rHuman Brain Mapping 30:2440–2452 (2009) r

Distinct Roles of Left Inferior Frontal Regionsthat Explain Individual Differences in Second
Language Acquisition
Kuniyoshi L. Sakai,1,2* Arihito Nauchi,1,2 Yoshinori Tatsuno,1,2 Kazuyoshi Hirano,2,3
Yukimasa Muraishi,2,3 Masakazu Kimura,4 Mike Bostwick,4 and Noriaki Yusa5
1

Department of Basic Science, The University of Tokyo, Komaba, Tokyo 153-8902, Japan
2
CREST, Japan Science and Technology Agency, Kawaguchi-shi 332-0012, Japan
3
The Secondary Education School Attached to the Faculty of Education of the University of Tokyo,
Tokyo 164-8654, Japan
4
Gyoshu Junior & Senior High School, Katoh Schools, Numazu-shi 410-0011, Japan
5
Department of English, Miyagi Gakuin Women’s University, Sendai-shi 981-8557, Japan

Abstract: Second language (L2) acquisition is more susceptible to environmental and idiosyncratic factors than first language acquisition. Here, we used functional magnetic resonance imaging for L2 learners of different ages of first exposure (mean: 12.6 and 5.6 years) in a formal school environment, andcompared the cortical activations involved in processing English sentences containing either syntacticor spelling errors, where the testing ages and task performances of both groups were matched. We
found novel activation patterns in two regions of the left inferior frontal gyrus (IFG) that correlated differentially with the performances of the late and early learners. Specifically, activations of the dorsal
and ventral triangular part (F3t) of the left IFG correlated positively with the accuracy of the syntactic
task for the late learners, whereas activations of the left ventral F3t correlated negatively with the accuracy for the early learners. In contrast, other cortical regions exhibited differential correlation patterns
with the reaction times (RTs) of the syntactic task. Namely, activations of the orbital part (F3O) of theleft IFG, as well as those of the left angular gyrus, correlated positively with the RTs for the late learners, whereas those activations correlated negatively with the RTs for the early learners. Moreover, thetask-selective activation of the left F3O was maintained for both the late and early learners. These
results explain individual differences in L2 acquisition, such that the acquisition of linguisticknowledge in L2 is subserved by at least two distinct inferior frontal regions of the left F3t and F3O.
Hum Brain Mapp 30:2440–2452, 2009. V 2008 Wiley-Liss, Inc.
C

Key words: fMRI; frontal cortex; sentence processing; syntax; language acquisition

Contract grant sponsor: Ministry of Education, Culture, Sports,
Science, and Technology of Japan; Contract grant numbers:
17022013, 20020022; Contract grant sponsor: Japan Society for the
Promotion of Science; Contract grant number: 17520274; Contract
grant sponsor: Japan Science and Technology Agency (JST).
*Correspondence to: Kuniyoshi L. Sakai, Department of Basic Science,
Graduate School of Arts and Sciences, The University of Tokyo,
Komaba, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan.
E-mail: sakai@mind.c.u-tokyo.ac.jp
C 2008 Wiley-Liss, Inc.
V

Received for publication 23 October 2007; Revised 11 September
2008; Accepted 12 September 2008
DOI: 10.1002/hbm.20681
Published online 11 November 2008 in Wiley InterScience (www.
interscience.wiley. com).

r Distinct Roles of Frontal Regions in L2 Acquisition r

INTRODUCTION
The concept of a ‘‘critical’’ or ‘‘sensitive’’ period for first
language (L1) acquisition is based on the loss of flexibility
in cerebral reorganization due to acquired aphasia after
puberty [Lenneberg, 1967], and it has been extended tosecond language (L2) acquisition, becoming the topic ofdebate [Birdsong and Molis, 2001; Flege et al., 1999; Friederici et al., 2002; Johnson and Newport, 1989]. It is possible that each language faculty is acquired through its own
developmental process, and that the timing and durationof its sensitive period varies according to the type of acquisition (i.e., multiple sensitive periods hypothesis)[Flege, 1999; Seliger, 1978]. Because there is now evidence
that some linguistic functions are separately executed in
distinct cortical regions [Price, 2000; Sakai, 2005], it is all
the more interesting to examine whether or not their acquisition processes differ, and if so, to what extent. Moreover, recent neuroimaging results have shown that both L1and L2 are processed in the same cortical regions [Peraniand Abutalebi, 2005; Sakai, 2005], indicating that the L2
acquisition mechanisms may be shared with L1 acquisition
mechanisms.
In previous functional magnetic resonance imaging(fMRI) studies, we examined whether learning English
past-tense verbs as L2 knowledge would alter brain activation. For 2 months, 13-year-old students received training
regarding English verbs during their regular English classroom education. When an English past-tense task was contrasted with a verb-matching task after the training period,
activation was found primarily in the left inferior frontal
gyrus (IFG), specifically the pars opercularis (F3op, Brodmann’s area (BA) 44) and the pars triangularis (F3t, BA 45)
of the left IFG [Sakai et al., 2004]. Moreover, the activation
increase of the left dorsal F3op/F3t predicted the extent towhich the individual participants improved their knowledge of the past tense. A recent fMRI study also reported
greater activation of the left IFG in nonproficient English(L2) than in French (L1) during a sentence production task
[Golestani et al., 2006]. To examine the effect of durationof exposure (DOE) to L2, we also tested 19-year-old participants who had studied English for 6 years. We found that
activation of the left dorsal F3t (dF3t) was lower, corresponding to a higher proficiency level (PL) [Tatsuno andSakai, 2005]. These results suggest that activation of theleft dF3t increases with PL improvements at the initialstage of L2 acquisition, and that it becomes lower when ahigher PL in L2 is attained [Indefrey, 2006; Sakai et al.,2005]. The acquisition of English past-tense verbs as L2
knowledge is one typical example of morphosyntactic
processes, and the left IFG may be required in the acquisition of syntax in general. To confirm the possibility that
this region is actually involved in the acquisition of syntactic structures of sentences, more direct evidence regarding
cortical activation for such syntactic knowledge is mandatory. The present study aimed to address this issue by
examining the correlation between activations of each cort-rical region and individual performances, that is, each participant’s mean accuracy or reaction times (RTs) that were
specifically related to a task about syntactic structures ofsentences. The second aim of the present study was to
examine how participant’s age of first exposure (AOE) to
L2 in a formal school environment would affect the cortical activations during syntactic decision, further clarifying
the nature of individual differences during language development. To dissociate the effects of AOE and DOE isnot, however, within the scope of the present study;
instead, we compared two groups of L2 learners with different AOEs (mean: 12.6 and 5.6 years) and DOE (2.4 and
8.7 years, respectively), whereas their developmental ages
at the time of testing (15.1 and 14.3 years, respectively)
were matched.
During the fMRI measurement, forced-choice errordetection tasks were performed: an English syntactic(Esyn) task and an English spelling (Espe) task. This paradigm is an extension of our previous experiment involving
word-order errors in English [Embick et al., 2000]. All sentence stimuli were visually presented, and the same set ofsentences was used for both tasks. The Esyn task directly
tested the correct use of English verbs in sentences [Levin,1993], and the syntactic errors used in the Esyn task werebasically related to argument structures of English verbs(Table I). For example, L2 learners tend to make a mistakeof omitting an object, and this is because objects of transitive verbs can be omitted quite freely in many languages
other than English [Cole, 1987; Park et al., 2004]. Similarly,
the null-subject (pro-drop) is allowed in Japanese as wellas in Spanish and Italian [Hyams, 1989], and Spanish
speakers often accept English sentences without overt subjects [White, 1985]. Because the present paradigm explicitly
requires judgment on the grammaticality of sentences, theacquisition of argument structures and their associatedsyntactic processes will be further elucidated. In the Espe
task, on the other hand, typographical errors were
included in half of the same set of sentences, to test the
English orthography of words. The Espe task was used asa baseline control for the word recognition and the readingof English sentences as L2, as well as decision andresponse processes. Moreover, the Espe task served as thegeneral control condition for each individual participant,and thus effects of overall developmental and educational
differences (e.g., experiences and exposures in L2 that do
not interact with sentence processing), if any, would becanceled out in the direct comparison of Esyn 2 Espe foreach fMRI experiment. Here, the performances of both
Esyn and Espe tasks were matched between the two participant groups, controlling the general level of intelligenceand proficiency in L2. Furthermore, the cross-linguistic
effects of L1 and L2 combinations (e.g., translation) arealso canceled out in Esyn 2 Espe, because they are common to both tasks using the same set of sentences. Corticalactivations specific to sentence processing in L2 can thus
be properly examined for individual participants.

2441 rr Sakai et al. r

TABLE I. 100 sets of syntactically normal and anomalous sentences
Associated sentence
Key sentence
Can you put your bag on the table?
Do you find a problem here?
Do you like dogs very much?
Do you play outside a lot?
Do you smile often?
Will you work today?
Do you often laugh?
Can you tell me the news now?
Can you walk today?
Do you enjoy tennis at school?
Can you bring your bag here?
Can you carry your bag now?
Can you speak here?
Will you fight here?
Do you often think about history?
Can you send this letter now?
Do you talk a lot?
Do you really love Mary?
Do you sleep a lot?
Do you often meet Mary?
You have a test today.
You can bring John here.
There are some problems here.
A battle will happen here.
You have an old glass.
There is a bag on the table.
There is a flower in the garden.
There are some plants in the garden.
You have a car.
There have been some accidents here.
John’s house is here.
There are many examinations at school.
You can kill many monsters in the game.
This window is closed now.
You have a nice hairstyle.
I know the news.
You can continue the game here.
That door is open now.
You can sell your house.
There is a strange sound in the room.
John thinks in his room.
Many accidents happen on the road.
A strange sound will occur in the room.
John speaks in the class.
John smiles at Mary.
There is a door over there.
John laughs at Mary.
John changes his hairstyle.
John plays in the park.
Some food still remains in the house.
John works at the office.
The news appears on TV today.
John walks to school.
John begins the test.
John talks in the room.
These flowers grow in the garden.
John sleeps on the floor.
It will rain today.
John can move the car.
John is fighting in the war.
We have a baseball game today.
John thinks in his room.

NormalNo, I can’t put it there.
No, I do not find one here.
Yes, I like them very much.
No, I don’t play outside a lot.
No, I do not smile often.
No, but I will work tomorrow.
Yes, I often laugh.
No, but I can tell it later.
No, I can’t walk today.
No, I don’t enjoy it there.
Yes, I can bring it there.
Yes, I can carry it now.
No, I can’t speak here.
Yes, I will fight here.
Yes, I do.
No, but I can send it later.
No, I don’t talk a lot.
Yes, I really love her.
Yes, I sleep a lot.
No, I don’t often meet her.
You must begin the test at 9.
John can come here.
Some problems still remain here.
You can stop the battle.
You can break the glass.
You can lay your bag there.
I can grow flowers here.
Plants can’t exist without water.
I can move the car.
Accidents often happen here.
John lives here.
We start examinations on Monday.
They will die in the game.
You can open the window.
You can change your hairstyle.
The news will appear on TV.
The game lasts till 5.
You can close the door.
You can increase its price.
The sound will occur soon.
He thinks carefully.
They often happen there.
It sometimes occurs there.
He speaks carelessly.
He smiles on purpose.
He will open it carefully.
He laughs on purpose.
It changes a lot.
He plays there willingly.
It still remains there.
He works hard.
It appears quickly.
He walks cautiously.
It begins now.
He talks carefully.
They always grow quickly.
He sleeps there willingly.
It will stop soon.
It moves slowly.
He fights cautiously.
It will be a long game.
He is a famous thinker.

r2442 rAnomalous
No, I can’t put there.
No, I do not find here.
Yes, I like very much.
No, I play not outside a lot.
No, I smile not often.
No, but I can tell later.
No, I walk not today.
No, I don’t enjoy there.
Yes, I can bring there.
Yes, I can carry now.
No, I speak not here.
Yes, I often think about.
No, I can’t send.
No, I talk not a lot.
Yes, I really love.
No, I don’t often meet.
You can come John.
You can remain some problems here.
You can lie your bag there.
You cannot exist plants without water.
You may happen accidents here.
You live John.
You can die them in the game.
You will appear the news on TV.
You can last the game.
You can occur the sound.
They happen carefully.
It will occur hard there.
It will open carefully.
It changes carelessly
It remains there carelessly.
It appears on purpose.
It begins cautiously.
They grow carefully.
It will stop willingly.
It moves carefully.
It will be a long laster.

r Distinct Roles of Frontal Regions in L2 Acquisition r

TABLE I. (continued)
Associated sentence
Key sentence

NormalThis rose grows in the garden.
John often speaks in the class.
John often dances on the stage.
John starts the train.
John often swims in the sea.
He will drop the bookJohn plays in the park.
John might die soon.
John works at the hospital.
Many car crashes happen at the corner.
John is beginning the card game of poker.
John walks to school.
Some food still remains in the house.
John often talks in the city hall.
John often sleeps on the street.
John stops the battle.
John is fighting in the war.
John moves the car.
John often comes to my house.
I am famous in this hospital.
John might tell the news at school.
John stopped the train at the station.
John begins the game here.
John is kind in the class.
Spotty finds a cake in the kitchen.
You are good at school.
John works in this hospital.
John thinks in his room.
Do you believe in Santa Claus?
We have bad weather in this town.
John is starting the computer game.
John is beginning the card game of poker.
John grows a rose.
I want to buy a violin.
I want to buy a new car.
John speaks English very well.
There once was an old man in the village.
There was no solution to this problem.

It is a nice flower.
He is a good speaker.
He is a famous dancer.
It is a slow train.
He is a good swimmer.
It is a heavy book.
He is a happy player.
It will be an early death.
He is a good worker.
They are terrible accidents.
It is a quiet game.
He is a fast walker.
It is a secret stock.
He is a nice talker.
He is a street sleeper.
It is a hard battle.
He is a strong fighter.
It is a quiet car.
He will come to my house.
I am a famous doctor.
He will tell it at school.
He will start it soon.
He begins it now.
He is a kind teacher.
He finds it quickly.
You are a good student.
He works very much.
He always thinks.
Santa Claus really exists.
We can’t change the weather.
He is a quiet starter.
He is a real beginner.
He is a famous grower.
We can play this violin like this.
We must keep new cars inside.
He can speak French, too.
There once lived an old man in the village.
There exists no solution to this problem even now.

MATERIALS AND METHODS
Participants
Thirty native Japanese speakers aged from 12 to 17 participated in two groups: late learners and early learners.
All of the participants had studied English as L2 in Japanese schools, and the L2 knowledge referred to here was
acquired in a formal school environment alone. The latelearners were 18 students (10 females and eight males,
ages at the time of retesting: 14.1–17.3 years, mean 6 SD:
15.1 6 1.2) from the Secondary Education School Attachedto the Faculty of Education of the University of Tokyo,
and their AOEs were 12.6 6 0.2. The early learners were
12 students (eight females and four males, ages: 12.3–16.4
years, 14.3 6 1.7) from Gyoshu Junior & Senior HighSchool (Numazu-shi, Japan) who had participated in an
English immersion program, and their AOEs were 5.6 6r

Anomalous
It is a nice grower.
It is a slow starter.
It is a heavy dropper.
He will be an early dier.
They are terrible happeners.
It is a quiet beginner.
It is a secret remainer.
It is a hard stopper.
It is a quiet mover.
Soon will come.
Am a famous doctor.
He will tell at school.
Soon will start it.
He begins now.
Is a kind teacher.
He finds quickly.
Are a good student.
Very much works.
Always thinks.
We can exist Santa Claus.

This violin can play like this.
New cars must keep inside.
Can speak French, too.

0.9. Informed consent was obtained from all participants
as well as from their parents/guardians. The study wasapproved by both the schools and by the institutional
review board of the University of Tokyo, Komaba.
The late learners received 10 sessions of classroom training at school within 1–2 months, in which the correct usageof English verbs was tested with 10 examples for eachsession. Each example consisted of a key sentence followedby its associated two sentences, one of which contained a
syntactic error in some cases (see Table I for 100 sets of a
key sentence and its associated sentences with or without asyntactic anomaly). The students first tried to guess
their grammaticality, and a teacher then provided themwith the correct answers and a brief explanation. They
further underwent two test sessions: Test 1 and Test 2,
which refer to the fMRI measurement before and after
the training, respectively. A new set of sentences with the2443 rr Sakai et al. rsame English verbs was used for Test 2 to ensure whether
they had actually acquired the knowledge of syntactic structures, rather than merely memorizing the sentence examples
used for Test 1 and the training. The early learners underwent a single fMRI measurement without any special training or instruction regarding English verbs.

Stimuli and Tasks
For the training and fMRI sessions, we selected 42 highfrequency English verbs (20 transitive and 22 intransitive,
including 12 unergatives and 10 unaccusatives [Yusa, 2003])
and made 200 sets of sentences using these verbs, 100 each
for Test 1 and Test 2 (Table I). The same words includingthese verbs were used for the two Tests but with different
word combinations. In each trial of the fMRI experiments,
stimuli in yellow letters against a dark background werevisually presented. For fixation, a red cross was always
shown at the center of the screen. The stimulus presentation
and behavioral data collection were controlled using LabVIEW software and interface (National Instruments, Austin,
TX). The participants wore earplugs and an eyeglass-like
MRI-compatible display (resolution: 800 3 600) (VisuaStim
XGA, Resonance Technology, Northridge, CA).
At the initiation of every trial of 7 s, the word ‘‘Syntax’’(Esyn) or ‘‘Spelling’’ (Espe) was presented as a cue for 400
ms, signaling the beginning of the task to be performed.
Next, a set of two English sentences (Table I) were shownfor 6,400 ms. The participants read the two sentencessilently and indicated whether or not the sentences contained an error by pushing one of two buttons within
6,400 ms. The tasks were conducted in a block design, andfive trials were tested in each of the Esyn and Espe blocks(35 s). Individual trials were regarded as independent
events, and only trials with correct responses were used
for analyses of RTs and activations. Japanese (L1) versionsof both tasks, that is, Jsyn and Jspe, were also conductedin separate blocks of five trials each. The sequence of a single fMRI run was in the order of either Jsyn-Espe-EsynEspe-Jspe or Jspe-Espe-Esyn-Espe-Jsyn, and their order
was counterbalanced across the participants. It might bepossible that switching between two languages exerted adifferential impact on the late and early learners, but it
was advantageous to control general conditions within thesame runs. Moreover, negative transfer effects of syntactic
knowledge from L1 to L2, if any, can be controlled byEspe that separated Esyn from Jsyn and Jspe. For each participant, 10 fMRI runs were carried out in a single day.

horizontal slices (each 6 mm thick and having a 1-mm
gap, covering z 5 249 to 62 mm). We set the timing of thefirst slice acquisition to 4,700 ms after the onset of sentence
stimuli, so that most of the task period was silent (i.e.,
without scanner noise). Group analyses were performed
using SPM5 statistical parametric mapping software (Wellcome Department of Imaging Neuroscience, London, UK).
We realigned the functional volume data in multiple runs,
and removed runs that included data with a translation of>2 mm in one of the three directions and a rotation of>1.48. Each individual brain was spatially normalized tothe standard brain space as defined by the Montreal Neurological Institute (MNI), resampled every 3 mm using
trilinear interpolation, and smoothed with an isotropic
Gaussian kernel of 9 mm full width at half maximum.
Low-frequency noise and global changes in activity were
further removed. The acquisition timing of each slice wascorrected using the first slice as a reference for the functional imaging data. By using event-related canonicalhemodynamic response functions, activations during thepresentation of sentence stimuli were analyzed. For random effects analyses, a contrast image was generated foreach participant and used for intersubject comparisons.
We used a high stringent task contrast of Esyn 2 Espe or
Jsyn 2 Jspe, and thus adopted a two stage procedure established in a previous study [Crinion et al., 2006], startingwith a whole brain search using a liberal statistical threshold for the voxel level (uncorrected P < 0.005). An inclusive
mask of Esyn/Jsyn (uncorrected P < 0.05) or Esyn 2 Espe
(uncorrected P < 0.05 for correlation analyses and groupcomparisons) was applied to eliminate any deactivation
under the reference condition. To exclude a false positive
activation, we then focused on effects that replicated across
our present and previous fMRI studies and used a small
volume correction (SVC) at the level of corrected P < 0.05
(16 mm radius for the late learners and 10 mm radius forthe early learners, depending on the number of participants). The center coordinates for the SVC are described in
the Tables III, IV, and V. For independent replication of the
fMRI data between the late and early learners, the combined probability of observing the same region in eachgroup was less than uncorrected P 5 2.5 3 1025, corresponding to a Z score of 4.1. Statistical significance of correlation between the task performances and activations (parameter estimates) at a local maximum of activation was
further confirmed using Spearman’s rank correlation, whichis resistant to outliers, that is, high leverage points.

RESULTSfMRI Data Acquisition and Analyses
The fMRI scans were conducted using a 1.5 T MRI system (STRATIS II, Premium; Hitachi Medical Corporation,
Tokyo, Japan). Using a gradient echo echo-planar imaging
sequence (repetition time 5 7 s, acquisition time 5 1850
ms, echo time 5 50.5 ms, flip angle 5 908, field of view 5
192 3 192 mm2, resolution 5 3 3 3 mm2), we scanned 16r

Behavioral Data
Behavioral data for the Esyn and Espe tasks are shownin Figure 1A and Table II. The late learners consistently
showed significant improvement from Test 1 to Test 2 inboth tasks. According to a repeated-measures analysis ofvariance (rANOVA) with task [Esyn, Espe] 3 test session

2444 r

r Distinct Roles of Frontal Regions in L2 Acquisition r

Figure 1.
Performance data in L2 for the late and early learners. A: Accuracy of the Esyn and Espe tasks. The performance data for Test
1 (before training) and Test 2 (after the training) are shown separately for the late learners; the early learners underwent no
training for the present study. Error bars denote standard errors
among the participants. Asterisks indicate the statistical significance (t-test, P < 0.005). N.S., not significant (P > 0.2). B: Correlation of the performance data for the late learners. The accuracy of Esyn for Test 2 correlated significantly with that of Espe
for Test 2 among the late learners.

among the late learners for Test 2 (r 5 0.77, Spearman
rank correlation coefficient: rs 5 0.71, P 5 0.003; Fig. 1B).
The correlation between the accuracy of Esyn and Espe for
Test 1 was marginally significant (r 5 0.50, rs 5 0.45, P 5
0.070), and the correlation between the accuracy of Esyn
and Espe for the early learners was also marginally significant (r 5 0.45, rs 5 0.56, P 5 0.065). These results suggestthat the training for the late learners enabled them to effectively acquire the L2 knowledge of both syntax and spellings.
After the training, the accuracy of the Esyn and Espe
tasks for the late learners became equally high with thatfor the early learners (Fig. 1A). According to an rANOVA
with task 3 group [early learners, late learners for Test 2],
the accuracy data showed a significant main effect of task
(F(1, 28) 5 114, P < 0.0001), but neither a significant main
effect of group (F(1, 28) 5 1.1, P 5 0.3) nor a significant
interaction (F(1, 28) 5 0.2, P 5 0.7). The RTs also showeda significant main effect of task (F(1, 28) 5 27, P < 0.0001),
but neither a significant main effect of group (F(1, 28) 5
0.2, P 5 0.7) nor a significant interaction (F(1, 28) 5 0.3,
P 5 0.6). These results indicate that the task performanceswere matched between the two groups after the training.
For the early learners, the correlation between the accuracy
and RTs of Esyn was not significant (r 5 0.02, rs 5 0.12,
P 5 0.7), but the negative correlation between the accuracy
and RTs of Espe was significant (r 5 20.65, rs 5 20.59,
P 5 0.05).
Behavioral data for the Jsyn and Jspe tasks are shown in
Table II. The late learners showed improvement from Test
1 to Test 2 in both tasks, but this effect was simply due torepeating the same tasks. According to an rANOVA withtask [Jsyn, Jspe] 3 test session [Test 1, Test 2], the accuracy
data showed significant main effects of task (F(1, 17) 5 9.3,
P 5 0.007) and test session (F(1, 17) 5 16, P 5 0.001) withno significant interaction (F(1, 17) 5 0.7, P 5 0.4). The RTs
also showed a significant main effect of test session (F(1,17) 5 29, P < 0.0001), but neither a significant main effect
TABLE II. Behavioral data for each groupand task condition
Accuracy (%)
Group[Test 1, Test 2], the accuracy data showed significant main
effects of task (F(1, 17) 5 69, P < 0.0001) and test session(F(1, 17) 5 35, P < 0.0001) with no significant interaction(F(1, 17) 5 0.1, P 5 0.7). The RTs also showed significant
main effects of task (F(1, 17) 5 25, P 5 0.0001) and test
session (F(1, 17) 5 25, P < 0.0001) with no significant interaction (F(1, 17) 5 0.009, P 5 0.9). For Test 2, however, thecorrelation between the accuracy and RTs of Esyn was not
significant (r 5 0.08, rs 5 0.22, P 5 0.4), and neither was
the correlation between the accuracy and RTs of Espe (r 520.36, rs 5 20.33, P 5 0.2). On the other hand, the accuracy of Esyn correlated significantly with that of Espe

r

Esyn

Espe

RTs (ms)
Esyn

Espe

Late learners, 52.3 6 8.0 69.3 6 15.9 4,414 6 588 4,137 6 524
Test 1
Late learners, 63.5 6 10.7 81.6 6 13.3 3,753 6 570 3,468 6 476
Test 2
Early learners 66.6 6 12.1 86.4 6 7.4 3,876 6 478 3,525 6 681
Jsyn
Early learners 89.2 6 7.4
Late learners, 89.8 6 8.0
Test 1
Late learners, 95.5 6 4.3
Test 2

Jspe

Jspe

3,507 6 619 3,485 6 639
3,707 6 513 3,671 6 409

88.6 6 8.5

3,037 6 563 3,105 6 649

Data are shown as mean 6 SD.

2445 rJsyn

83.7 6 7.9
84.7 6 9.8

r Sakai et al. rof task (F(1, 17) 5 0.05, P 5 0.8) nor a significant interaction (F(1, 17) 5 0.65, P 5 0.4). At the time of the first testing, the performances of the Jsyn and Jspe tasks were comparable between the late and early learners. According toan rANOVA with task 3 group [early learners, late learners for Test 1], the accuracy data showed a significant
main effect of task (F(1, 28) 5 7.3, P 5 0.01), but neither asignificant main effect of group (F(1, 28) 5 0.1, P 5 0.7)
nor a significant interaction (F(1, 28) 5 0.01, P 5 0.9). The
RTs showed neither significant main effects of task (F(1,28) 5 0.2, P 5 0.6) and group (F(1, 28) 5 1.0, P 5 0.3) nor
a significant interaction (F(1, 28) 5 0.01, P 5 0.9). These
results further confirm the matched general performances
between the two groups.

RTs of Esyn at the coordinates (239, 27, 212) of the left F3O(r 5 0.72, rs 5 0.68, P 5 0.0049; Fig. 2F), as well as at (239,275, 33) of the left AG (r 5 0.86, rs 5 0.82, P 5 0.0007; Fig.
2G). No significant activation showed negative correlation
with the accuracy or RTs of Esyn. Here it is interesting tonote that L1-related activation in Jsyn 2 Jspe was observedin the left LPMC and F3t as well as in the bilateral MTG (Fig.
2H, Table III). For this analysis, data for both Test 1 and Test
2 were combined to enhance the consistent activation. Furthermore, the direct comparison between L2 and L1 (i.e.,
Esyn 2 Espe vs. Jsyn 2 Jspe for Test 2) revealed significant
activation in the left dF3t (Fig. 2I). These results clearly indicate the critical roles of the left dF3t, F3O, and AG in L2.

Task-Selective Activation Patterns
for the Early Learners

Task-Selective Activation Patterns for
the Late Learners
Cortical activations selective to the Esyn task were identified by the contrast of Esyn 2 Espe, separately for Test 1
and Test 2 (Fig. 2A,B and Table III). For Test 1, the activation was scattered in both hemispheres, including the leftlateral premotor cortex (LPMC, BA 6), the pars orbitalis(F3O, BA 47) of the left IFG, two separated regions in theleft angular gyrus (AG, BA 39), and the left middle temporal gyrus (MTG, BA 21). The bilateral postcentral gyrus
and parietal operculum (BA 43) also showed activation
which was not directly related to linguistic functions. For
Test 2, however, it is striking to observe that the activation
clearly localized in the left hemisphere, and that the significant activation emerged in the left dF3t [(x, y, z) 5 (254,
24, 21); a yellow circle in Fig. 2B], in addition to the language-related regions of the left F3O, AG, and MTG. These
results suggest that the left dF3t is a region most cruciallyinvolved in training to understand syntactic structures,consistent with our hypothesis that this region subserves
syntactic processing.
Next, we tested whether or not the left dF3t activations
predicted the extent to which each individual participant
improved his/her knowledge of syntax in L2 after the
training (i.e., Test 2). We found that the left dF3t activations in Esyn showed a significant correlation with the accuracy of Esyn (Fig. 2C, Table III). At the coordinates(257, 24, 15) of the left dF3t, the activations in Esyn correlated significantly with the accuracy of Esyn (r 5 0.68, rs 5
0.54, P 5 0.026; Fig. 2E). Regarding activations in Esyn 2
Espe, both the left dF3t [(248, 27, 18), Z 5 2.4, uncorrected
P 5 0.008] and ventral F3t (vF3t) [(251, 27, 26), Z 5 2.6,
uncorrected P 5 0.010] showed a positive correlation justbelow the threshold. The modulation of the left F3t activation cannot be explained merely by task difficulty or otherdomain-general factors, because the easier the Esyn task
became the more strongly the left F3t was activated.
In contrast, a correlation analysis with the RTs of Esyn
(Test 2) revealed significant activation in the left F3O (awhite circle in Fig. 2D) and AG (a red circle in Fig. 2D). The
activations in Esyn 2 Espe correlated significantly with ther

In spite of the matched task performances of the latelearners (Test 2) and the early learners (Fig. 1A), the earlylearners showed strikingly different modulation patternsof activations. In Esyn 2 Espe, we observed significant
activation in the left F3O (a white circle in Fig. 3A, Table
IV), but not in the left F3t. The left F3O activation whichcentered on the coordinates (245, 36, 29), coincides with
(245, 30, 215) as reported in our recent study of L1 [Sakai
et al., 2005]. In Jsyn 2 Jspe, the left AG and MTG weresignificantly activated for the early learners (Fig. 3B); theleft MTG activation was consistent with that for the latelearners (Fig. 2H). On the other hand, no significant activation showed positive correlation with the accuracy or RTs
of Esyn. A correlation analysis in Esyn 2 Espe with the accuracy of Esyn as a negative regressor, however, revealed
a significant activation in the left vF3t (a yellow circle inFig. 3C, Table IV). The left vF3t activation, which centeredon the coordinates (242, 27, 0), also coincides with (251,24, 23) as reported previously [Momo et al., 2008]. At thecoordinates (242, 27, 0) of the left vF3t, activations in
Esyn 2 Espe correlated negatively with the accuracy ofEsyn (r 5 20.76, rs 5 20.73, P 5 0.015; Fig. 3E), and so
did the activations in Esyn (r 5 20.62, rs 5 20.61, P 5
0.044). In accordance with our previous study [Tatsuno
and Sakai, 2005], this proficiency-dependent negative correlation suggests that the syntactic knowledge may havebeen consolidated in the left vF3t for the early learners.
In contrast, a correlation analysis in Esyn 2 Espe with
the RTs of Esyn as a negative regressor revealed a significant activation in the left AG (a red circle in Fig. 3D). At
the coordinates (254, 257, 36) of the left AG, activationsin Esyn 2 Espe correlated negatively with the RTs of Esyn(r 5 20.84, rs 5 20.81, P 5 0.0071; Fig. 3F). The coordinates were anterolateral to those observed for the latelearners with the RTs of Esyn as a positive regressor (Fig.
2D). Because the left AG was activated in Jsyn 2 Jspe forthe early learners (Fig. 3B), more efficient processing in L2
with shorter RTs, which corresponded to more activations
for the early learners, may be extrapolated to linguistic
processing in L1.

2446 r

r Distinct Roles of Frontal Regions in L2 Acquisition r

Figure 2.
Task-selective activation patterns for the late learners (Table III). activations in Esyn at the left dF3t and the accuracy of Esyn for
A: Regions showing activation in Esyn 2 Espe for Test 1. The Test 2. Each filled dot represents a late learner. F: Significant
regions are projected onto a standard brain (L, left). B: Regions correlation between activations in Esyn 2 Espe at the left F3O
showing activation in Esyn 2 Espe for Test 2. Note the promi- and the RTs of Esyn for Test 2. G: Significant correlation
nent activation of the left dF3t (yellow circle), which is absent in between activations in Esyn 2 Espe at the left AG and the RTs
Fig. 2A. C: Regions showing activation in Esyn for Test 2, corre- of Esyn for Test 2. H: Regions showing activation in Jsyn 2 Jspe
lated with the accuracy (Acc) of Esyn for Test 2. Note the acti- for both Test 1 and Test 2. Activation of the left MTG (purple
vation of the left dF3t (yellow circle). D: Regions showing activa- circle) matches that in Fig. 2A, B. I: Regions showing activation
tion in Esyn 2 Espe for Test 2, correlated with the RTs of Esyn in (Esyn 2 Espe) 2 (Jsyn 2 Jspe) for Test 2. Activation of thefor Test 2. Note the prominent activation of the left F3O (white left dF3t (yellow circle) matches that in Fig. 2B,C.
circle) and AG (red circle). E: Significant correlation betweenr2447 rr Sakai et al. r

TABLE III. Activated regions for the late learners
Brain region

BA

Side

x

y

z

Z

x

y

z

SVC
Esyn 2 Espe: Test 1
LPMC
6
L
233
6
39 4.0 239
6
L
248
29
39 3.8 239
3
F3O
47
L
242
12 212 3.1 245
24
AG
39
L
254 251
21 4.3 251 260
39L
242 263
24 4.2 251 260
MTG
21L
266 239
3 3.9 254 242
Esyn 2 Espe: Test 2
dF3t
45
L
254
24
24 3.6 254
27
F3O
47
L
233
27
29 3.1 245
24
AG
39
L
239 272
33 3.1 245 275
MTG
21
L
254 245
6 3.7 254 242
Esyn: Test 2
Regressor: Acc (Esyn)
dF3t
45
L
257
24
15 3.1 254
27
Esyn 2 Espe: Test 2
Regressor: RTs (Esyn)
F3O
47
L
236
18 221 3.6 245
24
AG
39
L
239 275
33 4.5 245 275
Jsyn 2 Jspe: Test 1 1 Test 2
LPMC
6
L
242
12
48 3.8 239
3
F3t
45
L
251
21
9 3.0 254
27
MTG
21
L
251 239
0 3.2 254 242
21
R
54 2450 3.8
66 236(Esyn 2 Espe) 2 (Jsyn 2 Jspe): Test 2
dF3t
45
L
248
24
27 2.7 254
27

36a
42a
29b
27c
27c
3d

20.48, P 5 0.1; Fig. 4E). In contrast, a differential correlation analysis in Esyn 2 Espe with the RTs of Esyn resulted
in a significant activation in the left F3O (a white circle inFig. 4D) and the two separated regions in the left AG. At
the coordinates (233, 33, 215) of the left F3O, activationsin Esyn 2 Espe also correlated differentially between thelate and early learners with the RTs of Esyn (late learners:
r 5 0.64, rs 5 0.49, P 5 0.042; early learners: r 5 20.46, P
5 0.1, rs 5 20.36, P 5 0.2; Fig. 4F). These results fromdirect group comparisons further clarify the distinct functional roles of the left F3t and F3O in L2 acquisition.

21a
29b
36c
3d
21a
29b
36c
42a
21a
3d
3b
21a

a

[Hashimoto and Sakai, 2002].
[Homae et al., 2003].
c[Sakai et al., 2005].
d[Suzuki and Sakai, 2003].
Stereotactic coordinates (x, y, z) in the MNI space are shown foreach activation peak of Z values.
Acc, accuracy; AG, angular gyrus; BA, Brodmann’s area; F3O, orbital
part of the inferior frontal gyrus; F3t, triangular part of the inferior
frontal gyrus (d, dorsal; v, ventral); L, left hemisphere; LPMC, lateral
premotor cortex; MTG, middle temporal gyrus; RTs, reaction times.
b

Direct Comparisons Between the Lateand Early Learners
Because some contrasting results were obtained between
the late (Test 2) and early learners, we further performed
direct group comparisons in Esyn 2 Espe. First, the latelearners showed significantly more enhanced activation in
the left dF3t (Fig. 4A, Table V) than the early learners,
which strengthens the main results obtained for the latelearners. Moreover, when both groups were combined,
consistent activation in Esyn 2 Espe was observed in theleft LPMC and F3O, in addition to the left AG and MTG(Fig. 4B). A differential correlation analysis in Esyn 2 Espe
with the accuracy of Esyn as a positive regressor for thelate learners and as a negative regressor for the earlylearners revealed a significant activation in the left vF3t
alone (a yellow circle in Fig. 4C). At the coordinates (251,27, 0) of the left vF3t, activations in Esyn 2 Espe correlated differentially between the late and early learners
with the accuracy of Esyn (late learners: r 5 0.48, rs 5
0.54, P 5 0.025; early learners: r 5 20.63, P 5 0.03, rs 5

r

DISCUSSION
The results obtained for the two groups of L2 learners in
a formal school environment are novel and striking in two
respects. First, we found significant correlations between
activations in multiple cortical regions and individual performances that were specifically related to syntactic structures of sentences. Second, regarding the second aim of
the present study, the different AOE of the late and earlylearners actually affected activations during syntactic decision. More specifically, activations of the left dF3t (Fig.
2C,E) and vF3t (Fig. 4C,E) correlated positively with theaccuracy of the Esyn task for the late learners, whereas
activations of the left vF3t correlated negatively with thatfor the early learners (Figs. 3C,E and 4E). It should be
noted that this group difference in brain activations wasobserved even when the testing ages and task performances of both groups were matched, with overall developmental and educational differences controlled by the Espe
task. On the basis that cortical activation increases initiallyat the onset of L2 acquisition, followed by a reduction in
activation during the consolidation of linguistic competence [Sakai, 2005], we speculate that the functional development of the left F3t was in an initial stage for the latelearners and in a more advanced stage for the early learners. In contrast, other cortical regions exhibited differential

TABLE IV. Activated regions for the early learners
Brain region

BA

Side

x

y

z

Z

x

y

z

SVC
Esyn 2 Espe
F3O
Jsyn 2 Jspe
AG
MTG
Esyn 2 Espe
vF3t
Esyn 2 Espe
AG
a

47

L

245

30

215a

39
21

L
L

27a
3b

45

L

39

L

260 18 2.9 251 260
239
0 2.7 254 242
Regressor: Acc (2Esyn)
242
27
0 2.9 251
24
Regressor: RTs (2Esyn)
254 257 36 3.4 251 260[Sakai et al., 2005].
[Suzuki and Sakai, 2003].
c[Momo et al., 2008].
b

2448 r

242
254

36

29

3.0

245

23c
27a

Figure 3.
(legend on page 2450)

Figure 4.
(legend on page 2450)

r Sakai et al. r

TABLE V. Activated regions for the late (Test 2)
and/or early learners
Brain region BA Side

x

y

z

Z

x

y

z

SVC
Esyn 2 Espe: Late 2 Early
dF3t
45
L
251
Esyn 2 Espe: Late 1 Early
LPMC
6
L
245
F3O
47
L
242
AG
39
L
239
MTG
21
L
245
Esyn 2 Espe: Late 2 Early
vF3t
45
L
251
Esyn 2 Espe: Late 2 Early
F3O
47
L
236
AG
39
L
236
39
L
248

27
9
27
269
245
27
33
275
263

24 3.1 254

27

21a

45 3.1 239
342a
29 4.0 245
30 215b36 3.5 245 275
36b
6 3.8 254 242
3cRegressor: Acc (Esyn)0 3.0 251
24 23dRegressor: RTs (Esyn)
215 2.9 245
30 215b33 4.3 245 275
36b
33 2.6 251 260
27ba[Hashimoto and Sakai, 2002].
[Sakai et al., 2005].
c[Suzuki and Sakai, 2003].
d[Momo et al., 2008].
b

correlation patterns with the RTs of the Esyn task. Namely,
activations of the left F3O, as well as those of the left AG,
correlated positively with the RTs for the late learners (Fig.
2D,F,G), whereas those activations correlated negatively
with the RTs for the early learners (Figs. 3D,F and 4D,F).
Moreover, the task-selective activation of the left F3O wasmaintained for both the late and early learners (Figs. 2A,B,
3A, and 4B). These results explain individual differences in
L2 acquisition, such that the acquisition of linguisticknowledge in L2 is subserved by at least two distinct inferior frontal regions of the left F3t and F3O.

Functional specialization in the left IFG has been extensively examined by recent human brain mapping studies.
Accumulating evidence has indicated that the left F3op,
dF3t, vF3t, and LPMC are all specialized in syntactic processing [Dapretto and Bookheimer, 1999; Embick et al.,
2000; Friederici et al., 2000; Kinno et al., 2008; Momo et al.,2008; Musso et al., 2003; Stromswold et al., 1996; Suzuki
and Sakai, 2003]. The left LPMC is located at the junctionof the precentral sulcus and the inferior frontal sulcus, justdorsal to the left F3op/F3t, and this region was also activated in the present study (Figs. 2A,H and 3B). Recent
fMRI studies have also tried to specify the function of thisregion during sentence processing including the operationof movement [Ben-Shachar et al., 2004], syntactic linearization [Grewe et al., 2005], and processing of string patterns[Friederici et al., 2006]. We have previously demonstrated
that these regions showed prominent activation for syntactic
decision tasks even when they were directly compared withverbal short-term memory tasks [Hashimoto and Sakai,
2002]. The activation of the left LPMC and F3op/F3t is thus
related to the process of analyzing syntactic structures,
which cannot be explained either by task difficulty or byverbal short-term memory components. On the other hand,
we have reported that the left F3t/F3O is specialized in theselection and integration of semantic information within
sentences as revealed by a direct comparison of cortical activation during sentence comprehension tasks and lexical decision tasks under both auditory and visual conditions[Homae et al., 2002, 2003]. Moreover, we have recently clarified that the left F3t/F3O activation is indeed selective tosentence comprehension, irrespective of the modalities ofsign and speech [Sakai et al., 2005]. These results indicate
an essential and universal role of the left F3t/F3O, which
subserves sentence comprehension [Sakai, 2005].

Figure 3.
Task-selective activation patterns for the early learners (Table vF3t (yellow circle). D: Regions showing activation in Esyn 2IV). A: Regions showing activation in Esyn 2 Espe. Activation of Espe, correlated negatively with the RTs of Esyn. Note the actithe left F3O (white circle) matches that in Fig. 2A,B,D. B: vation of the left AG (red circle). E: Significant negative correlaRegions showing activation in Jsyn 2 Jspe. Note the activation tion between activations in Esyn 2 Espe at the left vF3t and theof the left AG (red circle) and MTG (purple circle). C: Regions accuracy of Esyn. Each open dot represents an early learner. F:
showing activation in Esyn 2 Espe, correlated negatively with Significant negative correlation between activations in Esyn 2
the accuracy of Esyn. Note the prominent activation of the left Espe at the left AG and the RTs of Esyn.
Figure 4.
Task-selective activation patterns for the late (Test 2) and/or vF3t (yellow circle), consistent with that in Fig. 3C. D: Regions
early learners (Table V). A: Regions showing activation in Esyn 2 showing activation in Esyn 2 Espe for the group comparison ofEspe for the group comparison of Late 2 Early. Note the promi- Late 2 Early, correlated with the RTs of Esyn. Note the activation
nent activation of the left dF3t (yellow circle), consistent with of the left F3O (white circle) and AG (red circles), consistentthat in Fig. 2B,C,I. B: Regions showing activation in Esyn 2 Espe with that in Figs. 2D and 3D. E: Significant correlation between
for combining both groups, that is, Late 1 Early. Note the promi- activations in Esyn 2 Espe at the left vF3t and the accuracy ofnent activation of the left F3O (white circle), consistent with that Esyn. Each filled dot represents a late learner, whereas each open
in Figs. 2A,B,D and 3A. C: Regions showing activation in Esyn 2 dot represents an early learner. F: Significant correlation between
Espe for the group comparison of Late 2 Early, correlated with activations in Esyn 2 Espe at the left F3O and the RTs of Esyn.
the accuracy of Esyn. Note the prominent activation of the leftr2450 r

r Distinct Roles of Frontal Regions in L2 Acquisition r

The detailed results obtained in the present study indicate more precise nature of the distinct functional roles ofthe frontal regions proposed above, namely, syntax (e.g.,building syntactic structures) in the left F3t and sentencecomprehension (e.g., reading off the meanings from thesyntactic structures) in the left F3O. The syntactic knowledge tested here may have been consolidated for the earlylearners, thus leading to the negative correlation between
the left vF3t activations and the accuracy of Esyn (Fig.
3C,E). Note, however, that some individuals in this groupstill showed the low accuracy of Esyn. In contrast, acquiring the ability of sentence comprehension usually takes
longer and requires more elaborative processes, because
sentence comprehension involves understanding not only
the literal meanings of sentences but also their hidden
meanings—‘‘reading between the lines.’’ RTs for bilinguals
might reflect differences in L2 proficiency, but the accuracy and RTs of Esyn showed no correlation at all forboth the late and early learners (see Behavioral Data).
The positive correlation between the left F3O activations
and the RTs of Esyn among the late learners (Figs. 2D,F
and 4D,F) suggests that the longer the sentences wereread the more the left F3O was utilized. Among the earlylearners, in contrast, the relationship between the activations and the RTs of Esyn was just reversed, such thatthe shorter the sentences were read the more efficiently
the left F3O and AG (Figs. 3D,F and 4D,F) were recruited.
It is thus possible that the cortical activations reflect theprocessing load itself for sentence comprehension, which
can be facilitated by the use of syntactic knowledge
required by the Esyn task. Unlike the left F3t, however,the left F3O activations were independent of the accuracyof Esyn itself. These results support the parallel processing of syntax in the left F3t and sentence comprehension
in the left F3O.
The activation of the left MTG both in L2 (Figs. 2A,B
and 4B) and in L1 (Figs. 2H and 3B) matches with its supporting role in sentence processing reported previously for
adult native speakers [Fiebach et al., 2005; Kinno et al.,2008; Momo et al., 2008; Suzuki and Sakai, 2003]. Moreover, the activation of the left AG basically paralleled thatof the left MTG in L2 and L1, further suggesting common
cortical mechanisms shared by L1 and L2. The activatedregions in Jsyn 2 Jspe, which included not only the left
LPMC, F3t, and MTG but also the right MTG (Fig. 2H),
replicated those in Sv 2 Pv (Sv: a sentence task under thevisual condition; Pv: a phrase task under the visual condition) reported previously in our fMRI study [Homae et al.,2003]. Furthermore, it is notable that the correlation of theleft AG activation with RTs of Esyn also paralleled that of
the F3O for both the late (Figs. 2D,G and 4D) and early(Figs. 3D,F and 4D) learners. The two separable regions in
the left AG (Figs. 2D, 3D, and 4D) correspond to activationfoci for sentence comprehension in visually presented Japanese Sign Language as well as in auditorily presented
Japanese [Sakai et al., 2005]. The activation modulation of
the left AG supports the proposal for its supporting role inrlexico-semantics [Sakai, 2005], which is essentially involved
in sentence comprehension subserved by the left F3O.
In the present study, the DOE of the early learners (8.7 61.7) was 6 years longer than that of the late learners (2.4 61.3), and their AOEs were also different. We found that theleft F3t activations on the Esyn task correlated positively
with the accuracy for the late learners at the initial stage ofL2 acquisition, whereas they correlated negatively for the
more experienced early learners, even if their testing ages
and task performances were matched. This result is consistent with our previous findings of the similar differential
activation patterns in the left IFG [Sakai et al., 2004; Tatsuno
and Sakai, 2005] (cf., the Introduction), in which the twoparticipant groups differed in 6 years of DOE, whereas their
AOEs were comparable. It is thus likely that the DOE effect,
which specifically interacts with sentence processing, ismore closely coupled with the left IFG activations than is
the AOE effect. One previous fMRI study reported that theleft IFG activation during grammatical judgments was
greater for participants at a later AOE than for those at an
earlier AOE, even when their high PLs were matched [Wartenburger et al., 2003]. However, our results indicate thatthe left IFG may show higher, lower, or comparable activation, depending on which stages of L2 acquisition are compared. It should also be noted that the groups’ mean DOE
to two languages in the study of Wartenburger et al. (2003)
differed by 16 years, and thus the differences between thosegroups might have disappeared if DOE had been equated.
Another fMRI study has suggested that DOE affects the left
IFG activation even if AOEs are comparable [Perani et al.,2003], which is consistent with the importance of DOE
noted above.
There are still remaining issues that were not addressedby the present study. First, further research is necessary to
determine whether the left IFG activation depends on exposure to a language at a particular stage of the developing brain, especially during the first several years. This
point is critical in order to clarify to what extent the L2 acquisition mechanisms are shared with L1 acquisition
mechanisms. Second, it remains unknown whether the L2
knowledge and use learned in EFL (English as a foreign
language) contexts examined here are identical to thoseacquired in ESL (English as a second language) contexts(e.g., in the United States). Notwithstanding these issues,
the present study clearly demonstrates that it is promising
to evaluate activations in a specific cortical region as adirect measure of L2 abilities in individual learners,
thereby opening new horizons for the neuroscience of
education.

ACKNOWLEDGMENTS
We thank T. Tsumoto for his encouragement, Y. Ochi, K.
Shiota, N. Saeki, and N. Komoro for their technical assistance, S. Matsukura and H. Matsuda for their administrative assistance.

2451 rr Sakai et al. r

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