Supplementary Material

Glutamatergic pre-ictal discharges emerge at the transition to seizure in human epilepsy.

Gilles Huberfeld, Liset Menendez de la Prida, Johan Pallud, Ivan Cohen,

Michel Le Van Quyen, Claude Adam, Stéphane Clemenceau, Michel Baulac

& Richard Miles.

Nature Neuroscience: doi:10.1038/nn.2790

Supplementary figure 1 Pharmacology of ictal events.

Intracellular (black upper trace, I) and extracellular (blue lower trace, E) records of epileptiform activities in the subiculum. The arrow indicates -60 mV.

(a) Two ictal events preceded by recurrent PID induced by 0.25 mM Mg2+ / 8 mM K+.

(b) Blockade of GABAA receptors by 20 μM bicuculline suppressed ictal events but did not affect PID.

(c) Blockade of NMDA receptors by 100 μM D-L-AP5 suppressed ictal events but did not block PID.

(d) Blockade of AMPA receptors by 20 μM NBQX suppressed both PID and ictal discharges.

100 µV

10 mV

10 s

—60mV

0.25 mM Mg2+ / 8 mM K+

I

E

a

b

c

d

0.25 mM Mg2+ / 8 mM K+

+ 20 µM bicuculline

0.25 mM Mg2+ / 8 mM K+

+ 100 µM D-L-AP5

0.25 mM Mg2+ / 8 mM K+

+ 20 µM NBQX

Nature Neuroscience: doi:10.1038/nn.2790

Supplementary figure 2 The duration of the transition period is not determined by the wash in of the convulsant solution.

Dual extracellular recording of the subiculum (black traces) and entorhinal cortex (purple traces) during the transition period induced by 8 mM K+ and 0.25 mM Mg++. The bottom traces show the extracellular signal. Field potentials amplitude ploted on the middle trace shows the progressive emergence of PID. Multiunit activity (MUA) frequency (top traces) reaches a steady state in the entorhinal cortex where no PID is recorded while it continues to increase in the subiclum generating PID.

50 µV

50 µV

50 AP per s

MUA frequency: subiculum

MUA frequency: entorhinal cortex

Field potentials amplitude (IID - PID): subiculum

Extracellular recording: subiculum

Extracellular recording: enthorinal cortex

8 mM K+ / 0.25 mM Mg2+

10 m

Nature Neuroscience: doi:10.1038/nn.2790

Supplementary figure 3 IID and PID are largely independent population events.

Plots of IID and PID dynamics. The amplitude and timing of IID (left) and PID (right) before and after each detected PID and IID respectively are shown in raster plots (top) and distribution histograms (bottom). Apart from a refractory period shorter than 200 ms after each PID, the timing and amplitude distribution of IID and PID are independent.

IID following PIDIID preceding PID PID following IIDPID preceding IID

IID dynamics PID dynamics

IID a

mpl

itude

IID a

mpl

itude

PID

am

plitu

de

PID

am

plitu

de

Time relative to PID Time relative to PID Time relative to IID Time relative to IID

Nature Neuroscience: doi:10.1038/nn.2790

Supplementary Table: Combination of ictogenic stimuli in patients.

STIMULUS 1 [K+]o: 6-8 mM [Mg2+]o/[Ca2+]o: 0.5 mM

ST

IMU

LS

2

[Mg2+]o: 0.25 mM 20 -

[HCO3-]o: 65-85 mM 11 11

Nature Neuroscience: doi:10.1038/nn.2790