In this paper, we propose a personal navigation system (called PNS) which navigates a tourist through multiple destinations efficiently. In our PNS, a tourist can specify multiple destinations with desired arrival/stay time and preference degree. The system calculates the route including part of the destinations satisfying tourist's requirements and navigates him/her. For the above route search problem, we have developed an efficient route search algorithm using a genetic algorithm. We have designed and implemented the PNS as a client-server system so that the portable device users can use the PNS through the Internet. Experiments using general map data and PDAs show that our PNS can calculate a semi-optimal route almost in real-time.

The details of auditory response at the subthreshold level in the rodent primary somatosensory cortex, the barrel cortex, have not been studied extensively, although several phenomenological reports have been published. Multisensory features may act as neuronal representations of links between inputs from one sensory modality to other sensory modalities. Here, we examined the basic multisensory postsynaptic responses in the rodent barrel cortex using in vivo whole-cell recordings of neurons. We observed robust responses to acoustic stimuli in most barrel cortex neurons. Acoustically evoked responses were mediated by hearing and reached approximately 60% of the postsynaptic response amplitude elicited by strong somatosensory stimuli. Compared to tactile stimuli, auditory stimuli evoked postsynaptic potentials with a longer latency and longer duration. Specifically, auditory stimuli in barrel cortex neurons appeared to trigger “up states”, episodes associated with membrane depolarization and increased synaptic activity. Taken together, our data suggest that barrel cortex neurons have multisensory properties, with distinct synaptic mechanisms underlying tactile and non-tactile responses.

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