Cortical Odor Processing in Health and Disease

Wilson, Donald A.; Xu, Wenjin; Sadrian, Benjamin; Courtiol, Emmanuelle; Cohen, Yaniv; Barnes, Dylan C.

doi:10.1016/b978-0-444-63350-7.00011-5

Cited by 72 publications

(72 citation statements)

References 239 publications

(320 reference statements)

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“…However, processing of olfactory information is distributed across a wide range of cerebral structures involving, for example, the piriform and entorhinal cortices, amygdala, thalamus, cerebellum, and orbitofrontal cortex [27]. This fact can probably explain why responses were not only seen in MTLE but also IGE whose ictogenic mechanisms involve the thalamus and frontal cortex [28].…”

Section: Discussionmentioning

confidence: 97%

Olfactory stimulation induces delayed responses in epilepsy

Lunardi

Lin

Mameniškienė

et al. 2016

Epilepsy & Behavior

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Precipitation and inhibition of seizures and epileptic discharges by sensory stimuli are receiving increasing attention because they provide insight into natural seizure generation in human epilepsies and can identify potential nonpharmacological therapies. We aimed to investigate modulation (provocation or inhibition) of epileptiform discharges (EDs) in mesial temporal lobe epilepsy (MTLE) versus idiopathic generalized epilepsy (IGE) by olfactory stimulation (OS) compared with standard provocation methods. The underlying hypothesis was that any response would be more likely to occur in MTLE, considering the anatomical connections of the temporal lobe to the olfactory system. This multicenter, international study recruited patients with either MTLE or IGE who were systematically compared for responses to OS using an EEG/video-EEG protocol including a 30-min baseline, twice 3-min olfactory stimulation with ylang-ylang, hyperventilation, and intermittent photic stimulation. The 95% confidence interval (CI) for the baseline EDs in each patient was calculated, and modulation was assumed when the number of EDs during any 3-min test period was outside this CI. A total of 134 subjects (55 with MTLE, 53 with IGE, and 26 healthy controls) were included. Epileptiform discharges were inhibited during OS in about half the patients with both MTLE and IGE, whereas following OS, provocation was seen in 29.1% of patients with MTLE and inhibition in 28.3% of patients with IGE. Olfactory stimulation was less provocative than standard activation methods. The frequent subclinical modulation of epileptic activity in both MTLE and IGE is in striking contrast with the rarity of reports of olfactory seizure precipitation and arrest. Inhibition during OS can be explained by nonspecific arousal. The delayed responses seem to be related to processing of olfactory stimuli in the temporal lobe, thalamus, and frontal cortex.

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Section: Discussionmentioning

confidence: 97%

Olfactory stimulation induces delayed responses in epilepsy

Lunardi

Lin

Mameniškienė

et al. 2016

Epilepsy & Behavior

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“…(256) for a review]. An early neuropathological report noted significant damage to the olfactory bulbs and stalks in children and fetuses prenatally exposed to alcohol (257) though few studies have examined the functional consequences of this damage.…”

Section: Behavioral Manipulationsmentioning

confidence: 99%

A Comparison of the Different Animal Models of Fetal Alcohol Spectrum Disorders and Their Use in Studying Complex Behaviors

2014

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Prenatal ethanol exposure (PNEE) has been linked to widespread impairments in brain structure and function. There are a number of animal models that are used to study the structural and functional deficits caused by PNEE, including, but not limited to invertebrates, fish, rodents, and non-human primates. Animal models enable a researcher to control important variables such as the route of ethanol administration, as well as the timing, frequency and amount of ethanol exposure. Each animal model and system of exposure has its place, depending on the research question being undertaken. In this review, we will examine the different routes of ethanol administration and the various animal models of fetal alcohol spectrum disorders (FASD) that are commonly used in research, emphasizing their strengths and limitations. We will also present an up-to-date summary on the effects of prenatal/neonatal ethanol exposure on behavior across the lifespan, focusing on learning and memory, olfaction, social, executive, and motor functions. Special emphasis will be placed where the various animal models best represent deficits observed in the human condition and offer a viable test bed to examine potential therapeutics for human beings with FASD.

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“…The effect of AβPP and its metabolites on the olfactory system and resulting consequences for odor processing are of particular interest given that olfactory dysfunction is one of the most commonly reported early symptoms of AD and other neurodegenerative diseases (Wilson, et al, 2014). This dysfunction has been shown to precede other cognitive impairments and although it can manifest as deficits in the detection and discrimination of odors in mild cognitive impairment and early AD (Bahar-Fuchs, et al, 2011, Murphy, 1999, Rahayel, et al, 2012), problems with odor identification appear most robust (Albers, et al, 2006, Calhoun-Haney and Murphy, 2005, Conti, et al, 2013, Devanand, et al, 2008, Devanand, et al, 2000, Rahayel, et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Early hyperactivity in lateral entorhinal cortex is associated with elevated levels of AβPP metabolites in the Tg2576 mouse model of Alzheimer's disease

Fitzgerald

Nixon

et al. 2015

Experimental Neurology

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Alzheimer’s disease (AD) is a neurodegenerative disorder that is the most common cause of dementia in the elderly today. One of the earliest symptoms of AD is olfactory dysfunction. The present study investigated the effects of amyloid β precursor protein (AβPP) metabolites, including amyloid-β (Aβ) and AβPP C-terminal fragments (CTF), on olfactory processing in the lateral entorhinal cortex (LEC) using the Tg2576 mouse model of human AβPP over-expression. The entorhinal cortex is an early target of AD related neuropathology, and the LEC plays an important role in fine odor discrimination and memory. Cohorts of transgenic and age-matched wild-type (WT) mice at 3, 6, and 16 months of age (MO) were anesthetized and acute, single-unit electrophysiology was performed in the LEC. Results showed that Tg2576 exhibited early LEC hyperactivity at 3 and 6 MO compared to WT mice in both local field potential and single-unit spontaneous activity. However, LEC single-unit odor responses and odor receptive fields showed no detectable difference compared to WT at any age. Finally, the very early emergence of olfactory system hyper-excitability corresponded not to detectable Aβ deposition in the olfactory system, but rather to high levels of intracellular AβPP-CTF and soluble Aβ in the anterior piriform cortex (aPCX), a major afferent input to the LEC, by 3 MO. The present results add to the growing evidence of AβPP-related hyper-excitability, and further implicate both soluble Aβ and non-Aβ AβPP metabolites in its early emergence.

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Cortical Odor Processing in Health and Disease

Cited by 72 publications

References 239 publications

Olfactory stimulation induces delayed responses in epilepsy

Olfactory stimulation induces delayed responses in epilepsy

A Comparison of the Different Animal Models of Fetal Alcohol Spectrum Disorders and Their Use in Studying Complex Behaviors

Early hyperactivity in lateral entorhinal cortex is associated with elevated levels of AβPP metabolites in the Tg2576 mouse model of Alzheimer's disease

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