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Abstract:
Goals: This study identifies the neural networks that support
response inhibition and investigates how these networks might be
modulated by a pharmacological challenge. Methods: Event-related
fMRI was used to scan participants as they performed a stop-signal
task. In this task, participants responded as quickly as possible
to a go-signal (i.e., an X or an O), and tried to withhold their
response whenever the go-signal was followed by a stop-signal
(i.e., the X or the O changed color). Participants then received a
moderate dose of ethanol (.56 g/kg) and were scanned as they
performed the stop-signal task a second time. Results: Functional
neuroimaging data were analyzed using two multivariate statistical
techniques that quantify neural networks associated with response
inhibition. These analyses identified a frontostriatal network that
covaried with successful inhibitions and failures to inhibit a
response on the stop-signal task: strong positive connections were
observed between the prefrontal cortex (PFC), the anterior
cingulate (AC), and the caudate. After drinking, participants made
fewer stopping responses, however reaction time to the go-signal
and response accuracy were not affected. Impaired response
inhibition following alcohol was associated with reductions in the
strengths of connections in the frontostriatal network.
Conclusions: A frontostriatal network supports response inhibition
on a stop-signal task and this network can be modulated by a
moderate dose of ethanol.
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