The following HTML text is provided to enhance online
readability. Many aspects of typography translate only awkwardly to HTML.
Please use the page image
as the authoritative form to ensure accuracy.
Colloquium on Neuroimaging of Human Brain Function
subject is engaging differentially a single, identified cognitive process. It should be noted that “a more sensitive behavioral test” cannot solve this problem because it is always possible that the subject engages unnecessary cognitive processes that either have no overt, measurable effects or are perfectly confounded with the process of interest. As a result, observed neural activity may be the result of some confounding neural computation that is not itself necessary for the execution of the cognitive process ostensibly under study. An equivalent formulation of these statements is to note that, essentially, neuroimaging is an observational, correlative method (72).
When combined, however, a stronger level of inference results from lesion and neuroimaging studies. One type of combination might be that (i) lesions to a cortical area impair a given cognitive process and that (ii) the cognitive process, when engaged by intact subjects, evokes neural activity in the same cortical area. The inference that the neuroanatomical area is computationally necessary for the cognitive process is now rendered less vulnerable to the faults detailed above for each method in isolation although it is still possible to conceive of failures. As a result, neuroimaging and lesion studies are complementary, in that each provides inferential support that the other lacks.
This work was supported by grants from the National Institute of Health (NS01762 and AG13483) and the McDonnell-Pew Program in Cognitive Neuroscience.
1. O’Keefe, J. & Nadel, L. (1978) The Hippocampus as a Cognitive Map (Oxford Univ. Press, Oxford).
2. Brewer, B. & Pears, J. (1993) in Spatial Representation, eds. Eilan, N., McCarthy, R. & Brewer, B. (Blackwell, Oxford), pp. 25–30.
3. Heft, H. (1979) Environ. Psychol. Nonverbal Behav.3, 172–185.