Here, we describe a protocol for inducing long-term plasticity of neuronal intrinsic excitability in relay neurons from the dorsal lateral geniculate nucleus maintained in ex vivo brain slices.
The dorsal lateral geniculate nucleus (dLGN) has long been held to act as a basic relay for visual information traveling from the retina to cortical areas, but recent findings suggest largely underestimated functional plasticity of dLGN principal cells. However, the cellular mechanisms supporting these changes have not been fully explored. Here, we report a protocol to induce long-term potentiation of intrinsic neuronal excitability (LTP-IE) in dorsal dLGN relay cells from acute brain slices of young rats. Intrinsic plasticity is generally induced in parallel with synaptic plasticity. However, in dLGN neurons, LTP-IE is reliably induced by spiking activity at a frequency of 40 Hz for 10 min. LTP-IE in dLGN relay neurons is long-lasting as it can be followed up to 40 min after the induction protocol. In conclusion, the results of this study provide the first evidence for the induction of intrinsic plasticity in dLGN relay cells, thus further pointing to the role of thalamic neurons in activity-dependent visual plasticity.
The overall goal of this method paper is to provide a simple way to induce long-lasting plasticity of neuronal excitability in visual thalamic neurons of the rat in vitro, using the standard current-clamp mode of the patch clamp technique1,2. The rationale behind the development of this technique is its simplicity and reproducibility. The advantage over alternative techniques, such as stimulation of synaptic inputs paired or not with postsynaptic action potentials delivered with a given timing, is its reliability.
Plasticity in the visual system is traditionally thought to be exclusively expressed at the cortical level, whereas the dorsal lateral geniculate nucleus (dLGN), a primary recipient structure of retinal inputs at the thalamic level, is traditionally considered to be just a relay of visual information3. However, this initial conclusion has been challenged by recent works indicating that this simplistic view does not hold longer4,5,6. For instance, functional deficits in visual response are already observed in amblyopic patients at the stage of the LGN7. In addition, a large proportion of dLGN relay neurons in a given monocular territory receive inputs from each eye, indicating potential binocularity for a large proportion of dLGN neurons8,9,10. Moreover, monocular deprivation produces a significant shift in ocular dominance in dLGN neurons5,11,12.
Among the mechanisms of functional plasticity that may occur in ocular dominance shift, plasticity of intrinsic neuronal excitability is a potential candidate. Indeed, many brain regions including visual areas express intrinsic plasticity following various behavioural tasks13,14. Long-term intrinsic plasticity has been reported in central neurons following stimulation of afferent glutamate inputs15,16,17,18, spiking activity19,20, sensory stimulation21 or following activity or sensory deprivation20,22,23. Here, we describe a protocol allowing the induction of long-term potentiation of intrinsic excitability (LTP-IE) in dLGN relay neurons following spiking activity at a frequency of 40 Hz. The 40 Hz firing frequency corresponds to a frequency observed in most dLGN neurons in vivo upon visual stimulation24,25.
We report here the induction of LTP-IE in dLGN neurons maintained alive in acute brain slices by stimulation of the recorded neuron to evoke action potentials at a frequency of 40 Hz for 10 min. This protocol is simple to implement in any neurophysiology lab as it requires a minimal number of equipment (slicer, microscope, 1 amplifier, 1 acquisition board and computer). However, a few critical steps must be respected in order to collect valuable data. The first critical step within the protocol is the quality of the…
The authors have nothing to disclose.
Supported by INSERM, CNRS (to DD), AMU (to MR), FRM (DVS20131228768 to DD and DEQ20180839583 to DD), NeuroSchool ("France 2030" program via A*Midex (Initiative d'Excellence d'Aix-Marseille Université, AMX-19-IET-004) and ANR funding (ANR-17-EURE-0029 to AW), and ANR (LoGiK, ANR-17-CE16-0022 to DD, Plastinex, ANR-21-CE16-013 to DD). We thank A Venture & K Milton for excellent animal care.
Automated vibrating blade microtome | Leica | VT-1200S | vibratome/slicer |
Borosilicate glass tube | Phymep | B-15086-10 | |
Controller Typ V | Luigs&Neumann | Typ V | temperature controller |
Igor software | wavemetrics | analysis software | |
Infrared videomicroscopy | Olympus | XM-10 Camera | |
Kynurenate | Merk/Sigma | K3375 | AMPA/NMDA receptors blocker |
Low-noise Data Acquisition System | Axon – Molecular devices | Digidata 1440A | analog/digital interface |
Micromanipulators | Luigs&Neumann | LN Mini25 | |
Multiclamp 200B | Axon – Molecular devices | N/A | Patch-clamp amplifier |
Multiclamp 700B | Axon – Molecular devices | N/A | patch-clamp amplifier |
PC-100 puller | Narishige | PC-100 | micropipette puller |
PClamp10 | Axon – Molecular devices | N/A | patch-clamp recording software |
Picrotoxin | AbCam | ab120315 | GABAA receptors blocker |
Slice mini chamber | Luigs&Neumann | LN Chambre Slice mini I-II | Submerged Chamber |
Upright microscope | Olympus | BX51 WI |
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