Brain of the African wild dog. I. Anatomy, architecture, and volumetrics

et al. 2020

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Employing a range of neuroanatomical stains, we detail the organization of the main and accessory olfactory systems of the African wild dog. The organization of both these systems follows that typically observed in mammals, but variations of interest were noted. Within the main olfactory bulb, the size of the glomeruli, at approximately 350 μm in diameter, are on the larger end of the range observed across mammals. In addition, we estimate that approximately 3,500 glomeruli are present in each main olfactory bulb. This larger main olfactory bulb glomerular size and number of glomeruli indicates that enhanced peripheral processing of a broad range of odorants is occurring in the main olfactory bulb of the African wild dog. Within the accessory olfactory bulb, the glomeruli did not appear distinct, rather forming a homogenous syncytia‐like arrangement as seen in the domestic dog. In addition, the laminar organization of the deeper layers of the accessory olfactory bulb was indistinct, perhaps as a consequence of the altered architecture of the glomeruli. This arrangement of glomeruli indicates that rather than parcellating the processing of semiochemicals peripherally, these odorants may be processed in a more nuanced and combinatorial manner in the periphery, allowing for more rapid and precise behavioral responses as required in the highly social group structure observed in the African wild dog. While having a similar organization to that of other mammals, the olfactory system of the African wild dog has certain features that appear to correlate to their environmental niche.

Section: Introductionsupporting

confidence: 53%

“…Ten adult African wild dog brains were obtained from Borås Zoo, Sweden (see Chengetanai et al, 2020 for full details of animals, permits and collection and treatment of tissue). All animals were treated and used according to the guidelines of the University of the Witwatersrand Animal Ethics Committee (AESC No.…”

Section: Specimensmentioning

confidence: 99%

The brain of the African wild dog. II. The olfactory system

et al. 2020

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“…The auditory cortical territory identifiable with the range of stains used in the current study was observed to occupy the ectosylvian gyrus, bordered medially by the suprasylvian sulcus and laterally by the ectosylvian sulcus (Figure 6, also see Chengetanai, Tenley, et al, 2020a for sulcal and gyral demarcations and nomenclature in the African wild dog). With the stains used in the current study we were able to identify the primary auditory cortex (AI), the anterior auditory field (AAF), and a larger region which we termed the secondary auditory cortex (AII), although we recognize that this region is likely to be comprised of at least two smaller cortical areas, the posterior pseudosylvian field and posterior suprasylvian field (e.g., Bajo, Nodal, Bizley, Moore, & King, 2007; Bizley, Nodal, Nelken, & King, 2005).…”

Section: Resultsmentioning

confidence: 56%

“…Ten adult African wild dog brains were obtained from Borås Zoo, Sweden (see Chengetanai, Tenley, et al, 2020a for full details of animals, permits, and collection and treatment of tissue). Antemortem observations for all these animals revealed that they were in good health with no obvious neural deficits or behavioral abnormalities, and were euthanized for population management reasons (Bertelsen, 2018).…”

Section: Methodsmentioning

confidence: 99%

“…In the current study the whole brain of one of these specimens (LP2, a male with a brain mass of 141.5 g) was sectioned, stained, and analyzed. While this study is primarily based on our observations from a single specimen, in a previous study this specimen and five others underwent MR imaging (Chengetanai, Tenley, et al, 2020a). When comparing the specimen used herein to these other MR scanned brains, no differences in terms of overall morphology of the auditory system, at the level of MRI resolution, were noted.…”

Section: Methodsmentioning

confidence: 99%

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The brain of the African wild dog. III. The auditory system

et al. 2020

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The large external pinnae and extensive vocal repertoire of the African wild dog (Lycaon pictus) has led to the assumption that the auditory system of this unique canid may be specialized. Here, using cytoarchitecture, myeloarchitecture, and a range of immunohistochemical stains, we describe the systems‐level anatomy of the auditory system of the African wild dog. We observed the cochlear nuclear complex, superior olivary nuclear complex, lateral lemniscus, inferior colliculus, medial geniculate body, and auditory cortex all being in their expected locations, and exhibiting the standard subdivisions of this system. While located in the ectosylvian gyri, the auditory cortex includes several areas, resembling the parcellation observed in cats and ferrets, although not all of the auditory areas known from these species could be identified in the African wild dog. These observations suggest that, broadly speaking, the systems‐level anatomy of the auditory system, and by extension the processing of auditory information, within the brain of the African wild dog closely resembles that observed in other carnivores. Our findings indicate that it is likely that the extraction of the semantic content of the vocalizations of African wild dogs, and the behaviors generated, occurs beyond the classically defined auditory system, in limbic or association neocortical regions involved in cognitive functions. Thus, to obtain a deeper understanding of how auditory stimuli are processed, and how communication is achieved, in the African wild dog compared to other canids, cortical regions beyond the primary sensory areas will need to be examined in detail.

The brain of the African wild dog.IV. The visual system

et al. 2020

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The variegated pelage and social complexity of the African wild dog (Lycaon pictus) hint at the possibility of specializations of the visual system. Here, using a range of architectural and immunohistochemical stains, we describe the systems‐level organization of the image‐forming, nonimage forming, oculomotor, and accessory optic, vision‐associated systems in the brain of one representative individual of the African wild dog. For all of these systems, the organization, in terms of location, parcellation and topology (internal and external), is very similar to that reported in other carnivores. The image‐forming visual system consists of the superior colliculus, visual dorsal thalamus (dorsal lateral geniculate nucleus, pulvinar and lateral posterior nucleus) and visual cortex (occipital, parietal, suprasylvian, temporal and splenial visual regions). The nonimage forming visual system comprises the suprachiasmatic nucleus, ventral lateral geniculate nucleus, pretectal nuclear complex and the Edinger–Westphal nucleus. The oculomotor system incorporates the oculomotor, trochlear and abducens cranial nerve nuclei as well as the parabigeminal nucleus, while the accessory optic system includes the dorsal, lateral and medial terminal nuclei. The extent of similarity to other carnivores in the systems‐level organization of these systems indicates that the manner in which these systems process visual information is likely to be consistent with that found, for example, in the well‐studied domestic cat. It would appear that the sociality of the African wild dog is dependent upon the processing of information extracted from the visual system in the higher‐order cognitive and affective neural systems.