Modulation of flash stimulation intensity and frequency: effects on visual evoked potentials and oscillatory potentials recorded in awake, freely moving mice

Lopez, Luisa; Brusa, Adriana; Fadda, Antonello; Loizzo, Stefano; Martinangeli, Alfredo; Sannita, Walter G.; Loizzo, Alberto

doi:10.1016/s0166-4328(01)00351-5

Cited by 18 publications

(22 citation statements)

References 27 publications

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“…VEP experiments were performed according to published procedures [ 37 , 38 ]. Briefly, mice were anaesthetized by intraperitoneal injection of a mixture of xylazine (Rompun, Bayer AG, Leverkusen-Germania, 20 mg/Kg i.p) and ketamine (Ketavet 100, Gellini Farmaceutici Spa, Peschira Borromea-MI, 32 mg/Kg i.p.)…”

Section: Methodsmentioning

confidence: 99%

Visual evoked potentials of Niemann-Pick type C1 mice reveal an impairment of the visual pathway that is rescued by 2-hydroxypropyl-ß-cyclodextrin

Palladino

Loizzo

Fortuna

et al. 2015

Orphanet J Rare Dis

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BackgroundThe lysosomal storage disorder, Niemann Pick type C1 (NPC1), presents a variable phenotype including neurovisceral and neurological symptoms. 2-Hydroxypropyl-ß-cyclodextrin (HPßCD)-based therapies are presently the most promising route of intervention. While severe cerebellar dysfunction remains the main disabling feature of NPC1, sensory functions including auditory and olfactory ones are also affected. Morphological and functional anomalies of Npc1−/− mouse retina have also been observed, although the functional integrity of the visual pathway from retina to visual cortex is still unsettled. We have addressed this issue by characterizing the visual evoked potential (VEP) response of Npc1−/− mice and determining if/how HPßCD administration influences the VEPs of both Npc1−/− and Npc1+/+ mice.MethodsVEP elicited by a brief visual stimulus were recorded from the scalp overlying the visual cortex of adult (PN, postnatal days 60, 75, 85 and 100) Npc1+/+ and Npc1−/− mice that had received repeated injections of either HPßCD or plain vehicle. The first injection was given at PN4 and was followed by a second one at PN7 and thereafter by weekly injections up to PN49. Cholesterol accumulation and myelin loss were finally assessed by filipin staining and myelin basic protein immunohistochemistry, respectively.Results and discussionWe have found that the transmission of visual signals from retina to visual cortex is negatively influenced by the loss of Npc1 function. In fact, the VEP response of Npc1−/− mice displayed a highly significant increase in the latency compared to that of Npc1+/+ mice. HPßCD administration fully rescued this defect and counteracted the cholesterol accumulation in retinal ganglion cells and dorsal lateral geniculate nucleus neurons, as well as the myelin loss in optic nerve fibers and axons projecting to the visual cortex observed in of Npc1−/− mice. By contrast, HPßCD administration had no effect on the VEP response of Npc1+/+ mice, further strengthening the treatment efficacy.ConclusionsThis study pinpoints the analysis of VEP response as a potentially accurate and non-invasive approach to assess neural activity and visual information processing in NPC1 patients, as well as for monitoring the progression of the disease and assessing the efficacy of potential therapies.Electronic supplementary materialThe online version of this article (doi:10.1186/s13023-015-0348-0) contains supplementary material, which is available to authorized users.

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Section: Methodsmentioning

confidence: 99%

Visual evoked potentials of Niemann-Pick type C1 mice reveal an impairment of the visual pathway that is rescued by 2-hydroxypropyl-ß-cyclodextrin

Palladino

Loizzo

Fortuna

et al. 2015

Orphanet J Rare Dis

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“…Therefore, the ERG and VEPs should be recorded in the conscious state to eliminate spurious drug-related effects. Visually evoked potentials have been recorded from awake animals, including mice [ 8 , 9 ]. Awake ERG recordings have also been achieved in animals, including rats [ 10 – 13 ], cats [ 14 ], and dogs[ 15 ], but there are no reports of awake ERG recordings in mice, the laboratory animal that meets most of the practical needs for eye research.…”

Section: Introductionmentioning

confidence: 99%

Measurement of Electroretinograms and Visually Evoked Potentials in Awake Moving Mice

et al. 2016

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The development of new treatments for intractable retinal diseases requires reliable functional assessment tools for animal models. In vivo measurements of neural activity within visual pathways, including electroretinogram (ERG) and visually evoked potential (VEP) recordings, are commonly used for such purposes. In mice, the ERG and VEPs are usually recorded under general anesthesia, a state that may alter sensory transduction and neurotransmission, but seldom in awake freely moving mice. Therefore, it remains unknown whether the electrophysiological assessment of anesthetized mice accurately reflects the physiological function of the visual pathway. Herein, we describe a novel method to record the ERG and VEPs simultaneously in freely moving mice by immobilizing the head using a custom-built restraining device and placing a rotatable cylinder underneath to allow free running or walking during recording. Injection of the commonly used anesthetic mixture xylazine plus ketamine increased and delayed ERG oscillatory potentials by an average of 67.5% and 36.3%, respectively, compared to unanesthetized mice, while having minimal effects on the a-wave and b-wave. Similarly, components of the VEP were enhanced and delayed by up to 300.2% and 39.3%, respectively, in anesthetized mice. Our method for electrophysiological recording in conscious mice is a sensitive and robust means to assess visual function. It uses a conventional electrophysiological recording system and a simple platform that can be built in any laboratory at low cost. Measurements using this method provide objective indices of mouse visual function with high precision and stability, unaffected by anesthetics.

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“…An oscillatory component of the visual evoked potentials (VEP) that resembles the retinal OP in frequency and timing has been independently described in the primary visual cortex (V1) (Lopez et al. ; Rajkai et al. ).…”

Section: Introductionmentioning

confidence: 99%

“…The retinal OP signal was discovered by Fr€ ohlich (1914), but its function in the transfer of visual information is still unclear. An oscillatory component of the visual evoked potentials (VEP) that resembles the retinal OP in frequency and timing has been independently described in the primary visual cortex (V1) (Lopez et al 2002;Rajkai et al 2008). The relationship between these two gamma-band oscillatory potentials (called omega-oscillations) was characterized partly by Munk and Neuenschwander (2000).…”

Section: Introductionmentioning

confidence: 99%

Retino-cortical stimulus frequency-dependent gamma coupling: evidence and functional implications of oscillatory potentials

et al. 2016

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Long‐range gamma band EEG oscillations mediate information transmission between distant brain regions. Gamma band‐based coupling may not be restricted to cortex‐to‐cortex communication but may include extracortical parts of the visual system. The retinogram and visual event‐related evoked potentials exhibit time‐locked, forward propagating oscillations that are candidates of gamma oscillatory coupling between the retina and the visual cortex. In this study, we tested if this gamma coupling is present as indicated by the coherence of gamma‐range (70–200 Hz) oscillatory potentials (OPs) recorded simultaneously from the retina and the primary visual cortex in freely moving, adult rats. We found significant retino‐cortical OP coherence in a wide range of stimulus duration (0.01–1000 msec), stimulus intensity (800–5000 mcd/mm2), interstimulus interval (10–400 msec), and stimulus frequency (0.25–25 Hz). However, at low stimulus frequencies, the OPs were time‐locked, flickering light at 25 Hz entrained continuous OP coherence (steady‐state response, SSR). Our results suggest that the retina and the visual cortex exhibit oscillatory coupling at high‐gamma frequency with precise time locking and synchronization of information transfer from the retina to the visual cortex, similar to cortico‐cortical gamma coupling. The temporal fusion of retino‐cortical gamma coherence at stimulus rates of theater movies may explain the mechanism of the visual illusion of continuity. How visual perception depends on early transformations of ascending sensory information is incompletely understood. By simultaneous measurement of flash‐evoked potentials in the retina and the visual cortex in awake, freely moving rats, we demonstrate for the first time that time‐locked gamma oscillatory potentials exhibit stable retino‐cortical synchrony across a wide range of stimulus parameters and that the temporal continuity of coherence changes with stimulus frequency according to the expected change in the visual illusion of continuity.

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Modulation of flash stimulation intensity and frequency: effects on visual evoked potentials and oscillatory potentials recorded in awake, freely moving mice

Cited by 18 publications

References 27 publications

Visual evoked potentials of Niemann-Pick type C1 mice reveal an impairment of the visual pathway that is rescued by 2-hydroxypropyl-ß-cyclodextrin

Visual evoked potentials of Niemann-Pick type C1 mice reveal an impairment of the visual pathway that is rescued by 2-hydroxypropyl-ß-cyclodextrin

Measurement of Electroretinograms and Visually Evoked Potentials in Awake Moving Mice

Retino-cortical stimulus frequency-dependent gamma coupling: evidence and functional implications of oscillatory potentials

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