PSYCH 017: Basic Science of Appetite

PSYCH 017: Basic Science of Appetite

Appetite is often mistaken for a simple biological drive, but it is in fact a finely regulated system integrating energy balance, reward, emotion, and cognition. This chapter explores how the brain determines when to eat, what to eat, and when to stop. In this episode, we examine the interplay between homeostatic systems - which monitor energy needs - and hedonic systems, which assign pleasure and reward to food. The hypothalamus plays a central role in maintaining balance, responding to hormonal signals such as leptin and ghrelin. At the same time, reward circuits involving dopamine shape motivation and craving. We explore how appetite is influenced by context, emotion, and environment. Eating is not simply about energy - it is embedded in social, psychological, and cultural frameworks. Dysregulation in these systems can lead to a range of psychiatric and behavioural conditions, from eating disorders to obesity and addiction-like patterns of consumption. These are not failures of willpower, but alterations in the systems that regulate need and reward. This chapter reframes appetite as a negotiation - between biological necessity and experiential desire - revealing how the brain balances survival with meaning. Key Takeaways * Appetite is regulated by both homeostatic and hedonic systems. * The hypothalamus monitors energy balance and responds to hormonal signals. * Hormones such as leptin and ghrelin influence hunger and satiety. * Reward systems, particularly dopamine pathways, shape food-related motivation. * Appetite is influenced by emotional, social, and environmental factors. * Dysregulation can contribute to eating disorders, obesity, and addictive behaviours. * Eating reflects both biological need and psychological meaning. 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 016: Pain Systems: Interface with Affective and Motivational Mechanisms

Pain is often described as a sensory experience, but in psychiatry it is something far more complex. This chapter explores how pain is constructed at the intersection of sensory input, emotional processing, and motivational systems. In this episode, we examine how nociceptive signals are only the beginning. The brain interprets these signals through networks involving the insula, anterior cingulate cortex, limbic structures, and prefrontal regions - transforming raw input into subjective experience. Pain is therefore not just about intensity, but about meaning. The same stimulus can be experienced differently depending on context, expectation, mood, and prior experience. This explains why pain and emotion are so tightly linked, and why chronic pain often coexists with depression and anxiety. We explore how pain influences behaviour - driving avoidance, attention, and adaptive responses - and how these mechanisms can become maladaptive when pain persists or becomes centralised. This chapter reframes pain as a multidimensional experience: sensory, emotional, and motivational. It challenges the idea of pain as purely physical, revealing it instead as a deeply integrated brain–mind phenomenon. Key Takeaways * Pain is not purely sensory; it includes emotional and motivational dimensions. * Brain regions such as the insula and anterior cingulate cortex are central to pain processing. * Context, expectation, and prior experience shape the perception of pain. * Pain and emotion are closely linked at the level of neural circuits. * Chronic pain involves changes in central processing, not just peripheral input. * Pain influences behaviour, attention, and decision-making. * Understanding pain requires integrating biological, psychological, and social factors. 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 015: Basic Science of Sleep

Sleep is often treated as absence - a passive state where the brain switches off. This chapter challenges that notion, revealing sleep as an active, highly organised process essential for brain function and mental health. In this episode, we explore the architecture of sleep - its stages, cycles, and regulatory systems. Non-REM and REM sleep represent distinct physiological states, each contributing differently to restoration, memory consolidation, and emotional processing. We examine how sleep is governed by two interacting systems: the circadian rhythm and the homeostatic drive. Together, they determine when we sleep, how deeply, and for how long. Disruptions to either system can destabilise the entire process. Sleep is not merely restorative - it is transformative. During sleep, the brain reorganises information, processes emotional experiences, and clears metabolic by-products. It is a period of recalibration, not inactivity. Clinically, disturbances in sleep are both symptoms and drivers of psychiatric disorders. Insomnia, hypersomnia, and altered sleep architecture are closely linked to mood disorders, anxiety, and psychosis. This chapter reframes sleep as foundational - not optional, but integral to how the brain maintains coherence and resilience. Key Takeaways * Sleep is an active, structured process essential for brain function. * Non-REM and REM sleep serve distinct roles in restoration and processing. * Sleep is regulated by circadian rhythms and homeostatic drive. * It supports memory consolidation, emotional regulation, and metabolic clearance. * Disruptions in sleep can both reflect and contribute to psychiatric disorders. * Sleep architecture (timing, depth, cycles) is clinically significant. * Rest is not passive - it is a critical component of neural health and function. 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 014: Chronobiology, Circadian Rhythm, and Psychiatry

The brain does not function in a constant state - it operates in rhythms. This chapter explores chronobiology and circadian systems, revealing how internal biological clocks organise sleep, energy, cognition, and emotional regulation across the day. In this episode, we examine the circadian system as a master regulator, synchronising physiological and psychological processes with environmental cues such as light and darkness. The suprachiasmatic nucleus acts as a central pacemaker, coordinating peripheral systems and maintaining temporal order. We explore how disruptions in these rhythms - whether through lifestyle, illness, or intrinsic vulnerability - can profoundly affect mental health. Sleep disturbances, mood instability, and cognitive changes are not random; they often reflect underlying temporal dysregulation. Conditions such as depression, bipolar disorder, and anxiety can be understood, in part, as disorders of rhythm - where timing, not just content, has gone awry. This chapter invites a subtle but powerful shift: to consider not only what the brain is doing, but when it is doing it - and how misalignment in time can alter the entire landscape of experience. Key Takeaways * Circadian rhythms regulate sleep, mood, cognition, and physiological processes. * The suprachiasmatic nucleus acts as the central biological clock. * Environmental cues (especially light) synchronise internal rhythms. * Disruptions to circadian systems can significantly impact mental health. * Sleep disturbances are often both symptoms and drivers of psychiatric disorders. * Mood disorders, particularly bipolar disorder, are closely linked to rhythm dysregulation. * Timing and synchronisation are as important as biological mechanisms themselves. 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 013: Immune–Brain Interactions in Psychiatry

The brain does not operate in isolation from the body’s defence systems. This chapter explores the evolving understanding of how the immune system and the brain interact - not only in illness, but as part of normal regulation of mood, behaviour, and cognition. In this episode, we examine how immune signalling molecules, particularly cytokines, influence brain function. These signals can alter neurotransmission, neural plasticity, and circuit activity - effectively shifting how the brain processes information. We explore the concept of “sickness behaviour” - a coordinated response to inflammation characterised by fatigue, low mood, reduced motivation, and social withdrawal. While adaptive in acute illness, similar patterns may become maladaptive when immune activation is prolonged or dysregulated. This provides a powerful framework for understanding aspects of depression, as well as emerging links between inflammation and other psychiatric conditions. The boundary between physical and mental illness becomes increasingly blurred - revealing shared biological pathways. This chapter invites a reframing of psychiatric symptoms: not solely as disorders of the brain, but as states influenced by systemic processes - where the immune system becomes an active participant in shaping experience. Key Takeaways * The immune system and brain interact through signalling molecules such as cytokines. * Immune activation can influence neurotransmission, plasticity, and neural circuits. * “Sickness behaviour” reflects adaptive responses that can resemble depressive symptoms. * Chronic or dysregulated inflammation may contribute to psychiatric disorders. * The distinction between physical and mental illness is increasingly blurred. * Immune–brain interactions offer new perspectives on mechanisms and treatment targets. * Psychiatry must consider systemic biology, not just brain-specific 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]