{
 "schema": "learn-deck/1",
 "module": "eeg",
 "deck": "eeg",
 "title": "EEG",
 "lang": "en",
 "cards": [
  {
   "id": "eeg:generators",
   "type": "flash",
   "q": "What generates the scalp EEG?",
   "a": "Summed postsynaptic potentials (50–200 ms) of parallel pyramidal cells in superficial cortex, not action potentials.",
   "ex": "Spikes last ~1 ms and rarely coincide; PSPs are slow, overlap in time and pass the tissue's low-pass filter.",
   "tags": [
    "origin"
   ]
  },
  {
   "id": "eeg:neuron-count",
   "type": "mcq",
   "q": "How many synchronous neurons dominate a scalp EEG signal?",
   "choices": [
    "About 100",
    "10^4 to 5×10^4",
    "About 10^8",
    "A single column"
   ],
   "a": 1,
   "ex": "Cohen ch. 5: mainly superficial layers. A single neuron's field is far too weak at the scalp.",
   "tags": [
    "origin"
   ]
  },
  {
   "id": "eeg:dipole-orient",
   "type": "mcq",
   "q": "Which dipole orientation gives the strongest scalp EEG?",
   "choices": [
    "Radial (gyral crown)",
    "Tangential (sulcal wall)",
    "Deep subcortical",
    "Opposing sulcal walls"
   ],
   "a": 0,
   "ex": "Tangential sources favour MEG; opposing sulcal walls cancel each other.",
   "tags": [
    "origin"
   ]
  },
  {
   "id": "eeg:deep-sources",
   "type": "flash",
   "q": "Why are thalamus or hippocampus hard to see on scalp EEG?",
   "a": "Field falls steeply with distance (scalp current density ~1/r^4) and deep cells lack parallel geometry, so fields cancel.",
   "ex": "Brainstem potentials need thousands of trials of averaging versus dozens for cortex.",
   "tags": [
    "origin"
   ]
  },
  {
   "id": "eeg:smoothing",
   "type": "flash",
   "q": "What area does one scalp electrode integrate?",
   "a": "Roughly 10 cm² of cortex, spatially smoothed by CSF, skull and scalp.",
   "ex": "Buzsáki's 'fish-eye lens': superficial layers dominate, subcortex is negligible.",
   "tags": [
    "origin"
   ]
  },
  {
   "id": "eeg:min-cortex",
   "type": "mcq",
   "q": "Minimum synchronous cortex for a seizure to show on scalp EEG?",
   "choices": [
    "About 0.5 cm²",
    "About 6 cm²",
    "About 20 cm²",
    "Any size"
   ],
   "a": 1,
   "ex": "Smaller or distant foci are 'surface negative'; frontal hyperkinetic seizures often are.",
   "tags": [
    "origin",
    "seizure"
   ]
  },
  {
   "id": "eeg:meg-vs-eeg",
   "type": "flash",
   "q": "MEG vs EEG: which sources does each see best?",
   "a": "EEG: radial sources, distorted by the skull. MEG: tangential (fissural) sources, undistorted, no scalp contact needed.",
   "ex": "Brain magnetic fields are <0.5 pT, sensed by SQUIDs at −270 °C.",
   "tags": [
    "origin"
   ]
  },
  {
   "id": "eeg:1020-landmarks",
   "type": "flash",
   "q": "10-20 system: how are electrodes spaced along nasion to inion?",
   "a": "10, 20, 20, 20, 20, 10 % of the distance: Fpz, Fz, Cz, Pz, Oz. Odd numbers left, even right, z midline.",
   "ex": "Same fractions on the preauricular line and around the circumference.",
   "tags": [
    "montage"
   ]
  },
  {
   "id": "eeg:1020-rename",
   "type": "mcq",
   "q": "Modern 10-10 names for T3/T4 and T5/T6?",
   "choices": [
    "T7/T8 and P7/P8",
    "F7/F8 and O1/O2",
    "C5/C6 and P5/P6",
    "TP7/TP8 only"
   ],
   "a": 0,
   "ex": "Rowan uses the 10-10 nomenclature throughout.",
   "tags": [
    "montage"
   ]
  },
  {
   "id": "eeg:polarity",
   "type": "flash",
   "q": "EEG polarity convention: input 1 negative relative to input 2 deflects the trace...",
   "a": "Upward. Negativity at input 1 is drawn up; most cortical spikes are surface negative.",
   "ex": "Rowan: 'negative up'. Positive blink artifact therefore goes down at Fp1/Fp2.",
   "tags": [
    "montage"
   ]
  },
  {
   "id": "eeg:phase-reversal",
   "type": "flash",
   "q": "What does a phase reversal in a bipolar chain mean?",
   "a": "The electrode shared by the two channels that deflect toward each other is the maximum of the field.",
   "ex": "Bipolar localises by phase reversal; referential localises by largest amplitude.",
   "tags": [
    "montage"
   ]
  },
  {
   "id": "eeg:bipolar-paradox",
   "type": "flash",
   "q": "Why can a widespread in-phase discharge vanish on a bipolar montage?",
   "a": "Adjacent electrodes see nearly equal voltage, so their difference cancels ('bipolar paradox'). Check a referential montage.",
   "ex": "Related trap: end-of-chain electrodes (Fp1, O1) never phase-reverse.",
   "tags": [
    "montage"
   ]
  },
  {
   "id": "eeg:montages",
   "type": "mcq",
   "q": "'Double banana' is which montage?",
   "choices": [
    "Longitudinal bipolar",
    "Transverse bipolar",
    "Common average",
    "Circumferential"
   ],
   "a": 0,
   "ex": "Circumferential runs through Fp and O; ideal for occipital and frontopolar spikes.",
   "tags": [
    "montage"
   ]
  },
  {
   "id": "eeg:avg-ref",
   "type": "flash",
   "q": "Common-average reference: main pitfall?",
   "a": "A large focal potential contaminates the average and appears inverted at every channel.",
   "ex": "Cohen: average reference is recommended with >100 electrodes; never reference to one lateral site.",
   "tags": [
    "montage",
    "preproc"
   ]
  },
  {
   "id": "eeg:impedance",
   "type": "mcq",
   "q": "Recommended scalp electrode impedance for clinical EEG?",
   "choices": [
    "≤50 kΩ",
    "≤5 kΩ",
    "≤500 Ω",
    "≤1 MΩ"
   ],
   "a": 1,
   "ex": "ACNS: differential input impedance ≥100 MΩ; up to 10 kΩ tolerated by modern amplifiers.",
   "tags": [
    "technical"
   ]
  },
  {
   "id": "eeg:zin-imbalance",
   "type": "flash",
   "q": "Zin 10 MΩ, electrodes 1 kΩ and 10 kΩ, 10 mV common-mode at 50 Hz. Differential error?",
   "a": "Vcm × (ZE2 − ZE1)/Zin = 0.01 × 9000/10^7 = 9 µV.",
   "ex": "Nieder ch. 5. Fix: keep all electrodes low and Zin as high as practical.",
   "tags": [
    "technical"
   ]
  },
  {
   "id": "eeg:high-z-look",
   "type": "mcq",
   "q": "A poor, high-impedance electrode usually makes its channel look...",
   "choices": [
    "Flat",
    "Unchanged",
    "Bigger, with line noise",
    "Noisier only above 30 Hz"
   ],
   "a": 2,
   "ex": "Nieder: apparent focal delta and a 'spike' at F4 were ECG and EMG entering via the unbalanced input.",
   "tags": [
    "technical",
    "artifacts"
   ]
  },
  {
   "id": "eeg:cmrr-spec",
   "type": "mcq",
   "q": "Minimum CMRR guideline for an EEG amplifier?",
   "choices": [
    "40 dB",
    "90 dB",
    "60 dB",
    "140 dB"
   ],
   "a": 1,
   "ex": "Also: noise <1 µV peak-to-peak between 0.5 and 100 Hz.",
   "tags": [
    "technical"
   ]
  },
  {
   "id": "eeg:filters-default",
   "type": "flash",
   "q": "Standard clinical EEG filter settings?",
   "a": "LFF 1 Hz, HFF 70 Hz, notch off. Digital systems acquire 0.1–100 Hz and filter at review.",
   "ex": "HFF 35 Hz for muscle-heavy records; never 15 Hz, it turns spikes into slow waves.",
   "tags": [
    "technical"
   ]
  },
  {
   "id": "eeg:notch-off",
   "type": "flash",
   "q": "Why keep the 50/60 Hz notch off by default?",
   "a": "It hides high-impedance electrodes and blunts epileptiform sharpness. Line noise is a diagnostic clue.",
   "ex": "Nieder ch. 5: notch is mostly done digitally when needed.",
   "tags": [
    "technical"
   ]
  },
  {
   "id": "eeg:sampling-rule",
   "type": "mcq",
   "q": "ACNS sampling guideline relative to the high filter?",
   "choices": [
    "≥3× the HFF cutoff",
    "2× the HFF",
    "10× the HFF",
    "Equal to the HFF"
   ],
   "a": 0,
   "ex": "Or anti-alias cutoff at 66 % of Nyquist. Cohen: record 500–2000 Hz; 1000 Hz makes 1 ms = 1 sample.",
   "tags": [
    "technical"
   ]
  },
  {
   "id": "eeg:display",
   "type": "flash",
   "q": "Standard paper speed, page length and sensitivity?",
   "a": "30 mm/s, 10 s per page, 7 µV/mm (15 µV/mm for high-voltage records).",
   "ex": "15 mm/s in Europe and for neonates.",
   "tags": [
    "technical"
   ]
  },
  {
   "id": "eeg:rc-cutoff",
   "type": "flash",
   "q": "RC filter cutoff and the attenuation there?",
   "a": "f = 1/(2πRC); output down by √2 (−3 dB), not by 2.",
   "ex": "Nieder: on log–log axes HF and LF curves are mirror images.",
   "tags": [
    "technical"
   ]
  },
  {
   "id": "eeg:thermal-noise",
   "type": "flash",
   "q": "Thermal noise of 1 kΩ electrodes over 70 Hz bandwidth?",
   "a": "About 0.035 µV rms: negligible for EEG. Needle EMG or BAEP with high-Z electrodes can reach signal level.",
   "ex": "Grows as √(4kTRB); amplifier noise adds several times more.",
   "tags": [
    "technical"
   ]
  },
  {
   "id": "eeg:gain",
   "type": "flash",
   "q": "Typical total gain and input range of an EEG chain?",
   "a": "Gain ~10^5 or more so that µV signals fit an ADC range like ±5 V.",
   "ex": "Displayed as sensitivity (µV/mm), not gain.",
   "tags": [
    "technical"
   ]
  },
  {
   "id": "eeg:blink",
   "type": "flash",
   "q": "Eye-blink artifact: why is it frontal positive?",
   "a": "The cornea is positive; on blinking the eye rolls up (Bell's phenomenon), so Fp1/Fp2 go positive (downward).",
   "ex": "Eye leads mirror each other on blinks; frontal GRDA has them in phase.",
   "tags": [
    "artifacts"
   ]
  },
  {
   "id": "eeg:lateral-eye",
   "type": "mcq",
   "q": "Lateral eye movement to the left produces...",
   "choices": [
    "F7 and F8 in phase",
    "Occipital positive",
    "No change",
    "F7 positive, F8 negative"
   ],
   "a": 3,
   "ex": "Out of phase at F7/F8. A preceding lateral-rectus spike can mimic a temporal spike.",
   "tags": [
    "artifacts"
   ]
  },
  {
   "id": "eeg:muscle-vs-spike",
   "type": "flash",
   "q": "Muscle potential vs epileptiform spike: durations?",
   "a": "Muscle <20 ms; spike 20–70 ms; sharp wave 70–200 ms.",
   "ex": "Muscle is fastest and lacks an after-going slow wave.",
   "tags": [
    "artifacts",
    "epileptiform"
   ]
  },
  {
   "id": "eeg:electrode-pop",
   "type": "flash",
   "q": "Signature of an electrode pop?",
   "a": "Abrupt artifact confined to one electrode: mirror images in its two bipolar channels, no field elsewhere.",
   "ex": "Field maps separate artifact from brain: brain has a field.",
   "tags": [
    "artifacts"
   ]
  },
  {
   "id": "eeg:ecg-artifact",
   "type": "flash",
   "q": "How to recognise ECG artifact in EEG?",
   "a": "Regular sharp deflections at the pulse rate, worst in ear-referential montages; compare the ECG channel.",
   "ex": "Pulse artifact: rhythmic slow waves at one electrode lying over an artery.",
   "tags": [
    "artifacts"
   ]
  },
  {
   "id": "eeg:shiver",
   "type": "mcq",
   "q": "Shivering artifact frequency?",
   "choices": [
    "10–14 Hz",
    "4–6 Hz",
    "1 Hz",
    "60 Hz"
   ],
   "a": 0,
   "ex": "Parkinsonian tremor 4–6 Hz; ventilator ~12/min; tooth grinding and patting are rhythmic too.",
   "tags": [
    "artifacts"
   ]
  },
  {
   "id": "eeg:glossokinetic",
   "type": "flash",
   "q": "Glossokinetic artifact?",
   "a": "Tongue movement (tip negative) produces slow frontotemporal waves while talking, sucking or chewing.",
   "ex": "Test: ask the patient to say 'la la la'.",
   "tags": [
    "artifacts"
   ]
  },
  {
   "id": "eeg:ica-blink",
   "type": "flash",
   "q": "What identifies a blink component in ICA?",
   "a": "Anterior topography and a flat time course with large brief spikes. Remove only components that are clearly artifact.",
   "ex": "Cohen ch. 8: in the best case you remove a single blink component.",
   "tags": [
    "preproc",
    "artifacts"
   ]
  },
  {
   "id": "eeg:emg-band",
   "type": "mcq",
   "q": "EMG bursts in EEG channels occupy mainly...",
   "choices": [
    "1–4 Hz",
    "8–12 Hz",
    "20–40 Hz and above",
    "Below 1 Hz"
   ],
   "a": 2,
   "ex": "Worst near face, neck and ears; ruins analyses above 15 Hz. Stable EMG cancels in baseline normalisation.",
   "tags": [
    "preproc",
    "artifacts"
   ]
  },
  {
   "id": "eeg:hp-continuous",
   "type": "flash",
   "q": "Why high-pass only continuous data, never epochs?",
   "a": "A 0.5 Hz filter's edge artifact can last ~6 s, longer than an epoch.",
   "ex": "Cohen ch. 7: 0.1–0.5 Hz high-pass on continuous data to remove drift.",
   "tags": [
    "preproc"
   ]
  },
  {
   "id": "eeg:edge-buffer",
   "type": "flash",
   "q": "Rule of thumb for epoch buffer zones in time-frequency analysis?",
   "a": "Three cycles of the lowest frequency on each side (1500 ms for 2 Hz), discarded after decomposition.",
   "ex": "If epochs are already cut short, reflect the data at both ends instead.",
   "tags": [
    "preproc",
    "wavelets"
   ]
  },
  {
   "id": "eeg:tf-baseline",
   "type": "mcq",
   "q": "A time-frequency baseline window should end...",
   "choices": [
    "At t=0, like ERPs",
    "After the stimulus",
    "It does not matter",
    "Before t=0, e.g. −500 to −200 ms"
   ],
   "a": 3,
   "ex": "Temporal smoothing leaks post-stimulus power backwards, worst at low frequencies.",
   "tags": [
    "preproc",
    "wavelets"
   ]
  },
  {
   "id": "eeg:trial-count",
   "type": "flash",
   "q": "Which analyses are most biased by low trial count?",
   "a": "Phase-based (positive bias), then power (values ≥0); ERPs are unbiased but noisier.",
   "ex": "Cohen: ~50 trials per condition is a reasonable floor; worry below 30.",
   "tags": [
    "preproc",
    "analysis"
   ]
  },
  {
   "id": "eeg:interp",
   "type": "flash",
   "q": "Cost of interpolating a bad electrode?",
   "a": "It is a weighted sum of the others: rank drops and matrix inverses need a pseudoinverse. Fix electrodes while recording.",
   "ex": "Check with a 30 Hz low-pass whether real signal survives before interpolating.",
   "tags": [
    "preproc"
   ]
  },
  {
   "id": "eeg:reference-cz",
   "type": "mcq",
   "q": "Poor reference choice for an error-monitoring (FCz) study?",
   "choices": [
    "Linked earlobes",
    "Averaged mastoids",
    "Average reference",
    "Cz"
   ],
   "a": 3,
   "ex": "Whatever the reference records appears in every channel; re-referencing is linear and can be done offline.",
   "tags": [
    "preproc",
    "montage"
   ]
  },
  {
   "id": "eeg:n-electrodes",
   "type": "flash",
   "q": "How many electrodes for topography and connectivity?",
   "a": "At least 64; >100 helps source reconstruction. Three suffice for a P3 amplitude.",
   "ex": "Templates are accurate to 1–2 cm; measure positions for Laplacian or beamforming.",
   "tags": [
    "preproc"
   ]
  },
  {
   "id": "eeg:markers",
   "type": "flash",
   "q": "How to encode more than 255 event codes with an 8-bit trigger port?",
   "a": "Send two markers 10 ms apart: 255 × 255 = 65 025 codes. Keep each pulse ~5 ms.",
   "ex": "Verify by sending codes 1–256 and reconstructing them from the file.",
   "tags": [
    "preproc"
   ]
  },
  {
   "id": "eeg:partial-error",
   "type": "flash",
   "q": "What is a partial error and why record response EMG?",
   "a": "A twitch of the wrong hand before the correct press; those trials show error-like FCz theta and pollute 'correct'.",
   "ex": "Detect: rectified z-scored EMG derivative >2 SD before the press.",
   "tags": [
    "preproc",
    "analysis"
   ]
  },
  {
   "id": "eeg:laplacian",
   "type": "flash",
   "q": "Why apply a surface Laplacian before connectivity analysis?",
   "a": "It is reference-free and suppresses volume conduction, so spurious zero-lag coupling drops.",
   "ex": "Apply to single-trial time-domain data before decomposition.",
   "tags": [
    "preproc",
    "analysis"
   ]
  },
  {
   "id": "eeg:clean-first",
   "type": "flash",
   "q": "Cohen's first rule of preprocessing?",
   "a": "No analysis rescues bad data: train subjects, watch the live trace every 30 s, pause and fix.",
   "ex": "Show subjects their own blink and jaw artifacts before the task.",
   "tags": [
    "preproc"
   ]
  },
  {
   "id": "eeg:pdr",
   "type": "flash",
   "q": "Posterior dominant rhythm in a normal adult?",
   "a": "8 to <13 Hz occipital alpha, attenuates with eye opening; must be >8.5 Hz; ≤2:1 amplitude asymmetry.",
   "ex": "~5 % of normals have no PDR. 'Alpha squeak': brief speed-up on eye closure.",
   "tags": [
    "normal"
   ]
  },
  {
   "id": "eeg:ap-gradient",
   "type": "flash",
   "q": "Normal anterior-posterior gradient?",
   "a": "Faster, lower-amplitude activity anteriorly; slower, higher-amplitude alpha posteriorly.",
   "ex": "Loss of PDR, gradient and sleep structures = poorly organised record.",
   "tags": [
    "normal"
   ]
  },
  {
   "id": "eeg:beta",
   "type": "mcq",
   "q": "Normal beta is maximal...",
   "choices": [
    "Occipitally",
    "Temporally",
    "Frontocentrally, 13–30 Hz",
    "At the vertex in sleep"
   ],
   "a": 2,
   "ex": "Benzodiazepines and barbiturates add 14–16 Hz beta; a breach rhythm accentuates beta over a skull defect.",
   "tags": [
    "normal"
   ]
  },
  {
   "id": "eeg:theta-awake",
   "type": "flash",
   "q": "Is awake theta normal in adults?",
   "a": "Some 4–8 Hz theta in ~35 % of young adults; abundant theta is mild diffuse slowing. Awake delta is abnormal.",
   "ex": "Judge slowing only during the most alert segment.",
   "tags": [
    "normal",
    "abnormal"
   ]
  },
  {
   "id": "eeg:mu",
   "type": "flash",
   "q": "Mu rhythm?",
   "a": "7–11 Hz arciform rhythm over C3/C4, blocked by contralateral movement or its imagination, not by eye opening.",
   "ex": "The key event-related desynchronisation feature for motor BCIs.",
   "tags": [
    "normal",
    "variants"
   ]
  },
  {
   "id": "eeg:lambda",
   "type": "mcq",
   "q": "Lambda waves are...",
   "choices": [
    "Vertex waves in sleep",
    "Temporal theta of the elderly",
    "Positive occipital waves while scanning",
    "Frontal spikes"
   ],
   "a": 2,
   "ex": "Disappear with eyes closed or lights off.",
   "tags": [
    "normal",
    "variants"
   ]
  },
  {
   "id": "eeg:posts",
   "type": "flash",
   "q": "POSTS?",
   "a": "Positive occipital sharp transients of sleep: 4–5 Hz sawtooth bursts in light sleep, normal.",
   "ex": "Positive polarity separates them from occipital spikes.",
   "tags": [
    "sleep",
    "variants"
   ]
  },
  {
   "id": "eeg:sleep-n1",
   "type": "flash",
   "q": "Stage I (N1) sleep markers?",
   "a": "PDR drops out, slow roving eye movements, vertex waves (<200 ms) and POSTs.",
   "ex": "Vertex waves are sharp; midline spikes in wakefulness are abnormal.",
   "tags": [
    "sleep"
   ]
  },
  {
   "id": "eeg:sleep-n2",
   "type": "mcq",
   "q": "Stage II (N2) markers?",
   "choices": [
    "Delta in >20 % of the epoch",
    "Low-voltage theta with REMs",
    "Alpha with mu",
    "12–14 Hz spindles, K-complexes >500 ms"
   ],
   "a": 3,
   "ex": "Spindles: asynchronous at 2 months, synchronous by 2 years.",
   "tags": [
    "sleep"
   ]
  },
  {
   "id": "eeg:rem",
   "type": "flash",
   "q": "REM sleep EEG?",
   "a": "Low-voltage mixed frequencies with theta, rapid eye movements, chin atonia; first REM after ~90 min.",
   "ex": "REM behaviour disorder: dream enactment without atonia.",
   "tags": [
    "sleep"
   ]
  },
  {
   "id": "eeg:hv",
   "type": "flash",
   "q": "Hyperventilation: normal response and limits?",
   "a": "Bilateral rhythmic slowing (more in children), resolving within ~1 min of stopping. Run 3 min.",
   "ex": "Abnormal: 3 Hz spike-wave, focal slowing, or slowing persisting >1 min.",
   "tags": [
    "activation"
   ]
  },
  {
   "id": "eeg:photic",
   "type": "mcq",
   "q": "A photoparoxysmal response is most likely at...",
   "choices": [
    "1–3 Hz",
    "14–16 Hz flashes",
    "30–35 Hz",
    "Only with eyes open"
   ],
   "a": 1,
   "ex": "Photic driving is normal; photomyogenic response is muscle. Stimulate 1–35 Hz.",
   "tags": [
    "activation"
   ]
  },
  {
   "id": "eeg:sleep-dep",
   "type": "flash",
   "q": "Yield of sleep deprivation for epileptiform activity?",
   "a": "Increases detection by ~30 %.",
   "ex": "Drowsiness itself is the most activating state for many discharges.",
   "tags": [
    "activation"
   ]
  },
  {
   "id": "eeg:wicket",
   "type": "flash",
   "q": "Wicket spikes?",
   "a": "7–11 Hz arciform temporal bursts in drowsy adults >30 y, no slow wave, no background disruption: benign.",
   "ex": "The most common spike mimic.",
   "tags": [
    "variants"
   ]
  },
  {
   "id": "eeg:rmtd",
   "type": "flash",
   "q": "RMTD?",
   "a": "Rhythmic mid-temporal theta of drowsiness: 5–6 Hz notched runs in young adults, benign.",
   "ex": "Formerly 'psychomotor variant'.",
   "tags": [
    "variants"
   ]
  },
  {
   "id": "eeg:sreda",
   "type": "flash",
   "q": "SREDA?",
   "a": "Subclinical rhythmic electrographic discharge of adults: 40–80 s of 5–7 Hz temporo-parietal rhythm in >50 y.",
   "ex": "Looks ictal but the patient stays responsive: benign.",
   "tags": [
    "variants"
   ]
  },
  {
   "id": "eeg:bets",
   "type": "flash",
   "q": "Small sharp spikes (BETS)?",
   "a": "Low-amplitude brief temporal spikes in drowsiness, no slow wave, vanish in deeper sleep: benign.",
   "ex": "'Benign epileptiform transients of sleep'.",
   "tags": [
    "variants"
   ]
  },
  {
   "id": "eeg:14-6",
   "type": "mcq",
   "q": "14- and 6-Hz positive spikes are...",
   "choices": [
    "Benign posterior temporal bursts",
    "Absence seizures",
    "Lennox–Gastaut",
    "Infantile spasms"
   ],
   "a": 0,
   "ex": "Adolescents in sleep, positive polarity, arciform: do not report as epileptiform.",
   "tags": [
    "variants"
   ]
  },
  {
   "id": "eeg:phantom",
   "type": "flash",
   "q": "Phantom (6 Hz) spike-and-wave?",
   "a": "Low-amplitude 5–6 Hz spike-wave in drowsiness; benign when occipital, low amplitude and in drowsiness.",
   "ex": "Benign 'FOLD' vs suspicious 'WHAM' (waking, high amplitude, anterior, male).",
   "tags": [
    "variants"
   ]
  },
  {
   "id": "eeg:alpha-variants",
   "type": "flash",
   "q": "Slow and fast alpha variants?",
   "a": "Harmonics at half (4–5 Hz notched) or double (16–20 Hz) the PDR, same distribution and reactivity: normal.",
   "ex": "Do not call a slow alpha variant 'slowing'.",
   "tags": [
    "variants"
   ]
  },
  {
   "id": "eeg:elderly",
   "type": "flash",
   "q": "Normal EEG in the elderly?",
   "a": "PDR stays ≥8.5 Hz; temporal slow transients and mild FIRDA in drowsiness can be seen.",
   "ex": "Marked slowing suggests dementia, drugs or a metabolic cause.",
   "tags": [
    "normal"
   ]
  },
  {
   "id": "eeg:neonatal-td",
   "type": "mcq",
   "q": "Tracé discontinu in a preterm: interburst interval?",
   "choices": [
    "Under 1 s",
    "4–6 s only",
    "Continuous",
    "6–35 s, longer the younger"
   ],
   "a": 3,
   "ex": "Tracé alternant of term quiet sleep alternates over 4–6 s.",
   "tags": [
    "pediatric"
   ]
  },
  {
   "id": "eeg:delta-brush",
   "type": "flash",
   "q": "Delta brush?",
   "a": "Delta wave with superimposed 8–20 Hz fast activity, characteristic of the premature EEG (28–34 wk).",
   "ex": "Persisting past term is abnormal. Encoches frontales: frontal sharp transients.",
   "tags": [
    "pediatric"
   ]
  },
  {
   "id": "eeg:synchrony-nadir",
   "type": "flash",
   "q": "Interhemispheric synchrony nadir in the preterm?",
   "a": "31–32 weeks conceptual age; near-complete synchrony by term.",
   "ex": "Always assess by conceptual age, not postnatal age.",
   "tags": [
    "pediatric"
   ]
  },
  {
   "id": "eeg:pdr-age",
   "type": "flash",
   "q": "PDR by age?",
   "a": "3–4 Hz at 3–4 mo, 5 Hz at 6 mo, 6 Hz at 1 y, 8 Hz at 3 y, adult ≥8.5 Hz by adolescence.",
   "ex": "Posterior slow waves of youth are normal in children and teens.",
   "tags": [
    "pediatric"
   ]
  },
  {
   "id": "eeg:hypnagogic",
   "type": "flash",
   "q": "Hypnagogic hypersynchrony?",
   "a": "High-voltage 3–5 Hz paroxysmal bursts at sleep onset in children under ~12: normal.",
   "ex": "Easily mistaken for spike-wave.",
   "tags": [
    "pediatric",
    "sleep"
   ]
  },
  {
   "id": "eeg:slowing-grades",
   "type": "flash",
   "q": "Grades of diffuse slowing in adults?",
   "a": "Mild: 7–8 Hz background; moderate: 4–7 Hz; severe: <4 Hz. Judge at maximal alertness.",
   "ex": "Alpha coma: no slowing yet severe dysfunction. Psychotropics can slow the record.",
   "tags": [
    "abnormal"
   ]
  },
  {
   "id": "eeg:focal-delta",
   "type": "mcq",
   "q": "Polymorphic focal delta points to...",
   "choices": [
    "Grey-matter irritability",
    "Drug effect",
    "Drowsiness",
    "White-matter structural lesion"
   ],
   "a": 3,
   "ex": "Rhythmic delta suggests grey matter. Delta foci are often falsely localised to the temporal chain.",
   "tags": [
    "abnormal"
   ]
  },
  {
   "id": "eeg:focal-atten",
   "type": "flash",
   "q": "Focal attenuation of fast activity means?",
   "a": "Cortical dysfunction (acute stroke) or an insulating fluid layer (subdural haematoma).",
   "ex": "Beta asymmetry is the earliest, most sensitive sign of a cortical lesion.",
   "tags": [
    "abnormal"
   ]
  },
  {
   "id": "eeg:breach",
   "type": "flash",
   "q": "Breach rhythm?",
   "a": "Sharply contoured, higher-amplitude beta over a skull defect after surgery, often with focal slowing.",
   "ex": "Ask the technologist to note craniotomy scars.",
   "tags": [
    "abnormal",
    "artifacts"
   ]
  },
  {
   "id": "eeg:spike-def",
   "type": "flash",
   "q": "Definition of an epileptiform spike?",
   "a": "Paroxysmal, very sharp, rise steeper than fall, 20–70 ms, usually surface negative, then a ~200 ms slow wave.",
   "ex": "Sharp wave: 70–200 ms. Polyspike: several spikes before the wave.",
   "tags": [
    "epileptiform"
   ]
  },
  {
   "id": "eeg:3hz-sw",
   "type": "mcq",
   "q": "Generalised 3 Hz spike-and-wave with brief staring...",
   "choices": [
    "Lennox–Gastaut",
    "JME",
    "Typical absence (CAE)",
    "BECTS"
   ],
   "a": 2,
   "ex": "200–300 µV, wave larger than spike, both negative; hyperventilation provokes it; ethosuximide works.",
   "tags": [
    "epileptiform",
    "syndromes"
   ]
  },
  {
   "id": "eeg:slow-sw",
   "type": "mcq",
   "q": "Slow spike-and-wave at 1.5–2.5 Hz?",
   "choices": [
    "Childhood absence",
    "Lennox–Gastaut syndrome",
    "JME",
    "Panayiotopoulos"
   ],
   "a": 1,
   "ex": "Triad: cognitive impairment, multiple seizure types (tonic commonest), slow SW. Also MISF and GPFA.",
   "tags": [
    "epileptiform",
    "syndromes"
   ]
  },
  {
   "id": "eeg:jme",
   "type": "mcq",
   "q": "Interictal EEG of juvenile myoclonic epilepsy?",
   "choices": [
    "3 Hz spike-wave",
    "4–6 Hz irregular polyspike-wave",
    "Centrotemporal spikes",
    "Hypsarrhythmia"
   ],
   "a": 1,
   "ex": "30–50 % photosensitive; morning jerks; treatment is lifelong.",
   "tags": [
    "epileptiform",
    "syndromes"
   ]
  },
  {
   "id": "eeg:bects",
   "type": "flash",
   "q": "BECTS discharges?",
   "a": "Centrotemporal (C3/T7, C4/T8) spikes with a horizontal dipole (frontal positive), strongly activated by sleep.",
   "ex": "In ~1 % of normal children; only ~10 % of those get epilepsy. Remits by 16.",
   "tags": [
    "epileptiform",
    "syndromes"
   ]
  },
  {
   "id": "eeg:hypsarrhythmia",
   "type": "flash",
   "q": "Hypsarrhythmia?",
   "a": "Chaotic high-voltage (>350 µV) slow background with multifocal spikes: West syndrome (spasms at 3–12 mo).",
   "ex": "Spasm: diffuse slow wave then electrodecrement. ACTH or vigabatrin.",
   "tags": [
    "epileptiform",
    "syndromes"
   ]
  },
  {
   "id": "eeg:temporal-spike",
   "type": "flash",
   "q": "Typical interictal finding in mesial temporal lobe epilepsy?",
   "a": "Anterior temporal sharp waves phase-reversing at F7/F8 in ~90 % of patients, sometimes with temporal slowing.",
   "ex": "F9/F10 leads raise yield. Ictal: rhythmic temporal theta or alpha within 30 s of onset.",
   "tags": [
    "epileptiform",
    "syndromes"
   ]
  },
  {
   "id": "eeg:occipital-spike",
   "type": "flash",
   "q": "Why do occipital spikes not phase-reverse on the double banana?",
   "a": "O1/O2 end the chain, so the spike only deflects down. Use the circumferential or a referential montage.",
   "ex": "Same for frontopolar spikes at Fp1/Fp2.",
   "tags": [
    "epileptiform",
    "montage"
   ]
  },
  {
   "id": "eeg:false-lat",
   "type": "flash",
   "q": "False lateralisation?",
   "a": "A mesial frontal focus can project its negativity onto contralateral frontocentral electrodes by geometry.",
   "ex": "Midline spikes in wakefulness are abnormal; in sleep think vertex waves first.",
   "tags": [
    "epileptiform",
    "montage"
   ]
  },
  {
   "id": "eeg:birds",
   "type": "flash",
   "q": "BIRDs?",
   "a": "Brief potentially ictal rhythmic discharges: <10 s (usually 0.5–4 s) of >4 Hz rhythm without evolution.",
   "ex": "High seizure risk. GPFA: diffuse >12 Hz bursts of 2–10 s, typical of LGS sleep.",
   "tags": [
    "epileptiform",
    "icu"
   ]
  },
  {
   "id": "eeg:grda",
   "type": "mcq",
   "q": "Frontally predominant GRDA (FIRDA) most often indicates...",
   "choices": [
    "A frontal tumour",
    "Toxic-metabolic or deep midline process",
    "Normal drowsiness",
    "Absence epilepsy"
   ],
   "a": 1,
   "ex": "OIRDA in children with absence. Vs blink: GRDA extends posteriorly and eye leads are in phase.",
   "tags": [
    "icu",
    "abnormal"
   ]
  },
  {
   "id": "eeg:lrda",
   "type": "flash",
   "q": "LRDA significance?",
   "a": "Lateralised rhythmic delta: grey-matter lesion with focal hyperexcitability; seizure risk similar to LPDs.",
   "ex": "'Bilateral asymmetric' when both sides show it with a clear predominance.",
   "tags": [
    "icu"
   ]
  },
  {
   "id": "eeg:lpds",
   "type": "flash",
   "q": "LPDs (PLEDs): commonest cause and ictal criteria?",
   "a": "Acute cortical lesion, most often ischaemic stroke (also HSV encephalitis). Ictal if >3 Hz or evolving.",
   "ex": "Evolution = at least 2 sequential changes in frequency, morphology or location.",
   "tags": [
    "icu",
    "seizure"
   ]
  },
  {
   "id": "eeg:gpds",
   "type": "mcq",
   "q": "GPDs with triphasic morphology and anterior-posterior lag suggest...",
   "choices": [
    "Hepatic or metabolic encephalopathy",
    "NCSE",
    "Alpha coma",
    "Breach rhythm"
   ],
   "a": 0,
   "ex": "CJD: 1 Hz periodic sharp waves on a suppressed background. NCSE usually lacks the A-P lag.",
   "tags": [
    "icu"
   ]
  },
  {
   "id": "eeg:acns-plus",
   "type": "flash",
   "q": "ACNS 'plus' modifiers: which raise seizure risk?",
   "a": "+F (fast) or +R (rhythmic) on PDs; +S (sharp) or +F on RDA. Plus patterns are more ictal than plain PD or RDA.",
   "ex": "SIRPIDs: stimulus-induced rhythmic, periodic or ictal discharges.",
   "tags": [
    "icu"
   ]
  },
  {
   "id": "eeg:acns-prevalence",
   "type": "flash",
   "q": "ACNS prevalence terms?",
   "a": "Continuous ≥90 %, abundant 50–89 %, frequent 10–49 %, occasional 1–9 %, rare <1 % of the record.",
   "ex": "Duration: very long ≥1 h, long 5–59 min, intermediate 1–4.9 min, brief 10–59 s, very brief <10 s.",
   "tags": [
    "icu"
   ]
  },
  {
   "id": "eeg:sz-criteria",
   "type": "flash",
   "q": "Unequivocal electrographic seizure criteria?",
   "a": "Spike-wave at ≥3 Hz, or any clearly evolving pattern reaching >4 Hz, generalised or focal.",
   "ex": "Below that: ictal–interictal continuum; give a fast AED and watch clinical and EEG response.",
   "tags": [
    "seizure",
    "icu"
   ]
  },
  {
   "id": "eeg:sz-evolution",
   "type": "mcq",
   "q": "Electrographic seizures generally evolve from...",
   "choices": [
    "Slower to faster",
    "Constant frequency",
    "Faster to slower, growing in amplitude",
    "Randomly"
   ],
   "a": 2,
   "ex": "They always disrupt the background; postictal slowing follows.",
   "tags": [
    "seizure"
   ]
  },
  {
   "id": "eeg:gtc-eeg",
   "type": "flash",
   "q": "EEG of a generalised tonic-clonic seizure?",
   "a": "Tonic: >10 Hz fast activity rising in amplitude and slowing (muscle obscures); clonic: rhythmic bursts; then slowing.",
   "ex": "Typical duration 1–2 min.",
   "tags": [
    "seizure"
   ]
  },
  {
   "id": "eeg:absence-types",
   "type": "flash",
   "q": "Typical vs atypical absence on EEG?",
   "a": "Typical: regular symmetric 3 Hz SW, abrupt on and off. Atypical: irregular <2.5 Hz SW, insidious, often atonic.",
   "ex": "Myoclonic absence: 3 Hz SW with 2.5–4 Hz jerks.",
   "tags": [
    "seizure"
   ]
  },
  {
   "id": "eeg:se-def",
   "type": "mcq",
   "q": "Practical definition of status epilepticus?",
   "choices": [
    "More than 30 min only",
    "Any seizure in ICU",
    "Two seizures in a day",
    "Seizure >5 min or repeats, no recovery"
   ],
   "a": 3,
   "ex": "~75 % of ICU seizures are non-convulsive; only EEG finds them.",
   "tags": [
    "seizure",
    "icu"
   ]
  },
  {
   "id": "eeg:alpha-coma",
   "type": "flash",
   "q": "Alpha coma?",
   "a": "Diffuse or frontal alpha, non-reactive, no sleep-wake cycling, usually post-anoxic: poor prognosis.",
   "ex": "If posterior and reactive, suspect a locked-in state.",
   "tags": [
    "icu"
   ]
  },
  {
   "id": "eeg:coma-types",
   "type": "flash",
   "q": "Spindle and beta coma: prognosis?",
   "a": "Spindle coma (mesencephalic lesion) and beta coma (benzodiazepine or barbiturate) both do better than alpha coma.",
   "ex": "Theta or delta coma: prognosis depends on the cause.",
   "tags": [
    "icu"
   ]
  },
  {
   "id": "eeg:burst-supp",
   "type": "flash",
   "q": "Burst-suppression definition?",
   "a": ">50 % of the record suppressed, alternating with 0.5–30 s bursts. Anaesthesia, post-anoxia, neonatal encephalopathy.",
   "ex": "Deepening anaesthesia: sleep patterns, delta, burst-suppression, isoelectric.",
   "tags": [
    "icu"
   ]
  },
  {
   "id": "eeg:eci",
   "type": "flash",
   "q": "Recording requirements for electrocerebral inactivity?",
   "a": "No activity >2 µV at 2 µV/mm for ≥30 min, LFF 0.5–1.5 Hz, HFF 70 Hz, impedance 1–10 kΩ, double-distance montage.",
   "ex": "Exclude hypothermia, sedation and metabolic causes first.",
   "tags": [
    "icu",
    "technical"
   ]
  },
  {
   "id": "eeg:reactivity",
   "type": "flash",
   "q": "What counts as EEG reactivity?",
   "a": "A change in frequency or amplitude to stimulation (noxious, passive eye opening); blink or muscle artifact does not.",
   "ex": "The technologist must mark stimulation times on the record.",
   "tags": [
    "icu"
   ]
  },
  {
   "id": "eeg:pnea",
   "type": "flash",
   "q": "EEG clues to psychogenic non-epileptic attacks?",
   "a": "Normal PDR visible in pauses, no postictal slowing, eyes closed, asynchronous movements.",
   "ex": "10–19 % of patients have both PNEA and epilepsy; capture events on video-EEG.",
   "tags": [
    "seizure"
   ]
  },
  {
   "id": "eeg:bancaud",
   "type": "flash",
   "q": "Bancaud's phenomenon?",
   "a": "Unilateral failure of PDR attenuation on eye opening: early sign of an ipsilateral parietal or temporal lesion.",
   "ex": "Occipital stroke: ipsilateral PDR loss and asymmetric photic driving.",
   "tags": [
    "abnormal"
   ]
  },
  {
   "id": "eeg:qeeg",
   "type": "flash",
   "q": "What do ICU quantitative EEG trends show?",
   "a": "Hours compressed: rhythmicity spectrogram, FFT power, asymmetry index, aEEG; seizures recur as a 'fingerprint'.",
   "ex": "Staff titrate drugs until the confirmed fingerprint remits.",
   "tags": [
    "icu",
    "analysis"
   ]
  },
  {
   "id": "eeg:evoked-induced",
   "type": "flash",
   "q": "Phase-locked vs non-phase-locked activity?",
   "a": "Phase-locked (evoked) survives ERP averaging; non-phase-locked (induced) is time-locked only: in TF power, not the ERP.",
   "ex": "Induced activity is stronger evidence of true oscillations.",
   "tags": [
    "analysis"
   ]
  },
  {
   "id": "eeg:erp-models",
   "type": "flash",
   "q": "Three models of ERP generation?",
   "a": "Additive (signal on top of oscillations), phase reset of ongoing rhythms, amplitude asymmetry or baseline shift.",
   "ex": "Hard to disentangle at the scalp; different components may differ.",
   "tags": [
    "analysis"
   ]
  },
  {
   "id": "eeg:osc-mechanism",
   "type": "flash",
   "q": "Main mechanism of cortical oscillations?",
   "a": "Alternation of pyramidal excitation and GABAergic interneuron inhibition (E–I loop); pure E or I nets can oscillate too.",
   "ex": "Cohen ch. 5 and Buzsáki, Rhythms of the Brain.",
   "tags": [
    "rhythms",
    "origin"
   ]
  },
  {
   "id": "eeg:dft",
   "type": "flash",
   "q": "What does the discrete Fourier transform compute?",
   "a": "Dot products of the signal with complex sines exp(−i2πft); N points give N/2+1 unique frequencies, 0 to Nyquist.",
   "ex": "DC term = mean. Negative frequencies mirror the positive ones for real data; keep them for the inverse.",
   "tags": [
    "analysis"
   ]
  },
  {
   "id": "eeg:fft-cost",
   "type": "mcq",
   "q": "Computational cost of DFT vs FFT?",
   "choices": [
    "Both N²",
    "N vs N²",
    "N log N vs N",
    "N² vs N log N"
   ],
   "a": 3,
   "ex": "Powers of two are fastest; gains reach ~1000× at millions of samples.",
   "tags": [
    "analysis"
   ]
  },
  {
   "id": "eeg:zero-pad",
   "type": "flash",
   "q": "Zero padding increases frequency...",
   "a": "Resolution (more bins) but not precision: no new information.",
   "ex": "Handy to make FFT convolution lengths convenient.",
   "tags": [
    "analysis"
   ]
  },
  {
   "id": "eeg:stationarity",
   "type": "flash",
   "q": "Why not just FFT the whole epoch?",
   "a": "Fourier assumes stationarity and discards time; EEG changes over hundreds of ms. Use wavelets, filter-Hilbert or STFT.",
   "ex": "Non-stationarity smears spectral peaks into neighbouring bins.",
   "tags": [
    "analysis"
   ]
  },
  {
   "id": "eeg:conv-theorem",
   "type": "flash",
   "q": "Convolution theorem?",
   "a": "Convolution in time = point-wise multiplication in frequency, so filtering = signal spectrum × kernel spectrum.",
   "ex": "FFT convolution needs length Ns + Nk − 1, then trim; check against conv(x, k, 'same').",
   "tags": [
    "analysis"
   ]
  },
  {
   "id": "eeg:morlet",
   "type": "flash",
   "q": "Morlet wavelet?",
   "a": "A complex sine exp(i2πft) tapered by a Gaussian with s = n/(2πf); n cycles sets the time–frequency trade-off.",
   "ex": "The wavelet must taper to zero; centre it at t = 0, e.g. over −2 to +2 s.",
   "tags": [
    "wavelets"
   ]
  },
  {
   "id": "eeg:cycles",
   "type": "mcq",
   "q": "More wavelet cycles give...",
   "choices": [
    "Better time precision",
    "Both better",
    "No change",
    "Better frequency, worse time precision"
   ],
   "a": 3,
   "ex": "3–4 cycles for transients, 7–10 for sustained activity, or ramp 3 to 10 with frequency.",
   "tags": [
    "wavelets"
   ]
  },
  {
   "id": "eeg:power-phase",
   "type": "flash",
   "q": "From a complex convolution result, power and phase are...",
   "a": "Power = |z|² (or z × conj(z)); phase = angle(z); the real part is the band-passed signal.",
   "ex": "Multiplying by the conjugate is about twice as fast on large matrices.",
   "tags": [
    "wavelets"
   ]
  },
  {
   "id": "eeg:freq-spacing",
   "type": "flash",
   "q": "Recommended frequency set for time-frequency analysis?",
   "a": "20–30 log-spaced frequencies over ~4–60 Hz; more bins only smooth the plot.",
   "ex": "Wavelets at 9 and 10 Hz largely overlap; log spacing keeps bandwidths comparable.",
   "tags": [
    "wavelets"
   ]
  },
  {
   "id": "eeg:real-wavelet-flaw",
   "type": "flash",
   "q": "Why are real-valued Morlet wavelets not enough?",
   "a": "Their dot product depends on phase lag (zero at 90°, negative at 180°), and they give no power or phase.",
   "ex": "Complex wavelets solve it: magnitude is phase-independent, angle gives phase.",
   "tags": [
    "wavelets"
   ]
  },
  {
   "id": "eeg:1f",
   "type": "flash",
   "q": "Why does EEG power fall as 1/f^α?",
   "a": "Slow rhythms recruit many neurons over large areas, fast ones stay local, and oscillators at many scales interact.",
   "ex": "Buzsáki: 'pink' noise, between white (1/f^0) and brown (1/f²).",
   "tags": [
    "rhythms"
   ]
  },
  {
   "id": "eeg:band-ratio",
   "type": "flash",
   "q": "Buzsáki's rule for adjacent oscillation bands?",
   "a": "Mean frequencies form a geometric progression with ratio ≈ e (2.7), linear on a natural-log axis.",
   "ex": "Non-integer ratios prevent stable locking: perpetual metastability.",
   "tags": [
    "rhythms"
   ]
  },
  {
   "id": "eeg:bands",
   "type": "flash",
   "q": "Classic clinical frequency bands?",
   "a": "Delta <4, theta 4–8, alpha 8–13, beta 13–30, gamma >30 Hz.",
   "ex": "Arbitrary 1974 borders; rodent hippocampal 'theta' runs 5–10 Hz.",
   "tags": [
    "rhythms"
   ]
  },
  {
   "id": "eeg:pink-db",
   "type": "mcq",
   "q": "Pink noise power falls per octave by...",
   "choices": [
    "3 dB",
    "6 dB",
    "0 dB",
    "10 dB"
   ],
   "a": 0,
   "ex": "Brown noise: 6 dB per octave (1/f²). White: flat.",
   "tags": [
    "rhythms"
   ]
  },
  {
   "id": "eeg:coh-vs-plv",
   "type": "flash",
   "q": "Coherence vs phase-locking value?",
   "a": "Coherence mixes amplitude and phase covariance; PLV measures phase consistency alone, independent of amplitude.",
   "ex": "Cross-frequency coupling: a fast rhythm's power modulated by a slow rhythm's phase.",
   "tags": [
    "analysis",
    "rhythms"
   ]
  },
  {
   "id": "eeg:whitening",
   "type": "flash",
   "q": "'Whitening' a spectrum?",
   "a": "Removing the 1/f slope so discrete band peaks (delta, theta, gamma, ripple) become visible.",
   "ex": "Long epochs average rhythms away; short behaviour-locked epochs reveal them.",
   "tags": [
    "rhythms",
    "analysis"
   ]
  },
  {
   "id": "eeg:ecog-amp",
   "type": "mcq",
   "q": "ECoG amplitude relative to scalp EEG?",
   "choices": [
    "Equal",
    "About 100× smaller",
    "About 10× larger",
    "Half"
   ],
   "a": 2,
   "ex": "Subdural grids: 20–64 contacts, no muscle or eye artifact; no PDR, spindles or vertex waves intracranially.",
   "tags": [
    "origin"
   ]
  },
  {
   "id": "eeg:tacs",
   "type": "flash",
   "q": "Evidence that oscillations are causal: a TACS example?",
   "a": "20 Hz tACS over motor cortex raises MEP size while other frequencies do not; tACS at the alpha peak raises alpha power.",
   "ex": "Optogenetic gamma in mice enhances signal transmission and noise suppression.",
   "tags": [
    "rhythms"
   ]
  },
  {
   "id": "eeg:tf-sampling",
   "type": "flash",
   "q": "Practical sampling advice for time-frequency analysis?",
   "a": "Record 500–2000 Hz and downsample later; keep ≥4 samples per cycle of the highest frequency for clean phase.",
   "ex": "1000 Hz makes 1 ms equal 1 sample.",
   "tags": [
    "technical",
    "analysis"
   ]
  },
  {
   "id": "eeg:size-vs-freq",
   "type": "flash",
   "q": "Relation between oscillation frequency and neuronal pool size?",
   "a": "The slower the rhythm, the larger and more distant the pool it can synchronise; fast rhythms stay local.",
   "ex": "Von Stein: gamma within V1, beta between adjacent areas, theta prefrontal–parietal.",
   "tags": [
    "rhythms"
   ]
  }
 ],
 "version": "1.0.0",
 "updated": "2026-09-14T14:57:54Z"
}