# Powerful activation of lambda waves with inversion of polarity by reading on tablet

Philippe Gélisse, Arielle Crespel

► To cite this version:

Philippe Gélisse, Arielle Crespel. Powerful activation of lambda waves with inversion of polarity by reading on tablet. Epileptic Disorders, 2024, 26 (2), pp.254-256. 10.1002/epd2.20197. hal-05079000

HAL Id: hal-05079000

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Submitted on 22 May 2025

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# Powerful activation of lambda waves with inversion of polarity by reading on tablet

Philippe Gélisse<fnref n="1" />,<fnref n="2" /> ID | Arielle Crespel<fnref n="1" />,<fnref n="2" /> ID

## Correspondence

Philippe Gélisse, Epilepsy Unit, Gui de Chauliac Hospital, 80 Avenue Augustin Fliche. Montpellier 38054, France.

Email: p-gelisse@chu-montpellier.fr

Lambda waves are physiological diphasic or triphasic sharp waves occurring in the occipital regions in wakefulness when individuals are visually scanning a picture in a well-illuminated room. The main component is positive, resulting in a prominent downward deflection in referential montages preceded by a negative component (Figure 1A). Lambda waves are associated with saccadic eye movements (Figure 2). Alvarez et al. (2011) reported that their occurrence is elicited by watching television.<fnref n="1" /> We report on a 40-year-old woman who displays abundant lambda waves while reading a book (Figures 1A and 2A). These lambda waves were enhanced when she was reading on her tablet

(Figures 1B and 2B), but not on her smartphone. When reading a book, her EEG showed typical lambda waves with a main positive phase, but while reading on the tablet, the main component was negative (Figure 1). This woman had left lateral temporal lobe epilepsy well controlled for many years. Waking and sleep EEG were normal and her treatment with zonisamide was definitively stopped at the end of the EEG video monitoring. The test book/mobile phone versus tablet was reproducible many times with a clear difference between her reading a book and using her tablet.

Reports have indicated significant similarities between lambda waves and visually evoked responses.<fnref n="2" />,³ Lambda

<figure><img src="image_3.png" /><figcaption>FIGURE 1 Cz-referential montage. (A) Patient reading a book. Typical lambda waves. The predominant phase is positive in occipital electrode O2 and O1. (B) Patient reading on tablet. Di- or triphasic lambda waves. The predominant phase is negative in occipital electrode O2 and O1.</figcaption></figure>

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

© 2024 The Authors. *Epileptic Disorders* published by Wiley Periodicals LLC on behalf of International League Against Epilepsy.

<footnote n="1">¹Epilepsy Unit, Gui de Chauliac Hospital, Montpellier, France</footnote>

<footnote n="2">²Research Unit (URCMA: Unité de Recherche sur les Comportements et Mouvements Anormaux), INSERM, Montpellier, France</footnote>
<figure><img src="image_4.png" /></figure>

<figure><img src="image_5.png" /><figcaption>**FIGURE 2** Longitudinal bipolar montage. (A) Patient reading a book. Presence of saccadic eye movements. Typical lambda waves at O2 and O1. (B) Patient reading on tablet. Lambda wave of high amplitude. The test book versus tablet was reproducible many times with a clear difference between her reading a book and using her tablet.</figcaption></figure>
waves disappear when the patient stares at a point and when the room is not as bright. People who visually scan a brightly illuminated and complex picture are more likely to have lambda waves. Scanning complex geometric patterns may result in lambda waves, which are mostly surface negative and have a spike-like configuration.⁴ Radhakrishnan et al. (2007) proposed to separate this pattern of surface negative sharp waves from typical surface-positive lambda waves and named it “Pattern-Induced Negative Occipital Potential” (PINOP).⁵ The major surface negative potential was often preceded or followed by a low-amplitude surface-positive potential. Three-quarters of their subjects also had typical positive lambda waves, while the others had little response. PINOP were more sharply contoured and shorter in duration than lambda waves, but like lambda waves, they share the same topography and reactivity and may only represent a powerful activation of lambda waves by complex geometric patterns. The intensity of illumination also greatly affects the amplitude of lambda waves.⁴ In this patient, light emission from her tablet was a powerful stimulus, but her smartphone was not.

## AUTHOR CONTRIBUTIONS

Ph. Gélisse: drafting/revision of the manuscript for content, including medical writing for content; major role in the acquisition of data; study concept or design; analysis or interpretation of data. A. Crespel: drafting/revision of the manuscript for content, including medical writing for content; analysis or interpretation of data.

## FUNDING INFORMATION

No targeted funding reported.

## CONFLICT OF INTEREST STATEMENT

Ph. Gélisse and A. Crespel report no disclosures relevant to the manuscript.

## ORCID

Philippe Gélisse https://orcid.org/0000-0001-9296-1957

Arielle Crespel https://orcid.org/0000-0002-2203-1938

## REFERENCES

1. Alvarez V, Maeder-Ingvar M, Rossetti AO. Watching television: a previously unrecognized powerful trigger of λ waves. J Clin Neurophysiol. 2011;28:400-3.

2. Schomer DL, da Silva FL. Niedermeyer's electroencephalography: basic principles, clinical applications, and related Fields. Philadelphia: Lippincott Williams & Wilkins; 2012.

3. Amin U, Nascimento FA, Karakis I, Schomer D, Benbadis SR. Normal variants and artifacts: importance in EEG interpretation. Epileptic Disord. 2023;25:591-648.

4. Kellaway P. Orderly approach to visual analysis: elements of the normal EEG and their characteristics in children and adults. In: Ebersole JS, Pedley TA, editors. Current practice of clinical electroencephalography. 3rd ed. Philadelphia: Lippincott Williams & Wilkins; 2003. p. 100-59.

5. Radhakrishnan K, Sunku AJ, Donat JF, Klass DW. Pattern-induced negative occipital potentials (PINOP). J Clin Neurophysiol. 2007;24:277-80.

## SUPPORTING INFORMATION

Additional supporting information can be found online in the Supporting Information section at the end of this article.

**How to cite this article:** Gélisse P, Crespel A. Powerful activation of lambda waves with inversion of polarity by reading on tablet. Epileptic Disord. 2024;26:254-256. https://doi.org/10.1002/epd2.20197

## Test yourself

1. Which of the following statements regarding lambda waves are correct?

A. Lambda waves are typically unilateral

B. Lambda waves disappear immediately at eye-opening

C. Lambda waves disappear during fixation of gaze

D. Lambda waves are associated with saccadic eye movements

E. Lambda waves disappear in darkness

2. Which of the following statements regarding lambda waves are correct?

A. Lambda waves are typically positive in a referential montage

B. Scanning complex geometric patterns may result in lambda waves, which are mostly surface negative

C. Lambda waves are usually monophasic

D. Lambda waves appear in the frontal region closed to the eyes

E. Lambda waves with sharper contours may be misinterpreted as pathological epileptiform discharges

*Answers may be found in the S1.*