Behavioural Brain Research 222 (2011) 51–56 Contents lists available at ScienceDirect Behavioural Brain Research journal homepage: www.elsevier.com/locate/bbr Research report Visual Wulst analyses “where” and entopallium analyses “what” in the zebra finch visual system Shigeru Watanabe a,∗ , Uwe Mayer b , Hans-Joachim Bischof b a Department of Psychology, Keio University, Mita 2-25-45, Minato-Ku, Tokyo, Japan b Department of Behavioural Biology, Bielefeld University, 33501 Bielefeld, Germany article info Article history: Received 2 February 2011 Received in revised form 10 March 2011 Accepted 14 March 2011 Keywords: Birds Zebra finch Visual system Pattern discrimination Spatial discrimination Brain lesions abstract Quite a lot of studies have tried to elucidate the differences in function of the two telencephalic targets of the avian visual system. We have tried to find out how the two systems are involved in orientation towards a food tray which is either marked by a special pattern or has to be identified by its relation to spatial cues. In this report, we compared in the zebra finch the effects of Wulst lesions on pattern discrimination with Wulst lesion effects on spatial discrimination, and we examined the effect of entopallium lesions on spatial discrimination. Birds with Wulst lesions showed deficits in spatial discrimination, but not in pattern discrimination. Entopallial lesions caused no deficits in spatial discrimination tasks. Combining the present results with a previous study revealing an impairment of pattern discrimination by such entopallial lesions [19], we are able to demonstrate a double dissociation: namely, an impairment of pattern discrimination by entopallial lesions and impairment of spatial discrimination by Wulst lesions, but no effects of the opposite pairing of task and lesion site. The entopallium is thus involved if the food source is identified by a pattern, and the Wulst if it has to be found by spatial cues. © 2011 Elsevier B.V. All rights reserved. 1. Introduction In birds and mammals, visual information is processed by three visual pathways. The so-called accessory system processes reti- nal image motion as produced by self motion of the subject. The two other pathways, the lemnothalamic and the collothalamic one, are thought to be involved in object detection and recognition. In birds, the telencephalic terminal of the lemnothalamic projection is called the “visual Wulst,” and consists of the hyperpallium apicale (HA), the hyperpallium intercalatum (HI), and the hyperpallium densocellulare (HD). It has been considered to be homologous to the primary visual cortex in mammals [11], but the finding of more than one retinotopic map in this region [8] may suggest that it also corresponds to other areas of the mammalian visual neocortex. The avian entopallium is the telencephalic terminal of the collotha- lamic pathway and a part of the dorsal ventricular ridge (DVR). In most mammals, the lateral geniculate–visual cortex projection (lemnothalamic pathway) is believed to be the main visual path- way, whereas in birds, the collothalamic pathway is the dominant one [4]. After a pioneering study by Hodos and Karten [5], it has been shown frequently that entopallial lesions cause deficits in pattern ∗ Corresponding author. E-mail address: swat@flet.keio.ac.jp (S. Watanabe). discrimination in pigeons [2,12–14]. Likewise, entopallial lesions led to deficits in discriminating pseudoconcepts, in which four food items and four nonfood items were classified into two arbitrary (pseudo) groups. Interestingly, no such deficits were detected in the case of food vs. non-food concept discrimination. The birds had already natural concepts about food before the training while they had to learn the pseudoconcepts in the course of the training [12]. Information on the function of the entopallium in birds other than pigeons is sparse. In a first attempt to investigate the interplay of the two pathways with hippocampus, we have com- pared the effects of entopallial lesions with those of hippocampal lesions on pattern discrimination in zebra finches [19]. The birds were trained to discriminate a feeder with a dot pattern from feeders with a stripe pattern. When the birds had learned the discrimination, either the entopallium or the hippocampus was damaged. The entopallial lesions caused deficits in this visual pat- tern discrimination, whereas hippocampal lesions did not. Effects of the entopallium lesions on pattern discrimination agree with effects shown in our previous experiments in pigeons. The avian hippocampus, in contrast, is obviously not involved in pattern dis- crimination learning, but, as we have shown previously, plays a dominant role in spatial learning [18]. Wulst lesions do not cause deficits in visual discrimination in pigeons [5,13,14]. Lesions of the principal optic thalamic nuclei of the lemnothalamic projection had little or no effect on intensity 0166-4328/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.bbr.2011.03.035