposed to psychedelic substances.

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This study utilized a combination of functional magnetic resonance imaging (fMRI), an imaging technique that measures changes in blood flow in the brain, and electroencephalography (EEG), a technique that measures electrical activity in the brain, to provide the most comprehensive view to date of the acute brain action of psychedelics.

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Below, we review the findings of this important study and discuss their implications for our understanding of the neurobiological mechanisms underlying the effects of psychedelic substances.

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Previous Findings on Psychedelic Brain Action

Studies using fMRI have found that psychedelics affect the brain in several ways. Typically, the connections within certain brain networks decrease, while the connections between different networks increase. This leads to a more flexible brain state, with more varied connectivity patterns and more transitions between different states.

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These effects seem to be centered on a specific part of the brain, called the transmodal association cortex pole (or "TOP"). TOP refers to the newer areas of the brain located at the highest point of the cortical hierarchy that create advanced predictions about the environment, and then sends those predictions down to other parts of the brain. This helps it control a lot of the lower parts of the brain that are more focused on processing sensory information.

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Findings to date suggest that dysregulation of TOP and other regions of the brain that integrate information to form complex representations of the world may be responsible for the subjective experiences induced by psychedelics. The dysregulation of these higher “association cortices” has previously been shown to lead to a disinhibition of lower brain systems, such as the limbic system.

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New Landmark DMT Neuroimaging Study

Previous studies on the effects of psychedelics on the brain could only make indirect connections between different types of brain activity. This new study is unique because it allowed for simultaneous measurement and correlation of different types of brain activity while taking advantage of the short duration of the drug's effects.

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By using both EEG and fMRI, researchers can directly observe the activity of neurons in the brain and better understand the effects of psychedelics on brain connectivity. EEG also provides high-resolution data that can be used to analyze changes in brain rhythms and connectivity. 

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This study built on previous research that looked at how psychedelics affect the brain. In this study, the researchers used two different techniques (fMRI and EEG) at the same time to study brain activity while participants were in a resting state.

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The researchers gave participants a 20 mg injection of DMT and a placebo 2 weeks apart, and measured their brain activity while they sat with their eyes closed.

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The Brain Effects of DMT: Findings from fMRI

The study found that DMT, compared to a placebo, caused decreased connections within brain networks (within network connectivity) and caused increased connections between certain networks (between network connectivity). 

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Specifically, the study found that:

• DMT reduced the segregation of certain brain networks. Networks that are usually well segregated from each other became more connected. 
• Connections within the default mode network, a network of brain regions that are active when an individual is not focused on the external environment or engaged in a specific task, decreased during the DMT experience.  
• Connections within the dorsal attentional network, involved in attentional processes and activated when an individual is engaged in a task that requires focused attention, also decreased during the DMT experience.
• The default mode network and the frontoparietal network, a large-scale brain network involved in attention, working memory, decision-making, and cognitive control, became more connected during the DMT experience. 
• Specific regions in the brain, such as the medial prefrontal cortex, dorsolateral prefrontal cortex, insula, and temporoparietal junction, became more connected during the DMT experience.
• In general, fMRI data showed that the more intense the DMT experience was, as reported by the study participants, the more significant the increase in global functional connectivity, which is a measure of the degree to which different regions of the brain are connected with or “speaking to” each other. Global functioning connectivity refers to the overall level of connectivity across the whole brain, rather than focusing on the connectivity of specific brain regions or networks.

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Insights from EEG Data 

EEG results showed that DMT caused changes in brain waves, specifically a decrease in alpha waves and an increase in delta and gamma waves.

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One of the major findings from the EEG data was that DMT caused a reduction in alpha waves, which travel down the cortical hierarchy. At the same time, there was an increase in gamma waves, which travel upwards. This kind of brain wave activity typically occurs when people’s eyes are open and they are taking in sensory information from the external environment.

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However, as mentioned above, the participants in this study had their eyes closed the entire time they were under the influence of DMT. This raises an interesting and somewhat controversial question as to whether the brain is actually receiving sensory information from a different environment during the DMT state.

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Apart from the sensory information that we receive from the environment, our experienced world is also influenced by the deep regions of the brain, such as the limbic system, which is associated with memory and emotion. Interestingly, EEG data showed that DMT increased the flow of information from the limbic system compared to the flow from higher-order cortical networks.

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Some have suggested that this increase in information flow from the limbic system may be responsible for the vivid and complex imagery experienced during the DMT state, but there is currently insufficient evidence to support this claim.

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An Advanced View of DMT Brain Action 

The recent study by Timmermann and colleagues utilizing EEG-fMRI imaging techniques provides valuable insights into the acute effects of DMT on the human brain.

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The results confirm previously established properties of the psychedelic state, such as network disintegration and desegregation, decreased alpha power, and increased flow of information from the limbic system. Perhaps the most significant finding is the global effect of DMT on the brain, implicating dysregulation of activity in the transmodal association cortex pole.  

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Overall, the study sheds further light on the brain action of psychedelics, potentially providing insight into conscious experience beyond psychedelic-induced altered state of consciousness. These findings enhance our understanding of the neural correlates of the psychedelic state and contribute to ongoing research in this field.

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