Pyramidal Cells in Piriform Cortex Receive Convergent Input from Distinct Olfactory Bulb Glomeruli

Center for Neural Circuits and Behavior, Neuroscience Department, School of Medicine, Neurobiology Section, Division of Biology, and Howard Hughes Medical Institute, University of California, San Diego, La Jolla, California 92093-0634, USA.
The Journal of Neuroscience : The Official Journal of the Society for Neuroscience (Impact Factor: 6.34). 10/2010; 30(42):14255-60. DOI: 10.1523/JNEUROSCI.2747-10.2010
Source: PubMed


Pyramidal cells in piriform cortex integrate sensory information from multiple olfactory bulb mitral and tufted (M/T) cells. However, whether M/T cells belonging to different olfactory bulb glomeruli converge onto individual cortical cells is unclear. Here we use calcium imaging in an olfactory bulb-cortex slice preparation to provide direct evidence that neurons in piriform cortex receive convergent synaptic input from different glomeruli. We show that the combined activity of distinct glomerular pathways recruits ensembles of pyramidal cells that are not activated by the individual pathways alone. This cooperative recruitment of cortical neurons only occurs over a narrow time window and is a feature intrinsic to the olfactory cortex that can be explained by the integration of converging, subthreshold synaptic input. Cooperative recruitment enhances the differences between cortical representations of partially overlapping input patterns and may contribute to the initial steps of olfactory discrimination.

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Available from: Alfonso junior Apicella,
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    • "The diverse cortical projections of a single mitral cell, the broad distribution of mitral cells axons and the overlapping of their information at their target neurons provide the basis for a diversification and combinatorial integration of the olfactory information processing (Ghosh et al., 2011). Recent work using anatomical and physiological techniques demonstrated that individual neurons in the piriform cortex receive convergent input from mitral/tufted cells connected to multiple glomeruli located all over the OB (Apicella et al., 2010; Davison and Ehlers, 2011; Miyamichi et al., 2011). The precise scheme of the olfactory pathway displayed by Cajal (Figure 1A) opened the door to the anatomical basis of olfactory processing (Gire et al., 2013). "
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    ABSTRACT: authors have contributed equally to this work. The olfactory system has a highly regular organization of interconnected synaptic circuits from the periphery. It is therefore an excellent model for understanding general principles about how the brain processes information. Cajal revealed the basic cell types and their interconnections at the end of the XIX century. Since his original descriptions, the observation and analysis of the olfactory system and its components represents a major topic in neuroscience studies, providing important insights into the neural mechanisms. In this review, we will highlight the importance of Cajal contributions and his legacy to the actual knowledge of the olfactory system.
    Frontiers in Neuroanatomy 07/2014; 8. DOI:10.3389/fnana.2014.00055 · 3.54 Impact Factor
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    • "For example, individual mitral cells project broadly throughout piriform cortex (Mitsui et al., 2011), and neighboring piriform cortical neurons can show completely different odor tuning and temporal entrainment to the respiratory cycle (Rennaker et al., 2007). Odor responses of piriform cortical neurons reflect both the combinatorial nature of their olfactory bulb afferent input (Apicella et al., 2010) as well as the nature of their intracortical association fiber input (Franks et al., 2011; Poo and Isaacson, 2011), which is also highly distributed and nontopographic (Haberly, 2001; Johnson et al., 2000). "
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    ABSTRACT: The olfactory system has a rich cortical representation, including a large archicortical component present in most vertebrates, and in mammals neocortical components including the entorhinal and orbitofrontal cortices. Together, these cortical components contribute to normal odor perception and memory. They help transform the physicochemical features of volatile molecules inhaled or exhaled through the nose into the perception of odor objects with rich associative and hedonic aspects. This chapter focuses on how olfactory cortical areas contribute to odor perception and begins to explore why odor perception is so sensitive to disease and pathology. Odor perception is disrupted by a wide range of disorders including Alzheimer's disease, Parkinson's disease, schizophrenia, depression, autism, and early life exposure to toxins. This olfactory deficit often occurs despite maintained functioning in other sensory systems. Does the unusual network of olfactory cortical structures contribute to this sensitivity?
    Progress in brain research 04/2014; 208:275-305. DOI:10.1016/B978-0-444-63350-7.00011-5 · 2.83 Impact Factor
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    • "These results show that spatially segregated channels of odor information become integrated in the PC (or the MB). In brain slice experiments, investigators found that coincident inputs from multiple M/T cells are required to activate PC neurons (Apicella et al. 2010). Measuring the response of the PC population to odor mixtures revealed interactions between odors, exhibiting crossodor suppression as well as supralinear excitation (Stettler & Axel 2009, Wilson & Sullivan 2011, Yoshida & Mori 2007). "
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    ABSTRACT: Howis sensory information represented in the brain?Along-standing debate in neural coding is whether and how timing of spikes conveys information to downstream neurons. Although we know that neurons in the olfactory bulb (OB) exhibit rich temporal dynamics, the functional relevance of temporal coding remains hotly debated. Recent recording experiments in awake behaving animals have elucidated highly organized temporal structures of activity in the OB. In addition, the analysis of neural circuits in the piriform cortex (PC) demonstrated the importance of not only OB afferent inputs but also intrinsicPCneural circuits in shaping odor responses. Furthermore, new experiments involving stimulation of the OB with specific temporal patterns allowed for testing the relevance of temporal codes. Together, these studies suggest that the relative timing of neuronal activity in the OB conveys odor information and that neural circuits in the PC possess various mechanisms to decode temporal patterns of OB input. Expected final online publication date for the Annual Review of Neuroscience Volume 37 is July 08, 2014. Please see for revised estimates.
    Annual Review of Neuroscience 07/2013; 37(1). DOI:10.1146/annurev-neuro-071013-013941 · 19.32 Impact Factor
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