title: Visuospatial learning and memory in the Cebus apella and microglial morphology in the molecular layer of the dentate gyrus and CA1 lacunosum molecular layer.
abstract: We investigated whether the morphology of microglia in the molecular layer of the dentate gyrus (DG-Mol) or in the lacunosum molecular layer of CA1 (CA1-LMol) was correlated with spatial learning and memory in the capuchin monkey (Cebus apella). Learning and memory was tested in 4 monkeys with visuo-spatial, paired associated learning (PAL) tasks from the Cambridge battery of neuropsychological tests. After testing, monkeys were sacrificed, and hippocampi were sectioned. We specifically immunolabeled microglia with an antibody against the adapter binding, ionized calcium protein. Microglia were selected from the middle and outer thirds of the DG-Mol (n=268) and the CA1-LMol (n=185) for three-dimensional reconstructions created with Neurolucida and Neuroexplorer software. Cluster and discriminant analyses, based on microglial morphometric parameters, identified two major morphological microglia phenotypes (types I and II) found in both the CA1-LMol and DG-Mol of all individuals. Compared to type II, type I microglia were significantly smaller, thinner, more tortuous and ramified, and less complex (lower fractal dimensions). PAL performance was both linearly and non-linearly correlated with type I microglial morphological features from the rostral and caudal DG-Mol, but not with microglia from the CA1-LMol. These differences in microglial morphology and correlations with PAL performance were consistent with previous proposals of hippocampal regional contributions for spatial learning and memory. Our results suggested that at least two morphological microglial phenotypes provided distinct physiological roles to learning-associated activity in the rostral and caudal DG-Mol of the monkey brain.
authors.affiliation: Laboratório de Investigações em Neurodegeneração e Infecção, Hospital Universitário João de Barros Barreto, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Pará, Brazil.
authors.forename: Carlos
authors.initials: C
authors.lastname: Santos-Filho
authors.affiliation: Laboratório de Investigações em Neurodegeneração e Infecção, Hospital Universitário João de Barros Barreto, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Pará, Brazil.
authors.forename: Camila M
authors.initials: CM
authors.lastname: de Lima
authors.affiliation: Laboratório de Investigações em Neurodegeneração e Infecção, Hospital Universitário João de Barros Barreto, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Pará, Brazil.
authors.forename: César A R
authors.initials: CA
authors.lastname: Fôro
authors.affiliation: Laboratório de Investigações em Neurodegeneração e Infecção, Hospital Universitário João de Barros Barreto, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Pará, Brazil.
authors.forename: Marcus A
authors.initials: MA
authors.lastname: de Oliveira
authors.affiliation: Laboratório de Investigações em Neurodegeneração e Infecção, Hospital Universitário João de Barros Barreto, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Pará, Brazil.
authors.forename: Nara G M
authors.initials: NG
authors.lastname: Magalhães
authors.affiliation: Laboratório de Investigações em Neurodegeneração e Infecção, Hospital Universitário João de Barros Barreto, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Pará, Brazil.
authors.forename: Cristovam
authors.initials: C
authors.lastname: Guerreiro-Diniz
authors.affiliation: Laboratório de Investigações em Neurodegeneração e Infecção, Hospital Universitário João de Barros Barreto, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Pará, Brazil.
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Diniz
authors.affiliation: Instituto Evandro Chagas, IEC, Ananindeua, Pará, Brazil.
authors.forename: Pedro F da C
authors.initials: PF
authors.lastname: Vasconcelos
authors.affiliation: Laboratório de Investigações em Neurodegeneração e Infecção, Hospital Universitário João de Barros Barreto, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Pará, Brazil. Electronic address: cwpdiniz@gmail.com.
authors.forename: Cristovam W P
authors.initials: CW
authors.lastname: Diniz
mesh_terms: D000818:Animals; D056547:CA1 Region, Hippocampal / Q000166:cytology* / Q000502:physiology; D002428:Cebus; D016000:Cluster Analysis; D018891:Dentate Gyrus / Q000166:cytology* / Q000502:physiology; D005260:Female; D021621:Imaging, Three-Dimensional; D007150:Immunohistochemistry; D008297:Male; D008568:Memory / Q000502:physiology*; D017628:Microglia / Q000166:cytology*; D065853:Spatial Learning / Q000502:physiology*
keywords: Cebus apella; Dentate gyrus; Microglial morphology; Paired associates learning; Spatial memory