Noninvasive fluorescence imaging in animal models of stroke.

Noninvasive fluorescence imaging (NFI) is a powerful tool to study physiology and pathophysiology in animal disease models. NFI has been successfully applied in a number of animal disease models including cancer, arthritis, and stroke. Furthermore, several applications in humans have been described. NFI is widely available in research laboratories because it has a number of advantages: It uses non-ionizing radiation and requires comparably simple, inexpensive instrumentation, and easy to handle. Fluorochromes can be detected with high sensitivity, and image acquisition time is relatively short. Furthermore, a plethora of fluorescent imaging agents is available including unspecific, target-specific, and activatable imaging probes. With these probes, biological processes such as inflammation, cell death or enzyme activity, and many others can be visualized in living animals. This review offers an overview of current approaches in NFI of stroke pathophysiology in animal models of cerebral ischemia. First, the instrumentation and the different types of imaging agents for NFI are described. Second, a short introduction to animal models of stroke is provided. Third, examples for NFI in animal models of stroke are given. Finally, the use of NFI in human stroke is critically discussed.

On structure-dependent grammars: a reply to Mabry.

In a recent paper, Mabry (1993) examines various aspects of Skinner's (1957) treatment of grammar, and he compares it with cognitivist approaches. Mabry gives convincing reasons for concluding that Skinner's approach is superior. But Mabry virtually ignores one of the most important features of grammatical behavior, namely, its structure dependence. Since Chomsky's main argument against Skinner's treatment of verbal behavior is based on this feature, Mabry's analysis must be expanded to include a behavior-analytic treatment of it. Only then can real progress be made in bringing cognitivists closer to functional analyses of verbal behavior. A brief outline of a behavior-analytic explanation of structure dependence is given in the present paper.

The behavior of the listener, generic extensions, and the communicative adequacy of verbal behavior.

Except for a few words, children first become listeners of a word before becoming speakers of the word. The analysis of listener behavior is therefore of fundamental importance for the complete analysis of verbal behavior. In this paper, some basic aspects of listener behavior are examined: in particular, the events that give origin to the behavior, the generic effects of these events, and intraspecific uniformities between these effects. By relying on the generic effects, the notion of extension is defined. This notion is then used for characterizing correct listener behavior. Finally, the uniformities between the generic effects are shown to play a crucial role in ensuring the communicative adequacy of verbal behavior.

Skinner and a solution to the problem of inner events.

Skinner's treatment of inner states has been criticized not only by cognitivists but also by people who are close to behaviorist views. In particular, critics have argued that because of the limited conceptual resources of his scientific framework, Skinner cannot account for "mental" phenomena such as the qualitative character of feelings, conscious contents, or states of awareness. The present paper claims that these criticisms are mistaken. By paying careful attention to Skinner's strict physicalist position and by employing a consistent physicalist terminology, it can be shown that Skinner is able to account for the phenomena in question.

Skinner's verbal behavior, Chomsky's review, and mentalism.

Skinner's Verbal Behavior (1957) is a comprehensive treatise that deals with most aspects of verbal behavior. However, its treatment of the learning of grammatical behavior has been challenged repeatedly (e.g., Chomsky, 1959). The present paper will attempt to show that the learning of grammar and syntax can be dealt with adequately within a behavior-analytic framework. There is no need to adopt mentalist (or cognitivist) positions or to add mentalist elements to behaviorist theories.

Natural concepts and generalization classes.

The results of an experiment performed by Herrnstein, Loveland, and Cable (1976) show that pigeons possess concepts that are not based on common elements. The conclusion they draw from these results is that these concepts are largely determined by genetic factors. In the present paper it is argued that, at least for some of the concepts, the conclusion is incorrect. These concepts-called here uncommon generalization classes-were acquired by the pigeons as a consequence of certain experiences through which they went during the experiment. The discussion will also suggest the fruitfulness of replacing the vague and misleading notion of concept by the more adequate notion of generalization class.