physiological amp pathological brain population rhythmic activities in rodent models Liang Zhang Toronto Western Research Institute University Health Network liangzuhnresutorontoca ID: 1046914
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1. Electrophysiological approaches for examining “physiological” & “pathological” brain population (rhythmic) activities in rodent modelsLiang ZhangToronto Western Research InstituteUniversity Health Networkliangz@uhnres.utoronto.caRm 13-411, Toronto Western Hospital
2. In vivo and in vitro approachesElectroencephalography (EEG) in behaving animals Extracellular and single cell recordings in acutely isolated brain tissues
3. Electroencephalography (EEG)
4. Positions of EEG electrodes Epidural electrodesScalp surface electrodesDeeperelectrodes
5. Pros & corns of EEG electrode positionsEpidural electrodesPresumably no damage to brain tissuesEasy to position Relatively weak but stable signals Deep electrodesPotential damage of brain tissues Local field potentials of targeted regionsHistology for verification of implanted electrodes
6. Types of electrodesSimple electrodesisolated and tip-exposed wires microelectrodes or wires (tip diameter ≤50 µm)fine electrodes (tip diameter of 100-200 µm)Multi-electrode arraySingle probe with vertically orientated multiple contactsHorizontally orientated arrays
7. Recording modes Differential recordings Signals - difference between paired electrodesOften used for epidural recordingsSingle end recordingsSignals – relative to ground or reference electrodeUsed for simple or multi-electrode recordings
8. Surgical procedure Animals anesthetized and held onto a stereotaxic frame Small holes drilled through the skull Electrodes inserted by micromanipulators according to XYZ coordinates of targeted regions Electrodes secured onto skull surface via dental cement or glue Baseline recordings after a few days of recovery. Brain histology at the end of experiments
9. Epidural / differential recordings often used with epidural electrodesSignals - difference between paired electrodesrejecting noises from common sources Relatively stableweak signals, not region-specific
10. Single end recordingsUsed for simple or multi-electrode recordingsregion-specific signalssignals relative to ground Relatively strong signals Precise position and histological verification Brain tissue damageInfluence by noise instability of electrodes
11. Simple intracranial electrodes we usedPolyamide-coated stainless steel wires0.12 mm O.D, <1Ω/10mm, 80-90 mg fro a 3-electrode arraySecured onto skull surface via glue Low cost, but need experience to makeMinimal brain damageFor mice from 19 day-old to 2 year-oldWu et al. J Neurosci Meth. 2008
12. Behavioral state-dependent EEG
13. Hypoxia-induced EEG discharges in a young mouseWais et alNeurosci 2009
14. Cortical discharges recorded via tethered EEG from MeCP2-dificient mice (a mouse model of Rett syndrome) Zhang et al, in preparation
15. Histological verification of implanted electrodes
16. Multi-electrode probes Ylinen et al., J Neurosci 1995Stable chronic monitoring?
17. Multi-electrode EEG recordings in mice Buzsaki et al. Neurosci. 2003
18. Transmitter for telemetricTransmitter implanted subcutaneously or in peritoneal cavityContinuous recording in home cage (24 hrs/day, up to 2 months) Simultaneous monitoring of EEG, temperature and gross movementMinimal cable/movement-related artifactsSingle bio-potential channel, low sampling rate (up to 200 Hz)Limitation by battery life 1.6g
19. Discharges recorded via telemetric EEG from MeCP2-dificient mice Wither et al, Plos One, 2012
20. Telemetric recordings of cortical EEG from wild type and MeCP2-dificient mice Wither et al, Plos One, 2012
21. Alterations of cortical delta periodicity in in MeCP2-deficient mice
22. SummaryFeasibility of intracranial EEG recordings in rodents models Tethered or telemetric or Multi-electrode recordingBrain activities under “physiological” and “pathophyological” conditionsExperienced rodent surgeonsExperienced electrode makersWays to secure electrodes onto skull
23. Examinations of population rhythms in isolated brain preparations in vitroIsolated whole brain from guinea pigsIsolated whole hippocampal preparation from rats or miceThick (0.7-1 mm) hippocampal-subicular-entorhinal slices from mice
24. In vitro approaches
25.
26. Spontaneous rhythmic activities of entorhinal cortex recorded from isolated whole brain of guinea pigsGnatkovsky et al., Eur J Neurosci 2007
27. 4-AP induced epileptiform activities in isolated whole brain of guinea pigsUva et al., Eur J Neurosci 2009
28. Issues about isolated whole brain preparation Macroscopic circuitryExtracellular-single cell recordingsPharmacological manipulationAnimal protocol Recordings from basal brain regionsSuitability for rats or mice?
29.
30. Isolated whole septal-hippocampal preparationManseau et al, J Neurosci 2008
31. Isolated whole septal-hippocampal preparationManseau et al, J Neurosci 2008
32. Issues about isolated whole hippocampal or septal-hippocampal preparationsMacroscopic circuitryFeasibility of extracellular-single cell recordingsPharmacological manipulationsWhole hippocampal preparation (neonatal animals, <postnatal day 10)Septal-hippocampal preparation (immature animals, postnatal day 12-18)
33. In vitro preparations Cultured neurons or slicesAcutely isolated brain slicesAcutely isolated whole hippocampal and hippocampal-septal tissues Acutely isolated whole brain
34. Thick hippocampal slices from adult miceThickness of ~0.4 mmCA1ECDGCA3subThickness of 0.7-1 mm
35. Hippocampal-entorhinal spread of in vitro sharp wavesCA1ECWu et al., unpublished data
36. Issues about thick slice preparationSuitable for adult mice (up to 9 month-old)Spontaneous and induced population activitiesExtracellular-single cell recordingsPharmacological manipulationPotential dissection damage or irritation Suitable for mouse models of diseases?
37. SummaryIn vitro preservation of relatively large circuitryGeneration, propagation and modulation of intrinsic rhythms or epileptiform activitiesMultiple extracellular and single cell recordings animal agedisease modelsinfluences by dissection damage and/or tissue deterioration in vitro
38. AcknowledgementChiping Wu Berj L. BardakjianJennifer Anne D'Cruz James H EubanksSinisa Colic Frances SkinnerRobert G. Wither Peter CarlenMin Lang Taufik Valiante Salman Aljarallah Kaushik Shampur Tariq ZahidYoussef El-HayekNSERC, CIHR International Rett Syndrome Foundation