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Olfaction, navigation, and the origin of isocortex.

Aboitiz F, Montiel JF - Front Neurosci (2015)

Bottom Line: These adaptations were linked with increasing sensory development, which provided selective pressure for the expansion of the dorsal pallium.The latter appeared as an interface in olfactory-hippocampal networks, contributing somatosensory information for navigating behavior.Sensory input from other modalities like vision and audition were subsequently recruited into this expanding region, contributing to multimodal associative networks.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Psiquiatría, Escuela de Medicina, Centro Interdisciplinario de Neurociencia, Pontificia Universidad Católica de Chile Santiago, Chile.

ABSTRACT
There are remarkable similarities between the brains of mammals and birds in terms of microcircuit architecture, despite obvious differences in gross morphology and development. While in reptiles and birds the most expanding component (the dorsal ventricular ridge) displays an overall nuclear shape and derives from the lateral and ventral pallium, in mammals a dorsal pallial, six-layered isocortex shows the most remarkable elaboration. Regardless of discussions about possible homologies between mammalian and avian brains, a main question remains in explaining the emergence of the mammalian isocortex, because it represents a unique phenotype across amniotes. In this article, we propose that the origin of the isocortex was driven by behavioral adaptations involving olfactory driven goal-directed and navigating behaviors. These adaptations were linked with increasing sensory development, which provided selective pressure for the expansion of the dorsal pallium. The latter appeared as an interface in olfactory-hippocampal networks, contributing somatosensory information for navigating behavior. Sensory input from other modalities like vision and audition were subsequently recruited into this expanding region, contributing to multimodal associative networks.

No MeSH data available.


Olfactory projections to the hippocampus in birds, reptiles, and mammals. Based on Striedter (2015), with permission. CA1, Cornu Ammonis 1; CA3, Cornu Ammonis 3; Cx, Cortex; DG, Dentate gyrus; DLA, Dorsolateral anterior nucleus; DLAm, medial part of the dorsolateral anterior nucleus; DTh, Dorsal thalamus; HTh, Hypothalamus; ERCx, Entorhinal cortex; DCx, Dorsal cortex; DL, dorsolateral division of the hippocampus; DM, dorsomedial division of the hippocampus; DMCx, Dorsomedial cortex; LCx, Lateral cortex; N, Nidopallium; MCx, Medial cortex; OCx, Olfactory cortex; Sept, Septum; V, ventral division of the hippocampus (also named V-shaped area).
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Figure 2: Olfactory projections to the hippocampus in birds, reptiles, and mammals. Based on Striedter (2015), with permission. CA1, Cornu Ammonis 1; CA3, Cornu Ammonis 3; Cx, Cortex; DG, Dentate gyrus; DLA, Dorsolateral anterior nucleus; DLAm, medial part of the dorsolateral anterior nucleus; DTh, Dorsal thalamus; HTh, Hypothalamus; ERCx, Entorhinal cortex; DCx, Dorsal cortex; DL, dorsolateral division of the hippocampus; DM, dorsomedial division of the hippocampus; DMCx, Dorsomedial cortex; LCx, Lateral cortex; N, Nidopallium; MCx, Medial cortex; OCx, Olfactory cortex; Sept, Septum; V, ventral division of the hippocampus (also named V-shaped area).

Mentions: Jacobs (2012) recently argued that more than as a sense involved in discriminating stimuli, olfaction works as a reference system for spatial navigation, guiding the animal to locate food sources, or mates (see also Eichenbaum, 1998). Furthermore, Jacobs (2012) suggested that the navigational properties of the olfactory system serve as scaffolding for the evolution of a parallel orientation map in the hippocampus. Despite some variations, a hippocampal region associated with spatial orientation (Day et al., 1999, 2001; Rodríguez et al., 2002), and an important olfactory-hippocampal projection (Striedter, 2015; Figure 2), are conserved features of all amniotes. In rodents, the olfactory system connects with the hippocampus through the entorhinal cortex, which also forms extensive associative networks with other sensory modalities in the isocortex (Lynch, 1986; Haberly, 1990; Figure 3).


Olfaction, navigation, and the origin of isocortex.

Aboitiz F, Montiel JF - Front Neurosci (2015)

Olfactory projections to the hippocampus in birds, reptiles, and mammals. Based on Striedter (2015), with permission. CA1, Cornu Ammonis 1; CA3, Cornu Ammonis 3; Cx, Cortex; DG, Dentate gyrus; DLA, Dorsolateral anterior nucleus; DLAm, medial part of the dorsolateral anterior nucleus; DTh, Dorsal thalamus; HTh, Hypothalamus; ERCx, Entorhinal cortex; DCx, Dorsal cortex; DL, dorsolateral division of the hippocampus; DM, dorsomedial division of the hippocampus; DMCx, Dorsomedial cortex; LCx, Lateral cortex; N, Nidopallium; MCx, Medial cortex; OCx, Olfactory cortex; Sept, Septum; V, ventral division of the hippocampus (also named V-shaped area).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4621927&req=5

Figure 2: Olfactory projections to the hippocampus in birds, reptiles, and mammals. Based on Striedter (2015), with permission. CA1, Cornu Ammonis 1; CA3, Cornu Ammonis 3; Cx, Cortex; DG, Dentate gyrus; DLA, Dorsolateral anterior nucleus; DLAm, medial part of the dorsolateral anterior nucleus; DTh, Dorsal thalamus; HTh, Hypothalamus; ERCx, Entorhinal cortex; DCx, Dorsal cortex; DL, dorsolateral division of the hippocampus; DM, dorsomedial division of the hippocampus; DMCx, Dorsomedial cortex; LCx, Lateral cortex; N, Nidopallium; MCx, Medial cortex; OCx, Olfactory cortex; Sept, Septum; V, ventral division of the hippocampus (also named V-shaped area).
Mentions: Jacobs (2012) recently argued that more than as a sense involved in discriminating stimuli, olfaction works as a reference system for spatial navigation, guiding the animal to locate food sources, or mates (see also Eichenbaum, 1998). Furthermore, Jacobs (2012) suggested that the navigational properties of the olfactory system serve as scaffolding for the evolution of a parallel orientation map in the hippocampus. Despite some variations, a hippocampal region associated with spatial orientation (Day et al., 1999, 2001; Rodríguez et al., 2002), and an important olfactory-hippocampal projection (Striedter, 2015; Figure 2), are conserved features of all amniotes. In rodents, the olfactory system connects with the hippocampus through the entorhinal cortex, which also forms extensive associative networks with other sensory modalities in the isocortex (Lynch, 1986; Haberly, 1990; Figure 3).

Bottom Line: These adaptations were linked with increasing sensory development, which provided selective pressure for the expansion of the dorsal pallium.The latter appeared as an interface in olfactory-hippocampal networks, contributing somatosensory information for navigating behavior.Sensory input from other modalities like vision and audition were subsequently recruited into this expanding region, contributing to multimodal associative networks.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Psiquiatría, Escuela de Medicina, Centro Interdisciplinario de Neurociencia, Pontificia Universidad Católica de Chile Santiago, Chile.

ABSTRACT
There are remarkable similarities between the brains of mammals and birds in terms of microcircuit architecture, despite obvious differences in gross morphology and development. While in reptiles and birds the most expanding component (the dorsal ventricular ridge) displays an overall nuclear shape and derives from the lateral and ventral pallium, in mammals a dorsal pallial, six-layered isocortex shows the most remarkable elaboration. Regardless of discussions about possible homologies between mammalian and avian brains, a main question remains in explaining the emergence of the mammalian isocortex, because it represents a unique phenotype across amniotes. In this article, we propose that the origin of the isocortex was driven by behavioral adaptations involving olfactory driven goal-directed and navigating behaviors. These adaptations were linked with increasing sensory development, which provided selective pressure for the expansion of the dorsal pallium. The latter appeared as an interface in olfactory-hippocampal networks, contributing somatosensory information for navigating behavior. Sensory input from other modalities like vision and audition were subsequently recruited into this expanding region, contributing to multimodal associative networks.

No MeSH data available.