Causal circuit explanations of behavior: Are necessity and sufficiency necessary and sufficient?

In the current advent of technological innovation allowing for precise neural manipulations and copious data collection, it is hardly questioned that the explanation of behavioral processes is to be chiefly found in neural circuits. Such belief, rooted in the exhausted dualism of cause and effect, is enacted by a methodology that promotes “necessity and sufficiency” claims as the goal-standard in neuroscience, thus instructing young students on what shall reckon as explanation. Here we wish to deconstruct and explicate the difference between what is done, what is said, and what is meant by such causal circuit explanations of behavior. Well-known to most philosophers, yet ignored or at least hardly ever made explicit by neuroscientists, the original grand claim of “understanding the brain” is imperceptibly substituted by the methodologically sophisticated task of empirically establishing counterfactual dependencies. But for the 21st century neuroscientist, after so much pride, this is really an excess of humility. I argue that to upgrade intervention to explanation is prone to logical fallacies, interpretational leaps and carries a weak explanatory force, thus settling and maintaining low standards for intelligibility in neuroscience. To claim that behavior is explained by a “necessary and sufficient” neural circuit is, at best, misleading. In that, my critique (rather than criticism) is indeed mainly negative. Positively, I briefly suggest some available alternatives for conceptual progress, such as adopting circular causality (rather than lineal causality in the flavor of top-down reductionism), searching for principles of behavior(rather than taking an arbitrary definition of behavior and rushing to dissect its “underlying” neural mechanisms), and embracing process philosophy (rather than substance-mechanistic ontologies). Overall, if the goal of neuroscience is to understand the relation between brain and behavior then, in addition to excruciating neural studies (one pillar), we will need a strong theory of behavior (the other pillar) and a solid foundation to establish their relation (the bridge)

Availability of animal food organisms and their utilization by cyprinids in Srilankan hillstream pools

The food and feeding of cyprinid fishes in three stream pools in South West Sri Lanka, was investigated from 29 June 1984 to 25 February 1986. S.W. Sri Lanka was chosen as a study site because the rainforest and its fish fauna are here severely threatened. Feeding ecology was studied by gut contents analysis. The availability of prey organisms in the environment was quantified and food utilization in each pool was estimated by comparing diet compositions of the fish species with the food availability. Seven cyprinid species represented more than 98% of the fish numbers caught. These were Pethia cumingii (PC), Puntius dorsalis (PD), Dawkinsia singhala (DS), Pethia nigrofasciata (PN), Systomus pleurotaenia (SP), Devario malabaricus (DM) and Rasbora daniconius (RD). Three of these species: the two surface feeders DM and RD and the generalist SP fed > 33 % (biovolume) on terrestrial arthropods. Since we were not able to quantify the availability of terrestrial arthropods - mainly ants falling from the trees into the stream - these three species were not included in part of the analysis. Chironomid larvae were most abundant and, on basis of biovolume, the most important animal food items of the remaining four cyprinid species (PC, PD, DS, PN). PD and PN strongly positively selected chironomid larvae, but DS and PC only weakly negatively. Although coleopterans and ephemeropterans were after chironomid larvae the most abundant food items in the environment the former were often negatively selected and ephemeropterans positively, so that the latter were generally after chironomid larvae the most frequently eaten food items