Reference Library
Glossary of Intelligence
Plain-language, sourced definitions for the 142 core terms behind brains, minds, and machines. Each term opens a dedicated page with a topical visual, deeper explanation, and further reading.
Showing 142 of 142 terms
Psychedelics & Consciousness
5-HT2A Receptor
Serotonin receptor subtype that mediates the primary effects of classic psychedelics.
Psychedelics & Consciousness
5-MeO-DMT
Short-acting tryptamine producing intense ego-dissolution experiences; investigated for depression and addiction.
Cognition
Active Inference
Free-energy framework where perception and action both minimize prediction error.
Mental Health
Addiction
Compulsive substance use or behavior despite negative consequences, mediated by reward and learning circuits.
Artificial Intelligence
Agentic AI
AI systems that pursue goals through multi-step planning, tool use, memory, and environmental interaction.
AI Safety
AI Alignment
The technical problem of ensuring AI systems pursue goals and values consistent with human intent.
Neuroscience
Alpha Waves
EEG oscillations in the 8–13 Hz range associated with relaxed wakefulness and reduced visual processing.
Psychedelics & Consciousness
Altered State of Consciousness
Any temporary modification of normal waking awareness — psychedelic, meditative, hypnotic, dream, or anesthetic.
Neuroscience
Alzheimer's Disease
Most common neurodegenerative dementia, characterized by amyloid plaques and tau tangles.
Neuroscience
Amygdala
Almond-shaped subcortical structure central to emotional learning, threat detection, and memory modulation.
Mental Health
Anxiety Disorders
Group of conditions characterized by excessive fear, worry, and physiological arousal.
Artificial Intelligence
Artificial General Intelligence (AGI)
AI systems capable of matching or exceeding human cognitive performance across the full breadth of intellectual tasks.
Artificial Intelligence
Artificial Superintelligence (ASI)
Hypothetical AI that vastly exceeds the best human minds in essentially every domain of interest.
Cognition
Attention
Selection and prioritization of information for further processing.
Psychedelics & Consciousness
Ayahuasca
Plant-based brew combining DMT-containing plants with MAO inhibitors to enable oral psychedelic activity.
Neuroscience
Basal Ganglia
Subcortical nuclei coordinating action selection, habit learning, and reward-driven behavior.
Cognition
Bayesian Brain
The hypothesis that the brain represents uncertainty and updates beliefs in approximately Bayesian fashion.
Neuroscience
BDNF
Brain-derived neurotrophic factor; a key protein supporting synaptic plasticity and neuronal survival.
Sound & Music
Binaural Beats
Perceptual illusion produced when two slightly different frequencies are presented to each ear separately.
Cognition
Brain Economy
Framework treating cognitive and mental-health resources as strategic economic capital.
Neurotechnology
Brain–Computer Interface (BCI)
A direct communication channel between neural activity and an external device.
Sound & Music
Brainwave Entrainment
Synchronization of brain oscillations to an external rhythmic stimulus.
AI Safety
Capability Control
Family of AI-safety techniques that constrain what a system can do, rather than what it wants.
Neuroscience
Central Executive Network
Frontoparietal network supporting working memory, task control, and goal-directed cognition.
Neuroscience
Cerebellum
Densely packed hindbrain structure essential for motor coordination, timing, and predictive learning.
Neuroscience
Cerebral Cortex
Outer layer of the brain responsible for higher cognitive functions.
Neurotechnology
Closed-Loop Brain System
System that reads neural state in real time and adjusts a stimulus accordingly.
Cognition
Cognitive Enhancement
Interventions intended to improve cognitive performance in healthy individuals.
Neuroscience
Connectome
The complete map of neural connections in a brain or nervous system.
Philosophy of Mind
Consciousness
The state of being aware of and able to report on one's own experiences, thoughts, and surroundings.
Neuroscience
Cortisol
Primary stress hormone regulated by the hypothalamic-pituitary-adrenal axis.
Neurotechnology
Deep Brain Stimulation
Surgically implanted electrodes that deliver electrical stimulation to specific brain targets.
Neuroscience
Default Mode Network
Large-scale brain network active during rest, self-referential thought, and mental simulation.
Neuroscience
Delta Waves
Slow (< 4 Hz) EEG oscillations dominant in deep, non-REM sleep.
Neuroscience
Dementia
Acquired persistent decline in multiple cognitive domains severe enough to impair daily function.
Neuroscience
Dendritic Spine
Tiny protrusion on a neuron's dendrite that receives most excitatory synaptic input.
Mental Health
Depression
Mood disorder characterized by persistent low mood, anhedonia, cognitive changes, and functional impairment.
Neurotechnology
Digital Therapeutic
Software product delivered as a regulated medical intervention.
Psychedelics & Consciousness
DMT
N,N-dimethyltryptamine, an endogenous tryptamine that produces short, intense psychedelic experiences when administered exogenously.
Neuroscience
Dopamine
A neurotransmitter central to motivation, reward learning, and motor control.
Psychedelics & Consciousness
Dreaming
Subjective experiences during sleep, especially REM, characterized by narrative imagery.
Neurotechnology
EEG
Electroencephalography: non-invasive recording of brain electrical activity from the scalp.
Psychedelics & Consciousness
Ego Dissolution
Subjective loss of the boundary between self and surroundings; characteristic of high-dose psychedelic states.
Artificial Intelligence
Embeddings
Dense vector representations that map words, tokens, or items into a continuous geometric space.
Cognition
Embodiment
The thesis that cognition is shaped by the body's sensors, actuators, and physical interaction with the world.
Artificial Intelligence
Emergent Abilities
Capabilities that appear abruptly in large models but are absent in smaller ones.
Cognition
Emotion
Coordinated physiological, cognitive, and behavioral responses to significant events.
Psychedelics & Consciousness
Entropic Brain Hypothesis
Theory that the richness of conscious states corresponds to the entropy of brain activity.
Psychedelics & Consciousness
Esketamine
S-enantiomer of ketamine, FDA-approved as a nasal spray for treatment-resistant depression.
Cognition
Executive Function
Higher-order cognitive processes that regulate goal-directed behavior: working memory, inhibition, and flexibility.
Artificial Intelligence
Fine-Tuning
Adapting a pre-trained model to a specific task or style by continuing training on a smaller targeted dataset.
Cognition
Flow State
Experience of absorbed, effortless engagement in a challenging task; characterized by reduced self-awareness and time distortion.
Neurotechnology
fMRI
Functional magnetic resonance imaging: measures brain activity via blood-oxygen-level-dependent (BOLD) signal.
Neuroscience
GABA
Primary inhibitory neurotransmitter in the mammalian brain.
Neuroscience
Gamma Waves
High-frequency (30–100 Hz) EEG oscillations associated with perceptual binding, attention, and conscious access.
Philosophy of Mind
Global Workspace Theory
Theory that consciousness arises from cortical broadcast of information via a frontoparietal workspace.
Neuroscience
Glutamate
Primary excitatory neurotransmitter in the mammalian brain.
Neuroscience
Glymphatic System
Brain waste-clearance pathway active primarily during sleep.
Neuroscience
Gut-Brain Axis
Bidirectional communication network linking the central nervous system and the gastrointestinal tract.
Philosophy of Mind
Hard Problem of Consciousness
Chalmers' question of why physical processes give rise to subjective experience at all.
Neuroscience
Hippocampus
A seahorse-shaped structure crucial for forming new episodic memories and spatial navigation.
Neuroscience
Human Connection
Social bonds and relational experiences with measurable effects on brain function and mental health.
Neuroscience
Hypothalamus
Small subcortical region that regulates homeostasis, hormones, and the autonomic nervous system.
Psychedelics & Consciousness
Ibogaine
Atypical psychedelic alkaloid from Tabernanthe iboga investigated for opioid use disorder.
Artificial Intelligence
Inference
The process of running a trained model on new inputs to produce predictions or generations.
AGI
Instrumental Convergence
Tendency for sufficiently capable agents with diverse final goals to pursue similar intermediate sub-goals like self-preservation and resource acquisition.
Neuroscience
Insula
Cortical region buried within the lateral sulcus, central to interoception, emotion, and salience processing.
Philosophy of Mind
Integrated Information Theory
Tononi's theory that consciousness corresponds to a system's capacity for irreducible integrated information (Φ).
Psychedelics & Consciousness
Integration (Psychedelic Therapy)
Structured psychotherapy after a psychedelic session that helps consolidate insights into lasting change.
Cognition
Interoception
Perception of the internal state of the body, including heart rate, breathing, and visceral sensations.
Sound & Music
Isochronic Tones
Single tones pulsed on and off at a steady rate; used in entrainment audio products.
Psychedelics & Consciousness
Ketamine
NMDA receptor antagonist with rapid antidepressant effects via downstream glutamate release and BDNF-mediated plasticity.
Artificial Intelligence
Large Language Model (LLM)
A neural network trained on massive text corpora to predict and generate human-like language.
Neuroscience
Limbic System
Group of subcortical structures (amygdala, hippocampus, hypothalamus, others) involved in emotion, memory, and motivation.
Neuroscience
Long-Term Potentiation
Persistent strengthening of synapses based on recent activity - the cellular basis of learning and memory.
Neuroscience
Long-Term Potentiation
Persistent strengthening of synapses following correlated activity; cellular basis of learning and memory.
Psychedelics & Consciousness
LSD
Lysergic acid diethylamide, a potent semi-synthetic classic psychedelic active at sub-milligram doses.
Psychedelics & Consciousness
MDMA
Entactogenic compound that releases serotonin, dopamine, and oxytocin; studied for PTSD-assisted therapy.
AI Safety
Mechanistic Interpretability
Research that reverse-engineers the internal computations of neural networks into human-understandable concepts.
Cognition
Meditation
Family of attentional practices that reliably produce neural and physiological changes.
Neurotechnology
MEG
Magnetoencephalography: measures magnetic fields produced by brain electrical activity.
Cognition
Memory
Encoding, storage, and retrieval of information across multiple specialized systems.
Neuroscience
Microbiome
Community of microorganisms living in and on the human body, especially the gut.
Psychedelics & Consciousness
Microdosing
Repeated administration of sub-perceptual psychedelic doses; consumer practice with limited rigorous evidence.
Cognition
Mindfulness
Quality of present-moment, non-judgmental awareness cultivated by specific meditative practices.
Artificial Intelligence
Mixture of Experts
Architecture where a router sends each token to a small subset of expert sub-networks, scaling capacity without proportional compute.
Sound & Music
Music Therapy
Clinical use of music to address physical, emotional, cognitive, and social needs.
Sound & Music
Music-Induced Emotion
Emotional responses elicited by music, mediated by limbic and reward circuits.
Neuroscience
Myelin
A fatty insulating sheath around axons that dramatically speeds neural signal conduction.
Psychedelics & Consciousness
Mystical Experience
Acute experiences of unity, sacredness, and noetic insight, commonly assessed via the MEQ-30.
Philosophy of Mind
Neural Correlates of Consciousness
Minimal neural mechanisms jointly sufficient for any specific conscious experience.
Neuroscience
Neural Entropy
Measure of the diversity of brain activity patterns over time; increased by classic psychedelics.
Philosophy of Mind
Neuroethics
Field examining ethical, legal, and social implications of neuroscience and neurotechnology.
Neurotechnology
Neurofeedback
Real-time display of brain activity that allows users to learn to self-regulate neural patterns.
Neuroscience
Neurogenesis
The generation of new neurons from neural stem cells, occurring throughout life in select brain regions.
Neuroscience
Neuron
Electrically excitable cell that processes and transmits information via electrochemical signals.
Neuroscience
Neuroplasticity
The molecular and structural changes that let neural circuits adapt with experience.
Psychedelics & Consciousness
Neuroplastogen
Compound that promotes structural neural plasticity, especially dendritic spine growth.
Philosophy of Mind
Neuroprivacy
Protection of information about brain activity and mental states.
Neuroscience
Neurotransmitter
Chemical messenger released at synapses to relay, amplify, or modulate signals between neurons.
Neuroscience
NMDA Receptor
Glutamate receptor critical for synaptic plasticity and learning; primary target of ketamine.
Cognition
Nootropic
Substance proposed to enhance cognition with minimal side effects; evidence varies sharply by compound.
AGI
Orthogonality Thesis
Claim that an agent's intelligence and its final goals can vary independently - any level of intelligence can pursue any goal.
Neuroscience
Oxytocin
Neuropeptide involved in social bonding, trust, and parental behavior.
Neuroscience
Parkinson's Disease
Progressive neurodegenerative disorder of dopaminergic neurons in the substantia nigra.
Neurotechnology
Perturbational Complexity Index
TMS-EEG measure that distinguishes conscious from unconscious brain states by quantifying the complexity of the response to a perturbation.
Neuroscience
Plasticity
The brain's capacity to reorganize itself by forming new connections throughout life.
Cognition
Predictive Coding
A theory that the brain continuously generates predictions about sensory input and learns from prediction errors.
Neuroscience
Prefrontal Cortex
Front-most cortical region implementing planning, working memory, inhibition, and executive control.
Psychedelics & Consciousness
Psilocin
Active metabolite of psilocybin and the molecule directly responsible for serotonin 5-HT2A agonism in the brain.
Psychedelics & Consciousness
Psilocybin
Naturally occurring tryptamine prodrug metabolized to psilocin, the active 5-HT2A agonist responsible for classic psychedelic effects.
Psychedelics & Consciousness
Psychedelic Renaissance
Revival of scientific and clinical interest in psychedelic compounds since the 1990s.
Psychedelics & Consciousness
Psychedelic-Assisted Therapy
Treatment paradigm combining one or more psychedelic dosing sessions with structured preparation and integration psychotherapy.
Mental Health
PTSD
Post-traumatic stress disorder: persistent psychological reaction to traumatic events.
Philosophy of Mind
Qualia
The subjective, experiential qualities of conscious states - what something is like to experience.
Artificial Intelligence
Reasoning Models
LLMs trained or prompted to perform extended chain-of-thought before answering, trading inference compute for accuracy.
Psychedelics & Consciousness
REBUS Model
Relaxed Beliefs Under Psychedelics: predictive-processing theory of psychedelic action.
AGI
Recursive Self-Improvement
Scenario in which an AI system iteratively improves its own design, producing rapid capability gains.
Neuroscience
REM Sleep
Rapid-eye-movement sleep stage characterized by vivid dreaming and high cortical activity.
Artificial Intelligence
Retrieval-Augmented Generation
Architecture that grounds LLM outputs by retrieving relevant documents before generation.
AI Safety
RLHF
Reinforcement Learning from Human Feedback - fine-tuning models against learned preferences from human raters.
Neuroscience
Salience Network
Brain network anchored in anterior insula and dorsal anterior cingulate that directs attention to behaviorally relevant stimuli.
Neuroscience
Serotonin
Monoamine neurotransmitter (5-HT) that modulates mood, perception, sleep, appetite, and many other functions.
Psychedelics & Consciousness
Set and Setting
Mindset of the person and the social/physical environment of a psychedelic experience; core therapeutic variables.
Neuroscience
Sleep
Recurring state of reduced consciousness essential for memory, restoration, and neural maintenance.
Mental Health
SSRI
Selective serotonin reuptake inhibitor, the most widely prescribed class of antidepressants.
Mental Health
Stress
Physiological and psychological response to demands exceeding perceived coping resources.
AI Safety
Superalignment
Research agenda focused on aligning AI systems substantially more capable than their human supervisors.
Neuroscience
Synapse
Junction between two neurons where signals are passed chemically or electrically.
Artificial Intelligence
Synthetic Data
Model-generated data used to train or augment AI systems when real data is scarce, sensitive, or biased.
Neurotechnology
tDCS
Transcranial direct-current stimulation: low-intensity electrical brain stimulation.
Neuroscience
Thalamus
Central relay nucleus that gates and routes nearly all sensory and cortical signals.
Neuroscience
Theta Waves
EEG oscillations in the 4–8 Hz range associated with memory, navigation, and deep meditation.
Neurotechnology
TMS
Transcranial magnetic stimulation: non-invasive modulation of cortical activity via magnetic pulses.
Artificial Intelligence
Transformer
A neural-network architecture built on self-attention; the foundation of modern LLMs.
Mental Health
Treatment-Resistant Depression
Major depression that has failed to respond to two or more adequate trials of standard antidepressants.
Neurotechnology
Vagus Nerve Stimulation
Electrical stimulation of the vagus nerve used in epilepsy, treatment-resistant depression, and inflammation research.
AI Safety
Value Alignment
The technical and philosophical problem of ensuring AI systems pursue goals consistent with human values.
Artificial Intelligence
Vector Database
Database optimized for storing and querying high-dimensional vectors via approximate nearest-neighbor search.
Neurotechnology
VR Therapy
Therapeutic use of immersive virtual environments, especially for phobias, PTSD, and pain.
Cognition
Working Memory
Short-term system for holding and manipulating information used in reasoning and decision-making.
Artificial Intelligence
World Models
Neural networks that learn internal simulations of an environment to predict future states and plan actions.