The study recorded EEG signals simultaneously from the scalp and thalamus of 7 patients undergoing deep brain stimulation for essential tremor. The patients performed a go/no-go task where they had to either execute or withhold a cued finger movement based on subsequent go or no-go cues. Event-related potentials differentiated between go and no-go conditions earlier at thalamic recording sites compared to scalp sites, suggesting the thalamus is involved in early classification of go and no-go instructions. Correlations between thalamic and frontal scalp responses were stronger for no-go activities, indicating the thalamus provides information to frontal areas involved in inhibiting prepared actions. The findings support a role for the thalamus

1. The Human Thalamus is Crucially Involved
in Executive Control Operations
Frank Marzinzik, Michael Wahl, Gerd-Helge Schneider,
Andreas Kupsch, Gabriel Curio, and Fabian Klostermann
Abstract
& The processing of executive control is thought to involve prepared movement had to be performed or withheld. In fronto-
cortical as well as thalamic brain areas. However, the questions central scalp as well as in thalamic recordings, event-related
of how thalamic structures contribute to the control of be- potentials upon go versus no-go instructions were expressed
havior and how cortical versus thalamic processing is coor- differentially. This task effect was unrelated to motor processes
dinated remain to be settled. We therefore aimed at specifying and emerged significantly prior at thalamic than at scalp level.
respective activations during the performance of a go/no-go Amplitude fluctuations of depth and scalp responses showed
task. To this end, an electroencephalogram was recorded simul- site- and task-dependent correlations, particularly between thal-
taneously from scalp and thalamic electrodes in seven patients amic and no-go-related activities at frontal recording sites. We
undergoing deep brain stimulation. Meanwhile, left- or right- conclude that an early classification of go and no-go instruc-
directed precues were presented indicating with which index tions is performed already thalamically. It further appears that
finger a button press should be putatively executed. Thereafter, this information is subsequently utilized by cortical areas en-
2 sec elapsed until a go or no-go stimulus determined if the gaged in the definite inhibition of the prepared action. &
INTRODUCTION
cal regions (Behrens et al., 2003; also see Sherman &
Human behavior has to be constantly aligned with novel Guillery, 1996 for a review). Indeed, different authors re-
environmental conditions. One of the essential abilities ported on patients with thalamic infarctions, presenting
to exert such executive control is the inhibition of con- with variable executive control dysfunctions (Van der
textually unsuited actions (see Smith & Jonides, 1999; Werf et al., 2003; Mennemeier, Fennell, Valenstein, &
Norman & Shallice, 1986; Logan, 1985; Logan & Cowan, Heilman, 1992; Eslinger, Warner, Grattan, & Easton, 1991;
1984 for reviews). Based on clinical observations in Sandson, Daffner, Carvalho, & Mesulam, 1991). Partic-
brain-lesioned patients and on functional imaging stud- ularly concerning inhibitory control, functional imaging
ies, the processing of such adaptive functions is mostly studies demonstrated thalamic next to prefrontal activa-
allocated to frontal areas, in particular, the dorsolateral tions when prepared motor responses had to be sup-
prefrontal and anterior cingulate cortices (Carter et al., pressed (de Jong & Paans, 2007; Garavan, Ross, Murphy,
1998; D’Esposito et al., 1995; Petrides, Alivisatos, Meyer, Roche, & Stein, 2002). However, as functional imaging
& Evans, 1993; Shallice & Burgess, 1991; Pardo, Pardo, hardly specifies the timing of rapidly changing activa-
Janer, & Raichle, 1990). tions across different brain areas, it cannot be said how
With the spread of neuroanatomical models on cortico- and in which position the thalamus is involved in such
basal connectivity (see Alexander, Crutcher, & DeLong, operations.
1990 for a review), respective research questions addi- Exceptionally, this issue can be addressed by electro-
tionally focused on the impact of subcortical structures encephalography (EEG), if conventional scalp recordings
on diverse higher-order operations (Rieger, Gauggel, are combined with derivations from thalamic electrodes,
& Burmeister, 2003; Kramer, Reed, Mungas, Weiner, & for instance, in patients with deep brain stimulation (DBS;
Chui, 2002; Rafal & Posner, 1987; also see Basso, Uhlrich, Kuhn et al., 2004; Foffani et al., 2003; Marsden, Ashby,
& Bickford, 2005; Heyder, Suchan, & Daum, 2004; Royall Limousin-Dowsey, Rothwell, & Brown, 2000). Intriguingly,
et al., 2002 for reviews). In this regard, the human thal- this approach combines the high temporal resolution of
amus appears in a strategically critical position for its EEG with otherwise inaccessible spatial information. Of
extensive reciprocal connections with almost all corti- note in the present context, simultaneous recordings from
the scalp and the ventral intermediate nucleus (VIM) of
the thalamus have recently been performed in DBS pa-
Charite—University Medicine Berlin
´ tients, who engaged in a classical oddball task. The most
D 2008 Massachusetts Institute of Technology Journal of Cognitive Neuroscience 20:10, pp. 1903–1914

2. unexpected finding of this study was that thalamic event- in VIM. At this time, patients were without medication
related potentials (ERPs), differentially expressed upon and almost tremor-free due to the short-lived post-
target stimuli, emerged prior to analog ERPs at scalp level operative microthalamotomy effect (Kondziolka & Lee,
(Klostermann et al., 2006), suggestive of a central role of 2004).
thalamic processes in attentive behavior. The externalization phase serves to confirm the cor-
The timing of thalamic versus cortical operations re- rect electrode localization by MRI (which cannot be per-
lated to executive control has not been studied so far. formed with the implanted stimulator) and to assess the
We therefore recorded EEGs simultaneously from scalp (side) effects of DBS by a disconnectable external test
and thalamic electrodes in a number of DBS patients stimulator, so that unfavorable electrode placements
engaging in a go/no-go task. They had to execute versus could be corrected at this stage (no revisions necessary
inhibit previously cued finger movements. Go versus in the present group). After this test phase, the definite
no-go instructions are known to elicit differential ERPs, DBS stimulator is implanted in the subclavicular region
reflecting the time course of activations due to response and subcutaneously connected with the electrode leads
inhibition in fronto-cortically assumed areas (Bokura, (making electrode revisions thereafter more complex).
Yamaguchi, & Kobayashi, 2001; Kiefer, Marzinzik, Weisbrod, From this programmable stimulator, high-frequency
Scherg, & Spitzer, 1998; Strik, Fallgatter, Brandeis, & electrical impulses are continuously delivered to the
Pascual-Marqui, 1998). These go- and no-go-related scalp electrodes, modulating the function of the target area
responses were used as a reference for the simulta- which, in the case of tremor, is VIM (Schuurman et al.,
neously recorded thalamic ERPs. Thus, task-related am- 2000). Accordingly, ET was strongly reduced by VIM DBS
plitude and timing differences could be assessed for in the present group (tremor scores without/with DBS:
scalp versus thalamic sites in order to analyze how pro- 3.1 ± 0.3/0.7 ± 0.7; 0 = absent; 1 = mild, intermittent;
cesses at either level related to response inhibition as a 2 = moderate; 3 = markedly abnormal, interfering with
basic function of executive control. many activities; 4 = severely abnormal, interfering with
most activities; scale according to Fahn et al., 1993).
METHODS
Subjects Visual Go/No-go task
Seven patients (2 women, 5 men; 36–74 years) with es- Three hundred sixty visual trials were presented per
sential tremor (ET) participated in this study. They were patient. Each trial was initiated by the presentation of
cognitively unimpaired (Mini-Mental State: 29 ± 1.3 a warning cue for 200 msec, either as an arrow directed
out of 30 points, range 27–30, cutoff for suspected de- to the left or to the right. The direction of arrows indi-
mentia 23; Fillenbaum, Heyman, Williams, Prosnitz, & cated with which index finger a motor response should
Burchett, 1990) and had normal presurgical magnetic be prepared (Figure 1). After 1800 msec, the imperative
resonance imaging (MRI) scans. They underwent thera- cue appeared for further 200 msec, either as a go cue
peutic DBS of the thalamic VIM, known to suppress ET (green square), upon which the prepared movement
effectively (Schuurman et al., 2000). All patients gave had to be executed, or as a no-go cue (red square),
informed consent to the study protocol, which was ap- upon which it had to be withheld. Left versus right di-
proved by the local Ethics Committee. rected arrows and green versus red squares, respec-
During the first days after DBS electrode placement tively, occurred with probabilities of 50%. The resulting
(Day 4.1 ± 1), the patients engaged in a go/no-go task, four conditions ‘‘left-go,’’ ‘‘right-go,’’ ‘‘left-no-go,’’ and
while a scalp EEG was performed together with record- ‘‘right-no-go’’ appeared in randomized order, each com-
ings from the externalized leads of the DBS electrodes prising 90 trials.
Figure 1. Go/no-go paradigm.
Each task trial consisted
of the presentation of a
side-instructive precue
followed by either a go or
no-go instruction. Left- versus
right-directed instructions
and go versus no-go signals
appeared equiprobably in
randomized order. The 360
trials per session appeared
at intervals of 4 sec.
1904 Journal of Cognitive Neuroscience Volume 20, Number 10

3. All stimuli popped up within a 5 Â 5-cm2 frame, cen- bipolar derivations of 4.5 mm (1–3) and 7.5 mm width
tered in the middle of a 15-in. computer screen and (0–3), respectively (cf. Figure 2). By subtraction of De-
present during the entire presentation time. The pa- rivation 1–3 from Derivation 0–3, the upper 4.5 mm of
tients, sitting at 1.5 m distance, were instructed to look the recording trajectory could be differentiated from
at this frame also in-between trials (intertrial interval = the residual lower 3 mm, as the difference signal ap-
1800 msec) in order to avoid EEG artifacts from gross proximates the physical bipolar derivation over this
eye movements. caudal portion. This partitioning was done as the ori-
gins of task effects could thus be estimated. First, if an
effect was obtained only in one of the two recording
Thalamic Recordings
regions, a generation near to the sensitive derivation
Electrodes were implanted bilaterally into the VIM could be assumed (otherwise, the effect should project
(Medtronic electrode 3387). For electrode placement, into the upper and lower derivation, covering adjacent
standard VIM positions from the stereotactic brain atlas areas of few millimeters along the same trajectory).
by Schaltenbrand and Wahren (1977) were referred to Second, the lowest contact was targeted to the cau-
the individual AC–PC line (the straight sagittal connec- dal border of VIM, which demarcates this nucleus to
tion between the anterior and posterior commissures), nonthalamic structures, namely, the Zona incerta. Con-
exactly identified by intraoperative ventriculography. trarily, at its posterior, anterior, cranial, and medial
Standard coordinates were adjusted for each case with limits, VIM is surrounded by further thalamic nuclei.
respect to the individual thalamic height (15.3 ± 1 mm) Thus, effects generated in subthalamic regions adjacent
and AC–PC length (24.8 ± 1.5 mm), determined by to VIM should, first of all, project into the lower deriva-
matching presurgical stereotactic MRI with ventriculo- tion, whereas processes, generated more centrally in the
graphic data. The thus-calculated coordinates for the thalamus, will rather become discernible in the upper
lowest contact of the right/left VIM electrode (see be- derivation.
low), expressed as (i) anteriority to PC, (ii) laterality
to AC–PC, and (iii) verticality to AC–PC, were: (i) 7.2 +
Surface Recordings
0.4 mm/7 + 0.5 mm, (ii) 14.6 + 0.5 mm/14.5 + 0.5 mm,
and (iii) À0.1 + 0.4 mm/À0.2 + 0.6 mm (minus in- Scalp electrodes (Neuroscan system) were positioned
dicating below AC–PC). Postsurgical MRI confirmed at F3, Fz, F4, C3, Cz, C4, P3, Pz, and P4 according to
that the planned placements were met by the implanted the 10–20 system (impedances <5 k
) and referenced
electrodes. to linked mastoid electrodes. By this array, the typical
DBS electrodes consist of four ring contacts (0–3 from spatio-temporal distribution of fronto-central P300 re-
basal to cranial), longitudinally spaced at distances of sponses upon go versus no-go stimuli could be con-
1.5 mm in VIM implants. On both recording sides, Con- firmed per patient. It was expected that the ‘‘no-go
tacts 0 and 1 were referenced to Contact 3, resulting in P300’’ would peak over frontal scalp sites upon the
Figure 2. Simultaneous scalp
and thalamic recordings.
Scalp EEG was derived
simultaneously with depth
recordings from the thalamic
ventral intermediate nucleus
(VIM; n = 14) in a group of
tremor patients. The MRIs
show representative DBS
electrode positions in one
patient. Two bipolar channels
covered the lower (light field)
and upper (dark field) portions
of the DBS electrodes, the
circles representing the
stereotactically defined edges
of these adjacent channels
per patient. The projection
of the recording fields on
the 13-mm paramedian slice
from the Schaltenbrand atlas
suggests that depth sampling
areas were at the lower
edge and well within VIM,
respectively.
Marzinzik et al. 1905

4. instruction to withhold a prepared movement. This ERP peak. At scalp level, this procedure referred to the maxi-
component is a positive potential in the time window mum component between 300 and 600 msec, a time
between 300 and 600 msec upon no-go signals and is of domain in which ERPs upon go and no-go signals began
markedly larger magnitude than the according ERPs in to differ and which is typical of P300 responses elicited
the go condition ( Weisbrod, Kiefer, Marzinzik, & Spitzer, in comparable paradigms. At thalamic level, latency and
2000; Roberts, Rau, Lutzenberger, & Birbaumer, 1994; amplitude values were assessed for the first component,
Eimer, 1993; Jodo & Inoue, 1990; Pfefferbaum & Ford, which was differentially expressed between go and
1988; Pfefferbaum, Ford, Weller, & Kopell, 1985; Simson, no-go conditions.
Vaughan, & Ritter, 1977). The origin of the no-go P300 The main statistical analysis primarily aimed at iden-
is allocated to prefrontal and cingulate cortical areas tifying factors for the amplitude and latency values of
(Kiefer et al., 1998). Thus, the time course of cortical scalp and thalamic ERPs. Therefore, three-way analyses
activations related to response inhibition can be delin- of variance (ANOVAs), with the test factors task con-
eated by comparing the respective ERPs in the go versus dition (two levels: go/no-go), response side (two levels:
no-go condition. left/right), and electrode position, were performed, sep-
Thalamic and scalp data were sampled continuously arately for the scalp (nine levels: F3/Fz/F4/C3/Cz/C4/P3/
at 2 kHz with a bandpass from 0.05–500 Hz. Horizontal Pz/P4) and the thalamus (four levels: lower left, upper
and vertical electrooculogram were registered to screen left, lower right, upper right).
against eye-blink artifacts. Further, in order to compare go/no-go-related ERPs at
scalp versus thalamic level chronometrically, the peak
latencies determined at the electrode positions with the
Analysis
largest amplitude effect for task condition (i) at scalp
Peristimulus EEG segments from À200 to +1000 msec level and (ii) at thalamic level were utilized for a further
were averaged separately over left-go, right-go, left-no-go, three-way ANOVA. This ANOVA comprised the test fac-
and right-no-go trials, unless they were handled incor- tors task condition (two levels: go/no-go), response side
rectly or contained eye-blink artifacts. Further, averages (two levels: left/right), and brain level (two levels: elec-
were calculated relative to the reaction times (button trode positions at which the effect of task condition on
presses) in the go condition. Thus, back averages from ERP amplitudes was strongest (i) at scalp level and (ii)
the motor response could be compared to the stimulus- at thalamic level). As post hoc comparisons, Newman–
triggered forward averages, determining if a component Keuls tests were performed.
reflected predominantly sensory or motor processes. If scalp and thalamic ERPs had different peak laten-
To assess if minor activity discernible in the back cies, the onset of the target effect was additionally de-
average was the residual of sensory components in the termined. Therefore, no-go ERPs were subtracted from
forward average or were proper motor potentials, an go ERPs at either level to better display the time course
additional analysis was performed. Per patient, the re- of differences between conditions. The task effect was
action times from the go trials were marked down to considered to start out with the first poststimulus inter-
the no-go trials which, on this basis, could be averaged val of at least 25 msec, in which the averaged amplitudes
in the very same way as the go trials. Such ‘‘sham aver- exceeded the standard deviation across baseline values
ages’’ in the no-go condition (not containing any motor by a factor > 2. Statistically, this was assessed with run-
responses) were individually compared with the back ning t tests based on moving averages over 50 data
averages (based on reaction times). Activity in the back points per patient.
average was considered a correlate of motor processing If task effects were proven at both thalamic and scalp
if it exceeded according activity in the sham average, sites, it was further tested if these effects were correlated
whereas it was viewed the residual of sensory compo- between the different recording levels, putatively indic-
nents if it was identically identified in the sham average. ative of thalamo-cortical networks active in executive
Analysis of scalp and thalamic data was performed at control. Therefore, per patient three subaverages, each
off-line filter settings from 0.5 to 20 Hz and from 20 to over one third of the artifact-free and correct left- and
50 Hz. The former bandpass was chosen with respect to right-hand go as well as no-go trials (each containing at
the main spectral energy of P300 components between least 20 trials), were built, reflecting the ERP fluctuations
5 and 10 Hz in line with conventional methodology, over subsequent time segments of the recording session
the latter was additionally applied as phase-locked tha- in either task condition. For the resulting (sub-)ERPs,
lamic activity has hardly been described and might the amplitude values of the monophasic thalamic com-
exceed the spectrum known from scalp ERPs, so that po- ponent, differentially expressed between go and no-go
tentially faster components would not escape this scru- condition (cf. Results), were then matched with the am-
tiny. Latency values were determined from the point in plitude values of the first component in the time domain
time at which the stimulus was delivered to the peak of of the task effect assessed at all scalp electrode sites.
a component. Amplitudes were measured from baseline For the interindividual comparability of the results, mag-
(defined over the 200 msec prestimulus interval) to nitudes were expressed in proportion to the mean of
1906 Journal of Cognitive Neuroscience Volume 20, Number 10

5. the three amplitudes determined per subject, condition, nitudes at scalp and thalamic levels. This difference
and recording site normalized to 1. In so doing, a between ‘‘forward’’ versus ‘‘back’’ averages suggests
Pearson’s coefficient of correlation could be determined that the described components predominantly reflect
across subjects for each thalamo-cortical electrode pair the processing of go and no-go stimuli rather than the
[per condition: 3 (subaverages) Â 2 (left/right response motor execution of the task. This was corroborated by
side) Â 7 (subjects)]. Thus, it could be assessed if ERPs the comparison of the ‘‘back averages’’ of the go trials
in the go and no-go condition covaried between depth with the ‘‘sham averages’’ of the no-go trials (replicating
and scalp recording sites or, alternatively, behaved inde- the time criteria in the back averages; for details, cf.
pendently from each other and, secondly, how putative under Methods, Analysis). In the sham averages, the
thalamo-cortical relations were spatially distributed. residual activity from scalp as well thalamic components
upon the no-go signal was undistinguishable from the
activity obtained in the back average of the go trials
(Figure 5). Thus, during the time domain of interest, the
RESULTS
attenuation of ERPs in both conditions was due to the
Overview jitter of activity, phase-locked to go as well as no-go trials
Patients responded correctly to 88 ± 14%/98 ± 3% of and not to motor activity proper.
go/no-go trials (difference of error rate not significant).
The mean reaction time was slightly faster for right- than
left-hand responses (596 ± 147 msec vs. 622 ± 178 msec; Amplitude Analysis
difference not significant).
Generally, ERPs were identified in the data filtered Scalp ERPs
from 0.5 to 20 Hz and were absent above this frequency An interaction Task condition  Electrode position was
band, regardless of the recording site. At scalp level, found [F(8, 48) = 12.85, p < .0001] according to the
positive scalp ERPs upon go as no-go stimuli peaked be- observation that P300 components were larger upon
tween 300 and 600 msec at all recording sites, according no-go stimuli than upon go stimuli at rostral recording
to typical P300 responses. At parietal sites, the P300 am- sites. Post hoc comparisons proved the difference be-
plitudes and latencies in the go condition were similar to tween ERP magnitudes of either condition to be sig-
those in the no-go condition. At fronto-central positions, nificant at all frontal and central positions but strongest
P300 components upon no-go stimuli were, however, at Fz ( p < .001). The effect was not modulated by the
larger and occurred later than upon go stimuli. In tha- response side.
lamic recordings, monophasic ERP components were
identified upon either stimulus class at almost identical
Thalamic ERPs
latencies around 280 msec. This component, which pre-
ceded the fronto-central P300, was found larger upon According to the observation that go stimuli elicited larger
go than upon no-go stimuli (cf. Table 1 and Figure 3). ERPs than no-go stimuli in thalamic recordings, task con-
Further, upon go instructions, differences due to the dition was shown a main effect [F(1, 6) = 8.45, p < .028].
laterality of the executed response emerged only after The interaction Task condition  Electrode position [F(3,
the peak of this thalamic component (cf. Figure 4). 18) = 4.12, p < .022] was due to the fact that a significant
Averaging with respect to the motor response (go difference between go- and no-go-related ERPs was only
condition), resulted in a strong attenuation of ERP mag- obtained at the upper portion of the DBS electrode, but
Table 1. Latencies and Amplitudes of ERP upon Go and No-go Stimuli
Thalamus Scalp (P300)
Stimulus Left Right F3 Fz F4 C3 Cz C4 P3 Pz P4
Peak Latencies (msec)
Go 278 ± 11 280 ± 15 410 ± 19 412 ± 17 413 ± 16 413 ± 16 411 ± 16 411 ± 16 412 ± 13 412 ± 13 407 ± 14
No-go 281 ± 12 272 ± 10 465 ± 16 471 ± 20 470 ± 20 472 ± 20 459 ± 27 467 ± 18 446 ± 15 436 ± 21 426 ± 23
Amplitudes (V)
Go 6.5 ± 1.4 5.7 ± 0.9 2.9 ± 0.9 3.4 ± 1 3.8 ± 0.9 4.5 ± 1.1 4.5 ± 1.3 5.2 ± 1.2 5.6 ± 1.4 6.6 ± 1.3 6.1 ± 1.2
No-go 4.1 ± 0.9 3 ± 0.5 6.4 ± 1 7.1 ± 1.1 6.8 ± 1.1 7 ± 1.6 7 ± 1.1 7.2 ± 1.3 6.3 ± 1.2 6.8 ± 1.3 6 ± 1.1
Peak latencies (± standard error) and amplitudes (± standard error) of thalamic (upper channel) and scalp ERPs.
Marzinzik et al. 1907

6. Figure 3. Distribution of scalp and thalamic go and no-go ERPs. Overview of grand-averaged frontal, central, and parietal (A) as well as thalamic
(B) ERPs, averaged over ipsilateral and contralateral responses. The ERPs upon the go signal are indicated by the dashed line, the ones upon
the no-go signal by the solid line. The scalp no-go P300 peaked later than the thalamic ERPs following go and no-go signals.
not at its lower part (post hoc tests for upper/lower chan- that P300 components upon no-go stimuli peaked signif-
nels: p .05/p .3). No further interactions were found. icantly later than upon go stimuli only at frontal and cen-
tral recording positions, this effect being strongest at Fz
( p .001).
Latency Analysis
Scalp ERPs
Thalamic ERPs
Task condition was shown a main factor [F(1, 5) = 8.32,
p .034], further interacting with electrode position [F(8, The monophasic thalamic ERPs upon go versus no-go
40) = 2.29, p .041]. The post hoc comparisons revealed stimuli did not differ in latency.
1908 Journal of Cognitive Neuroscience Volume 20, Number 10

7. Figure 4. Thalamic ERPs in left-hand versus right-hand conditions. The amplitude of the thalamic components at peak latency was not influenced
by the side of motor execution: (A) The upper traces show the lateralization of thalamic ERP upon go instructions, compared for left-hand
(dotted line) versus right-hand (solid line) responses. Side-related differences emerged only after the peak of the monophasic thalamic ERPs.
(B) Upon no-go instructions, no lateralization was obtained.
Chronometric Comparison of the Thalamic more than 2 standard deviations excess from baseline
and Scalp ERPs noise, as determined in the 200-msec interval before sig-
nal presentation; cf. Methods, cf. Figure 6).
Brain level was a main factor of peak latencies in tha-
lamic versus scalp ERPs based on the recording positions
displaying the strongest task effects on ERP amplitudes
Correlation between Thalamic and Scalp ERPs
of either level [left/right thalamus vs. Fz: F(1, 6) = 85.98/
76.09, p .0001]. Further, task condition was a cofactor Thalamic and scalp ERPs were correlated with respect to
[Brain level  Task condition for left/right thalamus vs. the amplitude fluctuations along the recording session
Fz: F(1, 6) = 9.01/8.45, p .024/ .027], according to (see Methods), but this thalamo-cortical correlation was
the fact that P300 components at Fz peaked later upon spatially distinct for go versus no-go ERPs. Specifically,
no-go than upon go stimuli ( p .01), whereas thalamic thalamic no-go ERPs behaved similarly to accompanying
ERP latencies were similar in the go and no-go condi- ERPs in the time domain of the task effect at frontal sites,
tion. Thalamic ERPs, in turn, peaked prior to scalp P300 where the no-go effect was largest. No such relation was
components both in the go and no-go condition ( p obtained for go ERPs which, instead, mostly correlated to
.001/p .001). the according parietal ERPs (for summary, see Table 2).
Accordingly, the onset of the task effect was deter-
mined earlier in thalamic than in scalp ERPs ( p .0001).
In the subtraction curves of go versus no-go ERPs, it was
DISCUSSION
determined to start at 196 ± 27 msec and 296 ± 57 msec
after signal presentation for thalamic ERPs and scalp The present study contained three major findings. First,
ERPs at Fz, respectively (criterion: during 25 msec as at fronto-central scalp sites, ERPs recorded from the
Marzinzik et al. 1909

8. Figure 5. Nonmotor character of frontal and thalamic go/no-go ERP. (A) The upper traces show scalp and thalamic ERPs to go/no-go stimuli,
contralateral to task execution/instruction, averaged to stimulus presentation (forward average). (B) The lower traces display the ERPs, averaged
with respect to the motor execution of the task for the go condition (back average; dashed line) and an according ‘‘sham ERP’’ for the no-go
condition (solid line). For the latter, the reaction times from the go trials were marked down to the no-go trials. Thus, no-go trials could be
averaged in the very same way as the go trials, although they did not contain any motor response. As activity in the back average was found
largely identical with that in the sham average, it was viewed the residual of the sensory components discernible in the forward average.
Figure 6. Difference curves
(go minus no-go condition) for
scalp and thalamic ERPs. The
task effect is shown as the
difference of ERPs in the go
versus no-go condition at scalp
and thalamic levels (grand
average). The beginning of
this effect was calculated per
patient as the first poststimulus
interval of at least 25 msec
exceeding the standard
deviation across the individual
baseline values by more
than a factor of 2. The
thus-determined onsets were
significantly earlier in thalamic
compared to scalp recordings
and are indicated by the
solid and dashed arrows,
respectively.
1910 Journal of Cognitive Neuroscience Volume 20, Number 10

9. Table 2. Co-fluctuations of Thalamic and Scalp ERP Amplitudes
Go Condition No-go Condition
Scalp Left Thalamus Right Thalamus Left Thalamus Right Thalamus
F3 r = .17 ( p .29) r = .13 ( p .42) r = .75**(p .001) r = .76** (p .001)
Fz r = .19 ( p .22) r = .19 ( p .23) r = .76** (p .001) r = .75** (p .001)
F4 r = .13 ( p .39) r = .23 ( p .15) r = .76** (p .001) r = .90** (p .001)
C3 r = .43** (p .005) r = .33* (p .05) r = .58** (p .001) r = .74** (p .001)
Cz r = .34* (p .03) r = .15 ( p .33) r = .24 ( p .12) r = .26 ( p .11)
C4 r = .35* (p .05) r = .45** (p .01) r = .18 ( p .26) r = .29 ( p .06)
P3 r = .45** (p .01) r = .45** (p .01) r = À.17 ( p .28) r = À.22 ( p .17)
Pz r = .52** (p .001) r = .55** (p .001) r = .07 ( p .65) r = .09 ( p .58)
P4 r = .49** (p .001) r = .57** (p .001) r = À.22 ( p .15) r = À.06 ( p .70)
r = Pearson’s correlation coefficient.
*Significant at .05 level.
**Significant at .01 level (two-tailed; cf. Methods).
upper intrathalamic electrode were differentially ex- of control processes exclusively refer to the cortical level,
pressed upon no-go versus go commands, and this dif- based on scalp ERPs. In this particular context, the re-
ference was not explained by motor processing. Second, ported depth ERPs merit a closer view.
whereas thalamic ERPs correlated to the parietal P300
component in the go condition, they corresponded to
Origin of VIM-recorded ERPs
the task-specific frontal ERP component in the no-go
condition. Third, task-specific scalp components started An intrathalamic origin of VIM-recorded ERPs can be
well after thalamic go as well as no-go ERPs. reasonably assumed for several reasons. First, if depth
signals were volume conducted from cortical generators,
time courses of components at scalp and thalamic levels
Relation to Previous Studies
should be synchronous. Accordingly, the discrepant la-
Worthwhile mentioning, the obtained spatio-temporal tencies of scalp versus VIM ERPs point to a closer, that is,
pattern of scalp ERPs was as described in numerous subcortical, origin of the latter. Second, the upper, but
studies applying comparable paradigms. Specifically, the not the lower, derivation from DBS electrodes caught
frontal component under scrutiny, often labeled ‘‘no-go significant differences between go and no-go-related
P300,’’ has been conceptualized as the reflection of ag- ERPs. This disparity points to an effect from near-field
gregate activity for the suppression of actions, according activities. Far-field spread would almost equally project
to its enhancement in no-go trials (Roberts et al., 1994; into upper and lower derivation because of similar rela-
Eimer, 1993). The recording array used in this study does tive positions to both recording fields, covering few adja-
not allow to deduce the origin of this component, but cent millimeters along the same trajectory only. Finally,
previous studies focused on this issue. Based on source the absence of a the task effect in the lower thalamic
analysis of frontal P300, the provision of assigned func- derivations suggests that its proof in the upper record-
tions has been allocated to the anterior cingulum, the ings was due to processes in proximate thalamic struc-
prefrontal cortex, and the premotor cortex (Kamarajan tures, and not to operations in nuclei adjacent to the
et al., 2005; Bokura et al., 2001; Kiefer et al., 1998; Strik caudal border of VIM outside the thalamus. However, an
et al., 1998). Accordingly, executive control operations origin in VIM proper seems unlikely, as both the upper
were proposed to be generated in a frontal lobe network, and lower depth recording areas were estimated to be
although a number of imaging studies and reports on predominantly within this nucleus.
patients with subcortical lesions point to an additional
involvement of thalamic structures (Van der Werf et al.,
Nonmotor Nature of Thalamically Recorded ERPs
2003; Garavan et al., 2002; Mennemeier et al., 1992;
Eslinger et al., 1991; also see Van der Werf, Witter, Several results indicate that the thalamic activation in
Uylings, Jolles, 2000, for a review). However, a more the time domain of interest is unrelated to proper motor
specific assignment of according subcortical functions is operations. First, thalamic ERPs in trials with left- versus
not available so far, and estimations on the chronometry right-sided motor responses did not differ in magnitude
Marzinzik et al. 1911

10. at their peak latencies. Such a difference could be rea- demands, appear aligned with more frontally located
sonably assumed if this component reflected primary areas than throughout facilitatory processing, compati-
motor processes, as observed in later time domains of ble with a particular involvement of dorsolateral prefron-
the ERPs. Second, thalamic ERPs were bound to stimulus tal and anterior cingulate cortices in executive control
presentation rather than to the motor execution of the (Carter et al., 1998; D’Esposito et al., 1995; Petrides et al.,
task, as they occurred upon go and no-go trials, al- 1993; Shallice Burgess, 1991; Pardo et al., 1990).
though in the latter motor responses were not executed. Such selective coupling might be a function of thalamo-
Third, a predominant binding of the ERPs to motor exe- cortical, together with thalamic reticular neurons, whose
cution was incompatible with the finding that they were firing properties and connectivity provide a mechanism
massively reduced in magnitude when averaged to the for scaling and funneling information through the wide-
motor response as compared to the go instruction. spread thalamic connections to frontal and temporo-
Fourth, the larger amplitude obtained in go versus no- parietal cortical regions (Behrens et al., 2003; Sherman
go conditions could finally not be explained by additive Guillery, 1996; Crick, 1984; see also Pinault, 2004;
motor operations. This was shown by the comparison of Guillery Sherman, 2002a, 2002b for reviews).
ERPs in go trials, averaged to the motor response, versus Intriguingly, the chronometric comparison of thalamic
ERPs in no-go trials, averaged to the very same points and scalp ERPs suggested that task-specific information
in time (‘‘sham average’’; cf. Methods and Results). In was propagated in thalamo-cortical direction, that is, no
so doing, activations in the critical interval became un- indication was found that the underlying thalamic pro-
distinguishable between conditions, delineating that the cesses occurred under the control of related cortical
added thalamic activity was due to the go instruction areas. This, together with the possibility of a thalamically
proper, but not to its execution. induced cortical coupling of go versus no-go-related
signaling, can be viewed as an experimental parallel to
‘‘centrencephalic’’ concepts, derived from the Penfield
Conceptual Considerations
and Jasper (1954) formulation that a subcortical struc-
In this context, a number of proposed thalamic func- ture can be ‘‘while anatomically subcortical, functionally
tions are of particular interest. During attentional and supra-cortical,’’ further relating to the principle question
arousal processes, activation has been described for in- if qualia can exist if subcortical structures work without
tralaminar thalamic regions (Fan, McCandliss, Fossella, a corresponding cortex (cf. Merker, 2007; Schiff et al.,
Flombaum, Posner, 2005; Hester, Fassbender, 2007).
Garavan, 2004; Woldorff et al., 2004; Garavan et al., The task-dependent expression of thalamic ERPs calls
2002; Portas et al., 1998; Coull, Frith, Dolan, Frackowiak, for the comparison with previous results. Both go and
Grasby, 1997; Frith Friston, 1996), which receive no-go instructions require specific performances with
afferent connections from the midbrain reticular forma- respect to previously established expectancies. There-
tion and project to multiple cortical areas (McFarland fore, their magnitudes do not appear to reflect thalamic
Haber, 2002; Macchi, Bentivoglio, Molinari, Minciacchi, weighing of signal relevance, given that both go and
1984; Steriade Glenn, 1982; Bentivoglio, Macchi, no-go signals convey behaviorally important informa-
Albanese, 1981; also see Merker, 2007; Jones, 1998 for tion. In this sense, go and no-go signals are compara-
reviews). It has been hypothesized that midbrain signals ble to target signals in oddball paradigms. Interestingly,
convey stimulus-related alert or orienting information in a recent study, oddball target signals, rarely inter-
to the thalamus (Kinomura, Larsson, Gulyas, Roland, spersed between nontarget instructions, led to consid-
1996), which in turn communicates with specific cortical erably larger thalamic ERPs than the present go and
regions, depending on the ongoing behavioral demands no-go instructions (cf. Klostermann et al., 2006). There-
(see Merker, 2007; Pinault, 2004 for reviews). Similarly, fore, our momentary working hypothesis is that the
it has been suggested that sensorily driven bottom–up mentioned thalamic ERPs reflect distinct (rather than
signals are integrated with top–down directed informa- unitary, but weighed) aggregate activities whose com-
tion in the center median and parafascicular nuclei of the position imply variable thalamic contributions, specifi-
thalamus (reviewed by Sarter, Givens, Bruno, 2001; cally defined by the given behavioral context. However,
LaBerge, 1997). the verification of this and the critical questions how and
Of course, from the present data, any brainstem con- by what task definitions are imposed upon the thalamus
tributions to the results remain speculative, but the cor- remain central issues for future studies.
relations between thalamic and scalp ERPs do hint at
differential thalamo-cortical processing. According in-
Conclusions
teractions appeared task-dependent, as in the no-go
condition, thalamic ERPs co-fluctuated with the frontal Principally, the distinct expression of thalamic ERPs upon
no-go P300, whereas in the go condition, they mainly did go versus no-go instructions indicates thalamic involve-
so with the parietal P300. This seems to imply thalamo- ment in executive control. Further, the fact that task-
cortical routes of information which, in case of inhibitory specific activity emerged prior in depth recordings than
1912 Journal of Cognitive Neuroscience Volume 20, Number 10

11. at scalp level suggests cortical operations of response Fan, J., McCandliss, B. D., Fossella, J., Flombaum, J. I.,
control to be subcortically prepared. Finally, the corre- Posner, M. I. (2005). The activation of attentional
networks. Neuroimage, 26, 471–479.
lation of thalamic to frontal ERPs in the no-go condition Fillenbaum, G., Heyman, A., Williams, K., Prosnitz, B.,
and of thalamic to parietal ERPs in the go condition in- Burchett, B. (1990). Sensitivity and specificity of
dicates that the underlying thalamo-cortical networks are standardized screens of cognitive impairment and
flexibly activated as a function of task demands. dementia among elderly black and white community
residents. Journal of Clinical Epidemiology, 43, 651–660.
Foffani, G., Priori, A., Egidi, M., Rampini, P., Tamma, F.,
Acknowledgments Caputo, E., et al. (2003). 300-Hz subthalamic oscillations
in Parkinson’s disease. Brain, 126, 2153–2163.
This study was supported by the Deutsche Forschungsgemein- Frith, C. D., Friston, K. J. (1996). The role of the thalamus
schaft (DFG KL 1276/3-1). We thank our reviewers for their in ‘‘top down’’ modulation of attention to sound.
constructive suggestions and comments. Neuroimage, 4, 210–215.
Reprint requests should be sent to Fabian Klostermann, Garavan, H., Ross, T. J., Murphy, K., Roche, R. A., Stein,
Neurology, Charite—University Medicine Berlin, Campus
´ E. A. (2002). Dissociable executive functions in the
Benjamin Franklin, Berlin, 12200, Germany, or via e-mail: dynamic control of behavior: Inhibition, error detection,
fabian.klostermann@charite.de. and correction. Neuroimage, 17, 1820–1829.
Guillery, R. W., Sherman, S. M. (2002a). Thalamic relay
functions and their role in corticocortical communication:
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