The influence of age on the electroretinogram and visual evoked potential

Wright, Christine E.; Williams, Dudley; Drasdo, Neville; Harding, G. F. A.

doi:10.1007/bf00159171

Cited by 96 publications

(61 citation statements)

References 22 publications

(23 reference statements)

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“…The flash VEP was demonstrated to be a specific indicator of dementia in human, particularly on the latency of P2 [4,18,22], since no P2 latency delayed was detected in the patient with depres-sion, confusion, and/or forgetfulness [15,18,22]. In addition, the amplitude of flash VEP showed more commonly in aged human [3,23], like as shown in N2-P2 and P2-N3 of aged dogs in this study.…”

supporting

confidence: 54%

“…Therefore, the delay of the latency of P2 and later peaks observed in aged dogs were considered to reflect the disturbance of the potentials from retina to brainstem and behind visual pathway. The dementia patient with Alzheimer's disease also showed the delay of the P2 latency [5,23], which reflects the potentials from brainstem to visual cortex, corresponding to N2 of the flash VEP in dogs. The pathophysiological mechanism for the delay of P2 was reported that the reduction of neurotrasmitter, especially cholinergic neurotransmitter, which was frequently observed in the temporal and parietal cortex and hippocumpus, induced the disturbance of neuronal transmission and functions [6,7,16].…”

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confidence: 98%

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Age-Associated Changes of Flash Visual Evoked Potentials in Dogs

Kimotsuki¹,

Yasuda

Tamahara

et al. 2006

The Journal of Veterinary Medical Science

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ABSTRACT. Age-associated changes of visual evoked potentials by flash stimulation (flash VEP) were evaluated in 53 beagle dogs aged from 1-to 15-year-old. Among the components of flash VEP consisted of 3 positive (P1, P2 and P3) and 2 negative (N1 and N2) peaks by 150 msec, the latency of P2 and the later peaks (N2 and P3) were significantly delayed with aging. Both amplitudes of the P2-N2 and N2-P3 also showed a significant correlation with aging. The flash VEP is considered to be an available and useful technique to evaluate not only for visual pathway, but also some disturbance of neurological functions, like as those reported in demented human. KEY WORDS: age-associated change, canine, flash VEP.J. Vet. Med. Sci. 68(1): 79-82, 2006 Visual evoked potentials (VEPs) indicated electrophysiological responses from retina to visual cortex is reported to be an useful technique for evaluating optic pathway [8] and also to be a sensitive indicator for dementia in human [4,18,22]. Visser et al. [21] demonstrated that the latency of the flash VEP components was delayed in the patients with dementia, especially Alzheimer's disease. The latency of the positive peak 2 (P2 :mean latency was 100 msec) and the later components were significantly delayed, although the similar results were sometimes detected in aged human. The flash VEP recorded in dogs showed 3 positive (P1, P2 and P3) and 2 negative (N1 and N2) components by 150 msec after the flash stimuli, like as those reported in human [11,17,19]. In addition, various age-associated pathological and/or physiological changes were commonly observed in aged dogs as well as aged human [5,10]. Since there are few diagnostic techniques for dementia in dogs, age-associated changes of the flash VEP were evaluated using various aged beagle dogs.Total 53 beagle dogs (25 male and 28 female) aged from 1-to 15-year-old kept in Medical Safety Research Laboratories, Sankyo Co., Ltd., were used.The flash VEP was recorded using needle electrodes inserted in the midline of the scalp according to the method reported by Strain et al. [18]. Briefly, electrodes of recording, reference, and ground were placed over the midline of the nuchal crest, forehead, and vertex, respectively. Prior to recording, the dogs were instilled the mydriatic drug, including tropicamide and phenylephrine hydrochloride, and subcutaneously given atropine sulfate (0.05 mg/kg) and intramuscularly given xylazine (2-3 mg/kg) for the sedation. Then the dogs were dark-adapted at least 1 hr and the flash VEP were recorded in the dark shielded room. The white flash stimulus was given 1/sec with the intensity of 0.6 joule using a photostimulator (SLS-3100 Photostimulator, Nihon Kohden Co., Tokyo, Japan). The xenon lamp was located about 15 cm in front of the examined eye and another eye was covered with the black cloth. The responses were recorded with signal averager (Neuropack Four Mini, Nihon Kohden Co, Tokyo, Japan). The bandpass filter was set at 1 Hz low and 1,000 Hz high. In this study, consecutive 30 responses wer...

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supporting

confidence: 54%

mentioning

confidence: 98%

Age-Associated Changes of Flash Visual Evoked Potentials in Dogs

Kimotsuki¹,

Yasuda

Tamahara

et al. 2006

The Journal of Veterinary Medical Science

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“…Several studies of pattern reversal potentials (N70, P100) show prolonged latencies with aging (Celesia and Daly, 1977;Wright et al, 1985) but further increment in Alzheimer's disease patients does not occur (Philpot et al, 1990;Wright et al, 1986). Human studies have shown that the P100 component from the primary visual cortex (Ducati et al, 1988) was not affected by cholinergic manipulations (e.g., scopolamine) (Bajalan et al, 1986;Sloan et al, 1992).…”

Section: Visual Potentials In Amnestic Mild Cognitive Impairment and mentioning

confidence: 99%

Cholinesterase inhibitors affect brain potentials in amnestic mild cognitive impairment

et al. 2007

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Amnestic mild cognitive impairment (MCI) is an isolated episodic memory disorder that hasa high likelihood of progressing to Alzheimer's disease. Auditory sensory cortical responses (P50, N100) have been shown to be increased in amplitude in MCI compared to older controls. We tested whether (1) cortical potentials to other sensory modalities (somatosensory and visual) were also affected in MCI and (2) cholinesterase inhibitors (ChEIs), one of the therapies used in this disorder, modulated sensory cortical potentials in MCI. Somatosensory cortical potentials to median nerve stimulation and visual cortical potentials to reversing checkerboard stimulation were recorded from 15 older controls and 15 amnestic MCI subjects (single domain). Results were analyzed as a function of diagnosis (Control, MCI) and ChEIs treatment (Treated MCI, Untreated MCI). Somatosensory and visual potentials did not differ significantly in amplitude in MCI subjects compared to controls.When ChEIs use was considered, somatosensory potentials (N20, P50) but not visual potentials (N70, P100, N150) were of larger amplitude in untreated MCI subjects compared to treated MCI subjects. Three individual MCI subjects showed increased N20 amplitude while off ChEIs compared to while on ChEIs. An enhancement of N20 somatosensory cortical activity occurs in amnestic single-domain MCI and is sensitive to modulation by ChEIs. IntroductionMild cognitive impairment (MCI) describes older individuals having cognitive impairments without accompanying functional impairments that characterize dementia (Petersen et al., 1999). Recent studies have suggested criteria for distinguishing among four subtypes of MCI based on the presence of both episodic memory impairment (amnestic or non-amnestic MCI) and other cognitive impairments (single-or multipledomain MCI) (Petersen, 2004). For example, amnestic singledomain MCI refers to patients with involvement of only memory deficit whereas amnestic multiple-domain MCI refers to patients with impairment of both memory and other cognitive domains such as language or executive function. MCI subjects have a high risk of converting to Alzheimer's disease Petersen et al., 1999) and show neuropathological features of β-amyloid plaques and neurofibrillary tangles similar to early Alzheimer's disease (Kordower et al., 2001;Mufson et al., 1999). These findings suggest that MCI can be a precursor of Alzheimer's disease. Cholinergic processes in neocortical areas are affected in Alzheimer's disease (Geula and Mesulam, 1989;Heckers et al., 1992) and are particularly apparent late in the course of

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“…Comparando-se os grupos especificados quanto às variá-veis para as quais as faixas de normalidade foram construídas e considerando diferença significativa valores menores que 5% (valor de p), verificou-se que para a amplitude das curvas P50 e N95 o efeito idade foi o mais significativo (p=0,0002), ocorrendo diminuição da amplitude com o aumento da idade, mostrando-se de acordo com a literatura (10,(20)(21)(22) . Para a latência das curvas houve diferenças significativas entre as faixas etárias e entre os olhos analisados (direito ou esquerdo), ocorrendo uma diminuição na latência da curva N95 para os pacientes acima de 60 anos, somente para a análise do olho direito (todos os exames foram iniciados pelo olho direito) e houve também um aumento da latência para a curva P50 para os indivíduos acima de 60 anos.…”

Section: I S C U S S ã Ounclassified

“…Para a latência das curvas houve diferenças significativas entre as faixas etárias e entre os olhos analisados (direito ou esquerdo), ocorrendo uma diminuição na latência da curva N95 para os pacientes acima de 60 anos, somente para a análise do olho direito (todos os exames foram iniciados pelo olho direito) e houve também um aumento da latência para a curva P50 para os indivíduos acima de 60 anos. Assim, observou-se um aumento na latência total do PERG com o aumento da idade, como sugere a literatura (10,(20)(21)(22) . Analisando a duração total do PERG, verificou-se um efeito da interação idade e sexo, diminuindo a duração com o aumento da idade, principalmente acima de 60 anos para o sexo feminino e acima de 40 anos para o sexo masculino.…”

Section: I S C U S S ã Ounclassified