Local and system mechanisms for action execution and observation in parietal and premotor cortices

The action observation network (AON) includes a system of brain areas largely shared with action execution in both human and nonhuman primates. Yet temporal and tuning specificities of distinct areas and of physiologically identified neuronal classes in the encoding of self and others’ action remain unknown. We recorded the activity of 355 single units from three crucial nodes of the AON, the anterior intraparietal area (AIP), and premotor areas F5 and F6, while monkeys performed a Go/No-Go grasping task and observed an experimenter performing it. At the system level, during task execution, F6 displays a prevalence of suppressed neurons and signals whether an action has to be performed, whereas AIP and F5 share a prevalence of facilitated neurons and remarkable target selectivity; during task observation, F5 stands out for its unique prevalence of facilitated neurons and its stronger and earlier modulation than AIP and F6. By applying unsupervised clustering of spike waveforms, we found distinct cell classes unevenly distributed across areas, with different firing properties and carrying specific visuomotor signals. Broadly spiking neurons exhibited a balanced amount of facilitated and suppressed activity during action execution and observation, whereas narrower spiking neurons showed more mutually facilitated responses during the execution of one’s own and others’ action, particularly in areas AIP and F5. Our findings elucidate the time course of activity and firing properties of neurons in the AON during one’s own and others’ action, from the system level of anatomically distinct areas to the local level of physiologically distinct cell classes

The Irish of Iorras Aithneach, County Galway; Volumes I-IV

This grammar is based on extensive fieldwork, published and unpublished lore, and recent as well as older recordings, particularly those held in the archives of Roinn Bhéaloideas Éireann and Raidió na Gaeltachta. These sources provide a picture of extensive variation and change across the six generations born between 1850 and 2000. The grammar draws on several branches of linguistics: descriptive and historical linguistics, dialectology and sociolinguistics. It is the most comprehensive treatment of any variety of Irish. Volume I provides an introduction and chapters on historical phonology, sandhi and nominal morphology. Volume II describes plural noun morphology, the verb and pronominals. Volume III contains chapters on prepositions, functors, initial mutations, higher register, borrowings and language contact, and onomastics. Volume IV presents transcriptions and a CD containing recordings of a slection of speakers across the generations. The final volume also contains a vocabulary, bibliography and four indexes

A Proposal for a Three Detector Short-Baseline Neutrino Oscillation Program in the Fermilab Booster Neutrino Beam

A Short-Baseline Neutrino (SBN) physics program of three LAr-TPC detectors located along the Booster Neutrino Beam (BNB) at Fermilab is presented. This new SBN Program will deliver a rich and compelling physics opportunity, including the ability to resolve a class of experimental anomalies in neutrino physics and to perform the most sensitive search to date for sterile neutrinos at the eV mass-scale through both appearance and disappearance oscillation channels. Using data sets of 6.6e20 protons on target (P.O.T.) in the LAr1-ND and ICARUS T600 detectors plus 13.2e20 P.O.T. in the MicroBooNE detector, we estimate that a search for muon neutrino to electron neutrino appearance can be performed with ~5 sigma sensitivity for the LSND allowed (99% C.L.) parameter region. In this proposal for the SBN Program, we describe the physics analysis, the conceptual design of the LAr1-ND detector, the design and refurbishment of the T600 detector, the necessary infrastructure required to execute the program, and a possible reconfiguration of the BNB target and horn system to improve its performance for oscillation searches.Comment: 209 pages, 129 figure

Aversive learning effect on odor coding in rat's piriform cortex

Olfaction, a sense for detecting and discriminating chemical molecules in the environment, is critical for animal survival, reproduction and other adaptive behaviors. The olfactory system is organized in three major stations (a sensor sheet, an initial processing and projection unit, and a central processing unit) that are shared across phyla, and has been functioning for millions of years. Since Buck and Axel identified a multigene family for coding the olfactory receptors, knowledge of the olfactory system has quickly accumulated in the last 20 years. This allows us to investigate fundamental questions in olfaction, including how odor percepts are formed, how olfactory information is used and stored, and how experiences shape olfactory perception in our daily life.Aversive events involving olfactory information are commonly experienced in nature. In the lab, aversive olfactory experiences have been shown to modify odor responses in rodents behaviorally and physiologically. Traditionally, studies regarding olfactory aversive learning were conducted by using odor-shock conditioning. Here, I explored the possibility of using 2-way active avoidance conditioning for awake unit recording in rats. The results confirmed previous findings that the rats can learn to actively avoid both auditory and olfactory cues that are associated with a dangerous event. Interestingly, the rats appeared to have rapid acquisition but poor behavioral retention. After comparing between the two paradigms, I decided to use odor-shock conditioning for chronic unit recording in awake rats.Three different odor-shock conditioning paradigms were used to investigate how aversive learning affects odor processing in the olfactory cortex. We first found that odor-evoked fear responses were training paradigm-dependent and each induced different levels of fear responses and odor generalization. In addition, we observed a decrease in spontaneous firing rate in the olfactory cortical neurons after conditioning and that was associative learning dependent. The results also suggested that generalized fear is associated with an impairment of olfactory cortical discrimination. In conclusion, changes in sensory processing are dependent on the nature of training, and can predict the behavioral outcome of the training

Smart chemical sensing microsystem : towards a nose-on-a-chip

The electronic nose is a rudimentary replica of the human olfactory system. However there has been considerable commercial interest in the use of electronic nose systems in application areas such as environmental, medical, security and food industry. In many ways the existing electronic nose systems are considerable inferior when compared to their biological counterparts, lacking in terms of discrimination capability, processing time and environmental adaptation. Here, the aim is to extract biological principles from the mammalian olfactory systems to create a new architecture in order to aid the implementation of a nose-on-a-chip system. The primary feature identified in this study was the nasal chromatography phenomena which may provide significant improvement by producing discriminatory spatio-temporal signals for electronic nose systems. In this project, two different but complimentary groups of systems have been designed and fabricated to investigate the feasibility of generating spatio-temporal signals. The first group of systems include the fast-nose (channel 10 cm x 500 μm2), proto-nose I (channel 1.2 m x 500 μm2) and II (channel 2.4 m x 500 μm2) systems that were build using discrete components. The fast-nose system was used to characterise the discrete sensors prior to use. The proto-nose systems, in many ways, resembles gas chromatography systems. Each proto-nose system consists of two microchannels (with and without coating) and 40 polymer-composite sensors of 10 different materials placed along it. The second group of systems include the hybrid-nose and the aVLSI-nose microsensor arrays assembled with microchannel packages of various lengths (5 cm, 32 cm, 7lcm, 240 cm) to form nose-on-a-chip systems. The hybrid-nose sensor array consists of 80 microsensors built on a 10 mm x 10 mm silicon substrate while the aVLSI-nose sensor array consists of 70 microsensors built on a 10 mm x 5 mm silicon substrate using standard CMOS process with smart integrated circuitries. The microchannel packages were fabricated using the Perfactory microstereolithography system. The most advanced microchannel package contains a 2.4 m x 500 J.lm2 microchannel with an external size of only 36 mm x 27 mm x 7 mm. The nose-on-a-chip system achieved miniaturisation and eliminates the need for any external processing circuitries while achieving the same capability of producing spatio-temporal signals. Using a custom-designed vapour test station and data acquisition electronics, these systems were evaluated with simple analytes and complex odours. The experimental results were in-line with the simulation results. On the coated proto-nose II system, a 25 s temporal delay was observed on the toluene vapour pulse compared to ethanol vapour pulse; this is significant compared to the uncoated system where no delay difference was obtained. Further testing with 8 analyte mixtures substantiated that spatio-temporal signals can be extracted from both the coated proto-nose and nose-on-a-chip (hybrid-nose sensor array with 2.4 m long microchannel) systems. This clearly demonstrates that these systems were capable of imitating certain characteristics of the biological olfactory system. Using only the temporal data, classification was performed with principal components analysis. The results reinforced that these additional temporal signals were useful to improve discrimination analysis which is not possible with any existing sensor-based electronic nose system. In addition, fast responding polymer-composite sensors were achieved exhibiting response times of less than 100 ms. Other biological characteristics relating to stereolfaction (two nostrils sniffing at different rates), sniffing rate (flow velocity) and duration (pulse width) were also investigated. The results converge with the biological observations that stereolfaction and sniffing at higher rate and duration improve discrimination. Last but not least, the characterisation of the smart circuitries on the aVLSI-nose show that it is possible to achieve better performance through the use of smart processing circuitries incorporating a novel DC-offset cancellation technique to amplify small sensor response with large baseline voltage. The results and theories presented in this study should provide useful contribution for designing a higher-performance electronic nose incorporating biological principles