John H. Krystal’s research while affiliated with Yale University and other places

What is this page?


This page lists works of an author who doesn't have a ResearchGate profile or hasn't added the works to their profile yet. It is automatically generated from public (personal) data to further our legitimate goal of comprehensive and accurate scientific recordkeeping. If you are this author and want this page removed, please let us know.

Publications (1,000)


Fig. 1. Spatial working memory task design, behavioral performance, and overall effect of ketamine on neural activation. (A) Spatial working memory (sWM) task; participants (N=40) reported the memorized location of a spatial cue (the black circle) after a delay period while keeping their fixation at the center of the display. At the end of the delay period, participants responded by positioning a joystick at the memorized location of the cue. sWM performance was calculated through the corrected angular error(θ AE ), defined as the angular distance between subject's response(the dashed circle) and the cue location(the solid circle). To remove the systematic angular bias that can arise on an individual level, we subtracted each participant's trial-mean directional error from each trial's uncorrected error. (B) Behavioral performance; The bar graph shows the group-mean ketamine-induced change in angular error, indicating that ketamine significantly increases the sWM error at the group level. The ridgeline plot shows the distribution of angular error across all participants under placebo and ketamine (dashed white lines indicate group means). The ordered histogram shows the worsening effect of ketamine on angular error across individual participants, indicating that 31 out of 40 participants had larger angular error under ketamine compared to placebo (the highlighted area). Each bar represents a single participant, and larger values indicate a stronger effect of ketamine on the angular error of sWM. The scatter plot depicts the relationship between angular error under ketamine and placebo conditions. Participants with larger angular error under placebo have larger error under ketamine, showing that ketamine does not affect the overall distribution of sWM performance across participants. The highlighted rectangle shows participants with larger angular error under ketamine, corresponding to the highlighted participants in the ordered histogram. (C) Ketamine-induced activation change; Ketamine-induced change in the activation measured as the difference between activation under placebo and ketamine (represented through the z-scored t-statistics). The warmer colors on the activation change map indicate stronger deactivating effects of ketamine relative to placebo. (D) Time course of neural activation; The time course of the group-level neural activation under placebo and ketamine within an area of interest (ROI) in the frontal (the left panel) and one in the precuneus cortices (the right panel). These exemplar ROIs were selected based on our previous findings on the effect of ketamine on neural activation (4) and functionally defined networks(29). Shaded areas in the plots correspond to one standard error across participants. Each ROI's surface color is proportional to the overall ketamine-induced change in activation within the corresponding ROI.
Fig. S1. Spatial working memory (sWM) angular bias. (A) Spatial working memory (sWM) angular bias; sWM performance was calculated as the combination of two components: angular bias (θ AB ) and angular error (θ AE ). Angular bias represents the systematic deviation in participants' responses and is calculated as the average directional distance from the target location across trials(43). Each white circle indicates the response for a single trial. To calculate angular bias, we rotated the target and response of each trial, maintaining their relative distances, so that all trial targets are positioned at the same location (the solid black circle). Angular error is defined as the angular distance between the participant's response and the target location, adjusted for the angular bias. The bar graph shows the group-mean ketamine-induced change in angular bias, indicating that ketamine significantly increases the sWM angular bias at the group level. The ridgeline plot shows the distribution of angular bias across all participants under placebo and ketamine (dashed white lines indicate group means). (B) The ordered histogram shows the worsening effect of ketamine on angular bias across individual participants, indicating that 29 out of 40 participants had worsened angular bias under ketamine compared to placebo (the highlighted area). Each bar represents a single participant, and larger values indicate a stronger effect of ketamine on the angular bias of sWM. The scatter plot depicts the relationship between angular bias under ketamine and placebo conditions. Participants with larger angular bias under placebo have larger error under ketamine, showing that ketamine does not affect the overall distribution of sWM performance across participants. The highlighted rectangle shows participants with worsened angular bias under ketamine, corresponding to the highlighted participants in the ordered histogram. (C & D) Spatial working memory (sWM) angular dispersion (plots show similar measures in panels A and B); Another measure of sWM performance, in addition to angular error and angular bias, is sWM dispersion (θ AD ). Dispersion is inversely proportional to each participant's overall sWM precision, reflecting the consistency of sWM responses across repeated attempts. sWM was more dispersed under ketamine, compared to placebo, in 31 out of 40 participants (the highlighted area in the scatter plot in panel D).
Ketamine Alters Tuning of Neural and Behavioral Spatial Working Memory Precision
  • Preprint
  • File available

February 2025

·

67 Reads

Masih Rahmati

·

·

·

[...]

·

Deficits in working memory (WM) are a hallmark of neuropsychiatric disorders such as schizophrenia, yet their neurobiological basis remains poorly understood. Glutamate N-methyl-D-aspartate receptors (NMDARs) are critical for spatial WM (sWM), with NMDAR antagonist ketamine known to attenuate task-evoked activation and reduce sWM accuracy. Cortical microcircuit models hypothesize that NMDAR antagonism impairs sWM by broadening neural spatial tuning, but this mechanism has not been directly tested in humans. Using a pharmacological fMRI approach, we showed how ketamine broadened neural spatial tuning, attenuated activation across visual, parietal, and frontal areas, and worsened sWM performance in healthy humans. Ketamine-induced changes in tuning were more consistent across individuals and brain regions than changes in overall activation and correlated with individual differences in sWM performance. These findings provide empirical evidence linking NMDAR antagonism to disruptions in cortical microcircuit dynamics, the resulting neural tuning alterations, and sWM impairments, advancing frameworks for therapeutic development.

Download


Psilocybin: From Psychiatric Pariah to Perceived Panacea

January 2025

·

24 Reads

·

1 Citation

American Journal of Psychiatry

Objective: The authors critically examine the evidence base for psilocybin administered with psychological support/therapy (PST) in the treatment of psychiatric disorders and offer practical recommendations to guide future research endeavors. Methods: PubMed was searched for English-language articles from January 1998 to November 2023, using the search term "psilocybin." A total of 1,449 articles were identified and screened through titles and abstracts. Of these, 21 unique open-label or randomized controlled trials (RCTs) were identified that examine psilocybin for the treatment of obsessive-compulsive and related disorders (N=2), anxiety/depression associated with a cancer diagnosis (N=5), major depressive disorder (MDD; N=8), substance use disorders (N=4), anorexia (N=1), and demoralization (i.e., hopelessness, helplessness, and poor coping) in AIDS survivors (N=1). Results: The most developed evidence base is for the treatment of MDD (three double-blind RCTs with positive signals spanning a range of severities). However, the evidence is tempered by threats to internal and external validity, including unsuccessful blinding, small samples, large variability in dosing and PST procedures, limited sample diversity, and possibly large expectancy effects. Knowledge of mechanisms of action and predictors of response is currently limited. Conclusions: The evidence is currently insufficient to recommend psilocybin with PST as a psychiatric treatment. Additional rigorously designed clinical trials are needed to definitively establish efficacy in larger and more diverse samples, address dosing considerations, improve blinding, and provide information on mechanisms of action and moderators of clinical response. Head-to-head comparisons with other evidence-based treatments will better inform the potential future role of psilocybin with PST in the treatment of major psychiatric disorders.


Novel Approaches for Treating Depression

January 2025

·

12 Reads

These are exciting times for psychiatry and clinical neuroscience. Our knowledge of basic brain function continues to increase at an accelerating pace as the experimental tools available to basic and clinical scientists become ever more powerful and penetrating. After decades of frustration and relatively slow progress, this explosion of knowledge of the brain is at long last beginning to define the etiology and pathophysiology of complex neuropsychiatric disorders that have long defied biological explanations, which in turn is being translated into clinical advances in diagnosis and treatment of an increasing number of these illnesses. This new, sixth edition of Neurobiology of Mental Illness addresses these challenging, yet very promising, times and reflects the continuing reintegration of psychiatry into the mainstream of biomedical science and the increasing synthesis of psychiatry and neurology into a fully integrated clinical neuroscience.


Novel Approaches for Treating Anxiety and Trauma-Related Disorders

January 2025

·

3 Reads

These are exciting times for psychiatry and clinical neuroscience. Our knowledge of basic brain function continues to increase at an accelerating pace as the experimental tools available to basic and clinical scientists become ever more powerful and penetrating. After decades of frustration and relatively slow progress, this explosion of knowledge of the brain is at long last beginning to define the etiology and pathophysiology of complex neuropsychiatric disorders that have long defied biological explanations, which in turn is being translated into clinical advances in diagnosis and treatment of an increasing number of these illnesses. This new, sixth edition of Neurobiology of Mental Illness addresses these challenging, yet very promising, times and reflects the continuing reintegration of psychiatry into the mainstream of biomedical science and the increasing synthesis of psychiatry and neurology into a fully integrated clinical neuroscience.





Next‐generation biomarkers for alcohol consumption and alcohol use disorder diagnosis, prognosis, and treatment: A critical review

This critical review summarizes the current state of omics‐based biomarkers in the alcohol research field. We first provide definitions and background information on alcohol and alcohol use disorder (AUD), biomarkers, and “omic” technologies. We next summarize using (1) genetic information as risk/prognostic biomarkers for the onset of alcohol‐related problems and the progression from regular drinking to problematic drinking (including AUD), (2) epigenetic information as diagnostic biomarkers for AUD and risk biomarkers for alcohol consumption, (3) transcriptomic information as diagnostic biomarkers for AUD, risk biomarkers for alcohol consumption, and (4) metabolomic information as diagnostic biomarkers for AUD, risk biomarkers for alcohol consumption, and predictive biomarkers for response to acamprosate in subjects with AUD. In the final section, the clinical implications of the findings are discussed, and recommendations are made for future research.



Citations (60)


... Ghaznavi et al. (13) review the critically important but often overlooked element of potential harms associated with psychedelic treatments, which range from common mild adverse events to rare but potentially serious psychiatric decompensation and life-threatening cardiac effects. In the first of two drug-specific deep-dives, Fonzo et al. (14) provide a systematic review of the evidence base for psilocybin in the treatment of psychiatric disorders and identifies major depression as the indication with the strongest evidence base. The authors emphasize that conclusions from the studies must be tempered by key limitations such as insufficient blinding, large variability in dosing and psychological procedures, threats to generalizability, and possibly large expectancy effects. ...

Reference:

Psychedelics in Psychiatry: Oh, What A Trip!
Psilocybin: From Psychiatric Pariah to Perceived Panacea
  • Citing Article
  • January 2025

American Journal of Psychiatry

... Functional connectivity provides insights into both normal brain function and the impacts of neurological disorders on the brain. Brain's functional states are not static but evolve over time [26], hence there is the need to study dynamic functional connectivity to understand the complex brain activity related to disorders like ASD. Studies [12], [18], [29] have highlighted how dynamic functional connectivity provides deeper insights into the temporal variability of brain networks, revealing patterns that static connectivity measures might miss. ...

Human brain state dynamics are highly reproducible and associated with neural and behavioral features

... Whilst the IAPS is good for standardising images used within studies examining affect, further standardisation in emotional processing task design is necessary. A shift towards consistency through the utilisation of reporting checklists [80], akin to what is observed in the cue reactivity literature with the formation of the ENIGMA Addiction Cue Reactivity Initiative [81,82], would help improve reliability and replicability of results. A similar initiative should be developed within the field of emotional processing. ...

Reporting checklists in neuroimaging: promoting transparency, replicability, and reproducibility
  • Citing Article
  • September 2024

Neuropsychopharmacology: official publication of the American College of Neuropsychopharmacology

... Lange et al. identified cerebellar lobule VI as essential for processing fear-related stimuli and memory consolidation (21). The reductions ob-served in our study may contribute to both motor and emotional impairments, reflecting the cerebellum's involvement in stress responses (22). In our study, no significant changes were observed in the volumes of the limbic system. ...

Cerebellar Contributions to Traumatic Autobiographical Memory in People with Post-Traumatic Stress Disorder

The Cerebellum

... Bonomi et al. ( 1 ) recently reported that a lipopolysaccharide (LPS) challenge in individuals with long-standing posttraumatic stress disorder (PTSD) was associated with anhedonia and a reduction in translocator protein-18 kDa (TSPO) positron emission tomography signal, a widely employed marker of microglial activation. They concluded that in people with long-standing PTSD, microglial response is blunted and that pharmacotherapies restoring microglial and neuroimmune function may play a role in treating certain symptoms associated with this disorder. ...

Microglia-mediated neuroimmune suppression in PTSD is associated with anhedonia

Proceedings of the National Academy of Sciences

... Functional magnetic resonance imaging (fMRI) and magnetic resonance imaging (MRI) studies of patients with mild TBI have demonstrated reduced default mode network (DMN) connectivity in the posterior cingulate and parietal regions, and increased connectivity in the medial prefrontal cortex [mPFC; (13,14)]. The DMN is anatomically comprised of mPFC, posterior cingulate cortex (PCC), inferior parietal lobe, lateral temporal cortex and hippocampal formation (15), with research supporting decreased prefrontal DMN connectivity and increased posterior connectivity in PTSD patients (16,17). These alterations to DMN connectivity also have consequences in cognitive impairment and emotional regulation, issues that trouble veterans long after military service ceases (3). ...

Findings of PTSD-specific deficits in default mode network strength following a mild experimental stressor

... Analogously, we did not find a relation between behavior and the probabilities of cortical/subcortical FC jumps (R 2 < 0.01). Consistently with our findings, Lee et al. 70 previously reported weak correlations of behavior with DT/FT co-activation patterns. These results suggest that temporal summary metrics of dynamic FC, such as FT/DT and jump probabilities, do not significantly contribute to explaining inter-individual behavioral variability. ...

Human Brain State Dynamics Reflect Individual Neuro-Phenotypes

Biological Psychiatry

... As such, subanesthetic doses of ketamine are used widely to model psychosis in humans and experimental animals [75][76][77][78]. Nevertheless, a recent study in humans showed that both the neural and behavioral effects of acute ketamine have robust inter-individual variability [79]. ...

Ketamine induces multiple individually distinct whole-brain functional connectivity signatures

eLife

... (Alonso et al., 2011) It has been noted that adults aged 50 y and older have recently experienced the fastest increase in depression of all age groups (Greenberg et al., 2015). Depression is a known risk factor for chronic diseases including obesity, (Shell et al., 2024) metabolic syndrome and diabetes, (Shell et al., 2024)cardiovascular disease, (Cao et al., 2024;Duivis et al., 2013) neurodegenerative diseases, (Hussain et al., 2024;Jimenez et al., 2024) substance use disorders, (Na et al., 2024) and others. (Eby & Eby, 2010;Karlsdotter et al., 2016) Strategies for earlier identification, prevention and treatment of depression are urgently needed to improve health and quality of life among older adults in the U.S. Older Latinos suffer a disproportionate burden of depression: the lifetime prevalence of Major Depressive Disorder (MDD) in Latinos aged between 54 and 65 is approximately 40% greater than in non-hispanic whites (NHW) of the same age. ...

Problem Opioid Use Among US Military Veterans: Prevalence, Correlates, and Psychiatric Characteristics
  • Citing Article
  • March 2024

Journal of Addiction Medicine

... Research indicates that about one-third of patients with TRD attempt suicide at least once in their lifetime (4,5), severely impairing social functioning, increasing societal burdens, and posing a significant challenge in clinical practice (6)(7)(8). ...

Recent Advances in the Treatment of Treatment-Resistant Depression: A Narrative Review of Literature Published from 2018 to 2023

Current Psychiatry Reports