non-restraining-eeg-radiotelemetry-epidural-deep-intracerebral

Non-restraining EEG Radiotelemetry: Epidural and Deep Intracerebral Stereotaxic EEG Electrode Placement

Implantable EEG radiotelemetry is of central relevance in the neurological characterization of transgenic mouse models of neuropsychiatric and ...

Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM)

Alzheimer's disease (AD) is a multifactorial disorder leading to progressive memory loss and eventually death. In this study an APPswePS1dE9 AD mouse model has been analyzed using implantable video-EEG radiotelemetry to perform long-term EEG recordings from the primary motor cortex M1 and the hippocampal CA1 region in both genders. Besides motor activity, EEG recordings were analyzed for electroencephalographic seizure activity and frequency characteristics using a Fast Fourier Transformation (FFT) based approach. Automatic seizure detection revealed severe electroencephalographic seizure activity in both M1 and CA1 deflection in APPswePS1dE9 mice with gender-specific characteristics. Frequency analysis of both surface and deep EEG recordings elicited complex age, gender, and activity dependent alterations in the theta and gamma range. Females displayed an antithetic decrease in theta (θ) and increase in gamma (γ) power at 18-19 weeks of age whereas related changes in males occurred earlier at 14 weeks of age. In females, theta (θ) and gamma (γ) power alterations predominated in the inactive state suggesting a reduction in atropine-sensitive type II theta in APPswePS1dE9 animals. Gender-specific central dysrhythmia and network alterations in APPswePS1dE9 point to a functional role in behavioral and cognitive deficits and might serve as early biomarkers for AD in the future.

Gender-Specific Hippocampal Dysrhythmia and Aberrant Hippocampal and Cortical Excitability in the APPswePS1dE9 Model of Alzheimer's Disease.

Alzheimer's disease (AD) is a multifactorial disorder leading to progressive memory loss and eventually death. In this study, an APPswePS1dE9 AD mouse model has been analyzed for motor cortex theta, beta and gamma frequency alterations using computerized 3D stereotaxic electrode positioning and implantable video-EEG radiotelemetry to perform long-term M1 recordings from both genders considering age, circadian rhythm and activity status of experimental animals. We previously demonstrated that APPswePS1dE9 mice exibit complex alterations in hippocampal frequency power and another recent investigation reported a global increase of alpha, beta and gamma power in APPswePS1dE9 in females of 16-17 weeks of age. In this cortical study in APPswePS1dE9 mice we did not observe any changes in theta, beta and particularly gamma power in both genders at the age of 14, 15, 18 and 19 weeks. Importantly, no activity dependence of theta, beta and gamma activity could be detected. These findings clearly point to the fact that EEG activity, particularly gamma power exhibits developmental changes and spatial distinctiveness in the APPswePS1dE9 mouse model of Alzheimer's disease.

Motor Cortex Theta and Gamma Architecture in Young Adult APPswePS1dE9 Alzheimer Mice.

This data article provides raw auditory evoked brainstem responses (ABRs) from controls and Ca2.3 transgenics, i.e. heterozygous Ca2.3 and Ca2.3 null mutants. Gender specific ABR recordings were performed in age-matched animals under ketamine/xylazine narcosis. Data presented here include ABRs upon both click and tone burst presentation in the increasing SPL mode using a commercially available ABR setup from Tucker Davis Technologies Inc. (TDT, USA). Detailed information is provided for the sound attenuating cubicle, electrical shielding, electrode parameters, stimulus characteristics and architecture, sampling rate, filtering processes and ABR protocol application during the course of data acquisition and recording. The later are important for subsequent analysis of click and tone burst related hearing thresholds, amplitude growth function and peak latencies. Raw data are available at MENDELEY DATA, DIO: 〈DOI:10.17632/g6ygz2spzx.1〉, URL: 〈https://data.mendeley.com/datasets/g6ygz2spzx/1〉).

Gender specific click and tone burst evoked ABR datasets from mice lacking the Ca2.3 R-type voltage-gated calcium channel.

Voltage-gated Ca channels (VGCCs) are of central relevance in regulating Ca influx into living cells. The low-voltage activated (LVA) Ca3 T-type Ca channels are widely distributed throughout the brain including the peripheral auditory system and ascending auditory tract. Their exact role in auditory information processing is still not fully understood. Within the LVA subgroup, Ca3.2 T-type Ca channels seem to be of special importance as qPCR revealed a steady increase in Ca3.2 transcript levels over age, e.g. in the cochlea and spiral ganglion neurons (SGN). Furthermore, pharmacological studies suggested an association between Ca3.2 expression and both age-related and noise-induced hearing loss. Given the potential functional relevance of Ca3.2 VGGCs in sensorineural hearing loss, we recorded gender specific auditory evoked brainstem responses (ABRs) upon both click and tone burst presentation. Here we present auditory brainstem response (ABR) data from Ca3.2, Ca3.2 and Ca3.2 mice from both genders which are of value for researchers who want to evaluate how Ca3.2 loss affects basic auditory parameters, e.g. click and tone burst based hearing thresholds, amplitude growth function and peak latencies.

Gender specific click and tone burst evoked ABR datasets from mice lacking the Ca3.2 T-type voltage-gated calcium channel.

Voltage-gated Ca channels (VGCCs) play key roles in auditory perception and information processing within the inner ear and brainstem. Pharmacological inhibition of low voltage-activated (LVA) T-type Ca channels is related to both age- and noise induced hearing loss in experimental animals and may represent a promising approach to the treatment of auditory impairment of various etiologies. Within the LVA Ca channel subgroup, Ca3.2 is the most prominently expressed T-type channel entity in the cochlea and auditory brainstem. Thus, we performed a complete gender specific click and tone burst based auditory brainstem response (ABR) analysis of Ca3.2 and Ca3.2 mice, including i.a. temporal progression in hearing loss, amplitude growth function and wave latency analysis as well as a cochlear qPCR based evaluation of other VGCCs transcripts. Our results, based on a self-programmed automated wavelet approach, demonstrate that both heterozygous and Ca3.2 null mutant mice exhibit age-dependent increases in hearing thresholds at 5 months of age. In addition, complex alterations in W amplitudes and latencies were detected that were not attributable to alterations in the expression of other VGCCs in the auditory tract. Our results clearly demonstrate the important physiological role of Ca3.2 VGCCs in the spatiotemporal organization of auditory processing in young adult mice and suggest potential pharmacological targets for interventions in the future.

Julien Soós

Department of Neuropsychopharmacology

Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM)

Non-restraining EEG Radiotelemetry: Epidural and Deep Intracerebral Stereotaxic EEG Electrode Placement