Organization of the Macaque Monkey Insular Cortex Based on Multimodal Receptor Architectonics
Poster No:
1719
Submission Type:
Abstract Submission
Authors:
Meiqi Niu1, Julia Driouk1, Nicola Palomero-Gallagher1
Institutions:
1Research Centre Jülich, Jülich, North Rhine-Westphalia
First Author:
Co-Author(s):
Introduction:
The insular cortex, as a separate cortical lobe in the primate brain, is located in the depth of the Sylvian sulcus and covered by the frontal, parietal and temporal lobes. The insula is known to be functionally segregated and architectonically heterogeneous in the macaque monkey. Since the insular cortex lies at the interface of different functional systems and receives multiple cross-modal afferents from sensory, limbic, autonomic and frontal cortical areas [1, 2], it has been functionally characterized as a multimodal integration site that plays a prominent role in linking sensory experience and emotional valence [3, 4]. Structurally, it has been classically divided into broad granular, dysgranular, and agranular architectonic sectors. Each sector can be further subdivided into more specific architectonic areas or potential "stripes" based on their distinct histological features [5, 6]. The heterogenous distribution of neurotransmitter receptors has been shown to correlate with cytoarchitectonic borders and to reflect functional organizational principles of the mammalian brain [7]. Thus, in the present study we aimed to characterize the cyto-, myelo- and receptor architecture of the macaque insular cortex to create a 3D map of this region, and explore the relationship between its structural and functional heterogeneity based on similarities and dissimilarities of receptor distribution patterns.
Methods:
To this end, we applied quantitative in vitro receptor autoradiography [7] to analyze the distribution patterns of fourteen different receptors for glutamate, GABA, acetylcholine, serotonin, and dopamine in the insula of four hemispheres from three adult male Macaca fascicularis monkeys. The positions of all borders between areas were identified using an observer-independent, statistically testable method that analyzed differences in receptor distribution patterns [8]. The extent and location of the identified areas were mapped onto a flat map of the insula. We measured mean receptor densities for each identified area, and applied a set of linear mixed-effects models to reveal putative differences among these areas [8]. Cluster analyses [9] were conducted with the receptor fingerprints of all identified areas to detect groupings based on the degree of (dis)similarity of their receptor organization.
Results:
Sixteen cyto-, myelo-, and receptor architectonically distinct areas were identified and mapped within the macaque insula: four granular areas (i.e. dfa, dfp, gd, and gv), five dysgranular areas (i.e. dds, ddi, dm, dv and vfp), and seven agranular areas (i.e. vfa, ap, apm, apl, al, ai and am). We largely confirmed the existence of previously described insular areas, but could also identify a novel subdivision of area dd based on differences in their receptor distribution patterns (Fig. A). As revealed by the cluster analysis of receptor fingerprints, the organization of the identified insular areas shows a tripartite segregation in the rostro-caudal direction: a rostral cluster with areas dfa, apl, al, ai and am; an intermediate cluster with areas ap, apm and vfa; and a caudal cluster encompassing all dysgranular areas plus dfp, gd and gv (Fig. B).
Conclusions:
By combining quantitative analyses of cyto-, myeloarchitecture and receptor distribution patterns, the present study provides a multimodal architectonic map of the macaque insular cortex, which reveals a high degree of segregation in this brain region. Based on the region-specific multireceptor balances, a tripartite organization of the macaque insula is proposed, which is similar, but not identical, to that based on the granularity of layer IV. This model not only outlines the approximate direction of information flow within this brain region but also offers a molecular perspective on the organizational principles underlying the regional and functional segregation of the macaque insula [3, 10].
Modeling and Analysis Methods:
Segmentation and Parcellation
Neuroanatomy, Physiology, Metabolism and Neurotransmission:
Cortical Anatomy and Brain Mapping 1
Cortical Cyto- and Myeloarchitecture
Transmitter Receptors
Neuroinformatics and Data Sharing:
Brain Atlases 2
Keywords:
Other - macaque monkey; insular cortex; multimodal receptor analysis; cytoarchitecture
1|2Indicates the priority used for review
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