Parallel organization of the avian sensorimotor arcopallium: Tectofugal visual pathway in the pigeon (Columba livia)

Abstract

The sensory–motor division of the avian arcopallium receives parallel inputs from primary and high‐order pallial areas of sensory and vocal control pathways, and sends a prominent descending projection to ascending and premotor, subpallial stages of these pathways. While this organization is well established for the auditory and trigeminal systems, the arcopallial subdivision related to the tectofugal visual system and its descending projection to the optic tectum (TeO) has been less investigated. In this study, we charted the arcopallial area displaying tectofugal visual responses and by injecting neural tracers, we traced its connectional anatomy. We found visual motion‐sensitive responses in a central region of the dorsal (AD) and intermediate (AI) arcopallium, in between previously described auditory and trigeminal zones. Blocking the ascending tectofugal sensory output, canceled these visual responses in the arcopallium, verifying their tectofugal origin. Injecting PHA‐L into the visual, but not into the auditory AI, revealed a massive projection to tectal layer 13 and other tectal related areas, sparing auditory, and trigeminal ones. Conversely, CTB injections restricted to TeO retrogradely labeled neurons confined to the visual AI. These results show that the AI zone receiving tectofugal inputs sends top‐down modulations specifically directed to tectal targets, just like the auditory and trigeminal AI zones project back to their respective subpallial sensory and premotor areas, as found by previous studies. Therefore, the arcopallium seems to be organized in a parallel fashion, such that in spite of expected cross‐modal integration, the different sensory–motor loops run through separate subdivisions of this structure.

Molecular specializations of deep cortical layer analogs in songbirds

“…Whereas RA receives input from HVC and from the LMAN core, the latter projection connecting the anterior forebrain and vocal-motor pathways, AId receives input from the LMAN shell and from the dorsal caudolateral nidopallium (dNCL) lateral to HVC 50 , 51 , 71 , 77 . The projection from dNCL to AId appears to be topographic 5 , 51 , 71 , 77 suggesting that a topographic organization might also be present in a medial to lateral map in AId, with possible somatotopy. Furthermore, both RA and AId are part of the intermediate arcopallium, which originates descending somatic projections 38 and is considered part of a general motor pathway 32 .…”

A canonical interlaminar circuit in the sensory dorsal ventricular ridge of birds: The anatomical organization of the trigeminal pallium

“…In the pigeon, zebra finch, and mallard, the NFT has been shown to be the source of long‐range projections to several other pallial areas, such as the somato‐motor arcopallium, and the associative, or higher order, caudal nidopallium. These connections could be compared to the ones arising from the NI, the intermediate layer of the visual DVR, which has recently been shown to be sole source of the long‐range intrapallial projections of the visual DVR complex (Fernández, Ahumada‐Galleguillos, et al, 2020; Fernández, Morales, et al, 2020). Establishing to what extent NFT and NI share similar structural and functional traits becomes of high interest and should be studied further.…”

“…According to this evidence, the forming layers of the sensory DVR consist of continuous fields of characteristic cell types, that extends along the whole rostro-caudal axis of the anterior DVR (Figure 3; Chen et al, 2013;Jarvis et al, 2013). In each domain receiving primary sensory afferents, the ventral most senso-recipient layer (trigeminal, Bas; (Fern andez, Ahumada-Galleguillos, et al, 2020;Fern andez, Morales, et al, 2020;Wild et al, 1985Wild et al, , 1993. Regarding projections toward the basal ganglia, as stated above two, different sources of efferents have been described in the tectovisual and trigeminal area (current study): one originated in the intermediate layer (NI and NFT) and another originated in the ventral division of the senso-recipient layer (ventral E and ventral Bas;Ahumada-Galleguillos et al, 2015;Fern andez, Ahumada-Galleguillos, et al, 2020;Krützfeldt & Wild, 2005).…”

Multidimensional Tuning in Motor Cortical Neurons during Active Behavior

“…Although this activity could be related to head movements, which we did not score comprehensively, another possibility is that activity in these neurons relates to non-motor factors such as visual processing, attention, or arousal (Knudsen et al, 1995;Rauske et al, 2003;Cardin and Schmidt, 2004;Winkowski and Knudsen, 2007;Fernández et al, 2020).…”