Within the avian telencephalon, the dorsal ventricular ridge (DVR) contains higher order and multimodal integration areas. Using multiple regressions on 17 avian taxa, we show that an operational estimate of behavioral flexibility, the frequency of feeding innovation reports in ornithology journals, is most closely predicted by relative size of one of these DVR areas, the hyperstriatum ventrale. Neither phylogeny, juvenile development mode, nor species sampled account for the relationship. Similar results are found when the hyperstriatum ventrale is lumped with a second DVR structure, the neostriatum. In simple correlations, size of the wulst and the striatopallidal complex is associated with feeding innovation rate, but the two structures are eliminated from the multiple regressions. Our results parallel those on primates showing a correlation between innovation rate and neocortex size and support the idea that the mammalian neocortex and the neostriatum-hyperstriatum ventrale complex in birds have similar integrative roles.

Tools are traditionally de ned as objects that are used as an extension of the body and held directly in the hand or mouth. By these standards, a vulture breaking an egg by hitting it with a stone uses a tool, but a gull dropping an egg on a rock does not. This distinction between true and borderline (or proto-tool) cases has been criticized for its arbitrariness and anthropocentrism. We show here that relative size of the neostriatum and whole brain distinguish the true and borderline categories in birds using tools to obtain food or water. From two sources, the specialized literature on tools and an innovation data base gathered in the short note sections of 68 journals in 7 areas of the world, we collected 39 true (e.g. use of probes, hammers, sponges, scoops) and 86 borderline (e.g. bait shing, battering and dropping on anvils, holding with wedges and skewers) cases of tool use in 104 species from 15 parvorders. True tool users have a larger mean residual brain size (regressed against body weight) than do users of borderline tools, con rming the distinction in the literature. In multiple regressions, residual brain size and residual size of the neostriatum (one of the areas in the avian telencephalon thought to be equivalent to the mammalian neocortex) are the best predictors of true tool use reports per taxon. Innovation rate is the best predictor of borderline tool use distribution. Despite the strong concentration of true tool use cases in Corvida and Passerida, independent constrasts suggest that common ancestry is not responsible for the association between tool use and size of the neostriatum and whole brain. Our results demonstrate that birds are more frequent tool users than usually thought and that the complex 1) Corresponding authors's e-mail address: louis.lefebvre@mcgill.ca 3) Current address: Ecole d'Optométrie, Université de Montréal. 4) We are grateful to Simon Reader for comments on earlier versions and to Sarah Timmermans for alerting us to the existence of Mlikovsky's data. We also thank Simran Kurir, Yutaka Nishioka and Johan Bolhuis for help with the German, Japanese and Dutchlanguage papers. This work was funded by an NSERC grant to LL and an FCAR fellowship to NN. © Koninklijke Brill NV, Leiden, 2002 Behaviour 139, 939-973 Also available online -940 LEFEBVRE, NICOLAKAKIS & BOIREcognitive processes involved in tool use may have repeatedly co-evolved with large brains in several orders of birds.

The purpose of this study was to identify and compare the afferent projections to the primary visual cortex in intact and enucleated C57BL/6 mice and in ZRDCT/An anophthalmic mice. Early loss of sensory-driven activity in blind subjects can lead to activations of the primary visual cortex by haptic or auditory stimuli. This intermodal activation following the onset of blindness is believed to arise through either unmasking of already present cortical connections, sprouting of novel cortical connections or enhancement of intermodal cortical connections. Studies in humans have similarly demonstrated heteromodal activation of visual cortex following relatively short periods of blindfolding. This suggests that the primary visual cortex in normal sighted subjects receives afferents, either from multisensory association cortices or from primary sensory cortices dedicated to other modalities. Here cortical afferents to the primary visual cortex were investigated to determine whether the visual cortex receives sensory input from other modalities, and whether differences exist in the quantity and/or the structure of projections found in sighted, enucleated and anophthalmic mice. This study demonstrates extensive direct connections between the primary visual cortex and auditory and somatosensory areas, as well as with motor and association cortices in all three animal groups. This suggests that information from different sensory modalities can be integrated at early cortical stages and that visual cortex activations following visual deprivations can partly be explained by already present intermodal corticocortical connections.

Relative brain size and the relative size of six brain regions (main olfactory bulbs, accessory olfactory bulbs, telencephalon, optic tectum, cerebellum and brain stem) in ten species of anurans from five habitats were examined to determine whether there was any evidence of adaptation in brain structure. A previously published data set was also reanalysed. Arboreal frogs have larger body-size corrected brains than frogs from other habitats. Arboreal ranid (Platymantis vitiensis) and hylid (Hyla versicolor) possess slightly larger cerebella than the ranids and hylids from other habitats. Platymantis vitiensis lacks an accessory olfactory bulb. The fully-aquatic Xenopus laevis (Pipidae) has a smaller optic tectum and cerebellum than the non-fossorial hylids and ranids. Adaptation to life underground appears to explain the modified brains of two fossorial frogs, Hemisus guineensis (Ranidae) and Rhinophrynus dorsalis (Rhinophrynidae). Both species of fossorial frogs have reduced optic tecta, larger main olfactory and smaller accessory olfactory bulbs, and larger torus semicircularis than non-fossorial species. Our data showed a strong negative correlation between the size of the optic tectum and the size of the main olfactory bulbs. We conclude that, although anuran brains are very similar across taxa in qualitative and general structure, there are some interesting, apparent adaptations, to fossorial and arboreal life.