Articles in PresS. J Neurophysiol (February 4, 2015). doi:10.1152/jn.00031.2015
1
DISTINCT EEG SEIZURE PATTERNS REFLECT DIFFERENT SEIZURE
2
GENERATION MECHANISMS
3 4
Pariya Salami, Maxime Lévesque, Jean Gotman and Massimo Avoli*
5 6
Montreal Neurological Institute and Departments of Neurology & Neurosurgery and of Physiology,
7
McGill University, Montréal, H3A 2B4 QC, Canada
8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
Running title: inhibition and seizure onsets
Words in the abstract: Number of pages: Number of figures:
* Correspondence to:
198 16 2
Massimo Avoli MD, PhD Montreal Neurological Institute 3801 University Street, Montréal, PQ, Canada, H3A 2B4 Tel: +1 514 998 6790 Fax: +1 514 398 8106 e-mail: [email protected]
28 29 30 31 32
CONFLICTS OF INTEREST None of the authors has any conflict of interest to disclose.
1
Copyright © 2015 by the American Physiological Society.
33
ABSTRACT
34
Low-voltage fast- (LVF) and hypersynchronous- (HYP) seizure onset patterns can be recognized
35
in the EEG of epileptic animals and patients with temporal lobe epilepsy. Ripples (80-200 Hz)
36
and fast ripples (250-500 Hz) have been linked to each pattern, with ripples predominating
37
during LVF seizures and fast ripples predominating during HYP seizures in the rat pilocarpine
38
model. This evidence led us to hypothesize that these two seizure-onset patterns reflect the
39
contribution of neural networks with distinct transmitter signaling characteristics. Here, we
40
tested this hypothesis by analysing the seizure activity induced with the K+ channel blocker 4-
41
aminopyridine (4AP, 4-5 mg/kg, i.p.) - which enhances both glutamatergic and GABAergic
42
transmission - or the GABAA receptor antagonist picrotoxin (3-5 mg/kg, i.p.); rats were
43
implanted with electrodes in the hippocampus, the entorhinal cortex and the subiculum. We
44
found that LVF-onset occurred in 82% of 4AP-induced seizures while seizures following
45
picrotoxin were always HYP. In addition, HFO analysis revealed that 4AP-induced LVF seizures
46
were associated to higher ripple rates compared to fast ripples (p
1
DISTINCT EEG SEIZURE PATTERNS REFLECT DIFFERENT SEIZURE
2
GENERATION MECHANISMS
3 4
Pariya Salami, Maxime Lévesque, Jean Gotman and Massimo Avoli*
5 6
Montreal Neurological Institute and Departments of Neurology & Neurosurgery and of Physiology,
7
McGill University, Montréal, H3A 2B4 QC, Canada
8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
Running title: inhibition and seizure onsets
Words in the abstract: Number of pages: Number of figures:
* Correspondence to:
198 16 2
Massimo Avoli MD, PhD Montreal Neurological Institute 3801 University Street, Montréal, PQ, Canada, H3A 2B4 Tel: +1 514 998 6790 Fax: +1 514 398 8106 e-mail: [email protected]
28 29 30 31 32
CONFLICTS OF INTEREST None of the authors has any conflict of interest to disclose.
1
Copyright © 2015 by the American Physiological Society.
33
ABSTRACT
34
Low-voltage fast- (LVF) and hypersynchronous- (HYP) seizure onset patterns can be recognized
35
in the EEG of epileptic animals and patients with temporal lobe epilepsy. Ripples (80-200 Hz)
36
and fast ripples (250-500 Hz) have been linked to each pattern, with ripples predominating
37
during LVF seizures and fast ripples predominating during HYP seizures in the rat pilocarpine
38
model. This evidence led us to hypothesize that these two seizure-onset patterns reflect the
39
contribution of neural networks with distinct transmitter signaling characteristics. Here, we
40
tested this hypothesis by analysing the seizure activity induced with the K+ channel blocker 4-
41
aminopyridine (4AP, 4-5 mg/kg, i.p.) - which enhances both glutamatergic and GABAergic
42
transmission - or the GABAA receptor antagonist picrotoxin (3-5 mg/kg, i.p.); rats were
43
implanted with electrodes in the hippocampus, the entorhinal cortex and the subiculum. We
44
found that LVF-onset occurred in 82% of 4AP-induced seizures while seizures following
45
picrotoxin were always HYP. In addition, HFO analysis revealed that 4AP-induced LVF seizures
46
were associated to higher ripple rates compared to fast ripples (p
