Science - 16.08.2019

Figure 1B shows the location of a typical CA1
recording site in one patient; Fig. 1C is a sche-
matic drawing of the depth electrode used in
our study (locations of hippocampal recording
sites in each patient are depicted in fig. S1).
Figure 1D shows typical SWR events as they
appear in the recordings. Our dataset included
8387 SWRs obtained from 15 patients (see Fig. 1,
E and F, for grand-average peri-ripple field po-
tential and spectral decomposition and Fig. 1G

for distribution of inter-ripple interval durations;

see table S1 for demographic information).

We analyzed four main conditions: (i) rest,

during which patients were instructed to rest

with eyes closed; (ii) viewing, during which pa-

tients inspected and memorized photographs of

famous faces and places; (iii) recall, referring to

times within the free-recall period in which pa-

tients verbally reported recalling a specific item

from the memorized set (i.e., epochs that began

3 s before the onset until the offset of each

“recall event,”a total of 269.5 s on average);

and (iv) search, referring to all complementary

time intervals between recall events, in which

patients attempted to recall but did not report

any recalled item (330.5 s on average).

SWR properties across cognitive states

We first examined whether the spectral signa-

tureoftheSWRsvariedacrossthedifferent

Normanet al.,Science 365 , eaax1030 (2019) 16 August 2019 2of14

Time (sec)

-300

0

300

Hippocampal

raw LFP

(μV)

-10

0

10

Ripple-band70-180Hz

(μV)

0 1 2 3 4 5

0

10

4

Squaredenvelope(z score)

detection thr.

Voltage (μV)

dB

0

10

-200-100 0 100200

50

100

150

200

Frequency (Hz)

Time (ms)

-500 -250 0 250 500

-40

-20

0

20

Grand-average

n = 8387 ripples (15 patients)

Time from ripple peak (ms)

0510

Mean = 2.4 s

Inter ripple interval (s)

Probability

0

0.2

0.4

Depth iEEG electrodes: 4.4mm

0.8mm

2mm

platinum contacts

Patient 4: Left Hippocampus

CA1

subiculum

presubiculum

parasubiculum

Hippocampal subfields:

molecular layer

hippocampal fissure

CA2/3

fimbria

GC-DG

recording sites

A

P

RL

RUN 1

time rest (200 s) viewing (130 s) counting

1500 ms 750 ms

recalling faces

(150 s)

verbalized free-recall

recalling places

(150 s)

time rest (200 s) viewing (130 s) counting recalling faces

(150 s)

recalling places

(150 s)

RUN 2

time

blindfold on

E

A

B C

D

F G

Fig. 1. Experimental design and hippocampal SWR detection.
(A) Experimental design and stimuli ( 91 ). After viewing pictures of famous
faces and places (see methods), participants were asked to freely recall
and describe as many pictures as possible, targeting each category in
separate blocks. (B) Coronal slice and 3D reconstruction of a hippocampal
depth electrode in one representative patient. White arrow indicates
CA1 recording site used for ripple detection. (C) Schematic diagram of

depth iEEG electrodes used in our study. (D) Example of SWR events

as they appear in the recordings. From top to bottom: raw hippocampal

LFP; ripple-band filtered LFP (70 to 180 Hz); normalized ripple-band

envelope used for ripple detection. (EandF) Grand average peri-ripple

field potential and wavelet spectrogram centered on ripple peak

(n= 8279 SWR events from 15 patients). (G) Overall distribution of inter-

ripple intervals (n= 15 patients; error bars represent SEM).

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