The of behavior is response inhibition. In this

The prefrontal cortex is considered to have an
important role in the control of various types of human behavior and one of its
functions is the inhibitory control of well organized action planning and motor
behavior (Goldman-Rakic, 1987).  One of
the most frequently used approaches to study the inhibitory control of behavior
is response inhibition. In this review, two experiments using the go/no-go
response paradigm are going to be presented. In this kind of experiments, the
participants have to respond to the go signals (e.g., a green light) and not to
respond to the no-go signals (e.g., a red light). The no-go signals activate
the inhibitory control over the response movements.


Eleven healthy male university students aged between
21 and 30 years participated in the experiment. All participants were right-handed
and had normal or corrected-to-normal vision. The stimuli shown were three types
of figures- circle, triangle and a rectangle drawn with frames who were filled
with three different patterns – empty, filled block and a stripe. The
probability of the presentation of the stimuli was equal, and the order of the
presentation was randomized in all tasks.

The subjects underwent four PET scans. Two recorded
regional cerebral blood flow (rCBF) in the control condition, and two recorded
rCBF in the go/no-go condition. In each condition, trials
began with a sign – Start. After a 500-ms interval the first (cue) stimulus
appeared for 1000 ms and then disappeared. After a further 500-ms interval, the
second (target) stimulus was presented and stayed on the screen until the subject
responded. The next Start sign was presented 500 ms after the participant had
responded. Participants were instructed to press the response button as quickly
as possible when the target was presented, and not to press the button but to
wait for the presentation of the next Start sign if the target was not
presented. In the control condition, the subjects had been informed that the
target will be presented in every trial which meant that pressing the button in
every trial was the correct response. In the go/no-go condition, the target was
not presented in 9 out of 27 trials. So, the participants had two options –
pressing or not pressing the response button. In the control condition,
participants did not need to inhibit any responses, whereas in the go/no-go
condition they did need to inhibit some responses. Participants were instructed
to perform each task with the designated hand.

To summarize the results –  the most significant activation was
observed in the right hemisphere. Those areas included the inferior frontal
sulcus (Brodmann’s area (BA) 10), inferior frontal gyrus (BA 45), middle
frontal gyrus (BA 46), superior frontal gyrus (BA 10), and premotor area (BA
6). The activated area in the right middle frontal gyrus was from the superior
frontal to the anterior orbital gyrus. In the subcortical areas, the caudate nucleus
in the basal ganglia was also activated. In the left hemisphere the calcarine
sulcus (BA 17) in the occipital cortex, subcallosal gyrus (BA 25), and middle
frontal gyrus (BA 45, 46). (Gondo, Y., Shimonaka, Y., Senda, M., Mishina, M.,
& Toyama, H. (2002)

The main goal of this study was to investigate the
brain regions that are involved in response inhibition. The results showed an
activation of the prefrontal cortex on the go/no-go scans. This
dominance in the activation in the right side is also similar with the finding
that the dominant activation areas for response inhibition are located in the
right prefrontal cortex (Kawashima et al., 1996)