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How do we communicate with the outside world? How are our senses of vision, smell, taste and pain controlled at the cellular and molecular levels? What causes medical conditions like allergies, hypertension, depression, obesity and various central nervous system disorders? G-protein coupled receptors (GPCRs) provide a major part of the answer to all of these questions. GPCRs constitute the largest family of cell-surface receptors and in humans are encoded by more than 1,000 genes. GPCRs convert extracellular messages into intracellular responses and are involved in essentially all physiological processes. GPCR dysfunction results in numerous human disorders, and over 50% of all prescription drugs on the market today directly or indirectly target GPCRs. In this course, we will discuss GPCR signal transduction pathways, GPCR oligomerization and the diseases caused by GPCR dysfunction. We will study the structure and function of rhodopsin, a dim-light photoreceptor and a well-studied GPCR that converts light into electric impulses sent to the brain and leads to vision. We will also discuss how mutations in rhodopsin cause retinal degeneration and congenital night blindness. This course is one of many Advanced Undergraduate Seminars offered by the Biology Department at MIT. These seminars are tailored for students with an interest in using primary research literature to discuss and learn about current biological research in a highly interactive setting. Many instructors of the Advanced Undergraduate Seminars are postdoctoral scientists with a strong interest in teaching.

How do we communicate with the outside world? How are our senses of vision, smell, taste and pain controlled at the cellular and molecular levels? What causes medical conditions like allergies, hypertension, depression, obesity and various central nervous system disorders? G-protein coupled receptors (GPCRs) provide a major part of the answer to all of these questions. GPCRs constitute the largest family of cell-surface receptors and in humans are encoded by more than 1,000 genes. GPCRs convert extracellular messages into intracellular responses and are involved in essentially all physiological processes. GPCR dysfunction results in numerous human disorders, and over 50% of all prescription drugs on the market today directly or indirectly target GPCRs. In this course, we will discuss GPCR signal transduction pathways, GPCR oligomerization and the diseases caused by GPCR dysfunction. We will study the structure and function of rhodopsin, a dim-light photoreceptor and a well-studied GPCR that converts light into electric impulses sent to the brain and leads to vision. We will also discuss how mutations in rhodopsin cause retinal degeneration and congenital night blindness. This course is one of many Advanced Undergraduate Seminars offered by the Biology Department at MIT. These seminars are tailored for students with an interest in using primary research literature to discuss and learn about current biological research in a highly interactive setting. Many instructors of the Advanced Undergraduate Seminars are postdoctoral scientists with a strong interest in teaching.

G-protein coupled receptors (GPCR) encompass a large number of protein receptors within the human genome. Because GPCRs are involved in numerous pathways including serotonin signaling in the brain, the receptors are often targets for drug development. Recent studies have demonstrated the presence of novel olfactory receptors (ORs), a member of the GPCR family, in the murine kidney but little is known about the function, and structure of these receptors. Spatial Intensity Distribution Analysis (SpIDA) has been used to measure the quaternary state (organization of receptor subunits) and surface density of GPCR proteins in live and fixed cells. In SpIDA, intensity histograms are generated and mathematically fitted from the cell images to obtain the quantal brightness (QB) of the receptor. This receptor QB can be compared to the QB of control proteins that are known to be monomer, or larger oligomers, therefore determining the quaternary, or oligomeric state of the receptor. Olfactory receptors (ORs) are members of the GPCR protein family and are responsible for our sense of smell. Several research groups have recently shown that olfactory receptors are not only located in the olfactory organs of our noses, but also present in many other organ systems including the renal system. Activation of the Olfr78 receptor can lead to various responses in the body, ranging from changes in blood pressure to preventing the proliferation of cancer cells. It was determined that short chain fatty acids (SCFAs) act as a potential ligand for both receptors. While less studied, Olfr691 demonstrates similar structures and reactions to SCFAs, inferring that these two receptors demonstrate similar functions. Both of these receptors were studied with and without the presence of butyric acid using SpIDA in attempts to gain knowledge pertaining to the structure-function relationship of these proteins. By determining the structural context of these receptors, further investigation of the conform

Lateralization is a wide-spread phenomenon in the animal kingdom. Often, lateralization can be observed at the population-level where most individuals of a population share the same direction of lateralization. Theoretical models predict that population-level lateralization is more likely to manifest in social than in non-social species. Especially functions relevant to social interactions should show a population-level lateralization. We evaluated olfaction in the eusocial ant species Camponotus floridanus, since olfaction is particularly relevant to many social behaviors in an ant colony. The direction of lateralization was tested using the maxilla labium extension reflex associative learning paradigm. Our results indicate that there are differences between colonies in the strength and direction of lateralization. And in at least two of the three colonies observed there was strong colony-level lateralization. These findings seem to support the hypothesis that social species exhibit lateralization at the population-level and suggest that lateralization may be expressed at the colony-level for ants.

Fish depend on olfaction for reproduction and survival. Here, using molecular to behavioural endpoints, we compared the effect of two neurotoxic contaminants, Cu ions (Cu2+) and copper nanoparticles (CuNPs) on rainbow trout olfaction. Exposure to equitoxic concentrations of Cu2+ and CuNPs resulted in distinct toxicity patterns over time in rainbow trout olfactory mucosa. During continuous exposure to Cu2+, fish olfactory function was partially recovered. However, the olfactory function of CuNP-exposed fish showed a steady decline over time. Gene-transcript profiles of Cu2+-exposed olfactory mucosa showed neural repair mechanisms were upregulated to recover the olfactory dysfunction. In the CuNP treatment, dysregulation of transcripts that regulate function and reestablishment of damaged olfactory mucosa represented key mechanisms of CuNP-induced olfactory toxicity. Moreover, our findings revealed the CuNP-induced olfactory dysfunction was irreversible after the 7-day recovery period. Collectively, CuNPs and Cu2+ exert their effects via separate mechanisms in rainbow trout olfactory mucosa.

Fish depend on olfaction for reproduction and survival. Here, using molecular to behavioural endpoints, we compared the effect of two neurotoxic contaminants, Cu ions (Cu2+) and copper nanoparticles (CuNPs) on rainbow trout olfaction. Exposure to equitoxic concentrations of Cu2+ and CuNPs resulted in distinct toxicity patterns over time in rainbow trout olfactory mucosa. During continuous exposure to Cu2+, fish olfactory function was partially recovered. However, the olfactory function of CuNP-exposed fish showed a steady decline over time. Gene-transcript profiles of Cu2+-exposed olfactory mucosa showed neural repair mechanisms were upregulated to recover the olfactory dysfunction. In the CuNP treatment, dysregulation of transcripts that regulate function and reestablishment of damaged olfactory mucosa represented key mechanisms of CuNP-induced olfactory toxicity. Moreover, our findings revealed the CuNP-induced olfactory dysfunction was irreversible after the 7-day recovery period. Collectively, CuNPs and Cu2+ exert their effects via separate mechanisms in rainbow trout olfactory mucosa.

Fish depend on olfaction for reproduction and survival. Here, using molecular to behavioural endpoints, we compared the effect of two neurotoxic contaminants, Cu ions (Cu2+) and copper nanoparticles (CuNPs) on rainbow trout olfaction. Exposure to equitoxic concentrations of Cu2+ and CuNPs resulted in distinct toxicity patterns over time in rainbow trout olfactory mucosa. During continuous exposure to Cu2+, fish olfactory function was partially recovered. However, the olfactory function of CuNP-exposed fish showed a steady decline over time. Gene-transcript profiles of Cu2+-exposed olfactory mucosa showed neural repair mechanisms were upregulated to recover the olfactory dysfunction. In the CuNP treatment, dysregulation of transcripts that regulate function and reestablishment of damaged olfactory mucosa represented key mechanisms of CuNP-induced olfactory toxicity. Moreover, our findings revealed the CuNP-induced olfactory dysfunction was irreversible after the 7-day recovery period. Collectively, CuNPs and Cu2+ exert their effects via separate mechanisms in rainbow trout olfactory mucosa.

Fish depend on olfaction for reproduction and survival. Here, using molecular to behavioural endpoints, we compared the effect of two neurotoxic contaminants, Cu ions (Cu2+) and copper nanoparticles (CuNPs) on rainbow trout olfaction. Exposure to equitoxic concentrations of Cu2+ and CuNPs resulted in distinct toxicity patterns over time in rainbow trout olfactory mucosa. During continuous exposure to Cu2+, fish olfactory function was partially recovered. However, the olfactory function of CuNP-exposed fish showed a steady decline over time. Gene-transcript profiles of Cu2+-exposed olfactory mucosa showed neural repair mechanisms were upregulated to recover the olfactory dysfunction. In the CuNP treatment, dysregulation of transcripts that regulate function and reestablishment of damaged olfactory mucosa represented key mechanisms of CuNP-induced olfactory toxicity. Moreover, our findings revealed the CuNP-induced olfactory dysfunction was irreversible after the 7-day recovery period. Collectively, CuNPs and Cu2+ exert their effects via separate mechanisms in rainbow trout olfactory mucosa.

Fish depend on olfaction for reproduction and survival. Here, using molecular to behavioural endpoints, we compared the effect of two neurotoxic contaminants, Cu ions (Cu2+) and copper nanoparticles (CuNPs) on rainbow trout olfaction. Exposure to equitoxic concentrations of Cu2+ and CuNPs resulted in distinct toxicity patterns over time in rainbow trout olfactory mucosa. During continuous exposure to Cu2+, fish olfactory function was partially recovered. However, the olfactory function of CuNP-exposed fish showed a steady decline over time. Gene-transcript profiles of Cu2+-exposed olfactory mucosa showed neural repair mechanisms were upregulated to recover the olfactory dysfunction. In the CuNP treatment, dysregulation of transcripts that regulate function and reestablishment of damaged olfactory mucosa represented key mechanisms of CuNP-induced olfactory toxicity. Moreover, our findings revealed the CuNP-induced olfactory dysfunction was irreversible after the 7-day recovery period. Collectively, CuNPs and Cu2+ exert their effects via separate mechanisms in rainbow trout olfactory mucosa.

Volatiles are of key importance for host-plant recognition in insects. In the pollination system of Lithophragma flowers and Greya moths, moths are highly specialized on Lithophragma, in which they oviposit and thereby pollinate the flowers. Floral volatiles in Lithophragma are highly variable between species and populations, and moths prefer to oviposit into Lithophragma flowers from populations of the local host species. Here we used gas chromatography coupled with electroantennographic detection (GC-EAD) to test whether Greya moths detect specific key volatiles or respond broadly to many volatiles of Lithophragma flowers. We also addressed whether olfactory detection in Greya moths varies across populations, consistent with a co-evolutionary scenario. We analyzed flower volatile samples from three different species and five populations of Lithophragma occurring across a 1400 km range in the Western USA, and their sympatric female Greya politella moths. We showed that Greya politella detect a broad range of Lithophragma volatiles, with a total of 23 compounds being EAD active. We chemically identified 15 of these, including the chiral 6, 10, 14-trimethylpentadecan-2-one (hexahydrofarnesyl acetone), which was not previously detected in Lithophragma. All investigated Lithophragma species produced the (6R, 10R)-enantiomer of this compound. We showed that Greya moths detected not only volatiles of their local Lithophragma plants, but also those from allopatric populations/species that they not encounter in local populations. In conclusion, the generalized detection of volatiles and a lack of co-divergence between volatiles and olfactory detection may be of selective advantage for moths in tracking hosts with rapidly evolving, chemically diverse floral volatiles.

Volatiles are of key importance for host-plant recognition in insects. In the pollination system of Lithophragma flowers and Greya moths, moths are highly specialized on Lithophragma, in which they oviposit and thereby pollinate the flowers. Floral volatiles in Lithophragma are highly variable between species and populations, and moths prefer to oviposit into Lithophragma flowers from populations of the local host species. Here we used gas chromatography coupled with electroantennographic detection (GC-EAD) to test whether Greya moths detect specific key volatiles or respond broadly to many volatiles of Lithophragma flowers. We also addressed whether olfactory detection in Greya moths varies across populations, consistent with a co-evolutionary scenario. We analyzed flower volatile samples from three different species and five populations of Lithophragma occurring across a 1400 km range in the Western USA, and their sympatric female Greya politella moths. We showed that Greya politella detect a broad range of Lithophragma volatiles, with a total of 23 compounds being EAD active. We chemically identified 15 of these, including the chiral 6, 10, 14-trimethylpentadecan-2-one (hexahydrofarnesyl acetone), which was not previously detected in Lithophragma. All investigated Lithophragma species produced the (6R, 10R)-enantiomer of this compound. We showed that Greya moths detected not only volatiles of their local Lithophragma plants, but also those from allopatric populations/species that they not encounter in local populations. In conclusion, the generalized detection of volatiles and a lack of co-divergence between volatiles and olfactory detection may be of selective advantage for moths in tracking hosts with rapidly evolving, chemically diverse floral volatiles.

Fish depend on olfaction for reproduction and survival. Here, using molecular to behavioural endpoints, we compared the effect of two neurotoxic contaminants, Cu ions (Cu2+) and copper nanoparticles (CuNPs) on rainbow trout olfaction. Exposure to equitoxic concentrations of Cu2+ and CuNPs resulted in distinct toxicity patterns over time in rainbow trout olfactory mucosa. During continuous exposure to Cu2+, fish olfactory function was partially recovered. However, the olfactory function of CuNP-exposed fish showed a steady decline over time. Gene-transcript profiles of Cu2+-exposed olfactory mucosa showed neural repair mechanisms were upregulated to recover the olfactory dysfunction. In the CuNP treatment, dysregulation of transcripts that regulate function and reestablishment of damaged olfactory mucosa represented key mechanisms of CuNP-induced olfactory toxicity. Moreover, our findings revealed the CuNP-induced olfactory dysfunction was irreversible after the 7-day recovery period. Collectively, CuNPs and Cu2+ exert their effects via separate mechanisms in rainbow trout olfactory mucosa.

Fish depend on olfaction for reproduction and survival. Here, using molecular to behavioural endpoints, we compared the effect of two neurotoxic contaminants, Cu ions (Cu2+) and copper nanoparticles (CuNPs) on rainbow trout olfaction. Exposure to equitoxic concentrations of Cu2+ and CuNPs resulted in distinct toxicity patterns over time in rainbow trout olfactory mucosa. During continuous exposure to Cu2+, fish olfactory function was partially recovered. However, the olfactory function of CuNP-exposed fish showed a steady decline over time. Gene-transcript profiles of Cu2+-exposed olfactory mucosa showed neural repair mechanisms were upregulated to recover the olfactory dysfunction. In the CuNP treatment, dysregulation of transcripts that regulate function and reestablishment of damaged olfactory mucosa represented key mechanisms of CuNP-induced olfactory toxicity. Moreover, our findings revealed the CuNP-induced olfactory dysfunction was irreversible after the 7-day recovery period. Collectively, CuNPs and Cu2+ exert their effects via separate mechanisms in rainbow trout olfactory mucosa.

Fish depend on olfaction for reproduction and survival. Here, using molecular to behavioural endpoints, we compared the effect of two neurotoxic contaminants, Cu ions (Cu2+) and copper nanoparticles (CuNPs) on rainbow trout olfaction. Exposure to equitoxic concentrations of Cu2+ and CuNPs resulted in distinct toxicity patterns over time in rainbow trout olfactory mucosa. During continuous exposure to Cu2+, fish olfactory function was partially recovered. However, the olfactory function of CuNP-exposed fish showed a steady decline over time. Gene-transcript profiles of Cu2+-exposed olfactory mucosa showed neural repair mechanisms were upregulated to recover the olfactory dysfunction. In the CuNP treatment, dysregulation of transcripts that regulate function and reestablishment of damaged olfactory mucosa represented key mechanisms of CuNP-induced olfactory toxicity. Moreover, our findings revealed the CuNP-induced olfactory dysfunction was irreversible after the 7-day recovery period. Collectively, CuNPs and Cu2+ exert their effects via separate mechanisms in rainbow trout olfactory mucosa.

Fish depend on olfaction for reproduction and survival. Here, using molecular to behavioural endpoints, we compared the effect of two neurotoxic contaminants, Cu ions (Cu2+) and copper nanoparticles (CuNPs) on rainbow trout olfaction. Exposure to equitoxic concentrations of Cu2+ and CuNPs resulted in distinct toxicity patterns over time in rainbow trout olfactory mucosa. During continuous exposure to Cu2+, fish olfactory function was partially recovered. However, the olfactory function of CuNP-exposed fish showed a steady decline over time. Gene-transcript profiles of Cu2+-exposed olfactory mucosa showed neural repair mechanisms were upregulated to recover the olfactory dysfunction. In the CuNP treatment, dysregulation of transcripts that regulate function and reestablishment of damaged olfactory mucosa represented key mechanisms of CuNP-induced olfactory toxicity. Moreover, our findings revealed the CuNP-induced olfactory dysfunction was irreversible after the 7-day recovery period. Collectively, CuNPs and Cu2+ exert their effects via separate mechanisms in rainbow trout olfactory mucosa.

Fish depend on olfaction for reproduction and survival. Here, using molecular to behavioural endpoints, we compared the effect of two neurotoxic contaminants, Cu ions (Cu2+) and copper nanoparticles (CuNPs) on rainbow trout olfaction. Exposure to equitoxic concentrations of Cu2+ and CuNPs resulted in distinct toxicity patterns over time in rainbow trout olfactory mucosa. During continuous exposure to Cu2+, fish olfactory function was partially recovered. However, the olfactory function of CuNP-exposed fish showed a steady decline over time. Gene-transcript profiles of Cu2+-exposed olfactory mucosa showed neural repair mechanisms were upregulated to recover the olfactory dysfunction. In the CuNP treatment, dysregulation of transcripts that regulate function and reestablishment of damaged olfactory mucosa represented key mechanisms of CuNP-induced olfactory toxicity. Moreover, our findings revealed the CuNP-induced olfactory dysfunction was irreversible after the 7-day recovery period. Collectively, CuNPs and Cu2+ exert their effects via separate mechanisms in rainbow trout olfactory mucosa.

Lateralization is a wide-spread phenomenon in the animal kingdom. Often, lateralization can be observed at the population-level where most individuals of a population share the same direction of lateralization. Theoretical models predict that population-level lateralization is more likely to manifest in social than in non-social species. Especially functions relevant to social interactions should show a population-level lateralization. We evaluated olfaction in the eusocial ant species Camponotus floridanus, since olfaction is particularly relevant to many social behaviors in an ant colony. The direction of lateralization was tested using the maxilla labium extension reflex associative learning paradigm. Our results indicate that there are differences between colonies in the strength and direction of lateralization. And in at least two of the three colonies observed there was strong colony-level lateralization. These findings seem to support the hypothesis that social species exhibit lateralization at the population-level and suggest that lateralization may be expressed at the colony-level for ants.

Volatiles are of key importance for host-plant recognition in insects. In the pollination system of Lithophragma flowers and Greya moths, moths are highly specialized on Lithophragma, in which they oviposit and thereby pollinate the flowers. Floral volatiles in Lithophragma are highly variable between species and populations, and moths prefer to oviposit into Lithophragma flowers from populations of the local host species. Here we used gas chromatography coupled with electroantennographic detection (GC-EAD) to test whether Greya moths detect specific key volatiles or respond broadly to many volatiles of Lithophragma flowers. We also addressed whether olfactory detection in Greya moths varies across populations, consistent with a co-evolutionary scenario. We analyzed flower volatile samples from three different species and five populations of Lithophragma occurring across a 1400 km range in the Western USA, and their sympatric female Greya politella moths. We showed that Greya politella detect a broad range of Lithophragma volatiles, with a total of 23 compounds being EAD active. We chemically identified 15 of these, including the chiral 6, 10, 14-trimethylpentadecan-2-one (hexahydrofarnesyl acetone), which was not previously detected in Lithophragma. All investigated Lithophragma species produced the (6R, 10R)-enantiomer of this compound. We showed that Greya moths detected not only volatiles of their local Lithophragma plants, but also those from allopatric populations/species that they not encounter in local populations. In conclusion, the generalized detection of volatiles and a lack of co-divergence between volatiles and olfactory detection may be of selective advantage for moths in tracking hosts with rapidly evolving, chemically diverse floral volatiles.

Volatiles are of key importance for host-plant recognition in insects. In the pollination system of Lithophragma flowers and Greya moths, moths are highly specialized on Lithophragma, in which they oviposit and thereby pollinate the flowers. Floral volatiles in Lithophragma are highly variable between species and populations, and moths prefer to oviposit into Lithophragma flowers from populations of the local host species. Here we used gas chromatography coupled with electroantennographic detection (GC-EAD) to test whether Greya moths detect specific key volatiles or respond broadly to many volatiles of Lithophragma flowers. We also addressed whether olfactory detection in Greya moths varies across populations, consistent with a co-evolutionary scenario. We analyzed flower volatile samples from three different species and five populations of Lithophragma occurring across a 1400 km range in the Western USA, and their sympatric female Greya politella moths. We showed that Greya politella detect a broad range of Lithophragma volatiles, with a total of 23 compounds being EAD active. We chemically identified 15 of these, including the chiral 6, 10, 14-trimethylpentadecan-2-one (hexahydrofarnesyl acetone), which was not previously detected in Lithophragma. All investigated Lithophragma species produced the (6R, 10R)-enantiomer of this compound. We showed that Greya moths detected not only volatiles of their local Lithophragma plants, but also those from allopatric populations/species that they not encounter in local populations. In conclusion, the generalized detection of volatiles and a lack of co-divergence between volatiles and olfactory detection may be of selective advantage for moths in tracking hosts with rapidly evolving, chemically diverse floral volatiles.

Volatiles are of key importance for host-plant recognition in insects. In the pollination system of Lithophragma flowers and Greya moths, moths are highly specialized on Lithophragma, in which they oviposit and thereby pollinate the flowers. Floral volatiles in Lithophragma are highly variable between species and populations, and moths prefer to oviposit into Lithophragma flowers from populations of the local host species. Here we used gas chromatography coupled with electroantennographic detection (GC-EAD) to test whether Greya moths detect specific key volatiles or respond broadly to many volatiles of Lithophragma flowers. We also addressed whether olfactory detection in Greya moths varies across populations, consistent with a co-evolutionary scenario. We analyzed flower volatile samples from three different species and five populations of Lithophragma occurring across a 1400 km range in the Western USA, and their sympatric female Greya politella moths. We showed that Greya politella detect a broad range of Lithophragma volatiles, with a total of 23 compounds being EAD active. We chemically identified 15 of these, including the chiral 6, 10, 14-trimethylpentadecan-2-one (hexahydrofarnesyl acetone), which was not previously detected in Lithophragma. All investigated Lithophragma species produced the (6R, 10R)-enantiomer of this compound. We showed that Greya moths detected not only volatiles of their local Lithophragma plants, but also those from allopatric populations/species that they not encounter in local populations. In conclusion, the generalized detection of volatiles and a lack of co-divergence between volatiles and olfactory detection may be of selective advantage for moths in tracking hosts with rapidly evolving, chemically diverse floral volatiles.

The insect odorant receptor, OR, gene family has been hypothesized to play a critical role in reproduction. Odorant receptor proteins, located on the olfactory sensory neuronal dendrites, detect odorant chemicals such as pheromones and then mediate key behaviors such as mate choice. Although olfaction is known to play a predominant role in sexual communication, there are still large numbers of olfactory genes that have not been studied in many insect species including fireflies. In this study, I investigated the sequencing data of one of the common eastern fireflies, Photinus pyralis (Coleoptera: Lampyridae). This firefly species is well known for their use of light signals to attract mates, but our knowledge of their odorant receptors is still incomplete. Recent advances in genome sequencing have provided tools to identify the OR gene repertoires in P. pyralis sequencing data. The aim of this study was to develop an OR gene repertoire of P. pyralis, which might shed light on our knowledge about their ability to detect chemical signals at the molecular level. Using computational analysis, I identified a set of 27 putative OR genes including one odorant receptor co-receptor (ORco) gene in the P. pyralis genome and antennal transcriptome. A phylogenetic tree was constructed from OR sequences of P. pyralis and other beetle species to show the relationship of ORs among beetles. Results of this study will provide a basis foundation for future studies on the expression and function of the P. pyralis OR candidates.

Differentiation of olfactory neurons is modulated by odor stimulation; exposure to stimulatory odorants induces acquisition of olfactory neuronal properties in cultured chick olfactory neurons. The mechanism by which odor-mediated neuronal differentiation remains unclear. It is known that cyclic adenosine monophosphate (cAMP) serves as a second messenger for odor signal transduction. To determine if stimulus-induced differentiation can occur in the absence of odorants, elements of the odor signal transduction cascade were directly stimulated using pharmacological agents. Cultured olfactory neurons from an E17 chick embryo were exposed to either an adenylyl cyclase activator (forskolin) or adenylyl cyclase inhibitors (MDL-12,330A or SQ 22,536) for 12-hour periods daily for five days. Neuron differentiation was determined using immunocytochemistry to stain for proteins characteristic of olfactory neurons. Cells were stained for olfactory marker protein (mature olfactory neurons only), Golf (functional olfactory neurons), and beta-tubulin III (neuron-specific tubulin; both mature and immature neurons). Data suggest that direct inhibition of adenylyl cyclase with MDL-12,330A increases the total number of neurons, while activation of the cyclase has no effect. Data also suggest that inhibition of adenylyl cyclase with SQ 22,536 decreases the percentage of functional mature neurons. Thus, MDL-12,330A increases neuronal proliferation and SQ 22,536 affects specific acquisition of olfactory neuronal properties, which suggests that adenylyl cyclase could play a role in stimulus-induced neuronal proliferation and differentiation.

The monogenic and monoallelic expression of only one out of >1000 mouse olfactory receptor (ORs) genes requires the formation of large heterochromatic chromatin domains that sequester the OR gene clusters. Within these domains, intergenic transcriptional enhancers evade heterochromatic silencing and converge into interchromosomal hubs that assemble over the transcriptionally active OR. The significance of this nuclear organization in OR choice remains elusive. Here, we show that transcription factors Lhx2 and Ebf specify OR enhancers by binding in a functionally cooperative fashion to stereotypically spaced motifs that defy heterochromatin. Specific displacement of Lhx2 and Ebf from OR enhancers resulted in pervasive, long-range, and trans downregulation of OR transcription, whereas pre-assembly of a multi-enhancer hub increased the frequency of OR choice in cis. Our data provide genetic support for the requirement and sufficiency of interchromosomal interactions in singular OR choice and generate general regulatory principles for stochastic, mutually exclusive gene expression programs.

The ability of humans to discriminate enantiomeric odour pairs is substance-specific. Current literature suggests that psychophysical discrimination of odour enantiomers mainly depends on the peripheral processing at the level of the olfactory sensory neurons (OSN). To study the influence of central processing in discrimination, we investigated differences in the electrophysiological responses to psychophysically indistinguishable (+)- and (-)- rose oxide enantiomers at peripheral and central-nervous levels in humans. We recorded the electro-olfactogram (EOG) from the olfactory epithelium and the EEG-derived olfactory event-related potentials (OERP). Results from a psychophysical three alternative forced choice test indicated indistinguishability of the two odour enantiomers. In a total of 19 young participants EOG could be recorded in 74 and OERP in 95% of subjects. Significantly different EOG amplitudes and latencies were recorded in response to the 2 stimuli. However, no such differences in amplitude or latency emerged for the OERP. In conclusion, although the pair of enantiomer could be discriminated at a peripheral level this did not lead to a central-nervous/cognitive differentiation of the two stimuli.

The monogenic and monoallelic expression of only one out of >1000 mouse olfactory receptor (ORs) genes requires the formation of large heterochromatic chromatin domains that sequester the OR gene clusters. Within these domains, intergenic transcriptional enhancers evade heterochromatic silencing and converge into interchromosomal hubs that assemble over the transcriptionally active OR. The significance of this nuclear organization in OR choice remains elusive. Here, we show that transcription factors Lhx2 and Ebf specify OR enhancers by binding in a functionally cooperative fashion to stereotypically spaced motifs that defy heterochromatin. Specific displacement of Lhx2 and Ebf from OR enhancers resulted in pervasive, long-range, and trans downregulation of OR transcription, whereas pre-assembly of a multi-enhancer hub increased the frequency of OR choice in cis. Our data provide genetic support for the requirement and sufficiency of interchromosomal interactions in singular OR choice and generate general regulatory principles for stochastic, mutually exclusive gene expression programs.

Obesity is a major health problem that can be influenced by eating behaviors. Evidence suggests that the sensory properties of food influence eating behaviors and lead to overeating and overweight. A previous genome-wide linkage scan for eating behavior traits assessed with the Three-Factor Eating Questionnaire (cognitive dietary restraint, disinhibition and hunger) performed in the Quebec Family Study (QFS) revealed a quantitative trait locus for disinhibition on chromosome 19p13. This region encodes a cluster of seven olfactory receptor (OR) genes, including OR7D4, previously associated with odor perceptions. Direct sequencing of the OR7D4 gene revealed 16 sequence variants. Nine OR7D4 sequence variants with minor allele frequency (MAF) > 1% as well as 100 SNPs spanning the cluster of OR genes on 19p13 were tested for association with age- and sex-adjusted eating behaviors as well as adiposity traits in 890 subjects. One OR7D4 sequence variant (rs2878329 G > A) showed evidence of association with reduced levels of adiposity (p = 0.03), cognitive dietary restraint (p = 0.05) and susceptibility to hunger (p = 0.008). None of the OR7D4 SNPs was associated with disinhibition, but a SNP (rs2240927) in another OR gene (OR7E24) showed evidence of association (p = 0.03). Another SNP in the OR7G3 gene (rs10414255) was also found to be associated with adiposity and eating behaviors. These results are the first to suggest that variations in human olfactory receptor genes can influence eating behaviors and adiposity. The associations reported in the present study should be interpreted with caution considering the number of tests performed and considered as potential new hypotheses about the effects OR polymorphisms on eating behaviors and obesity that need to be further explored in other populations.

This study aims to improve our understanding of the interaction between olfactory receptors and odorants to develop highly selective biosensing devices. Natural nanovesicles (NVs) from Saccharomyces cerevisiae, ∼100 nm in diameter, carrying either the human OR17-40 or the chimpanzee OR7D4 olfactory receptor (OR) tagged with the c-myc epitope at their N-terminus, are presented as model systems to quantify the interaction between odorant and olfactory receptors. The level of expression of olfactory receptors was determined at individual NVs using a novel competitive ELISA immunoassay comparing the values obtained against those from techniques involving the solubilization of cell membrane proteins and the identification of c-myc-carrying receptors. Surface Plasmon Resonance (SPR) measurements on L1 Biacore chips indicate that cognate odorants bind to their Ors, thereby quantifying the approximate number of odorants that interact with a given olfactory receptor. The selectivity of OR17-40-carrying NVs towards helional and OR7D4-carrying NVs towards androstenone has been proven in cross-check experiments with non-specific odorant molecules (heptanal and pentadecalactone, respectively) and in control receptors. © 2017 The Author(s).

Since its national debut in 1987, Fresh Air with Terry Gross has been a highly acclaimed and much adored weekday magazine among public radio listeners. Each week, nearly 4.8 million people turn to Peabody Award-winning host Terry Gross for insightful conversations with the leading voices in contemporary arts and issues. The renowned program reaches a global audience, with over 620 public radio stations broadcasting Fresh Air, and 3 million podcast downloads each week. Fresh Air has broken the mold of 'talk show' by weaving together superior journalism and intimate storytelling from modern-day intellectuals, politicians and artists alike. Through probing questions and careful research, Gross's interviews are lauded for revealing a fresh perspective on cultural icons and trends. Her thorough conversations are often complemented by commentary from well-known contributors. Fresh Air is produced at WHYY-FM in Philadelphia and broadcast nationally by NPR., (1.) ALEXANDRA HOROWITZ is author of the new book BEING A DOG: FOLLOWING THE DOG INTO THE WORLD OF SMELL. She also wrote the bestseller INSIDE OF A DOG: WHAT DOGS SEE, SMELL AND KNOW. HOROWITZ writes about how dogs perceive the world mostly through their noses and how humans too can do more with their sense of smell, if they try. She founded the dog cognition lab at Barnard College. (CONTINUES INTO SECOND HALF OF THE SHOW)(2.) Rock critic Ken Tucker reviews the debut album "No Burden" by singer-songwriter Lucy Dacus

The yellow-fever mosquito Aedes aegypti is a major vector of human diseases, such as dengue, yellow fever chikungunya and West Nile viruses. Chemoreceptor organs on the labella and tarsi are involved in human host evaluation and thus serve as potential foci for the disruption of blood feeding behavior. In addition to host detection, these contact chemoreceptors mediate feeding, oviposition and conspecific recognition; however, the molecular landscape of chemoreception in these tissues remains mostly uncharacterized. Here we report the expression profile of all putative chemoreception genes in the labella and tarsi of both sexes of adult Ae. aegypti and discuss their possible roles in the physiology and behavior of this important disease vector., Published in Insect Biochemistry and Molecular Biology, v48 p8-16, 2014.

The main problem with sensory processing is the difficulty in relating sensory input to physiological responses and perception. This is especially problematic at higher levels of processing, where complex cues elicit highly specific responses. In olfaction, this relationship is particularly obfuscated by the difficulty of characterizing stimulus statistics and perception. The core questions in olfaction are hence the so-called stimulus problem, which refers to the understanding of the stimulus, and the structure–activity and structure–odor relationships, which refer to the molecular basis of smell. It is widely accepted that the recognition of odorants by receptors is governed by the detection of physico-chemical properties and that the physical space is highly complex. Not surprisingly, ideas differ about how odor stimuli should be classified and about the very nature of information that the brain extracts from odors. Even though there are many measures for smell, there is none that accurately describes all aspects of it. Here, we summarize recent developments in the understanding of olfaction. We argue that an approach to olfactory function where information processing is emphasized could contribute to a high degree to our understanding of smell as a perceptual phenomenon emerging from neural computations. Further, we argue that combined analysis of the stimulus, biology, physiology, and behavior and perception can provide new insights into olfactory function. We hope that the reader can use this review as a competent guide and overview of research activities in olfactory physiology, psychophysics, computation, and psychology. We propose avenues for research, particularly in the systematic characterization of receptive fields and of perception., QC 20130723

The main problem with sensory processing is the difficulty in relating sensory input to physiological responses and perception. This is especially problematic at higher levels of processing, where complex cues elicit highly specific responses. In olfaction, this relationship is particularly obfuscated by the difficulty of characterizing stimulus statistics and perception. The core questions in olfaction are hence the so-called stimulus problem, which refers to the understanding of the stimulus, and the structure–activity and structure–odor relationships, which refer to the molecular basis of smell. It is widely accepted that the recognition of odorants by receptors is governed by the detection of physico-chemical properties and that the physical space is highly complex. Not surprisingly, ideas differ about how odor stimuli should be classified and about the very nature of information that the brain extracts from odors. Even though there are many measures for smell, there is none that accurately describes all aspects of it. Here, we summarize recent developments in the understanding of olfaction. We argue that an approach to olfactory function where information processing is emphasized could contribute to a high degree to our understanding of smell as a perceptual phenomenon emerging from neural computations. Further, we argue that combined analysis of the stimulus, biology, physiology, and behavior and perception can provide new insights into olfactory function. We hope that the reader can use this review as a competent guide and overview of research activities in olfactory physiology, psychophysics, computation, and psychology. We propose avenues for research, particularly in the systematic characterization of receptive fields and of perception., QC 20130723

Dioecious Caenorhabditis remanei and androdioecious C. elegans are two closely related species belonging to the ELEGANS group of the subgenus Caenorhabditis. Despite their distinct mating systems and evolutionary divergence, our lab has demonstrated that virgin C. remanei females secrete a potent sex-specific pheromone that attracts young adult males of both species from afar. Intriguingly, this chemotaxic behavior requires AWA and CEM neurons in male C. elegans. I will present the experiment data suggesting the requirement of the G-protein coupled receptor SRD-1 in AWA neurons in male C. elegans for sensing the pheromone secreted by C. remanei females. The srd-1 was previously reported being expressed in both AWA and ASI neurons. The sub-cellular localization of SRD-1 receptor in male AWA neurons was found in the tip of cilia. Using the chemotaxis assay, we found that the srd-1 mutant males lost their pheromone responsiveness. This defect can be rescued using srd-1 cDNA driven by AWA specific promoter of gene odr-7. We visualized the excitation of AWA neurons upon treatments of multiple odors and found that AWA neurons of the srd-1 mutant males cannot be stimulated by the pheromone extract, but are responsive to other chemo-attractants. Consistent with this finding, heterologously expressing srd-1 cDNA in HEK293 FT mammalian cell line can mildly confer the host sensitivity to concentrated pheromone extract. Moreover, we employed the C. elegans ARR-1 protein from the desensitization pathway and constructed a protein complementation system with two split beta-lactamase fragments separately tagged onto ARR-1 and GPCRs (ODR-10 and SRD-1). When expressing the system in HEK293 FT cell line, we visualized the desensitization of both ODR-10 and SRD-1 upon the stimuli of diacetyl and concentrated pheromone extract, respectively, using an auto FRET substrate of beta-lactamase, CCF-2 AM. With the above evidence, we conclude that SRD-1 is one receptor responsible for sensing a

Dioecious Caenorhabditis remanei and androdioecious C. elegans are two closely related species belonging to the ELEGANS group of the subgenus Caenorhabditis. Despite their distinct mating systems and evolutionary divergence, our lab has demonstrated that virgin C. remanei females secrete a potent sex-specific pheromone that attracts young adult males of both species from afar. Intriguingly, this chemotaxic behavior requires AWA and CEM neurons in male C. elegans. I will present the experiment data suggesting the requirement of the G-protein coupled receptor SRD-1 in AWA neurons in male C. elegans for sensing the pheromone secreted by C. remanei females. The srd-1 was previously reported being expressed in both AWA and ASI neurons. The sub-cellular localization of SRD-1 receptor in male AWA neurons was found in the tip of cilia. Using the chemotaxis assay, we found that the srd-1 mutant males lost their pheromone responsiveness. This defect can be rescued using srd-1 cDNA driven by AWA specific promoter of gene odr-7. We visualized the excitation of AWA neurons upon treatments of multiple odors and found that AWA neurons of the srd-1 mutant males cannot be stimulated by the pheromone extract, but are responsive to other chemo-attractants. Consistent with this finding, heterologously expressing srd-1 cDNA in HEK293 FT mammalian cell line can mildly confer the host sensitivity to concentrated pheromone extract. Moreover, we employed the C. elegans ARR-1 protein from the desensitization pathway and constructed a protein complementation system with two split beta-lactamase fragments separately tagged onto ARR-1 and GPCRs (ODR-10 and SRD-1). When expressing the system in HEK293 FT cell line, we visualized the desensitization of both ODR-10 and SRD-1 upon the stimuli of diacetyl and concentrated pheromone extract, respectively, using an auto FRET substrate of beta-lactamase, CCF-2 AM. With the above evidence, we conclude that SRD-1 is one receptor responsible for sensing a

Dioecious Caenorhabditis remanei and androdioecious C. elegans are two closely related species belonging to the ELEGANS group of the subgenus Caenorhabditis. Despite their distinct mating systems and evolutionary divergence, our lab has demonstrated that virgin C. remanei females secrete a potent sex-specific pheromone that attracts young adult males of both species from afar. Intriguingly, this chemotaxic behavior requires AWA and CEM neurons in male C. elegans. I will present the experiment data suggesting the requirement of the G-protein coupled receptor SRD-1 in AWA neurons in male C. elegans for sensing the pheromone secreted by C. remanei females. The srd-1 was previously reported being expressed in both AWA and ASI neurons. The sub-cellular localization of SRD-1 receptor in male AWA neurons was found in the tip of cilia. Using the chemotaxis assay, we found that the srd-1 mutant males lost their pheromone responsiveness. This defect can be rescued using srd-1 cDNA driven by AWA specific promoter of gene odr-7. We visualized the excitation of AWA neurons upon treatments of multiple odors and found that AWA neurons of the srd-1 mutant males cannot be stimulated by the pheromone extract, but are responsive to other chemo-attractants. Consistent with this finding, heterologously expressing srd-1 cDNA in HEK293 FT mammalian cell line can mildly confer the host sensitivity to concentrated pheromone extract. Moreover, we employed the C. elegans ARR-1 protein from the desensitization pathway and constructed a protein complementation system with two split beta-lactamase fragments separately tagged onto ARR-1 and GPCRs (ODR-10 and SRD-1). When expressing the system in HEK293 FT cell line, we visualized the desensitization of both ODR-10 and SRD-1 upon the stimuli of diacetyl and concentrated pheromone extract, respectively, using an auto FRET substrate of beta-lactamase, CCF-2 AM. With the above evidence, we conclude that SRD-1 is one receptor responsible for sensing a

The main problem with sensory processing is the difficulty in relating sensory input to physiological responses and perception. This is especially problematic at higher levels of processing, where complex cues elicit highly specific responses. In olfaction, this relationship is particularly obfuscated by the difficulty of characterizing stimulus statistics and perception. The core questions in olfaction are hence the so-called stimulus problem, which refers to the understanding of the stimulus, and the structure–activity and structure–odor relationships, which refer to the molecular basis of smell. It is widely accepted that the recognition of odorants by receptors is governed by the detection of physico-chemical properties and that the physical space is highly complex. Not surprisingly, ideas differ about how odor stimuli should be classified and about the very nature of information that the brain extracts from odors. Even though there are many measures for smell, there is none that accurately describes all aspects of it. Here, we summarize recent developments in the understanding of olfaction. We argue that an approach to olfactory function where information processing is emphasized could contribute to a high degree to our understanding of smell as a perceptual phenomenon emerging from neural computations. Further, we argue that combined analysis of the stimulus, biology, physiology, and behavior and perception can provide new insights into olfactory function. We hope that the reader can use this review as a competent guide and overview of research activities in olfactory physiology, psychophysics, computation, and psychology. We propose avenues for research, particularly in the systematic characterization of receptive fields and of perception., QC 20130723

The main problem with sensory processing is the difficulty in relating sensory input to physiological responses and perception. This is especially problematic at higher levels of processing, where complex cues elicit highly specific responses. In olfaction, this relationship is particularly obfuscated by the difficulty of characterizing stimulus statistics and perception. The core questions in olfaction are hence the so-called stimulus problem, which refers to the understanding of the stimulus, and the structure–activity and structure–odor relationships, which refer to the molecular basis of smell. It is widely accepted that the recognition of odorants by receptors is governed by the detection of physico-chemical properties and that the physical space is highly complex. Not surprisingly, ideas differ about how odor stimuli should be classified and about the very nature of information that the brain extracts from odors. Even though there are many measures for smell, there is none that accurately describes all aspects of it. Here, we summarize recent developments in the understanding of olfaction. We argue that an approach to olfactory function where information processing is emphasized could contribute to a high degree to our understanding of smell as a perceptual phenomenon emerging from neural computations. Further, we argue that combined analysis of the stimulus, biology, physiology, and behavior and perception can provide new insights into olfactory function. We hope that the reader can use this review as a competent guide and overview of research activities in olfactory physiology, psychophysics, computation, and psychology. We propose avenues for research, particularly in the systematic characterization of receptive fields and of perception., QC 20130723

The main problem with sensory processing is the difficulty in relating sensory input to physiological responses and perception. This is especially problematic at higher levels of processing, where complex cues elicit highly specific responses. In olfaction, this relationship is particularly obfuscated by the difficulty of characterizing stimulus statistics and perception. The core questions in olfaction are hence the so-called stimulus problem, which refers to the understanding of the stimulus, and the structure–activity and structure–odor relationships, which refer to the molecular basis of smell. It is widely accepted that the recognition of odorants by receptors is governed by the detection of physico-chemical properties and that the physical space is highly complex. Not surprisingly, ideas differ about how odor stimuli should be classified and about the very nature of information that the brain extracts from odors. Even though there are many measures for smell, there is none that accurately describes all aspects of it. Here, we summarize recent developments in the understanding of olfaction. We argue that an approach to olfactory function where information processing is emphasized could contribute to a high degree to our understanding of smell as a perceptual phenomenon emerging from neural computations. Further, we argue that combined analysis of the stimulus, biology, physiology, and behavior and perception can provide new insights into olfactory function. We hope that the reader can use this review as a competent guide and overview of research activities in olfactory physiology, psychophysics, computation, and psychology. We propose avenues for research, particularly in the systematic characterization of receptive fields and of perception., QC 20130723

Obesity is a major health problem that can be influenced by eating behaviors. Evidence suggests that the sensory properties of food influence eating behaviors and lead to overeating and overweight. A previous genome-wide linkage scan for eating behavior traits assessed with the Three-Factor Eating Questionnaire (cognitive dietary restraint, disinhibition and hunger) performed in the Quebec Family Study (QFS) revealed a quantitative trait locus for disinhibition on chromosome 19p13. This region encodes a cluster of seven olfactory receptor (OR) genes, including OR7D4, previously associated with odor perceptions. Direct sequencing of the OR7D4 gene revealed 16 sequence variants. Nine OR7D4 sequence variants with minor allele frequency (MAF) > 1% as well as 100 SNPs spanning the cluster of OR genes on 19p13 were tested for association with age- and sex-adjusted eating behaviors as well as adiposity traits in 890 subjects. One OR7D4 sequence variant (rs2878329 G > A) showed evidence of association with reduced levels of adiposity (p = 0.03), cognitive dietary restraint (p = 0.05) and susceptibility to hunger (p = 0.008). None of the OR7D4 SNPs was associated with disinhibition, but a SNP (rs2240927) in another OR gene (OR7E24) showed evidence of association (p = 0.03). Another SNP in the OR7G3 gene (rs10414255) was also found to be associated with adiposity and eating behaviors. These results are the first to suggest that variations in human olfactory receptor genes can influence eating behaviors and adiposity. The associations reported in the present study should be interpreted with caution considering the number of tests performed and considered as potential new hypotheses about the effects OR polymorphisms on eating behaviors and obesity that need to be further explored in other populations.

Neural representations of odors get associated with other stimuli through experience. Are action potentials the neural representation that directly gets associated with reinforcement during conditioning? In Manduca , I found that odor presentations elicited only one or two spikes at odor onset (and sometimes offset) in each of a small portion of Kenyon cells, a population of neurons known to be crucial for olfactory associative learning. By using a series of odor-taste associative conditioning paradigms with various sucrose presentation timings, I carefully controlled the temporal overlap between Kenyon cell spiking and sucrose reinforcement timing. I found that in paradigms that led to learning, spiking in Kenyon cells ended well before the reinforcement was given. Further, increasing the temporal overlap between Kenyon cell spiking and sucrose reinforcement actually reduced learning efficacy. Therefore, spikes in Kenyon cells are not the neural representation that gets directly reinforced, and Hebbian spike timing--dependent plasticity in Kenyon cells alone cannot underlie this learning., Two important focuses in neuroscience are to study how animals process sensory stimuli, and how such stimuli get associated with other sensory modalities through experience. Often, sensory stimuli elicit the oscillatory synchronization of neurons in different parts of the brain, and thus may constitute an important stage in sensory processing. Odor-evoked oscillatory synchronization has been observed in a wide variety of animals, including mammals and insects. Despite differences in details of anatomical structure, animals from widely different phyla appear to use similar strategies to encode odors. Here, using the moth Manduca sexta, I examined the factors that cause odor-evoked oscillatory synchronization of olfactory neurons and that determine the frequency of these oscillations. I found that frequency of oscillations decreased from ∼40 Hz to ∼20 Hz during the course of a lengthy odor pulse. This decrease in oscillatory frequency appeared in parallel with a decrease in net olfactory receptor output, suggesting that the intensity of olfactory receptor neuron input to the antennal lobe, the first olfactory relay center, may determine oscillatory frequency. However, I found that changing odor concentration had little effect on oscillatory frequency. Combining the results of recordings made in vivo and computational models, I found that increasing odor concentration recruited additional, but less well-tuned olfactory receptor neurons to respond to the odor. Firing rates of these neurons were tightly constrained by adaptation and saturation. My work established that, in the periphery, odor concentration is mainly encoded by the size of the olfactory receptor neuron population that responded to the odor, whereas oscillatory frequency is determined by the adaptation and saturation of this response., Ong, Chik Ying Rose., Advisers: Siu Kai Kong; Mark Stopfer., Source: Dissertation Abstracts International, Volume: 72-04, Section: B, page: ., Thesis (Ph.D.)--Chinese University of Hong Kong, 2010., Includes bibliographical references (leaves 132-147)., Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web., Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web., also in Chinese., isbn: 9781124494203, Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/)

The olfactory system is a very efficient biological setup capable of odor information processing with neural signals. The nature of neural signals restricts the information representation to multidimensional temporal sequences of spikes. The information is contained in the inter-spike intervals in each individual neural signal and in inter-spike intervals between multiple signals. A mechanism of interactions between random excitations evoked by odorants in the olfactory receptors of the epithelium and deterministic operation of the olfactory bulb is proposed and evaluated in this project. Inverse Frobenius-Perron models of the bulbs temporal sequences are fitted to the inter-spike distributions of temporally modulated receptor signals. Ultimately, such pattern matching results in an ability to recognize odors and offers a hypothetical model for signal processing occurring in the primary stage of the olfactory system., Prepared in cooperation with Southern Illinois Univ. at Edwardsville.