A commentary on Decision threshold modulation in the human brain by Domenech, P., and Dreher, J. C. (2010). J. Neurosci. 30, 14305–14317. When faced with a visual stimulus, how does our brain process sensory information to decide which action to take? Only in the last 10 years have researchers begun to unravel the neural bases of such perceptual decisions (Heekeren et al., 2004; Gold and Shadlen, 2007). A popular theory holds that dedicated neural circuits achieve this by accumulating evidence from the environment until they reach a threshold an

Myers, Nicholas

Wyart, Valentin

English

PubMed

Myers, N

Wyart, V

Oxford University Research Archive (ORA)

Frontiers in Human Neuroscience

Conservative decisions guided by the anterior cingulate cortex

Oxford University Research Archive

Nicholas Myers

Valentin Wyart

Frontiers - Publisher Connector

Conservative Decisions Guided by the Anterior Cingulate Cortex

HUMAN NEUROSCIENCE
occur. In their task, subjects responded to 
target shapes (e.g., triangles) appearing in 
a stream of distractor shapes. The authors 
varied the likelihood with which any partic-
ular stimulus (or sequence of two stimuli) 
would be followed by a target. Since partici-
pants were not told about these regularities 
(and indeed failed to notice them during 
the experiment), predictive information 
was learned implicitly during each block.
In an elegant analysis of reaction time 
distributions (Carpenter and Williams, 
1995), the authors were able to test whether 
predictive information influenced the deci-
sion threshold, the accumulation rate of 
sensory evidence, or both. They found that 
more predictive information lowered the 
decision threshold but did not accelerate 
the rate of evidence accumulation, biasing 
participants to make faster responses when 
they were expecting a target shape on the 
basis of previous distractors. However, 
since all stimuli were easily discriminable, 
perceptual processes had likely reached 
asymptotic performance and could not be 
further improved by gain control mecha-
nisms. When stimuli are harder to discrimi-
nate, predictive information may influence 
perceptual processing as well (Liston and 
Stone, 2008; Melloni et al., 2011).
If predictive information lowers the deci-
sion threshold, any evidence- accumulation 
brain region should respond less to targets 
when predictive information is high, but 
should respond more when the accumula-
tion rate is fast. Only the right dorsolateral 
prefrontal cortex (dlPFC) had both response 
properties (their Figure 7), partially con-
firming previous findings in humans and 
monkeys that the dlPFC represents the 
amount of accumulated sensory evidence 
(Heekeren et al., 2004; Gold and Shadlen, 
2007). Predictive information itself was neg-
atively correlated with a large, distributed 
network. It consisted of the inferior frontal 
gyri, the right intra-parietal sulcus, the left 
and right dlPFC, and, most importantly, 
Conservative decisions guided by the anterior  
cingulate cortex
Nicholas Myers* and Valentin Wyart
Department of Experimental Psychology, University of Oxford, Oxford, UK
*Correspondence: nicholas.myers@psy.ox.ac.uk
A commentary on
Decision threshold modulation in the 
human brain 
by Domenech, P., and Dreher, J. C. (2010). J. 
Neurosci. 30, 14305–14317.
When faced with a visual stimulus, how 
does our brain process sensory informa-
tion to decide which action to take? Only 
in the last 10 years have researchers begun 
to unravel the neural bases of such percep-
tual decisions (Heekeren et al., 2004; Gold 
and Shadlen, 2007). A popular theory holds 
that dedicated neural circuits achieve this 
by accumulating evidence from the envi-
ronment until they reach a threshold and 
commit to a decision (such as whether a 
briefly presented shape is a triangle or a 
circle). Tasks have classically been designed 
such that each decision is independent of 
past decisions, and so the accumulation of 
information starts anew at the beginning 
of each trial. However, in ordinary situa-
tions, we use prior experience to help us 
decide. Expecting an upcoming stimulus 
to have a particular shape should therefore 
make the next decision easier and faster. 
While the representation of expectations 
in the brain has been related to faster reac-
tion times (Summerfield and Koechlin, 
2008), the neural mechanisms underlying 
this behavioral advantage remain unclear. 
Theoretical decision-making models have 
proposed two ways to produce this effect, 
either (1) by lowering the decision threshold 
(Carpenter and Williams, 1995), or (2) by 
accelerating the accumulation rate of sen-
sory evidence. Recent behavioral evidence 
suggests that both may occur in parallel 
(Liston and Stone, 2008).
Recently, Domenech and Dreher (2010) 
addressed this issue by testing how varying 
amounts of predictive information influ-
ence perceptual decisions, and used func-
tional magnetic resonance imaging (fMRI) 
to test where in the brain this influence may 
the anterior cingulate cortex (ACC, their 
Figure 5). In this network, only the ACC 
responsiveness to predictive information 
was related to how much participants used 
that information to make faster decisions. 
In other words, while a large fronto-parietal 
network was involved in tracking predic-
tive information, the ACC seemed to have a 
special role in using this information to set 
the decision threshold. Furthermore, when 
predictive information needed to be tracked 
further back into the past to be useful, the 
coupling between the ACC and parts of the 
right dlPFC increased (their Figure 8). The 
authors ensured that predictive information 
was not correlated with other measures that 
could have influenced ACC activity, such 
as error likelihood, prediction-error mag-
nitude, entropy, or overall target probability 
(their Figure 6).
The authors claim that the ACC is 
involved in the “contextual guidance of the 
decision process” by changing the decision 
threshold in response to the amount of pre-
dictive information. Although their results 
support a model in which ACC reacts to 
recent stimulus history, it is unclear how 
the ACC actually implements this contex-
tual guidance, or whether it is truly involved 
in changing the decision threshold. Their 
main finding indicates that the ACC tends 
to “turn off” when we are able to rely on 
predictive information, whereas its activ-
ity increases when we have little predictive 
information and therefore need to rely more 
on the current sensory input to make an 
accurate decision. This result mirrors a 
recent finding in a study on reward-guided 
decision-making by Behrens et al. (2007), in 
which they showed that increased volatility 
(i.e., a decrease in the stability of contextual 
contingencies) correlates with ACC activity 
at long time scales. When volatility is high, 
Behrens et al. have shown that human sub-
jects give more weight to the immediate 
reward history by increasing their learning 
rate, and that this increase in learning rate 
Frontiers in Human Neuroscience www.frontiersin.org April 2011 | Volume 5 | Article 44 | 1
General Commentary
published: 27 April 2011
doi: 10.3389/fnhum.2011.00044
Gold, J. I., and Shadlen, M. N. (2007). The neural basis 
of decision making. Annu. Rev. Neurosci. 30, 535–574.
Heekeren, H. R., Marrett, S., Bandettini, P. A., and 
Ungerleider, L. G. (2004). A general mechanism for 
perceptual decision-making in the human brain. 
Nature 431, 859–862.
Koechlin, E., and Summerfield, C. (2007). An information 
theoretical approach to prefrontal executive function. 
Trends Cogn. Sci. (Regul. Ed.) 11, 229–235.
Liston, D. B., and Stone, L. S. (2008). Effects of prior infor-
mation and reward on oculomotor and perceptual 
choices. J. Neurosci. 28, 13866–13875.
Melloni, L., Schwiedrzik, C. M., Müller, N., Rodriguez, E., 
and Singer, W. (2011). Expectations change the sig-
natures and timing of electrophysiological correlates 
of perceptual awareness. J. Neurosci. 31, 1386–1396.
Summerfield, C., and Koechlin, E. (2008). A neural rep-
resentation of prior information during perceptual 
inference. Neuron 59, 336–347.
Received: 28 February 2011; accepted: 14 April 2011; pub-
lished online: 27 April 2011.
Citation: Myers N and Wyart V (2011) Conservative deci-
sions guided by the anterior cingulate cortex. Front. Hum. 
Neurosci. 5:44. doi: 10.3389/fnhum.2011.00044
Copyright © 2011 Myers and Wyart. This is an open-
access article subject to a non-exclusive license between 
the authors and Frontiers Media SA, which permits use, 
distribution and reproduction in other forums, provided the 
original authors and source are credited and other Frontiers 
 conditions are complied with.
over slightly longer intervals. Contextual 
information may be held over even longer 
time scales in ventromedial prefrontal 
cortex (Koechlin and Summerfield, 2007). 
By integrating the influence of expecta-
tion into a computational model and by 
testing its neural bases, Domenech and 
Dreher (2010) have helped to formalize 
the influence of memory on perceptual 
decision-making.
Acknowledgments
We would like to thank Christopher 
Summerfield and Anna C. Nobre for help-
ful comments.
RefeRences
Behrens, T. E., Woolrich, M. W., Walton, M. E., and 
Rushworth, M. F. (2007). Learning the value of 
information in an uncertain world. Nat. Neurosci. 
10, 1214–1221.
Carpenter, R., and Williams, M. (1995). Neural computa-
tion of log likelihood in control of saccadic eye move-
ments. Nature 377, 59–62.
Domenech, P., and Dreher, J. C. (2010). Decision thresh-
old modulation in the human brain. J. Neurosci. 30, 
14305–14317.
correlates with increased ACC activity. The 
results obtained by Domenech and Dreher 
(2010) show that the ACC can also track 
changes in predictive information at much 
faster time scales.
Together, the results indicate that the 
ACC is recruited for maintaining a con-
servative decision threshold whenever the 
past provides little predictive informa-
tion. It may have been interesting to see 
whether the ACC also shows an increased 
response when predictive information is 
high, but no target appears. Indeed, by 
showing that ACC activity correlates with 
increases in decision threshold following 
disconfirmations of predictive informa-
tion, Domenech and Dreher (2010) could 
have made an even stronger case for the 
hypothesis that the ACC is involved in 
threshold regulation. Furthermore, differ-
ent brain regions may represent predictive 
information over different time scales. The 
dlPFC may react on the shortest time scale 
by integrating sensory evidence of the cur-
rent stimulus set. The ACC may respond 
to higher-order  predictive  information 
Frontiers in Human Neuroscience www.frontiersin.org April 2011 | Volume 5 | Article 44 | 2
Myers and Wyart Conservative decisions in the ACC


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Conservative Decisions Guided by the Anterior Cingulate Cortex

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