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Cognition

Matthew Rushworth

Our recent experiments have been concerned with two themes. First, we have carried out a number of experiments that have examined the neural mechanisms that underlie decision making. There has been a particular focus on the anterior cingulate cortex (Figure 1).

Figure 1


Figure 1(a) A dorsal ACC sulcal region (ACd) is active when the outcomes of exploratory actions are monitored. It was the only region to be more active when subjects were generating actions and monitoring their outcomes (G&M) than when subjects always made the same fixed response and monitored the outcome (F&M) condition. (b) Signal change in the ACC plotted in the G&M and F&M conditions and when subjects were simply generating actions without monitoring their outcomes (G) and in a fourth “control” condition (C) requiring neither action generation nor outcome monitoring From Walton et al., (2004, Nat. Neurosci.).


We have been particularly interested in the possibility that a region within the sulcus of the ACC is concerned with the generation of exploratory actions and the monitoring of the subsequent feedback that ensues (Walton et al., 2004) and the way in which fundamental behavioural parameters, such as the learning rate, depend on the manner in which such feedback is registered by the ACC (Behrens et al., 2007). Second, we have carried out a number of experiments which have examined the interaction between brain areas during cognition (O'Shea et al., 2007; Taylor et al., 2007). This has been done by recording activity in one brain and manipulating activity in another brain area with transcranial magnetic stimulation (Figure 2).


Figure 2

Figure 2. Compensatory activation increases in the action selection network after left dorsal premotor (lPMd) TMS. A whole-brain random effects analysis showed that lPMd TMS induced increased activation that was most prominent in right PMd (rPMd) and the right cingulate motor area (rCMA). Additional changes were seen in right primary motor cortex (rM1), the left supplementary motor area (lSMA) and the left cingulate motor area (lCMA). For each of these regions the graphs show mean percent BOLD signal change (%BSC) values for each Task (Select/Execute) and TMS condition (pre-/post-TMS). Note that the TMS-induced activation increases are specific to the process of action selection. White bars = Execute; Black bars = Select. Error bars = 1SEM. From O’Shea et al., (2007, Neuron).

References

  • Behrens TE, Woolrich MW, Walton ME, Rushworth MF (2007) Learning the value of information in an uncertain world. Nat Neurosci. 10:1214-21.
  • O'Shea J, Johansen-Berg H, Trief D, Gobel S, Rushworth MF (2007) Functionally specific reorganization in human premotor cortex. Neuron 54:479-490.
  • Taylor PC, Nobre AC, Rushworth MFS (2007) Sub-second changes in top-down control exerted by human medial frontal cortex during conflict and actoin selection: a combined TMS-EEG study. The Journal of Neuroscience. 27:11343-53.
  • Walton ME, Devlin JT, Rushworth MFS (2004) Interactions between decision making and performance monitoring within prefrontal cortex. Nat Neurosci 7:1259-1265.
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