Study the R. EEG T. domains as one integrated skill: reading a recording and defending what you see. For every pattern you encounter in practice, state its field distribution, morphology, state, reactivity, and the parameters in effect before assigning it a name. Train with real epochs displayed in multiple montages, classify each artifact by its source, verify electrode placements by measurement rather than memory, and document activation procedures in observable terms. This habit of evidence-first description ties the placement, instrumentation, pattern, artifact, and patient care content into a single reviewable framework.
Turning 10-20 placement into a verifiable habit
The 10-20 system is proportional measurement, not visual recall. Verify electrode positions by measuring from anatomical landmarks and checking symmetry, so any placement can be defended and corrected on the spot.
Anchor your practice in the landmarks and percentages: the nasion-to-inion distance defines the sagittal row, the preauricular points define the coronal row, and the 10% and 20% steps divide them. Fix the naming logic — odd numbers left, even numbers right, z for midline — and connect each label to its anatomical meaning, such as F7 as left anterolateral temporal or Pz at the parietal midline. When you know what each label means anatomically, montage pages stop being electrode chains and start being maps of brain regions.
Build a verification routine you can repeat: measure a colleague's head or a mannequin, mark each electrode, then re-measure the opposite side and compare. Check symmetry across the midline, confirm that Cz sits at the intersection of both rows, and confirm T3/T4 fall on the coronal row rather than drifting anteriorly. Expected observations for this exercise are consistent step distances on both sides and symmetric distances from Cz to each temporal electrode. Repeating this until it is routine is what makes placement questions and lab-based work feel mechanical rather than stressful.
Reading montages instead of memorizing electrode chains
Each montage answers a different question. Bipolar chains localize through phase reversal at shared electrodes; referential montages display amplitude and field extent directly. Practice switching between them on the same epoch.
In a longitudinal bipolar (double-banana) chain, a localized negative discharge shows a phase reversal — the deflection points toward each other at the involved electrode — while a broad or distant pattern appears as simultaneous deflections in the same direction. Referential montages compare each electrode to a common reference, so the discharge's field appears as amplitude spread across the derivations instead of a reversal. Polarity convention matters here: negativity is displayed upward on most clinical systems, so practice reading deflection direction as a polarity statement, not just a shape.
Practical exercise: take one 30-second epoch containing a temporal sharp transient and display it in longitudinal bipolar, transverse bipolar, and referential montages. Expected observations: the transient keeps the same timing and morphology but changes position and deflection pattern with each display; a true focal discharge remains a coherent field across montages, while a single-electrode problem appears confined to one derivation everywhere. Self-check rubric — for each pattern you can: (1) name the montage in use, (2) state the likely field, (3) assign polarity, (4) explain why the display changed the way it did. Four out of four is the milestone to aim for before moving on; treat it as a learning target, not a pass prediction.
Predicting what sensitivity and filter changes do to a trace
Amplitude and frequency descriptions are only meaningful relative to the parameters in effect. Train yourself to read the sensitivity and filter labels first, then predict each change's effect before looking at the next page.
Sensitivity scales voltage to deflection: at 7 µV/mm a normal posterior rhythm looks one size, at 3 µV/mm the identical activity looks dramatically taller, and at 15 or 20 µV/mm it looks flattened. The low-frequency filter attenuates slow drifts (sweat, respiration-related baseline movement), the high-frequency filter attenuates fast content (muscle), and the 60 Hz notch targets line-frequency interference specifically. None of these filters changes the underlying brain activity — they change what reaches the display.
Worked scenario: a page is displayed at 3 µV/mm and a reviewer describes the background as 'excessively high amplitude' compared with the preceding pages at 7 µV/mm. The mistake is comparing amplitude across pages without checking the sensitivity label. The better decision is to read the parameter box first and restate the observation as 'amplitude appears increased at 3 µV/mm; at the standard sensitivity it is within the same range as adjacent pages.' This matters because amplitude statements in a report are only defensible at a stated sensitivity, and a mislabeled amplitude description can misdirect the entire interpretation downstream.
Separating benign variants from epileptiform discharges
Benign variants are typically state-dependent, often rhythmic or repetitive, and usually lack a consistent aftergoing slow wave. Epileptiform discharges typically stand out from the background with a defined field and after-slowing.
Compare the classic drowsy-state transients rather than memorizing them as isolated pictures. Wicket spikes appear as arciform, often rhythmic sharp activity in temporal regions during drowsiness and light sleep; small sharp spikes (BETS) are brief, low-amplitude, widely distributed in sleep; 14 and 6 Hz positive bursts show positive polarity at posterior temporal electrodes in drowsiness; phantom spike-and-wave is a 6 Hz burst best seen in drowsiness. Each is best distinguished from a true discharge by its state-dependence, its tendency to occur in runs, and the absence of a consistent field with aftergoing slow wave.
Worked scenario: a drowsy tracing shows sharp-appearing temporal activity at T4/T6 that a reviewer labels epileptiform. The mistake is judging sharpness alone. The better decision is to check four things: does it occur in a run of similar waveforms, does the background state match the conditions under which wicket activity is described, is there a clear aftergoing slow wave, and does the referential display show a broad rather than sharply focal field. Why it matters: the difference between 'epileptiform discharge' and 'benign variant' in the report changes how the recording is interpreted clinically, so the technologist's descriptive precision carries real weight.
- Check state first: most benign variants are drowsiness- or sleep-dependent, so a discharge appearing only in one state deserves a state check before a label.
- Check polarity: 14 and 6 Hz positive bursts are defined by positive polarity at posterior temporal electrodes, which a referential display makes easier to assess.
- Check context: wicket spikes sit within a rhythmic theta background, while a true spike typically interrupts an otherwise unremarkable background.
- Avoid overreach: variant recognition supports description, not diagnosis — the report should say what was seen and under what conditions.
| Pattern | Typical state | Morphology clue | First check to run |
|---|---|---|---|
| Wicket spikes | Drowsiness / light sleep | Arciform, in runs, rhythmic | Look for the run and the theta background |
| Small sharp spikes (BETS) | Sleep | Brief, low amplitude, broad field | Confirm state and scattered distribution |
| 14 & 6 Hz positive bursts | Drowsiness | Positive polarity, posterior temporal | Referential display for polarity |
| Phantom spike-and-wave (6 Hz) | Drowsiness | Bursts of low-amplitude spike-and-wave | Check amplitude and burst structure |
| True focal sharp wave | Any state | Stands out, defined field, after-slowing | Field check in second montage |
Splitting artifact from cerebral activity in real time
Classify artifact by source — electrode, physiologic, environmental — and test each candidate with field distribution, timing correlation with physiologic channels, and response to parameters.
Electrode problems typically confine the abnormality to one derivation and often show a blocking or abrupt character; physiologic artifacts repeat with a body rhythm (ECG, pulse, muscle, eye movement, sweat-related slow drifts); environmental interference often shows a fixed frequency relationship to line power. Your strongest tools are the EKG channel, the eye leads, and a second montage: an artifact tied to the heartbeat appears on distant electrodes simultaneously and at a fixed interval from each QRS, while a cerebral discharge keeps its field regardless of the cardiac cycle.
Worked scenario: sharp transients appear at T3 and T4, and a reviewer calls them bilateral temporal spikes. The mistake is reading morphology without checking timing. The better decision is to overlay the EKG channel: each transient falls at a fixed interval after the QRS, and similar transients appear on electrodes nowhere near the temporal lobes — both hallmarks of ECG artifact, often worsened when an ECG or neck electrode sits too close to head leads. Why it matters: bilateral independent epileptiform discharges and ECG artifact lead to entirely different report language, and the EKG channel exists precisely to make this discrimination a 30-second check instead of a guess.
Documenting activation procedures with observable evidence
Hyperventilation and photic stimulation are observation tasks. Document baseline, timing, the observed response, and any interruption in factual behavioral terms, and distinguish driving from a photoparoxysmal response.
For hyperventilation, record the baseline rhythm first, note that the patient is overbreathing and how well, then describe any build-up — rhythmic slowing — with its onset and offset relative to the procedure, and stop factually if a defined observation such as marked focal slowing appears. For photic stimulation, annotate each flash frequency applied and describe what occurred at each: entrainment of the posterior rhythm (driving) keeps a fixed relationship to the stimulus and stops when it stops, whereas a photoparoxysmal response is a self-sustaining epileptiform discharge that outlasts the stimulus and may extend beyond the flashing period.
Exercise: write annotations for a simulated hyperventilation run and a simulated photic run using only observable terms — times, frequencies, rhythm descriptions, behavioral notes. Then swap annotations with a study partner and check whether they can reconstruct what happened without seeing the tracing. Expected observations: your annotation names the procedure, its duration in the record, the specific response, and any technical problem (electrode pop during overbreathing, patient count slowing), and it never substitutes interpretation where description is the technologist's role. This habit of precise annotation is exactly what the patient care and professional issues content asks you to demonstrate.
Building an adaptable review sequence with readiness checks
Sequence your review by waveform-level skills first, integration second, and self-observation last. Track readiness through concrete checks you can perform, not through feelings of familiarity with the content.
An adaptable sequence: start with placement measurement and montage construction until you can draw the 10-20 array and name every derivation chain from memory. Move to instrumentation by deliberately changing one parameter at a time on practice epochs and predicting the trace change. Then spend the longest block on pattern work — normal rhythms and variants, epileptiform discharges, and artifact — using the five-question habit on every pattern. Close with activation procedure documentation and patient care scenarios. Compress or extend each block to fit your calendar; the order matters more than the dates.
Readiness checks: (1) you can draw and label the full 10-20 array with naming logic within a few minutes from memory; (2) given any practice epoch, you can state the montage, sensitivity, filters, patient state, and every significant pattern with its supporting evidence; (3) you can distinguish a benign variant from an epileptiform discharge and an ECG artifact from a temporal sharp wave, each in a spoken sentence citing field, state, and timing; (4) you can write a complete activation-procedure annotation set. Reaching all four checks, scored honestly against your own output, is a reasonable milestone before scheduling; treat them as learning targets rather than predictions of any outcome. For eligibility rules, application steps, and other administrative details, rely on ABRET directly at abret.org rather than secondary summaries.
References and further reading
Use these references to explore the concepts and check the latest information from the relevant organizations.