A histological study of the song system of the carrion crow (Corvus corone)

Abstract

The song system of songbirds (oscines) is one of the best studied neuroethological model systems. So far, it has been treated as a relatively constrained sensorimotor system. Songbirds such as crows, however, are also known for their capability to cognitively control their audio‐vocal system. Yet, the neuroanatomy of the corvid song system has never been explored systematically. We aim to close this scientific gap by presenting a stereotactic investigation of the extended song system of the carrion crow (Corvus corone), an oscine songbird of the corvid family that has become an interesting model system for cognitive neuroscience. In order to identify and delineate the song nuclei, the ascending auditory nuclei, and the descending vocal‐motor nuclei, four stains were applied. In addition to the classical Nissl‐, myelin‐, and a combination of Nissl‐and‐myelin staining, staining for tyrosine hydroxylase was used to reveal the distribution of catecholaminergic neurons (dopaminergic, noradrenergic, and adrenergic) in the song system. We show that the crow brain contains the important song‐related nuclei, including auditory input and motor output structures, and map them throughout the brain. Fiber‐stained sections reveal putative connection patterns between the crow's song nuclei comparable to other songbirds.

A brain atlas of the carrion crow (Corvus corone)

“…Four staining protocols were applied to alternating sections (Kersten et al., 2021). For the first series of every brain, a Nissl stain (0.1% cresyl violet) was applied; the second series was stained for myelin (using 0.2% gold chloride solution; Schmued, 1990), while the third series was stained for both Nissl and myelin by combining the staining protocols.…”

“…A volume increase in associative pallial structures and particularly high associative neuron numbers seem to accompany enhanced cognitive skills in corvids (Burish et al., 2004; Iwaniuk & Hurd, 2005; Mehlhorn et al., 2010; Rehkämper et al., 1991; Ströckens et al., 2022). However, with the exception of a few specialized neuroanatomical studies (Izawa & Wiatanabe, 2007; Kersten et al., 2021; Sen et al., 2019; von Eugen et al., 2020), a detailed brain atlas of the corvid brain is lacking.…”

Cell-type specific pallial circuits shape categorical tuning responses in the crow telencephalon

“…Glass-coated tungsten microelectrodes with 2 MΩ impedance (Alpha Omega) were used. The electrodes targeted the corvid NCL, which is characterized by dopaminergic cells 63 – 65 . Each recording session started with adjusting the electrodes, until a proper neuronal signal (of at least 3:1 signal to noise) was detected on at least one channel (see also Fig.…”

“…We verified the NCL and the location of the electrodes in NCL (according to the implantation coordinates provided above). We immunohistochemically stained for tyrosine hydroxylase to identify dopaminergic cells, which characterize the NCL 65 (see Fig. 3 in Veit and Nieder 63 ).…”

Neural Code of Motor Planning and Execution during Goal-Directed Movements in Crows

“…Such coordinated actions require acute senses (Iwaniuk and Wylie, 2020), but most of all delicate motor planning and motor execution capabilities (Davies and Green, 1994;Brecht et al, 2019). With the exception of birdsong research, a research area that resulted in detailed knowledge on the neuroanatomy and neurophysiology of song production (Elemans, 2014;Schmidt and Wild, 2014;Murphy et al, 2017;Kersten et al, 2021), and despite the solid understanding of the neuroanatomy of the avian motor system (Dubbeldam, 2000), the neurophysiological mechanisms of motor plans and actions are rarely explored in birds. This is particularly true for cognitively-controlled and intentional motor plans that in corvid songbirds are comparable to those found in primates (Kabadayi et al, 2016;Miller et al, 2019).…”