About this test
Cognitive enhancers improve performance on this task; read more to find out why...
The spatial search task assesses your ability to retain and manipulate information in spatial working memory. To find all of the yellow circles you are required to maintain and update an ongoing representation of previous searches and to develop an appropriate searching strategy. You may have found yourself retracing a systematic route and editing the locations along this route when yellow circles were found; if so, you have found one of the most successful problem solving approaches to this task!
We have used versions of this task to investigate memory for nearly 20 years (Owen et al., 1990). The task, is a version of the 'traveling salesman problem' so called because it refers to the difficulty that traveling salesmen have in remembering which houses they have already visited and in which of those houses they have made a successful sale. We have been investigating which areas of the brain are responsible for this type of memory by examining patients with damage to specific areas of their brains. We found that patients with frontal-lobe damage were impaired at the spatial search task even at very easy levels, despite performing well on equivalent verbal and visual working memory tests (Owen et al, 1996). By analyzing the sorts of errors that the patients made, we we were able to show that this impairment was the result of them being unable to adopt an efficient searching strategy. Thus, their memory per se was not impaired, but their ability to organise the contents of memory was, suggesting that the frontal lobes are involved in monitoring and modifying ones behaviours (Owen 1996). Patients with temporal lobe damage or amygdalo-hippocampectomy lesions, on the other hand, were impaired only at the most difficult levels of this task. In addition, they performed poorly on a visual working memory version of this test. From this, we learned that these brain structures are responsible for memory capacity. Using positron emission tomography (or 'PET') we also looked for areas of the brain that become activated in healthy volunteers when they perform the spatial search task (Owen et al., 1996). The results showed that posterior parietal cortex, the mid-dorsolateral and mid-ventrolateral frontal cortices and premotor cortices are all engaged when solving this task. However, close comparisons with other memory tasks showed that it was the mid-dorsolateral frontal region that really contributed most specifically to this task (Owen et al 1996).
Although only legally available on prescription, so-called 'cognitive enhancers' (otherwise known as 'smart drugs') are becoming increasingly popular alternatives to 'everyday drugs' such as caffeine for boosting mental performance. One such drug is methylphenidate (Ritalin) originally developed as an effective treatment for attentional deficit hyperactivity disorder (or 'ADHD'). Methylphenidate is now known to have cognitive enhancing properties, which include focusing of attention, increased alertness and better working memory. Together with our colleagues in the Department of Experimental Psychology in Cambridge, we have been looking into how this drug produces its beneficial effects on the brain and on behaviour. Performance on the spatial search task was found to improve while under the influence of methylphenidate (Mehta et al., 2000). Brain scanning with positron emsiion tomography ('PET') revealed that this improvement was related to reductions in blood flow in the frontal and parietal cortices, structures previously associated with performance in this task. The use of cognitive enhancers has provoked strong ethical, social and legal debate and their use among non-clinical populations remains illegal in the UK.
-Mehta, M. A., Owen, A. M., Sahakian, B. J., Mavaddat, N., Pickard, J. D., Robbins, T. W (2000). Methylphenidate enhances working memory by modulating discrete frontal and parietal lobe regions in the human brain. Journal of Neuroscience. 20(6), RC65. Download PDF
-Owen, A.M., Herrod, N.J., Menon, D.K., Clark, J.C., Downey, S.P.M.J., Carpenter, T.A., Minhas, P.S., Turkheimer, F.E., Williams, E.J., Robbins, T.W., Sahakian, B.J., Petrides, M. and Pickard, J.D (1999). Redefining the functional organisation of working memory processes within human lateral prefrontal cortex. European Journal of Neuroscience, 11(2), 567-574Read Abstract
-Owen, A.M., Morris, R.G, Sahakian, B.J., Polkey, C.E. and Robbins, T.W (1996). Double dissociations of memory and executive functions in working memory tasks following frontal lobe excisions, temporal lobe excisions or amygdalo-hippocampectomy in man. Brain, 119 (Pt 5), 1597-1615. Download PDF
-Owen A.M., Evans, A.C. and Petrides, M. (1996). Evidence for a two-stage model of spatial working memory processing within the lateral frontal cortex: a positron emission tomography study. Cerebral Cortex, 6(1), 31-38. Download PDF
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