#psychedelicsbrainscience — Public Fediverse posts
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DATE: July 30, 2026 at 06:00AM
SOURCE: PSYPOST.ORG** Research quality varies widely from fantastic to small exploratory studies. Please check research methods when conclusions are very important to you. **
-------------------------------------------------TITLE: Neuroscientists just upended a core assumption about how psychedelics alter brain function
Recent research published in the Proceedings of the National Academy of Sciences suggests that psychedelic substances change how brain activity travels across the surface of the brain. The study provides evidence that drugs like LSD, psilocybin, and MDMA reliably reduce the flow of information traveling up into a core brain network associated with self-reflection. These findings offer a new biological explanation for both the therapeutic potential and the psychological risks of using psychedelics to treat mental health conditions.
The default mode network is a collection of interconnected brain regions that are highly active when a person is resting and thinking about themselves. Scientists link this network to introspection, daydreaming, and maintaining a rigid sense of self. In many mental health disorders, such as depression or schizophrenia, the default mode network tends to function abnormally. Because of this connection, researchers want to know exactly how potential psychiatric treatments impact this specific network.
“Psychedelic use is growing faster than our understanding of how these drugs impact the brain, particularly at the level of large-scale brain networks,” said Adam Pines, a postdoctoral scholar at Stanford University, who led the study alongside the study’s senior author, Leanne M. Williams. “Clinically, these unresolved questions limit our ability to know which patients are likely to benefit from psychedelic treatments, and which are at risk of harm.”
Previous studies usually measured brain activity as if it were fixed in place. They looked at average activity in stationary regions over time instead of tracking how signals physically move across the brain tissue.
Brain activity constantly travels in specific directions, either from lower-level sensory areas up to higher-level thinking areas, or vice versa. The upward movement is called bottom-up processing, which involves reacting to basic sensory input. The downward movement is known as top-down processing, where the brain applies past experiences and expectations to interpret incoming information.
“Existing theories on how psychedelics work tend to disagree on a core point: whether psychedelics increase or decrease ‘bottom-up’ brain activity (activity moving from lower-order to higher-order brain areas),” Pines said. “From our perspective, this core premise had not been systematically tested.”
To test this premise, the researchers adapted an analytical method called optical flow. This technique is typically used in computer vision to track the movement of physical objects across video frames. By applying this technique to brain scans, the researchers could evaluate the directional flow of brain activity frame by frame, capturing the exact movement of signals across the cortical surface.
The researchers combined data from four independent studies to test how different psychedelics impact brain activity flow. “Drawing conclusive evidence from psychedelic studies is notoriously difficult,” Pines said. “We tried to establish our results beyond reasonable doubt by replicating our findings across nine different case-control comparisons, involving four datasets and two completely different neuroimaging technologies.”
The first three studies involved human participants who received a specific drug and underwent functional magnetic resonance imaging. This type of brain scan, often called fMRI, measures changes in blood flow to detect active brain areas. Before running their optical flow analysis, the authors masked out segments of data interrupted by head motion to ensure their measurements were highly accurate.
In the first study, fourteen healthy adult participants received either a placebo, eighty milligrams of MDMA, or one hundred and twenty milligrams of MDMA. MDMA is a synthetic substance that alters mood and perception. Participants completed multiple scanning sessions across different days, allowing researchers to compare their brain activity with and without the active drug.
The second study evaluated the effects of psilocybin, the active hallucinogenic compound found in magic mushrooms. Six healthy participants underwent numerous fMRI scans. During some sessions, they received twenty-five milligrams of psilocybin. On other days, they received either no drug or an active placebo called methylphenidate, a stimulant medication that mimics the physical arousal caused by psilocybin.
The third study focused on LSD, a powerful chemical that alters perception and thought. Eighteen healthy participants received an intravenous infusion of either LSD or a saline placebo. Following a short acclimatization period, they completed about one hour of fMRI scanning to capture their brain activity under the influence of the substance.
The fourth study involved an entirely different species and measurement technique. Fourteen mice were administered LSD, a sedative called diazepam, or another sedative called dexmedetomidine. Instead of using fMRI, the scientists measured the mouse brain activity using widefield calcium imaging. This technique uses fluorescent markers to directly observe the electrical activity of neurons across the brain surface, providing a different perspective on brain function.
Across all four datasets, the authors looked at two main features of brain signals moving within the default mode network. First, they calculated the magnitude, which is the total volume and strength of the traveling brain waves. Second, they measured directionality, specifically looking at the proportion of signals traveling in a bottom-up direction from sensory regions into the default mode network.
The researchers found that all the tested psychedelics significantly reduced the overall magnitude of cortical activity propagations in the default mode network. In the first study, MDMA lowered the strength of these traveling signals compared to both placebo and baseline scans. The exact same pattern appeared in the second study for psilocybin and the third study for LSD.
When observing the mice in the fourth study, the authors noticed a similar reduction in signal magnitude after administering LSD. The active sedatives given to the mice produced the opposite effect, increasing the magnitude of brain signal movement. This suggests that the reduction in traveling waves is a specific feature of psychedelics rather than a general effect of taking any psychoactive drug.
In addition to shrinking the magnitude of these signals, psychedelics altered the direction of their travel. The human studies showed that MDMA, psilocybin, and LSD all reduced the percentage of signals moving in a bottom-up direction. Instead of information flowing freely from sensory areas up into the default mode network, the overall balance of activity shifted away from bottom-up processing.
The mouse study replicated this directional shift, as LSD significantly decreased bottom-up propagations in the mouse brains. Interestingly, the psilocybin study showed that this attenuation of bottom-up directionality persisted for days after the initial dosage. Scans taken within two days of the psilocybin sessions still exhibited proportionately fewer bottom-up propagations.
The scientists also checked whether these movement changes were linked to the subjective psychological effects of the drugs. In the human studies, participants filled out comprehensive questionnaires about their experiences. The scientists found that greater reductions in bottom-up signaling correlated with more intense negative feelings, such as the dread of losing one’s sense of self and feelings of impaired control.
The results went against the original expectations of the research team. “How psychedelics impact large-scale brain function is not settled science,” Pines told PsyPost. “Our study challenges one of the field’s core assumptions. Many researchers, myself included, expected psychedelics to increase ‘bottom-up’ activity.”
Pines noted that the actual data told a different story. “Instead, we found the opposite,” Pines said. “However, like any study, there are caveats and limitations that come along with this new evidence.”
One prospective issue is the way the researchers interpreted the data at a broad level. “In our human data, we described a group-level effect rather than something that occurs 100% of the time for every individual every time they ingest psychedelics,” Pines said. “This is a standard practice for human neuroimaging studies, but it’s worth keeping in mind that the impact of psychedelics on individual people can be quite variable.”
The concept of bottom-up processing also comes with its own complexities. “Scientists still don’t fully understand what we call bottom-up activity, or the different ways it can occur,” Pines said. “Analytically, we only measured bottom-up activity in one way rather than comprehensively resolving all possible bottom-up activity in the brain.”
The researchers acknowledge that they had to narrow their focus to run the optical flow analyses. “While we had to be reductionistic to evaluate our questions of interest, there are undoubtedly more nuanced aspects of bottom-up and top-down activity that are yet to be discovered in psychedelic research and neuroscience broadly,” Pines said.
These brain wave changes might explain why psychedelics have specific therapeutic effects. For instance, ruminative depression involves excessive, automatic negative thoughts, which researchers link to an overabundance of bottom-up cortical propagations. By reducing these bottom-up signals, psychedelics might interrupt the automatic negative thought loops associated with depression.
A reduction in bottom-up processing could also pose risks for certain vulnerable populations. People at risk for psychosis already experience impaired bottom-up processing, often relying too heavily on top-down expectations, which can lead to hallucinations. Taking a psychedelic might exacerbate this existing imbalance, providing a biological explanation for why these drugs can trigger psychotic episodes in susceptible individuals.
The researchers plan to expand this analytical approach beyond psychedelics to other chemical compounds. “Our lack of understanding of large-scale brain function is not unique to psychedelic drugs,” Pines said. “Although decades of thorough research have revealed a lot about how alcohol, nicotine, and neurologically-active pharmaceuticals operate on individual neurons, our knowledge of how they impact large-scale brain function is quite limited.”
Applying this knowledge could eventually help doctors provide more personalized medical care. “If we can clarify the impacts of neurologically-active substances broadly, we can better anticipate the effects of any given therapeutic drug on individual psychiatric patients and tailor prescriptions accordingly,” Pines said. “This gives us more confidence in our findings, but doesn’t mean that the question is closed. Further study is still needed.”
The study, “Psychedelics disrupt hierarchical cortical propagations in the default mode network of humans and mice,” was authored by Adam R. Pines, Xue Zhang, John Kochalka, Sam S. Vesuna, Isaac V. Kauvar, Divya Rajasekharan, T. Rick Reneau, Teddy J. Akiki, Laura M. Hack, Joshua S. Siegel, and Leanne M. Williams.
-------------------------------------------------
Private, vetted email list for mental health professionals: https://www.clinicians-exchange.org
Unofficial Psychology Today Xitter to toot feed at Psych Today Unofficial Bot @PTUnofficialBot
-------------------------------------------------
#psychology #counseling #socialwork #psychotherapy @psychotherapist @psychotherapists @psychology @socialpsych @socialwork @psychiatry #mentalhealth #psychiatry #healthcare #depression #psychotherapist #PsychedelicsBrainScience #DefaultModeNetwork #BottomUpProcessing #PsychedelicsAndMentalHealth #MDMA #Psilocybin #LSD #NeuroscienceResearch #BrainConnectivity #OpticalFlowNeuroimaging
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DATE: July 30, 2026 at 06:00AM
SOURCE: PSYPOST.ORG** Research quality varies widely from fantastic to small exploratory studies. Please check research methods when conclusions are very important to you. **
-------------------------------------------------TITLE: Neuroscientists just upended a core assumption about how psychedelics alter brain function
Recent research published in the Proceedings of the National Academy of Sciences suggests that psychedelic substances change how brain activity travels across the surface of the brain. The study provides evidence that drugs like LSD, psilocybin, and MDMA reliably reduce the flow of information traveling up into a core brain network associated with self-reflection. These findings offer a new biological explanation for both the therapeutic potential and the psychological risks of using psychedelics to treat mental health conditions.
The default mode network is a collection of interconnected brain regions that are highly active when a person is resting and thinking about themselves. Scientists link this network to introspection, daydreaming, and maintaining a rigid sense of self. In many mental health disorders, such as depression or schizophrenia, the default mode network tends to function abnormally. Because of this connection, researchers want to know exactly how potential psychiatric treatments impact this specific network.
“Psychedelic use is growing faster than our understanding of how these drugs impact the brain, particularly at the level of large-scale brain networks,” said Adam Pines, a postdoctoral scholar at Stanford University, who led the study alongside the study’s senior author, Leanne M. Williams. “Clinically, these unresolved questions limit our ability to know which patients are likely to benefit from psychedelic treatments, and which are at risk of harm.”
Previous studies usually measured brain activity as if it were fixed in place. They looked at average activity in stationary regions over time instead of tracking how signals physically move across the brain tissue.
Brain activity constantly travels in specific directions, either from lower-level sensory areas up to higher-level thinking areas, or vice versa. The upward movement is called bottom-up processing, which involves reacting to basic sensory input. The downward movement is known as top-down processing, where the brain applies past experiences and expectations to interpret incoming information.
“Existing theories on how psychedelics work tend to disagree on a core point: whether psychedelics increase or decrease ‘bottom-up’ brain activity (activity moving from lower-order to higher-order brain areas),” Pines said. “From our perspective, this core premise had not been systematically tested.”
To test this premise, the researchers adapted an analytical method called optical flow. This technique is typically used in computer vision to track the movement of physical objects across video frames. By applying this technique to brain scans, the researchers could evaluate the directional flow of brain activity frame by frame, capturing the exact movement of signals across the cortical surface.
The researchers combined data from four independent studies to test how different psychedelics impact brain activity flow. “Drawing conclusive evidence from psychedelic studies is notoriously difficult,” Pines said. “We tried to establish our results beyond reasonable doubt by replicating our findings across nine different case-control comparisons, involving four datasets and two completely different neuroimaging technologies.”
The first three studies involved human participants who received a specific drug and underwent functional magnetic resonance imaging. This type of brain scan, often called fMRI, measures changes in blood flow to detect active brain areas. Before running their optical flow analysis, the authors masked out segments of data interrupted by head motion to ensure their measurements were highly accurate.
In the first study, fourteen healthy adult participants received either a placebo, eighty milligrams of MDMA, or one hundred and twenty milligrams of MDMA. MDMA is a synthetic substance that alters mood and perception. Participants completed multiple scanning sessions across different days, allowing researchers to compare their brain activity with and without the active drug.
The second study evaluated the effects of psilocybin, the active hallucinogenic compound found in magic mushrooms. Six healthy participants underwent numerous fMRI scans. During some sessions, they received twenty-five milligrams of psilocybin. On other days, they received either no drug or an active placebo called methylphenidate, a stimulant medication that mimics the physical arousal caused by psilocybin.
The third study focused on LSD, a powerful chemical that alters perception and thought. Eighteen healthy participants received an intravenous infusion of either LSD or a saline placebo. Following a short acclimatization period, they completed about one hour of fMRI scanning to capture their brain activity under the influence of the substance.
The fourth study involved an entirely different species and measurement technique. Fourteen mice were administered LSD, a sedative called diazepam, or another sedative called dexmedetomidine. Instead of using fMRI, the scientists measured the mouse brain activity using widefield calcium imaging. This technique uses fluorescent markers to directly observe the electrical activity of neurons across the brain surface, providing a different perspective on brain function.
Across all four datasets, the authors looked at two main features of brain signals moving within the default mode network. First, they calculated the magnitude, which is the total volume and strength of the traveling brain waves. Second, they measured directionality, specifically looking at the proportion of signals traveling in a bottom-up direction from sensory regions into the default mode network.
The researchers found that all the tested psychedelics significantly reduced the overall magnitude of cortical activity propagations in the default mode network. In the first study, MDMA lowered the strength of these traveling signals compared to both placebo and baseline scans. The exact same pattern appeared in the second study for psilocybin and the third study for LSD.
When observing the mice in the fourth study, the authors noticed a similar reduction in signal magnitude after administering LSD. The active sedatives given to the mice produced the opposite effect, increasing the magnitude of brain signal movement. This suggests that the reduction in traveling waves is a specific feature of psychedelics rather than a general effect of taking any psychoactive drug.
In addition to shrinking the magnitude of these signals, psychedelics altered the direction of their travel. The human studies showed that MDMA, psilocybin, and LSD all reduced the percentage of signals moving in a bottom-up direction. Instead of information flowing freely from sensory areas up into the default mode network, the overall balance of activity shifted away from bottom-up processing.
The mouse study replicated this directional shift, as LSD significantly decreased bottom-up propagations in the mouse brains. Interestingly, the psilocybin study showed that this attenuation of bottom-up directionality persisted for days after the initial dosage. Scans taken within two days of the psilocybin sessions still exhibited proportionately fewer bottom-up propagations.
The scientists also checked whether these movement changes were linked to the subjective psychological effects of the drugs. In the human studies, participants filled out comprehensive questionnaires about their experiences. The scientists found that greater reductions in bottom-up signaling correlated with more intense negative feelings, such as the dread of losing one’s sense of self and feelings of impaired control.
The results went against the original expectations of the research team. “How psychedelics impact large-scale brain function is not settled science,” Pines told PsyPost. “Our study challenges one of the field’s core assumptions. Many researchers, myself included, expected psychedelics to increase ‘bottom-up’ activity.”
Pines noted that the actual data told a different story. “Instead, we found the opposite,” Pines said. “However, like any study, there are caveats and limitations that come along with this new evidence.”
One prospective issue is the way the researchers interpreted the data at a broad level. “In our human data, we described a group-level effect rather than something that occurs 100% of the time for every individual every time they ingest psychedelics,” Pines said. “This is a standard practice for human neuroimaging studies, but it’s worth keeping in mind that the impact of psychedelics on individual people can be quite variable.”
The concept of bottom-up processing also comes with its own complexities. “Scientists still don’t fully understand what we call bottom-up activity, or the different ways it can occur,” Pines said. “Analytically, we only measured bottom-up activity in one way rather than comprehensively resolving all possible bottom-up activity in the brain.”
The researchers acknowledge that they had to narrow their focus to run the optical flow analyses. “While we had to be reductionistic to evaluate our questions of interest, there are undoubtedly more nuanced aspects of bottom-up and top-down activity that are yet to be discovered in psychedelic research and neuroscience broadly,” Pines said.
These brain wave changes might explain why psychedelics have specific therapeutic effects. For instance, ruminative depression involves excessive, automatic negative thoughts, which researchers link to an overabundance of bottom-up cortical propagations. By reducing these bottom-up signals, psychedelics might interrupt the automatic negative thought loops associated with depression.
A reduction in bottom-up processing could also pose risks for certain vulnerable populations. People at risk for psychosis already experience impaired bottom-up processing, often relying too heavily on top-down expectations, which can lead to hallucinations. Taking a psychedelic might exacerbate this existing imbalance, providing a biological explanation for why these drugs can trigger psychotic episodes in susceptible individuals.
The researchers plan to expand this analytical approach beyond psychedelics to other chemical compounds. “Our lack of understanding of large-scale brain function is not unique to psychedelic drugs,” Pines said. “Although decades of thorough research have revealed a lot about how alcohol, nicotine, and neurologically-active pharmaceuticals operate on individual neurons, our knowledge of how they impact large-scale brain function is quite limited.”
Applying this knowledge could eventually help doctors provide more personalized medical care. “If we can clarify the impacts of neurologically-active substances broadly, we can better anticipate the effects of any given therapeutic drug on individual psychiatric patients and tailor prescriptions accordingly,” Pines said. “This gives us more confidence in our findings, but doesn’t mean that the question is closed. Further study is still needed.”
The study, “Psychedelics disrupt hierarchical cortical propagations in the default mode network of humans and mice,” was authored by Adam R. Pines, Xue Zhang, John Kochalka, Sam S. Vesuna, Isaac V. Kauvar, Divya Rajasekharan, T. Rick Reneau, Teddy J. Akiki, Laura M. Hack, Joshua S. Siegel, and Leanne M. Williams.
-------------------------------------------------
Private, vetted email list for mental health professionals: https://www.clinicians-exchange.org
Unofficial Psychology Today Xitter to toot feed at Psych Today Unofficial Bot @PTUnofficialBot
-------------------------------------------------
#psychology #counseling #socialwork #psychotherapy @psychotherapist @psychotherapists @psychology @socialpsych @socialwork @psychiatry #mentalhealth #psychiatry #healthcare #depression #psychotherapist #PsychedelicsBrainScience #DefaultModeNetwork #BottomUpProcessing #PsychedelicsAndMentalHealth #MDMA #Psilocybin #LSD #NeuroscienceResearch #BrainConnectivity #OpticalFlowNeuroimaging
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DATE: July 30, 2026 at 06:00AM
SOURCE: PSYPOST.ORG** Research quality varies widely from fantastic to small exploratory studies. Please check research methods when conclusions are very important to you. **
-------------------------------------------------TITLE: Neuroscientists just upended a core assumption about how psychedelics alter brain function
Recent research published in the Proceedings of the National Academy of Sciences suggests that psychedelic substances change how brain activity travels across the surface of the brain. The study provides evidence that drugs like LSD, psilocybin, and MDMA reliably reduce the flow of information traveling up into a core brain network associated with self-reflection. These findings offer a new biological explanation for both the therapeutic potential and the psychological risks of using psychedelics to treat mental health conditions.
The default mode network is a collection of interconnected brain regions that are highly active when a person is resting and thinking about themselves. Scientists link this network to introspection, daydreaming, and maintaining a rigid sense of self. In many mental health disorders, such as depression or schizophrenia, the default mode network tends to function abnormally. Because of this connection, researchers want to know exactly how potential psychiatric treatments impact this specific network.
“Psychedelic use is growing faster than our understanding of how these drugs impact the brain, particularly at the level of large-scale brain networks,” said Adam Pines, a postdoctoral scholar at Stanford University, who led the study alongside the study’s senior author, Leanne M. Williams. “Clinically, these unresolved questions limit our ability to know which patients are likely to benefit from psychedelic treatments, and which are at risk of harm.”
Previous studies usually measured brain activity as if it were fixed in place. They looked at average activity in stationary regions over time instead of tracking how signals physically move across the brain tissue.
Brain activity constantly travels in specific directions, either from lower-level sensory areas up to higher-level thinking areas, or vice versa. The upward movement is called bottom-up processing, which involves reacting to basic sensory input. The downward movement is known as top-down processing, where the brain applies past experiences and expectations to interpret incoming information.
“Existing theories on how psychedelics work tend to disagree on a core point: whether psychedelics increase or decrease ‘bottom-up’ brain activity (activity moving from lower-order to higher-order brain areas),” Pines said. “From our perspective, this core premise had not been systematically tested.”
To test this premise, the researchers adapted an analytical method called optical flow. This technique is typically used in computer vision to track the movement of physical objects across video frames. By applying this technique to brain scans, the researchers could evaluate the directional flow of brain activity frame by frame, capturing the exact movement of signals across the cortical surface.
The researchers combined data from four independent studies to test how different psychedelics impact brain activity flow. “Drawing conclusive evidence from psychedelic studies is notoriously difficult,” Pines said. “We tried to establish our results beyond reasonable doubt by replicating our findings across nine different case-control comparisons, involving four datasets and two completely different neuroimaging technologies.”
The first three studies involved human participants who received a specific drug and underwent functional magnetic resonance imaging. This type of brain scan, often called fMRI, measures changes in blood flow to detect active brain areas. Before running their optical flow analysis, the authors masked out segments of data interrupted by head motion to ensure their measurements were highly accurate.
In the first study, fourteen healthy adult participants received either a placebo, eighty milligrams of MDMA, or one hundred and twenty milligrams of MDMA. MDMA is a synthetic substance that alters mood and perception. Participants completed multiple scanning sessions across different days, allowing researchers to compare their brain activity with and without the active drug.
The second study evaluated the effects of psilocybin, the active hallucinogenic compound found in magic mushrooms. Six healthy participants underwent numerous fMRI scans. During some sessions, they received twenty-five milligrams of psilocybin. On other days, they received either no drug or an active placebo called methylphenidate, a stimulant medication that mimics the physical arousal caused by psilocybin.
The third study focused on LSD, a powerful chemical that alters perception and thought. Eighteen healthy participants received an intravenous infusion of either LSD or a saline placebo. Following a short acclimatization period, they completed about one hour of fMRI scanning to capture their brain activity under the influence of the substance.
The fourth study involved an entirely different species and measurement technique. Fourteen mice were administered LSD, a sedative called diazepam, or another sedative called dexmedetomidine. Instead of using fMRI, the scientists measured the mouse brain activity using widefield calcium imaging. This technique uses fluorescent markers to directly observe the electrical activity of neurons across the brain surface, providing a different perspective on brain function.
Across all four datasets, the authors looked at two main features of brain signals moving within the default mode network. First, they calculated the magnitude, which is the total volume and strength of the traveling brain waves. Second, they measured directionality, specifically looking at the proportion of signals traveling in a bottom-up direction from sensory regions into the default mode network.
The researchers found that all the tested psychedelics significantly reduced the overall magnitude of cortical activity propagations in the default mode network. In the first study, MDMA lowered the strength of these traveling signals compared to both placebo and baseline scans. The exact same pattern appeared in the second study for psilocybin and the third study for LSD.
When observing the mice in the fourth study, the authors noticed a similar reduction in signal magnitude after administering LSD. The active sedatives given to the mice produced the opposite effect, increasing the magnitude of brain signal movement. This suggests that the reduction in traveling waves is a specific feature of psychedelics rather than a general effect of taking any psychoactive drug.
In addition to shrinking the magnitude of these signals, psychedelics altered the direction of their travel. The human studies showed that MDMA, psilocybin, and LSD all reduced the percentage of signals moving in a bottom-up direction. Instead of information flowing freely from sensory areas up into the default mode network, the overall balance of activity shifted away from bottom-up processing.
The mouse study replicated this directional shift, as LSD significantly decreased bottom-up propagations in the mouse brains. Interestingly, the psilocybin study showed that this attenuation of bottom-up directionality persisted for days after the initial dosage. Scans taken within two days of the psilocybin sessions still exhibited proportionately fewer bottom-up propagations.
The scientists also checked whether these movement changes were linked to the subjective psychological effects of the drugs. In the human studies, participants filled out comprehensive questionnaires about their experiences. The scientists found that greater reductions in bottom-up signaling correlated with more intense negative feelings, such as the dread of losing one’s sense of self and feelings of impaired control.
The results went against the original expectations of the research team. “How psychedelics impact large-scale brain function is not settled science,” Pines told PsyPost. “Our study challenges one of the field’s core assumptions. Many researchers, myself included, expected psychedelics to increase ‘bottom-up’ activity.”
Pines noted that the actual data told a different story. “Instead, we found the opposite,” Pines said. “However, like any study, there are caveats and limitations that come along with this new evidence.”
One prospective issue is the way the researchers interpreted the data at a broad level. “In our human data, we described a group-level effect rather than something that occurs 100% of the time for every individual every time they ingest psychedelics,” Pines said. “This is a standard practice for human neuroimaging studies, but it’s worth keeping in mind that the impact of psychedelics on individual people can be quite variable.”
The concept of bottom-up processing also comes with its own complexities. “Scientists still don’t fully understand what we call bottom-up activity, or the different ways it can occur,” Pines said. “Analytically, we only measured bottom-up activity in one way rather than comprehensively resolving all possible bottom-up activity in the brain.”
The researchers acknowledge that they had to narrow their focus to run the optical flow analyses. “While we had to be reductionistic to evaluate our questions of interest, there are undoubtedly more nuanced aspects of bottom-up and top-down activity that are yet to be discovered in psychedelic research and neuroscience broadly,” Pines said.
These brain wave changes might explain why psychedelics have specific therapeutic effects. For instance, ruminative depression involves excessive, automatic negative thoughts, which researchers link to an overabundance of bottom-up cortical propagations. By reducing these bottom-up signals, psychedelics might interrupt the automatic negative thought loops associated with depression.
A reduction in bottom-up processing could also pose risks for certain vulnerable populations. People at risk for psychosis already experience impaired bottom-up processing, often relying too heavily on top-down expectations, which can lead to hallucinations. Taking a psychedelic might exacerbate this existing imbalance, providing a biological explanation for why these drugs can trigger psychotic episodes in susceptible individuals.
The researchers plan to expand this analytical approach beyond psychedelics to other chemical compounds. “Our lack of understanding of large-scale brain function is not unique to psychedelic drugs,” Pines said. “Although decades of thorough research have revealed a lot about how alcohol, nicotine, and neurologically-active pharmaceuticals operate on individual neurons, our knowledge of how they impact large-scale brain function is quite limited.”
Applying this knowledge could eventually help doctors provide more personalized medical care. “If we can clarify the impacts of neurologically-active substances broadly, we can better anticipate the effects of any given therapeutic drug on individual psychiatric patients and tailor prescriptions accordingly,” Pines said. “This gives us more confidence in our findings, but doesn’t mean that the question is closed. Further study is still needed.”
The study, “Psychedelics disrupt hierarchical cortical propagations in the default mode network of humans and mice,” was authored by Adam R. Pines, Xue Zhang, John Kochalka, Sam S. Vesuna, Isaac V. Kauvar, Divya Rajasekharan, T. Rick Reneau, Teddy J. Akiki, Laura M. Hack, Joshua S. Siegel, and Leanne M. Williams.
-------------------------------------------------
Private, vetted email list for mental health professionals: https://www.clinicians-exchange.org
Unofficial Psychology Today Xitter to toot feed at Psych Today Unofficial Bot @PTUnofficialBot
-------------------------------------------------
#psychology #counseling #socialwork #psychotherapy @psychotherapist @psychotherapists @psychology @socialpsych @socialwork @psychiatry #mentalhealth #psychiatry #healthcare #depression #psychotherapist #PsychedelicsBrainScience #DefaultModeNetwork #BottomUpProcessing #PsychedelicsAndMentalHealth #MDMA #Psilocybin #LSD #NeuroscienceResearch #BrainConnectivity #OpticalFlowNeuroimaging