Hippocampal - diencephalic - cingulate networks for memory and emotion: An anatomical guide

This review brings together current knowledge from tract tracing studies to update and reconsider those limbic connections initially highlighted by Papez for their presumed role in emotion. These connections link hippocampal and parahippocampal regions with the mammillary bodies, the anterior thalamic nuclei, and the cingulate gyrus, all structures now strongly implicated in memory functions. An additional goal of this review is to describe the routes taken by the various connections within this network. The original descriptions of these limbic connections saw their interconnecting pathways forming a serial circuit that began and finished in the hippocampal formation. It is now clear that with the exception of the mammillary bodies, these various sites are multiply interconnected with each other, including many reciprocal connections. In addition, these same connections are topographically organised, creating further subsystems. This complex pattern of connectivity helps explain the difficulty of interpreting the functional outcome of damage to any individual site within the network. For these same reasons, Papez’s initial concept of a loop beginning and ending in the hippocampal formation needs to be seen as a much more complex system of hippocampal–diencephalic–cingulate connections. The functions of these multiple interactions might be better viewed as principally providing efferent information from the posterior medial temporal lobe. Both a subcortical diencephalic route (via the fornix) and a cortical cingulate route (via retrosplenial cortex) can be distinguished. These routes provide indirect pathways for hippocampal interactions with prefrontal cortex, with the preponderance of both sets of connections arising from the more posterior hippocampal regions. These multi-stage connections complement the direct hippocampal projections to prefrontal cortex, which principally arise from the anterior hippocampus, thereby creating longitudinal functional differences along the anterior–posterior plane of the hippocampus

Potential distribution and new records of Trinomys species (Rodentia: Echimyidae) in the state of Rio de Janeiro

The spiny rats of the genus Trinomys Thomas, 1921 have a broad distribution in the Atlantic Forests of southeastern Brazil. However, some species are known only from their type locality and adjacent areas. In our study, nine areas in the state of Rio de Janeiro were surveyed and three species of the genus were captured - Trinomys dimidiatus (Günther, 1877), T. setosus (Desmarest, 1817) and T. gratiosus bonafidei (MOOJEN, 1948). We extended the distribution of T. gratiosus bonafidei in 100 km, in a straight line to the northwest, and into an area of Semidecidual Seasonal Forest. We captured T. setosus, which had not been previously recorded in the state, in the municipality of Cambuci, extending its distribution 150 km, in a straight line to the east of its closest record, in Juiz de Fora, state of Minas Gerais. The state of Rio de Janeiro has now six recognized species of Trinomys, however none of them were collected above 1300 m of altitude. We used occurrence points provided by our inventories data and from the literature to model the potential distribution of Trinomys species. We used climatic, topographic and phytogeographic variables to prepare the potential distribution maps. The algorithm used for modeling was provided by the software Maxent, version 3.2.1. Although species boundaries within Trinomys in Rio de Janeiro State are not yet clear, their distributions seem to be parapatric, except for T. iheringi and T. dimidiatus