Scaling of Network Excitability and Inhibition may Contribute to the Septotemporal Differentiation of Sharp Waves–Ripples in Rat Hippocampus In Vitro

Trompoukis, George; Leontiadis, Leonidas J.; Rigas, Pavlos; Papatheodoropoulos, Costas

doi:10.1016/j.neuroscience.2020.12.033

Cited by 2 publications

(2 citation statements)

References 92 publications

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“…The relationship between SWRs and baseline neuronal excitability is not necessarily linear in that optimal generation of SWRs may occur at intermediate levels of baseline excitability where excitation is balanced by inhibition, while insufficient or excessive levels in baseline excitability may disrupt normal organization of SPWs (Karlócai et al, 2014). Interestingly, balanced enhancement in excitation and inhibition that occur under normal conditions in the hippocampus in vitro appear to be beneficial for the generation of SWRs (Trompoukis et al, 2021). It is therefore conceivable to hypothesize that an enhancement of the network excitation in the dorsal KO hippocampus that is not accompanied by an analogous change in inhibition results in an increased network excitability and disturbance of excitation-inhibition balance that reduces the probability of occurrence of SWRs and disorganizes neuronal activity during SWRs, thereby affecting information processing in the dorsal hippocampus.…”

Section: Fxs-associated Effects On Normal Spontaneous Activitiesmentioning

confidence: 99%

Rescue of sharp wave-ripples and prevention of network hyperexcitability in the ventral but not the dorsal hippocampus of a rat model of fragile X syndrome

Leontiadis,

Trompoukis,

Tsotsokou

et al. 2023

Front. Cell. Neurosci.

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Fragile X syndrome (FXS) is a genetic neurodevelopmental disorder characterized by intellectual disability and is related to autism. FXS is caused by mutations of the fragile X messenger ribonucleoprotein 1 gene (Fmr1) and is associated with alterations in neuronal network excitability in several brain areas including hippocampus. The loss of fragile X protein affects brain oscillations, however, the effects of FXS on hippocampal sharp wave-ripples (SWRs), an endogenous hippocampal pattern contributing to memory consolidation have not been sufficiently clarified. In addition, it is still not known whether dorsal and ventral hippocampus are similarly affected by FXS. We used a Fmr1 knock-out (KO) rat model of FXS and electrophysiological recordings from the CA1 area of adult rat hippocampal slices to assess spontaneous and evoked neural activity. We find that SWRs and associated multiunit activity are affected in the dorsal but not the ventral KO hippocampus, while complex spike bursts remain normal in both segments of the KO hippocampus. Local network excitability increases in the dorsal KO hippocampus. Furthermore, specifically in the ventral hippocampus of KO rats we found an increased effectiveness of inhibition in suppressing excitation and an upregulation of α1GABAA receptor subtype. These changes in the ventral KO hippocampus are accompanied by a striking reduction in its susceptibility to induced epileptiform activity. We propose that the neuronal network specifically in the ventral segment of the hippocampus is reorganized in adult Fmr1-KO rats by means of balanced changes between excitability and inhibition to ensure normal generation of SWRs and preventing at the same time derailment of the neural activity toward hyperexcitability.

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Section: Fxs-associated Effects On Normal Spontaneous Activitiesmentioning

confidence: 99%

Rescue of sharp wave-ripples and prevention of network hyperexcitability in the ventral but not the dorsal hippocampus of a rat model of fragile X syndrome

Leontiadis,

Trompoukis,

Tsotsokou

et al. 2023

Front. Cell. Neurosci.

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“…In each experimental day, acute slices were prepared from, at least, two of the investigated mouse strains, and electrophysiological recordings were done in parallel from slices obtained from different mouse strains. This experimental design was used to minimize the potential impact of differences in the time of in vitro slice maintenance on analysed network oscillation and evoked field potential parameters between the strains as previously reported (Trompoukis et al, 2021). Mice were deeply anesthetized with isoflurane and decapitated.…”

Section: Methodsmentioning

confidence: 99%

Comparison of three common inbred mouse strains reveals substantial differences in hippocampal GABAergic interneuron populations and in vitro network oscillations

Çalışkan,

Demiray,

Stork

2023

Eur J of Neuroscience

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A major challenge in neuroscience is to pinpoint neurobiological correlates of specific cognitive and neuropsychiatric traits. At the mesoscopic level, promising candidates for establishing such connections are brain oscillations that can be robustly recorded as local field potentials with varying frequencies in the hippocampus in vivo and in vitro. Inbred mouse strains show natural variation in hippocampal synaptic plasticity (e.g. long‐term potentiation), a cellular correlate of learning and memory. However, their diversity in expression of different types of hippocampal network oscillations has not been fully explored. Here, we investigated hippocampal network oscillations in three widely used inbred mouse strains: C57BL/6J (B6J), C57BL/6NCrl (B6N) and 129S2/SvPasCrl (129) with the aim to identify common oscillatory characteristics in inbred mouse strains that show aberrant emotional/cognitive behaviour (B6N and 129) and compare them to “control” B6J strain. First, we detected higher gamma oscillation power in the hippocampal CA3 of both B6N and 129 strains. Second, higher incidence of hippocampal sharp wave‐ripple (SPW‐R) transients was evident in these strains. Third, we observed prominent differences in the densities of distinct interneuron types and CA3 associative network activity, which are indispensable for sustainment of mesoscopic network oscillations. Together, these results add further evidence to profound physiological differences among inbred mouse strains commonly used in neuroscience research.

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Scaling of Network Excitability and Inhibition may Contribute to the Septotemporal Differentiation of Sharp Waves–Ripples in Rat Hippocampus In Vitro

Cited by 2 publications

References 92 publications

Rescue of sharp wave-ripples and prevention of network hyperexcitability in the ventral but not the dorsal hippocampus of a rat model of fragile X syndrome

Rescue of sharp wave-ripples and prevention of network hyperexcitability in the ventral but not the dorsal hippocampus of a rat model of fragile X syndrome

Comparison of three common inbred mouse strains reveals substantial differences in hippocampal GABAergic interneuron populations and in vitro network oscillations

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