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Processes that stabilize or reorganize information after acquisition. Synaptic consolidation concerns cellular changes, whereas systems consolidation concerns changing interactions among brain regions. Better later performance need not mean a literal transfer of a complete memory between two stores.

Inflammation of the membranes surrounding the brain and spinal cord. Its location differs from encephalitis, though both can occur together.

Coauthor of research on brain responses to skin warming and cooling. The study connected controlled thermal stimulation with regional signals measured by positron emission tomography in awake humans.^[ref]

Coauthor of research on brain responses to skin warming and cooling. The study connected controlled thermal stimulation with regional signals measured by positron emission tomography in awake humans.^[ref]

A brain region containing structures involved in sensory processing and action, including the superior colliculus.

The mind is the collection of mental processes and capacities involved in perception, attention, human memory, thought, emotion and consciousness. In scientific psychology, these processes are investigated through specified tasks, reports, behavior and measurements of the brain. The mind is not one directly observed score: remembering a location and noticing a flash require different explanations and measurements.

A useful experiment separates available information from the ability to report it. In 1960, George Sperling used briefly displayed arrays of symbols and partial report paradigms. Asking for only part of a display helped test whether a limited whole report reflected unavailable visual information or a limit on retaining and reporting it. Tones could specify which portion to report after the display had ended.^[ref]

For an invented sampling example, suppose a display has three rows and a randomly selected row can be reported with an average of three correct symbols. Under equal sampling and accessibility assumptions, multiplying by three estimates nine available symbols across the display. That is an inference from a task, not a direct inspection of a mental store. Its assumptions must be checked, and a cue delivered much later can test how availability changes with time.

The example links perception, sensory memory and reporting while keeping them distinguishable. An operational definition identifies the actual response to be measured; construct validity asks whether the proposed interpretation of that response is justified. The scientific study of the mind becomes more precise when these connections are explicit.

Morgan D. Barense studies relationships between human memory, perception and medial temporal brain systems. Her patient study examined online discrimination of complex objects, asking whether impairments concern only retaining information across a delay or also representing objects while they are present. Comparisons between lesion patterns and task demands help separate these explanations. ^[ref]

A researcher who coauthored a two-stage choice experiment comparing model-based and model-free influences. Behavioral modeling and striatal signals tested contributions of these computations rather than assigning each brain response to only one strategy.^[ref]

Nervous tissue, also called neural tissue, is the organized tissue of the nervous system, containing neurons and glial cells. Neurons specialize in communication, including action potentials and signaling between cells. Glial cells maintain the local environment, form insulating myelin in particular locations, and perform other active functions. The brain, spinal cord and peripheral nerves contain different arrangements of these components; a drawing of one isolated neuron is not a complete picture of nervous tissue.^[ref]

A useful example is the median eminence, where hormone-releasing axon endings interact with tanycytes and blood-vessel endothelium. In a 2004 experiment, investigators compared female-rat tissue explants after 30 minutes with or without 500 micromolar arginine, a precursor for nitric oxide production. Electron microscopy showed identified gonadotropin-releasing hormone terminals close to the vascular boundary after treatment, with fewer intervening tanycyte processes than in controls.^[ref]

The observation makes tissue organization experimentally meaningful: changes in the position of a glial cell process can alter a neuron's access to a vascular interface. This specialized arrangement should not be mistaken for the structure of every synapse or every region of nervous tissue.

An embryonic epithelial structure giving rise to the central nervous system, including the brain and spinal cord in vertebrates.

A person whose participation in research on neurological function provides evidence about cognition or brain mechanisms. Case studies may be published under initials or patient codes.

Neurology is the medical study of disorders affecting the nervous system. It connects changes in brain, spinal cord and peripheral nerve function to symptoms and examination findings, while using neuroscience to investigate the underlying mechanisms.

A neurological deficit is an observation to explain, rather than a diagnosis by itself. Comparing muscle strength, sensation, coordination and reflexes can help distinguish damage to different pathways even when two people report a similar difficulty.

A misconception presented as a consequence of brain knowledge or used as a brain-based educational explanation. Not every unsupported educational claim is specifically neuroscientific, so survey categories and definitions need examination.

A neuron is a specialized biological cell that receives, integrates and transmits signals. Its shape separates places where inputs arrive from places where outputs reach other biological cells: this functional asymmetry is neuronal polarity. Understanding a neuron therefore means connecting its anatomy to changes in membrane potential, rather than treating it as a wire that merely forwards every input.

In a common multipolar neuron, branching dendrites receive inputs at synapses; the soma contains the cell nucleus and most major organelles; the axon carries signals to distant or nearby targets; and axon terminals form output contacts. All these regions belong to one biological cell enclosed by a continuous cell membrane. An axon can branch, allowing one neuron to influence several receiving biological cells.^[ref]

At an input chemical synapse, a neurotransmitter acts on a receptor, changing an electric current directly or through signal transduction.^[ref] A resulting synaptic potential contributes to synaptic integration in the dendrites and soma. In many spiking neurons, sufficiently strong depolarization recruits voltage-gated ion channels in the axon initial segment, initiating an action potential that propagates along the axon. At an output chemical synapse, calcium entry through voltage-gated ion channels promotes synaptic vesicle exocytosis, releasing neurotransmitter. An action potential is thus regenerated electrically along a cell membrane; it is not a packet of neurotransmitter travelling from the dendrites to the axon terminals.^[ref]

The compartments are specializations, not exclusive jobs. Inputs can contact the soma or axon as well as dendrites; dendrites can support active voltage-gated ion channels. Paired recordings from a pyramidal neuron's soma and dendrite or axon established that an action potential can begin in the axon and propagate back into the dendrites. The usual output direction therefore does not make every electrical signal strictly one-way.^[ref] An electrical synapse, which directly couples cytoplasms through gap junctions, also differs from the sending-and-receiving arrangement of a chemical synapse.^[ref]

Nor does every neuron have the upper diagram's shape. A bipolar neuron has two main processes, one dendrite and one axon; a multipolar neuron has several dendrites; and a pseudounipolar neuron has a single process from the soma that divides into peripheral and central branches. In the last arrangement, sensory signals can travel past the soma rather than obligatorily through it. These shape categories do not specify every neuron's receptor, connectivity or firing behavior.^[ref] Some neurons in the retina communicate through graded changes in membrane potential without generating action potentials.^[ref]

Why timing changes the computation. Synaptic integration can combine inputs at different locations, called spatial summation, and inputs arriving at different times, called temporal summation. A minimal example uses the leaky integrate-and-fire model with the illustrative parameters already given there: resting and reset membrane potential $-65\mathrm{mV}$, firing threshold $-50\mathrm{mV}$, electrical resistance $R=100\mathrm{M\Omega }$, capacitance $C=200\mathrm{pF}$, time constant $\tau =RC=20\mathrm{ms}$ and neuronal refractory period $2\mathrm{ms}$. These are chosen model values, not measured properties of a particular neuron. Before firing, a constant inward electric current $I$ starting from rest givesThe exponential function expresses the competition between charging the cell membrane's capacitance and leakage through its electrical resistance.^[ref]

Two $100\mathrm{pA}$ inputs, each lasting $40\mathrm{ms}$, produce different outputs depending on their timing. Either input alone reaches only $-56.3534\mathrm{mV}$. Applied together, they give $I=200\mathrm{pA}$ and reach threshold after $20\ln 4\mathrm{ms}\approx 27.7259\mathrm{ms}$, producing one action potential event during the pulse. If instead the second input begins $20\mathrm{ms}$ after the first ends, the earlier depolarization has partly decayed: the second pulse peaks at approximately $-55.9229\mathrm{mV}$ and neither pulse produces an action potential. The two-input protocols deliver the same total electric charge, $8\mathrm{pC}$, yet only the coincident protocol fires. Counting total input alone misses this timing dependence.

This example makes a neuron a detector of sufficiently clustered input, not a perfect logical gate: different parameters change the result. Actual dendrites introduce location-dependent filtering and active responses, and an inhibitory postsynaptic potential or shunting inhibition can change whether another input succeeds. The single-compartment leaky integrate-and-fire model omits these mechanisms.^[ref] Across connected neurons, branching axons distribute outputs while converging synapses combine inputs; spike trains can support temporal coding and rate coding, and synaptic plasticity changes the influence of an input. Connectivity and cellular dynamics together determine the computation.^[ref][ref]

Testing the connection between structure and function. Whole-cell recording connects anatomy to a measured membrane potential. In a published mouse protocol, a two-photon microscope guides solution-filled glass pipettes to neurons; an amplifier and bath reference electrode complete the electrical recording apparatus. A high-resistance seal forms against the cell membrane, then brief suction opens the membrane patch beneath the tip. In current clamp, the amplifier supplies a chosen electric current and records the resulting membrane potential, unlike voltage clamp, which controls voltage and measures electric current. The investigators used $500\mathrm{ms}$ current steps of several amplitudes to characterize excitability and firing, and negative current pulses to estimate input electrical resistance.^[ref]

The observable is a voltage trace, including graded responses and action potentials. Comparing injected electric current with that trace tests how input becomes output; it does not identify every underlying ion channel. The protocol checks access electrical resistance, which can distort voltage and action potential measurements, and includes intervals without stimulation to record spontaneous activity. In a teaching replication, repeated zero-input trials and monitoring baseline drift would provide further controls; these are recommended comparisons, not additional results attributed to the paper. A recording at the soma also cannot establish the local voltage everywhere in a branching dendrite, and this anesthetized preparation does not establish behavior in every awake neuron.^[ref]

A complementary experiment used simultaneous whole-cell recordings from the soma and an apical dendrite or axon of the same pyramidal neuron in a brain slice. The relative onset times of action potentials, together with sodium currents in excised dendrite membrane patches, supported axonal initiation followed by active propagation into dendrites. Pairing sites within one neuron is a useful comparison because it avoids confusing differences between cells with differences between compartments. Instrument timing and comparable recording quality would be essential controls when reproducing the inference. Only the published abstract was accessible here, so no unverified timing values, drug controls or channel distributions are supplied.^[ref]

A neuropsychologist investigates relationships between brain function and cognition or behavior, including patterns associated with neurological injury. A double dissociation can distinguish abilities that a single broad impairment would otherwise group together. Clinical assessment combines a participant’s pattern across tasks with history and functional context; a low score on one task does not uniquely identify the damaged brain region or cognitive process. ^[ref]

Neuropsychology studies relationships between brain function and cognition or behavior, including patterns of impairment and preservation after brain lesions. A task comparison can reveal a selective difficulty rather than a uniform loss of all abilities. Double dissociations strengthen the distinction between processes, but task demands, lesion extent and connected-system effects still matter. The classic amnesia studies illustrate how preserved abilities can be as informative as impaired ones. ^[ref]

Understanding relevant brain science and how to evaluate claims derived from it. Knowing isolated facts should be distinguished from reasoning about a new educational claim and selecting an effective intervention.

A vertebrate brain structure receiving projections from olfactory sensory neurons.

An olfactory sensory neuron is a neuron that detects odorant molecules and sends an electrical signal toward the brain. Receptor-bearing sensory endings sample chemicals at the nasal surface, while the axon carries the resulting output toward the olfactory bulb. Detection and interpretation are therefore distributed across peripheral cells and central circuits.

Genetically labelled receptor-expressing neurons allowed investigators to trace where their axons converged in the olfactory bulb. Receptor-swap experiments further tested how receptor identity contributes to that projection pattern. ^[ref] This connects molecular recognition to circuit organization without implying that a single active neuron uniquely identifies every odour: an odour can recruit a pattern across receptor classes.

Delay-period activity explains important properties of working memory when its information content and dynamics predict behavior; elevated activity alone is not a complete storage mechanism. An explanation must account for maintaining an absent stimulus, limited working memory capacity, variable precision, interference and flexible prioritization. Different measurements reveal different aspects: extracellular single-unit recording measures individual neurons, electroencephalography measures aggregated electrical signals, and functional magnetic resonance imaging measures a slower hemodynamic response. None directly reads a unitary store.

The classic case for persistent neural activity came from delayed-response tasks. In Shintaro Funahashi and colleagues' 1989 experiment, monkeys maintained fixation after a briefly presented peripheral cue and later made a memory-guided saccade. Dorsolateral prefrontal cortex neurons could maintain location-selective firing during the intervening blank interval; delay-period activity was reduced or absent on some error trials. This connects a maintained code to a remembered location rather than merely to stimulus presence. It also supplies a plausible bridge between a short-lived sensory event and a later response. However, the remembered location and intended eye movement covaried, so the experiment does not isolate human mnemonic storage from prospective action coding.^[ref]

More explanatory leverage comes from linking population dynamics to the pattern of errors. A bump attractor maintains a localized pattern through recurrent excitation and inhibition. Noise can move its center while leaving a memory trace present, predicting increasing uncertainty and trial-specific directional errors. Klaus Wimmer and colleagues tested such predictions against monkey prefrontal recordings and memory-guided eye movements: neural variability was related to fine-grained response errors in ways predicted by a diffusing representation. This is stronger than a generic activation–accuracy association because competing models need to explain that structured relationship. Nevertheless, it is evidence from a trained spatial task in monkeys; it does not by itself explain verbal rehearsal, binding errors or every source of human forgetting.^[ref]

Human recordings link delay signals to working memory capacity. In Edward K. Vogel and colleagues' visual-memory experiments, people remembered arrays on one side of fixation while ignoring the other. The contralateral delay activity increased with memory load and approached an asymptote associated with each person's behavioral working memory capacity. Its usefulness is the relation between a physiological load function and an independently estimated behavioral limit. It does not prove that the brain has exactly a fixed number of universal slots: stimulus complexity, filtering, allocation and the measurement's sensitivity can influence the signal. A plateau is evidence constraining a working memory capacity mechanism, not the mechanism itself.^[ref]

Delay-period activity also contains specific sensory information. Stephenie A. Harrison and Frank Tong presented oriented patterns and cued which orientation to remember. Multivariate pattern analysis of early visual cortex functional magnetic resonance imaging could identify the remembered orientation during the delay, even when mean activation was weak. This supports sensory recruitment and helps explain why visual memories retain feature-specific detail and may compete with new sensory input. Decoding establishes accessible information, however, not necessarily a local storage site: top-down feedback, attention or task preparation could generate a decodable pattern. Its slow hemodynamics cannot establish uninterrupted moment-to-moment firing.^[ref]

The temporal and priority structure of working memory challenges an exclusively tonic account. Mikael Lundqvist and colleagues recorded monkey prefrontal spiking and local field potentials and found brief gamma oscillation and beta oscillation bursts rather than uniformly sustained oscillatory activity. A smooth trial average can conceal intermittent events. This finding qualifies the interpretation of averaged persistence; it does not show that every neuron becomes silent between bursts, or that recurrent activity is irrelevant.^[ref]

Human perturbation experiments distinguish current priority from continued retention. In Nathan S. Rose and colleagues' task, a temporarily unattended item could cease to be decodable yet remain relevant for a later probe. A transcranial magnetic stimulation pulse reinstated a detectable representation under appropriate relevance conditions. In Michael J. Wolff and colleagues' experiment, a neutral visual impulse during the delay evoked an electroencephalography response carrying information about remembered items, including temporarily unattended ones; instructed forgetting and temporary inattention had different consequences, and the hidden-state measure related to working memory precision. These results explain how an item may remain available without occupying the same active state as the current focus of attention.^[ref][ref]

An activity-silent working memory interpretation proposes temporarily altered network responsiveness, potentially involving short-term synaptic plasticity. Neither an absent decoding result nor a successful perturbation identifies that molecular mechanism uniquely: weak or recoded activity can evade a particular measurement, and perturbation can recruit distributed networks. The strongest conclusion is therefore pluralistic. Persistent neural activity offers a plausible mechanism for some maintenance and precision effects, while intermittent and latent states help explain prioritization and retained but unattended information. A successful theory must jointly predict errors, load effects and perturbation consequences at the appropriate time scale. Delay-period activity provides substantial mechanistic constraints, but human working memory is better explained by interacting representations and control states than by equating storage with continuously elevated firing.