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Balthasar Bickel is a linguist studying the diversification of languages and the mechanisms that constrain it. His research combines comparisons of grammars, lexicons and text corpus resources with experimental methods including electroencephalography and eye tracking. He describes these as complementary approaches to language change and its biological foundations.^[ref]

The combination illustrates two different sources of evidence. Comparing documented syntactic dependencies across languages can reveal recurring patterns; an experiment can instead hold an input contrast fixed and measure processing in participants. These are examples of the questions those methods can address, rather than findings inferred from a biography.

Balthasar Bickel also co-developed the Leipzig Glossing Rules by Bernard Comrie and others with Bernard Comrie and Martin Haspelmath. Their shared conventions make linguistic annotation easier to compare while leaving grammatical analysis open to argument.^[ref]

Electroencephalography records differences in electric potential using electrodes, commonly at the scalp. Summed activity in neural tissue contributes to the measured signal, providing millisecond-scale information about changes over time.

An event-related potential compares or averages this activity relative to defined events. Volume conduction and overlapping sources limit direct localization, so a scalp waveform cannot simply be equated with one small neural generator.

An epileptic seizure is a transient event caused by abnormal excessive or synchronized activity in brain networks. Its manifestations depend on the recruited circuits and can include motor changes, altered sensation or impaired awareness.

The mechanism distinguishes it from a superficially similar event with another cause. Electroencephalography can supply physiological evidence, but the observed behavior and the clinical time course remain important to interpretation.

A cognitive neuroscientist who used impulse-evoked electroencephalography to investigate hidden states of working memory.^[ref]

Neuroimaging measures structural or functional properties of the nervous system. Different methods record different physical signals, so anatomical images and activity-sensitive measurements support different inferences.

For example, electroencephalography records electrical potential differences, while many functional vascular measurements depend on neurovascular coupling. Spatial overlap in an image is not by itself proof that one location implements a complete psychological process.

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.

Combined recording used to classify sleep and waking, commonly including electroencephalography, eye-movement signals and muscle activity. Classification of a sleep stage is not itself a measure of the content of a memory.

Slow-wave sleep is a deep stage of non-rapid eye movement sleep characterized by prominent slow, high-amplitude activity in an electroencephalography recording. It is a physiological classification based on measured brain activity and other sleep criteria, rather than simply an unusually motionless posture. In current human staging it broadly corresponds to N3. ^[ref]

Sleep-stage identification can guide interventions. In a human experiment, an odour associated with earlier learning was presented again during slow-wave sleep; subsequent declarative-memory performance was compared with control conditions. ^[ref] This links a defined physiological state to an experimentally timed cue; it does not establish that every kind of memory depends exclusively on that one stage.

A spherical volume conductor model approximates a conducting body by a sphere, usually with uniform or radially stratified conductivity. It provides explicit forward models for electroencephalography and magnetoencephalography. Its symmetry makes a radial current dipole magnetically silent outside the sphere; departures from spherical symmetry need not retain that property.