A growing glossary of interesting terms.

A proposed operating mode in which input to a pyramidal neuron’s apical integration zone mainly drives its output. The paper argues that this could help generate dream experiences from internal brain activity. Its role in dreaming remains a hypothesis.

For example Internal signals arriving at a neuron’s apical dendrites could help produce experience without current sensory input.

A state or set of states that a dynamical system approaches from nearby starting conditions. An attractor can be a fixed state, a repeating cycle, or a more complicated pattern of motion.

For example In some memory-network models, activity approaches a pattern representing a stored memory.

Behavior in a deterministic system where tiny differences in the starting conditions can grow into very different outcomes. The rules can be fixed even when long-term prediction becomes difficult.

For example Two nearly identical starting positions can send a double pendulum along very different paths.

Behavior near a transition between qualitatively different states. In some neural models, this is a boundary where activity neither quickly dies out nor grows unchecked; whether brain networks operate there is an active research question.

For example Plasticity rules in a model may keep activity near a transition between fading and spreading.

Experiences of imagery, thoughts, and feelings during sleep. Dreams can occur in different sleep stages; their purpose is still being studied.

For example A remembered dream is one way to study experience while the brain is asleep.

A boundary between ordered and chaotic behavior in a dynamical model. It has been proposed as a useful regime for computation, but the reservoir-computing papers show that it is not always the best operating point.

For example A reservoir may perform better away from its instability boundary when that better suits the task.

Brief periods when the spatial pattern of electrical activity measured across scalp electrodes remains relatively stable. A microstate describes the pattern across the scalp rather than a single brain region or rhythm.

For example The dreams paper compares the occurrence of different microstate patterns before awakenings with and without dream recall.

A pattern or property that appears through interactions among parts of a system. Understanding each part on its own may not explain the behavior of the whole.

For example A flock forms a coordinated moving pattern through the interactions of individual birds.

In thermodynamics, a measure related to how many microscopic arrangements can produce the same large-scale state. In information theory, entropy instead measures uncertainty in a probability distribution.

For example A gas spread through a room has more available microscopic arrangements than the same gas confined to one corner.

The study of changes in gene activity associated with chemical modifications to DNA or its associated proteins, without changing the underlying DNA sequence. Some modifications can persist through cell division.

For example DNA methylation can change how active a gene is without rewriting its DNA letters.

Literally, never dying. Here it is a research theme for aging, longevity, and the limits of biological repair; extending healthy life does not establish immortality.

For example A paper on slowing cellular aging belongs to this theme without showing that an organism can live forever.

A thought experiment in which an agent uses information about a physical system to sort particles or extract work. Accounting for the physical costs of information processing resolves the apparent challenge to the second law of thermodynamics.

For example The quantum-circuit paper uses measurement and feedback to investigate converting information into work.

The processes that stabilize and reorganize a memory after initial learning. These include changes at synapses and interactions among brain regions over time.

For example Sleep-and-rest experiments test what happens to newly learned information after the learning session ends.

Small ecosystems: communities of organisms interacting with one another and with their physical surroundings. Small scale still allows complex food webs and feedback.

For example A tide pool contains a small community shaped by nutrients, predators, sunlight, and changing water conditions.

A broad category here for living systems, ecosystems, and the physical processes around them. It is a starting point for exploring how organisms interact with their environments.

For example A study of how a forest recovers after disturbance sits within this category.

Gerald Edelman’s theory that development and experience select among diverse groups of neurons by changing the strength of their connections. It applies selection ideas to brain organization.

For example Repeated experience can favor some patterns of neural connections over others.

A burst or cascade of neural activity separated from other bursts by quieter periods. Researchers study the range of avalanche sizes and durations to understand collective brain dynamics.

For example A neural-network model can produce many small activity cascades and occasional much larger ones.

The nervous system’s ability to change its structure or function with development and experience. Changes in connections between neurons are one way learning can leave a lasting trace.

For example Practice can change how a neural circuit responds to a familiar task.

The study of the nervous system, from individual cells and their signals to the networks involved in perception, memory, movement, and behavior.

For example Recording neural activity during sleep is a neuroscience experiment.

A personal category for research on how memories are formed, stabilized, retrieved, and forgotten, and what may improve those processes. It names an interest rather than one scientific mechanism.

For example Comparing memory after sleep and after quiet rest explores how consolidation works.

Repeated variations over time, often around a typical level. Neural oscillations are rhythms in the activity of neurons or groups of neurons; their speed and timing can vary.

For example Slow waves, sleep spindles, and faster ripples are different rhythms studied during sleep.

A debated term for the ways plants sense conditions, communicate signals, and adjust their behavior. Calling those abilities intelligence depends on the definition being used.

For example Roots adjust their growth as they encounter different local conditions.

The physics of matter and light at scales where quantum effects matter. Energy exchanges can occur in discrete amounts, and quantum states determine probabilities for measurement outcomes.

For example An atom absorbs or emits light through transitions between allowed energy levels.

The rebuilding or replacement of lost or damaged biological structures. The extent of regeneration differs between organisms and tissues.

For example Some salamanders can regrow a lost limb.

A computing system that feeds inputs into a dynamical “reservoir” whose changing state retains traces of recent input. A trained readout converts those states into useful outputs; in standard reservoir computing, the reservoir itself stays fixed.

For example A reservoir can learn to predict a chaotic signal by training the readout on examples of its changing state.

A category label here for a local decrease in thermodynamic entropy. Such a decrease can occur while entropy in the surroundings increases; it does not reverse the second law for an isolated system.

For example A refrigerator uses energy to cool its interior while releasing heat into the room.

The formation of large-scale order through interactions within a system, without a controller specifying the final pattern. Feedback among the parts shapes what emerges.

For example In neural-network models, local changes to synapses can help organize the network’s overall activity.

The systems that detect physical or chemical changes and turn them into signals the nervous system can use. Perception involves further processing of those signals.

For example Vibrations at the skin can be encoded as touch signals and interpreted by the brain.

A mechanical wave traveling through a material such as air, water, or a solid. Hearing is the sensory process that turns some of those vibrations into an experience.

For example A vibrating speaker creates pressure changes that travel through air.

Involving randomness, described through probabilities. A stochastic model allows a range of possible outcomes even when it starts from the same state.

For example A model that gives a neuron a probability of firing includes stochastic behavior.

Changes in how effectively signals pass between neurons at their synapses. These changes can last briefly or persist, and are one part of the broader concept of neuroplasticity.

For example A synapse can become stronger or weaker as a result of neural activity.

The adjustment of timing between interacting systems so that their rhythms become coordinated. This can mean a stable timing relationship rather than identical activity.

For example Coupled oscillators can settle into a shared rhythm or a steady phase difference.

Made or assembled rather than simply observed in its naturally occurring form. The meaning depends on the field: in synthetic psychology, artificial systems are built to explore how behavior can arise.

For example Braitenberg’s imagined vehicles combine sensors, motors, and simple wiring to produce behavior that looks purposeful.

The experience and judgment of duration, timing, and the passage of time. Subjective duration can differ from elapsed clock time and can depend on sensory input.

For example In one study, stronger vibrations were judged to last longer even when their physical duration was unchanged.