22 research outputs found

    Spatial Representation and Navigation in a Bio-inspired Robot

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    A biologically inspired computational model of rodent repre-sentation?based (locale) navigation is presented. The model combines visual input in the form of realistic two dimensional grey-scale images and odometer signals to drive the firing of simulated place and head direction cells via Hebbian synapses. The space representation is built incrementally and on-line without any prior information about the environment and consists of a large population of location-sensitive units (place cells) with overlapping receptive fields. Goal navigation is performed using reinforcement learning in continuous state and action spaces, where the state space is represented by population activity of the place cells. The model is able to reproduce a number of behavioral and neuro-physiological data on rodents. Performance of the model was tested on both simulated and real mobile Khepera robots in a set of behavioral tasks and is comparable to the performance of animals in similar tasks

    Hippocampal projections to the ventral striatum: from spatial memory to motivated behavior

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    Multiple regions of the hippocampal formation project to the ventral striatum, a central node in brain circuits that subserve aspects of motivation. These projections emphasize information flow from the ventral (temporal) pole of the hippocampus and interact with converging projections and neuromodulatory inputs upon arrival in the ventral striatum. Simultaneous neural recordings in the rat show that ventral striatal activity displays intricate timing relationships with the hippocampus, spanning multiple timescales and behavioral states, such as theta phase precession during reward approach and reactivation of place-reward associations during sleep. Disconnection of the hippocampus and ventral striatum results in impairments in the use of spatial information for place preference, as well as in location-appropriate responding to reward-predictive cues. Together, these findings indicate that spatial and contextual information from the hippocampus shapes reward-predictive activity in the ventral striatum, which in turn contributes to the learning and expression of place-reward associations

    Dehorning of cattle in the EU Member States: A quantitative survey of the current practices.

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    A survey was carried out to describe the extent and current practice of cattle disbudding/dehorning in the EU Member States. Disbudding was defined as removal of horns in calves of up to 2 months of age, whereas dehorning was defined as removal of horns in older animals. Specific questionnaires were created regarding dairy, beef, and suckler production systems and they were submitted to local experts of each country belonging to relevant institutions like universities, national farmers' associations, cattle breeders associations, farm veterinarians and practitioners. Figures on disbudding/dehorning practices were produced for each production system for both the whole European Union and the North, Centre, East and South EU macro-regions. A total of 652 questionnaires were collected and 64%, 24% and 12% of them related to dairy cattle, beef cattle and suckler cows, respectively. Data from the survey showed that in Europe, 81% of the dairy, 47% of the beef and 68% of the suckler currently keep disbudded/dehorned animals, while the prevalence of polled cattle is rather low, especially in the dairy cattle sector (5% of all cattle farms; <1% of dairy farms). Regardless of production system, prevalence of dehorned animals is the highest in the North macro-region. Polled cattle farms are almost exclusively located in the North where polled beef breeds are raised for fattening. Dehorning is performed primarily on loose housed cattle to reduce the risk of injuries for herdmates and the stockman. Dehorning is less frequently performed in organic farms. As method of horns removal, disbudding is generally preferred over surgical removal of the horns in older cattle. Hot-iron is the most used disbudding method especially in the North and Centre. Use of caustic paste is reported more frequently in the South and the East. In the large majority of EU farms, the stockman is the person in charge for disbudding and some kind of medication for pain relief is administered to the animals only in a small percentage of farms (<30%). Surgical dehorning of more aged cattle is mainly performed with the wire/saw method. Compared to disbudding, it is more often carried out by a veterinarian and pre- and post operative medications (44% farms) is also more common