Laminar Origin of Corticostriatal Projections to the Motor Putamen in the Macaque Brain

In the macaque brain, projections from distant, interconnected cortical areas converge in specific zones of the striatum. For example, specific zones of the motor putamen are targets of projections from frontal motor, inferior parietal, and ventrolateral prefrontal hand-related areas and thus are integral part of the so-called "lateral grasping network." In the present study, we analyzed the laminar distribution of corticostriatal neurons projecting to different parts of the motor putamen. Retrograde neural tracers were injected in different parts of the putamen in 3 Macaca mulatta (one male) and the laminar distribution of the labeled corticostriatal neurons was analyzed quantitatively. In frontal motor areas and frontal operculum, where most labeled cells were located, almost everywhere the proportion of corticostriatal labeled neurons in layers III and/or VI was comparable or even stronger than in layer V. Furthermore, within these regions, the laminar distribution pattern of corticostriatal labeled neurons largely varied independently from their density and from the projecting area/sector, but likely according to the target striatal zone. Accordingly, the present data show that cortical areas may project in different ways to different striatal zones, which can be targets of specific combinations of signals originating from the various cortical layers of the areas of a given network. These observations extend current models of corticostriatal interactions, suggesting more complex modes of information processing in the basal ganglia for different motor and nonmotor functions and opening new questions on the architecture of the corticostriatal circuitry

The complex hodological architecture of the macaque dorsal intraparietal areas as emerging from neural tracers and DW-MRI tractography

In macaque monkeys, dorsal intraparietal areas are involved in several daily visuo-motor actions. However, their border and sources of cortical afferents remain loosely defined. Combining retrograde histological tracing and MRI diffusion-based tractography we found a complex hodology of the dorsal bank of the IPS, which can be subdivided into a rostral area PEip, projecting to the spinal cord, and a caudal area MIP lacking such projections. Both include a rostral and a caudal sector, emerging from their ipsilateral, gradient-like connectivity profiles. As tractography estimations, we used the cross-sectional volume of the white matter bundles connecting each area with other parietal and frontal regions, after selecting ROIs corresponding to the injection sites of neural tracers. For most connections, we found a significant correlation between the proportions of cells projecting to all sectors of PEip and MIP along the continuum of the dorsal bank of the IPS and tractography. The latter also revealed “false positive” but plausible streamlines awaiting histological validation

GRUND 2008 nella sub area geografica 16 (GSA 16, Stretto di Sicilia): relazione finale

Il progetto Grund, finanziato a partire dal 1985 dapprima dalla D.G. Pesca e Acquacolura del Ministero per le politiche agricole, alimentari e forestali (MIPAAF) con i fondi della legge 41, in seguito dal MIPAAF e dalla DG IV della Commissione Europea, ha l’obiettivo generale di valutare la distribuzione, l’abbondanza e la composizione per taglia delle specie oggetto di pesca presenti nei mari Italiani. L’Istituto di ricerche sulle Risorse Marine e l’Ambiente, Sezione di Mazara del Vallo di IAMC-CNR, effettua campagne di ricerca in mare nella GSA 16 (FAO, 2001) dello Stretto di Sicilia, tramite rete a strascico (trawl survey), sin dalla primavera del 1985, con l’obiettivo generale di studiare l’abbondanza ed i cicli vitali delle risorse demersali e di stimarne lo stato di sfruttamento

The impact of cluster mergers on arc statistics

We study the impact of merger events on the strong lensing properties of galaxy clusters. Previous lensing simulations were not able to resolve dynamical time scales of cluster lenses, which arise on time scales which are of order a Gyr. In this case study, we first describe qualitatively with an analytic model how some of the lensing properties of clusters are expected to change during merging events. We then analyse a numerically simulated lens model for the variation in its efficiency for producing both tangential and radial arcs while a massive substructure falls onto the main cluster body. We find that: (1) during the merger, the shape of the critical lines and caustics changes substantially; (2) the lensing cross sections for long and thin arcs can grow by one order of magnitude and reach their maxima when the extent of the critical curves is largest; (3) the cross section for radial arcs also grows, but the cluster can efficiently produce this kind of arcs only while the merging substructure crosses the main cluster centre; (4) while the arc cross sections pass through their maxima as the merger proceeds, the cluster's X-ray emission increases by a factor of $\sim5$. Thus, we conclude that accounting for these dynamical processes is very important for arc statistics studies. In particular, they may provide a possible explanation for the arc statistics problem.Comment: 16 pages, submitted to MNRAS, revised version after referee' Comments. Gzipped file including full resolution images can be downloaded at http://dipastro.pd.astro.it/~cosmo/massimo/high-res-images.tar.g

Large-scale temporo-parieto-frontal networks for motor and cognitive motor functions in the primate brain.

The extent to which neural circuits and mechanisms underlying sensory, motor, and cognitive cortical functions in the human brain are shared with those of other animals, especially non-human primates, is currently a key issue in the field of comparative neuroscience. Cortical functions result from the conjoint function of different, reciprocally connected areas working together as large-scale functionally specialized networks, which can be investigated in human subjects thanks to the development of non-invasive functional and connectional imaging techniques. In spite of their limitations in terms of spatial and temporal resolution, these techniques make it possible to address the issue of how and to what extent the neural mechanisms for different cortical functions differ from those of non-human primates. Indeed, 30 million years of independent evolution have resulted in significant differences between the brains of humans and macaques, which are the experimental model system phylogenetically closest to humans for obtaining highly detailed anatomical and functional information on the organization of cortical networks. In the macaque brain, architectonic, connectional, and functional data have provided evidence for functionally specialized large-scale cortical networks involving temporal, parietal, and frontal areas. These networks appear to play a primary role in controlling different aspects of motor and cognitive motor functions, such as hand action organization and recognition, or oculomotor behavior and gaze processing. In the present review, based on the comparison of these data with data from human studies, we will argue that there is clear evidence for human counterparts of these networks. These human and macaque putatively homolog networks appear to share phylogenetically older neural mechanisms, which, in the evolution of the human lineage, could have been exploited and differentiated, resulting in the emergence of human-specific higher-order cognitive functions. These considerations are fully in line with the notion of "neural reuse" in primate evolution

Premotor cortex

The frontal lobe of primates consists of two large regions, a rostral region involved in cognitive functions (prefrontal lobe) and a caudal region mostly devoted to motor functions (agranular frontal cortex). This last region is formed, posteriorly, by the primary motor cortex and, anteriorly, by a mosaic of distinct areas called premotor areas. Premotor areas can be subdivided into two main classes: caudal premotor areas and rostral premotor areas. The caudal premotor areas elaborate sensory information for action. The rostral premotor areas appear to play a control role on the caudal areas, relaying to them information from the prefrontal and cingulate cortex on individuals' motivation and long-term plans. In this way, potential motor actions formed in the caudal premotor areas can be executed or not according to the individual's needs

The cortical motor system

AbstractThe cortical motor system of primates is formed by a mosaic of anatomically and functionally distinct areas. These areas are not only involved in motor functions, but also play a role in functions formerly attributed to higher order associative cortical areas. In the present review, we discuss three types of higher functions carried out by the motor cortical areas: sensory-motor transformations, action understanding, and decision processing regarding action execution. We submit that generating internal representations of actions is central to cortical motor function. External contingencies and motivational factors determine then whether these action representations are transformed into actual actions

Motor functions of the parietal lobe

There is now general agreement that the posterior parietal cortex is part of the motor system. New data have confirmed its fundamental role in visuomotor transformations. Most interestingly, recent data showed that the inferior parietal lobule codes motor acts (such as grasping) in a specific way according to the action in which they are embedded. This particular motor organization appears to provide a neural mechanism for higher order cognitive motor functions, including understanding of intention. These functions, and peripersonal space representation, are represented in areas of the inferior parietal lobule, where visual information from both the dorsal and the ventral stream is integrated with motor information

Comparative anatomy of the macaque and the human frontal oculomotor domain

In non-human primates, at the junction of the prefrontal with the premotor cortex, there is a sector designated as frontal eye field (FEF), involved in controlling oculomotor behavior and spatial attention. Evidence for at least two FEFs in humans is at the basis of the still open issue of the possible homologies between the macaque and the human frontal oculomotor system. In this review article we address this issue suggesting a new view solidly grounded on evidence from the last decade showing that, in macaques, the FEF is at the core of an oculomotor domain in which several distinct areas, including areas 45A and 45B, provide the substrate for parallel processing of different aspects of oculomotor behavior. Based on comparative considerations, we will propose a correspondence between some of the macaque and the human oculomotor fields, thus suggesting sharing of neural substrate for oculomotor control, gaze processing, and orienting attention in space. Accordingly, this article could contribute to settle some aspects of the so-called "enigma" of the human FEF anatomy