Is Cerebellar Architecture Shaped by Sensory Ecology in the New Zealand Kiwi <b><i>(Apteryx mantelli)</i></b><b>?</b>

Abstract

Among some mammals and birds, the cerebellar architecture appears to be adapted to the animal's ecological niche, particularly their sensory ecology and behavior. This relationship is, however, not well understood. To explore this, we examined the expression of zebrin II (ZII) in the cerebellum of the kiwi (Apteryx mantelli), a fully nocturnal bird with auditory, tactile, and olfactory specializations and a reduced visual system. We predicted that the cerebellar architecture, particularly those regions receiving visual inputs and those that receive trigeminal afferents from their beak, would be modified in accordance with their unique way of life. The general stripe-and-transverse region architecture characteristic of birds is present in kiwi, with some differences. Folium IXcd was characterized by large ZII-positive stripes and all Purkinje cells in the flocculus were ZII positive, features that resemble those of small mammals and suggest a visual ecology unlike that of other birds. The central region in kiwi appeared reduced or modified, with folium IV containing ZII+/- stripes, unlike that of most birds, but similar to that of Chilean tinamous. It is possible that a reduced visual system has contributed to a small central region, although increased trigeminal input and flightlessness have undoubtedly played a role in shaping its architecture. Overall, like in mammals, the cerebellar architecture in kiwi and other birds may be substantially modified to serve a particular ecological niche, although we still require a larger comparative data set to fully understand this relationship.

Zebrin II Is Expressed in Sagittal Stripes in the Cerebellum of Dragon Lizards (<b><i>Ctenophorus </i></b>sp<b><i>.</i></b>)

“…4 b): an AR covering lobules I-V and consisting of alternating ZII+ and ZII-stripes; a CR covering lobules VI and VII where all Purkinje cells are ZII+; a PR that includes lobule VIII and part of IX and consisting of ZII stripes; and an NR covering lobule X and the posterior part of lobule IX where all Purkinje cells are ZII+. A strikingly similar pattern occurs in birds [Pakan et al, 2007;Iwaniuk et al, 2009, Marzban et al, 2010Vibulyaseck et al, 2015;Corfield et al, 2015Corfield et al, , 2016. The pattern of ZII expression in the pigeon is shown on an unfolded cerebellum [based on Corfield et al, 2015] and as a schematic ( Fig.…”

“…These are known as the central region (CR) and the nodular region (NR), respectively. ZII has also been studied in several species of birds [Pakan et al, 2007;Iwaniuk et al, 2009;Marzban et al, 2010;Corfield et al, 2015Corfield et al, , 2016. As in mammals, ZII is expressed heterogeneously such that there are ZII+ and ZII-sagittal stripes, and the pattern of expression is remarkably similar to that observed in mammals: alternating ZII+ and ZII-stripes are apparent in lobules II-V (AR) and VIII and IX (PR), whereas most Purkinje cells in lobules VI, VII (CR), and X (NR) are ZII+.…”

Beyond Endocasts: Using Predicted Brain-Structure Volumes of Extinct Birds to Assess Neuroanatomical and Behavioral Inferences

“…Other authors have already established that the endocasts of birds closely match their brains in terms of volume [6], so the volumes of the endocasts of extinct birds in the sample were regarded as a proxy for brain volume. Brain-and endocast-structure size relative to brain and endocast size rather than to body size were analyzed to generate results that were as directly comparable as possible to existing histological studies on relative brain-structure size [52,[63][64][65][66][67][68][69][70][71].…”

“…To determine if any extinct taxa had brain-structure volumes that were significantly different from the extant birds studied, their predicted mean brain-structure volume and brain-remainder volume (endocast volume, as a proxy for brain volume, minus brain-structure volume) were compiled. These values were added to a dataset of actual brain-structure volume and brain-remainder volume (brain volume minus brain-structure volume) of all extant taxa for which these values were available in the literature [51,52,[63][64][65][66][67][68][69][70][71] (Table S1). These values were also added to a second dataset that included endocast-structure surface area, endocast-remainder surface area, and foramen magnum metrics, although this dataset was limited to the extinct and extant birds for which endocasts were available.…”

Topographic Organization of Inferior Olive Projections to the Zebrin II Stripes in the Pigeon Cerebellar Uvula

“…ZII is expressed heterogeneously such that bands of high ZII expression (ZII+) are interdigitated with bands of little to no ZII expression (ZII−; Figure 1 ). ZII stripes are seen in several mammalian (Leclerc et al, 1992 ; Ozol et al, 1999 ; Armstrong and Hawkes, 2000 ; Sanchez et al, 2002 ; Marzban et al, 2003 , 2015 ; Sillitoe et al, 2003a , b ; Marzban and Hawkes, 2011 ) and avian species (Pakan et al, 2007 ; Iwaniuk et al, 2009 ; Marzban et al, 2010 ; Corfield et al, 2015 , 2016 ; Vibulyaseck et al, 2015 ), as well as in one genus of lizards (Wylie et al, 2016 ). The prevalence of ZII stripes across various species suggests that the role for ZII is highly conserved, and is likely crucial to cerebellar function.…”