Creating focal lesions in primary visual cortex (V1) provides an opportunity to study the role of extra-geniculo-striate pathways for activating extrastriate visual cortex. Previous studies have shown that more than 95% of neurons in macaque area V2 and V3 stop firing after reversibly cooling V1 [1,2,3]. However, no studies on long term recovery in areas V2, V3 following permanent V1 lesions have been reported in the macaque. Here we use macaque fMRI to study area V2, V3 activity patterns from 1 (...) to 22 months after lesioning area V1. We find that visually driven BOLD responses persist inside the V1-lesion projection zones (LPZ) of areas V2 and V3, but are reduced in strength by ,70%, on average, compared to prelesion levels. Monitoring the LPZ activity over time starting one month following the V1 lesion did not reveal systematic changes in BOLD signal amplitude. Surprisingly, the retinotopic organization inside the LPZ of areas V2, V3 remained similar to that of the non-lesioned hemisphere, suggesting that LPZ activation in V2, V3 is not the result of input arising from nearby (non-lesioned) V1 cortex. Electrophysiology recordings of multi-unit activity corroborated the BOLD observations: visually driven multi-unit responses could be elicited inside the V2 LPZ, even when the visual stimulus was entirely contained within the scotoma induced by the V1 lesion. Restricting the stimulus to the intact visual hemi-field produced no significant BOLD modulation inside the V2, V3 LPZs. We conclude that the observed activity patterns are largely mediated by parallel, V1-bypassing, subcortical pathways that can activate areas V2 and V3 in the absence of V1 input. Such pathways may contribute to the behavioral phenomenon of blindsight. (shrink)
Behaviourist Learning Theory and Utility Theory. Comparisons between theories are rare, especially in social theory which is believed to be a "multi-paradigmatic" science. Against this prevailing impression it is shown that there are logically reconstructable inter-theory-relations at least between different basic theories of individual action. Following Wladyslaw Krajewski a formal model of theory-approximation is developed and applied to behaviourist learning theory and utility theory. Comparing both theories leads to the result that the latter has to be preferred to Behaviourism. That (...) utility theory has a richer content than learning theory helps to explain why George Caspar Homans explanatory programme which leans on a Skinnerian version of learning theory finally did not succeed in becoming the leading approach in social science. (shrink)
Popper has proposed a ?theory of situational rationality? as a basis for the social sciences. This theory of rational action is reconstructed and its methodological and substantial implications discussed. It is shown that methodologically Popper's idea of rational action leads to a version of theoretical instrumentalism which is incompatible with his general philosophy of science, and that substantially it implies an unacceptable theory of social institutions. Instrumentalism can be avoided by a more contentful theory of human action encompassing ?non?rational? or (...) ?irrational? kinds of action; Popper's theory of institutions might be improved through a more comprehensive theory of collective action. (shrink)
Reconstructing Popper's research programme for the Human Sciences, Noretta Koertge (Inquiry, Vol. 18 ) has given a deductive?nomological account of explanations of actions by means of a Rationality Principle. It is argued here that such a Rationality Principle is fundamentally redundant. Neither is it logically necessary in order to deduce a cognitive action?explanandum, nor can it be given a semantic non?empty interpretation, at least not within Koertge's own syllogism. Any attempt to save the Rationality Principle as unfalsifiablc but nevertheless indispensable (...) for action explanations is rejected in the light of possible alternative action explanations by empirical and therefore in principle falsifiable psychological laws. (shrink)
Zusammenfassung Es wird auf einige MiÃverstÃ¤ndnisse in B. Juhos' Interpretation der Popperschen Ansichten zum Falsifikationsproblem verwiesen und betont, daÃ B. Juhos' Hauptthese der Symmetrie von Verifikation und Falsifikation, woraus auf die Berechtigung verifikationistischer Forschungspraktiken geschlossen wird, auf einer Verwechslung von Falsifizierbarkeit und Falsifikation beruht.