PSYCH 027: Radiotracer Imaging with Positron Emission Tomography and Single Photon Emission Computed Tomography: Fundamental Principles, Methodology and Role in Neuropsychiatric Research

PSYCH 027: Radiotracer Imaging with Positron Emission Tomography and Single Photon Emission Computed Tomography: Fundamental Principles, Methodology and Role in Neuropsychiatric Research

While MRI shows structure and EEG captures electrical activity, radiotracer imaging reveals something different: the brain’s molecular activity in action. This chapter explores PET and SPECT - techniques that allow us to track specific biological processes in vivo. In this episode, we examine how radiolabelled tracers bind to particular receptors, transporters, or metabolic pathways, enabling us to visualise neurotransmitter systems and functional activity. These methods provide a window into processes such as dopamine transmission, glucose metabolism, and receptor availability. We explore how PET and SPECT have advanced our understanding of psychiatric disorders - particularly in areas such as schizophrenia, addiction, and mood disorders - by linking symptoms to underlying neurochemical dynamics. A key strength of these techniques is specificity. Unlike broader imaging methods, radiotracer studies can target particular systems, offering insights into mechanisms at a molecular level. However, these approaches are complex, resource-intensive, and primarily research tools. Interpretation requires caution, and findings are often probabilistic rather than definitive. This chapter highlights a powerful idea: that understanding the mind requires not only seeing the brain, but tracing the chemistry that animates it. Key Takeaways * PET and SPECT use radiotracers to visualise molecular processes in the brain. * These techniques can assess neurotransmitter systems, receptor binding, and metabolism. * They provide high biochemical specificity compared to other imaging methods. * Radiotracer imaging has advanced understanding of disorders such as schizophrenia and addiction. * These methods are primarily used in research rather than routine clinical practice. * Interpretation is complex and findings are not always definitive. * Molecular imaging links symptoms to underlying neurochemical processes. This is a public episode. If you'd like to discuss this with other subscribers or get access to bonus episodes, visit drmanaankarray.substack.com/subscribe [https://drmanaankarray.substack.com/subscribe?utm_medium=podcast&utm_campaign=CTA_2]

PSYCH 026: Electroencephalography in Psychiatry

If imaging reveals structure, electroencephalography (EEG) captures activity in real time. This chapter explores how electrical signals generated by neuronal populations can be recorded from the scalp, offering a dynamic view of brain function. In this episode, we examine how EEG reflects synchronised activity across neural networks, producing patterns that can be analysed in terms of frequency, amplitude, and coherence. These rhythms - from slow delta waves to fast gamma activity - represent different states of brain function. We explore how EEG is used clinically, particularly in epilepsy and sleep medicine, but also its growing role in psychiatric research. Subtle alterations in brain rhythms have been associated with conditions such as schizophrenia, depression, and attention disorders. A key theme is temporal resolution. Unlike structural imaging, EEG captures the brain as it unfolds moment by moment - revealing patterns of timing, synchrony, and disruption that are otherwise invisible. However, EEG also has limitations. Its spatial precision is limited, and interpretation requires careful contextualisation. It offers a window into function, but not a complete map. This chapter highlights the importance of timing in brain activity - showing that when signals occur, and how they synchronise, is as important as where they originate. Key Takeaways * EEG records electrical activity from neuronal populations in real time. * Brain activity is reflected in rhythmic patterns across different frequencies. * EEG provides high temporal resolution but limited spatial precision. * It is widely used in epilepsy and sleep medicine, with growing psychiatric applications. * Altered brain rhythms are associated with various psychiatric conditions. * EEG reveals patterns of synchrony, timing, and network dynamics. * Functional insight requires careful interpretation within clinical context. This is a public episode. If you'd like to discuss this with other subscribers or get access to bonus episodes, visit drmanaankarray.substack.com/subscribe [https://drmanaankarray.substack.com/subscribe?utm_medium=podcast&utm_campaign=CTA_2]

PSYCH 025: Nuclear Magnetic Resonance Imaging and Spectroscopy: Basic Principles and Recent Findings in Neuropsychiatric Disorders

Much of psychiatry has historically relied on inference - understanding brain function indirectly through behaviour and experience. Nuclear magnetic resonance (NMR) techniques, including MRI and spectroscopy, have transformed this landscape, allowing us to visualise both structure and chemistry in vivo. In this episode, we explore the principles underlying magnetic resonance imaging - how magnetic fields and radiofrequency signals are used to generate detailed images of brain anatomy. We then move beyond structure to spectroscopy, which provides insight into the brain’s biochemical composition. These tools allow us to observe patterns associated with psychiatric disorders - changes in volume, connectivity, and neurochemical markers. Yet interpretation remains complex: findings are often subtle, variable, and not specific to a single condition. We examine how these technologies contribute to research and, increasingly, clinical practice - while also recognising their limitations. Imaging does not “diagnose” psychiatry in isolation; it adds another layer of understanding to an already complex picture. This chapter reflects a broader shift: from unseen processes to visualised systems - offering a window into the living brain, while reminding us that what we see is only part of the story. Key Takeaways * MRI uses magnetic fields and radiofrequency signals to image brain structure. * Spectroscopy provides information about brain biochemistry in vivo. * These techniques allow observation of structural and chemical changes in psychiatric disorders. * Findings are often subtle and not specific to individual diagnoses. * Imaging enhances understanding but does not replace clinical assessment. * Interpretation requires integration with broader clinical and scientific context. * Neuroimaging is a tool for insight, not a standalone diagnostic solution. This is a public episode. If you'd like to discuss this with other subscribers or get access to bonus episodes, visit drmanaankarray.substack.com/subscribe [https://drmanaankarray.substack.com/subscribe?utm_medium=podcast&utm_campaign=CTA_2]

PSYCH 025: Nuclear Magnetic Resonance Imaging and Spectroscopy: Basic Principles and Recent Findings in Neuropsychiatric Disorders

Much of psychiatry has historically relied on inference - understanding brain function indirectly through behaviour and experience. Nuclear magnetic resonance (NMR) techniques, including MRI and spectroscopy, have transformed this landscape, allowing us to visualise both structure and chemistry in vivo. In this episode, we explore the principles underlying magnetic resonance imaging - how magnetic fields and radiofrequency signals are used to generate detailed images of brain anatomy. We then move beyond structure to spectroscopy, which provides insight into the brain’s biochemical composition. These tools allow us to observe patterns associated with psychiatric disorders - changes in volume, connectivity, and neurochemical markers. Yet interpretation remains complex: findings are often subtle, variable, and not specific to a single condition. We examine how these technologies contribute to research and, increasingly, clinical practice - while also recognising their limitations. Imaging does not “diagnose” psychiatry in isolation; it adds another layer of understanding to an already complex picture. This chapter reflects a broader shift: from unseen processes to visualised systems - offering a window into the living brain, while reminding us that what we see is only part of the story. Key Takeaways * MRI uses magnetic fields and radiofrequency signals to image brain structure. * Spectroscopy provides information about brain biochemistry in vivo. * These techniques allow observation of structural and chemical changes in psychiatric disorders. * Findings are often subtle and not specific to individual diagnoses. * Imaging enhances understanding but does not replace clinical assessment. * Interpretation requires integration with broader clinical and scientific context. * Neuroimaging is a tool for insight, not a standalone diagnostic solution. This is a public episode. If you'd like to discuss this with other subscribers or get access to bonus episodes, visit drmanaankarray.substack.com/subscribe [https://drmanaankarray.substack.com/subscribe?utm_medium=podcast&utm_campaign=CTA_2]

PSYCH 024: Computational Modelling Approaches to Psychiatry

Psychiatry often deals with processes that cannot be directly observed - beliefs, predictions, learning, and perception. Computational psychiatry offers a way to formalise these processes, translating them into models that can be tested, refined, and understood. In this episode, we explore how mathematical and computational frameworks are used to describe how the brain processes information. Concepts such as prediction, uncertainty, reinforcement learning, and Bayesian inference provide a language for understanding cognition and behaviour. We examine how the brain can be conceptualised as a prediction-generating system - constantly updating its expectations based on incoming information. When these processes are disrupted, perception, belief formation, and decision-making can become distorted. This provides powerful insights into psychiatric conditions. Psychosis, for example, can be framed as a disturbance in how the brain assigns meaning or salience to information. Anxiety may reflect altered processing of uncertainty and threat prediction. Computational models do not replace clinical understanding - they deepen it. They allow psychiatry to move from descriptive frameworks to mechanistic explanations of how the mind works. This chapter represents a shift towards precision - where subjective experience is linked to underlying computational processes. Key Takeaways * Computational psychiatry models how the brain processes information. * Key concepts include prediction, uncertainty, and reinforcement learning. * The brain can be understood as a system that generates and updates expectations. * Psychiatric disorders may reflect disruptions in these computational processes. * Models provide a bridge between subjective experience and biological mechanisms. * Computational approaches enhance mechanistic understanding of mental illness. * These frameworks complement, rather than replace, clinical insight. This is a public episode. If you'd like to discuss this with other subscribers or get access to bonus episodes, visit drmanaankarray.substack.com/subscribe [https://drmanaankarray.substack.com/subscribe?utm_medium=podcast&utm_campaign=CTA_2]