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M Tonoike

Publications and source records attributed to M Tonoike.

24 records · Page 2Linked to original sources
PubMed1994

Local distribution of odor responsivities of mouse olfactory receptor neurons.

The local distribution of odor responsivity was studied in isolated mouse olfactory neurons retaining their original spatial relationships in intact tissue. The selectivity for three odorants and population of responsive cells were estimated from the odor-induced increase in cytoplasmic calcium. It was found that cells with different odor selectivities coexisted with a shorter distance than cells of the same type. Cells with a similar odor responsivity were arranged somewhat more densely than a complete random distribution. The results indicated the coexistence of different subtypes of odor responsive cells in the septal epithelium with sparse clustering of similarly responsive cells.

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PubMed1994

Tuning specificities to aliphatic odorants in mouse olfactory receptor neurons and their local distribution.

1. Odor responses to two homologous series of n-fatty acids (nFA) and n-aliphatic alcohols (nAA) with a straight chain of three to nine carbons were examined by measuring odor-induced [Ca2+]i increase in mouse olfactory receptor neurons (ORNs) isolated by the tissue-printing method. 2. One-third of the ORNs responsive to nFA and/or nAA were alternately sensitive to either type of odorant. Their sensitivities were usually near maximal for one or two odorants and decreased with differences in the carbon chain length from the tuned odorants. 3. Two-thirds of the ORNs responsive to nFA and/or nAA were sensitive to both types of odorants. Most of them were also tuned to one or two odorants in each series with similar carbon chain lengths and showed a decrease of sensitivity with increasing stereochemical discrepancy, similar to nFA/nAA discriminating ORNs. 4. In 10 of 20 non-nFA/nAA discriminating ORNs, the sensitivity to nFA was > 10 times greater than to nAA, and 80% of them were localized in a central region of olfactory epithelium on the septum wall where ORNs preferentially project to the dorsomedial or centromedial regions of the olfactory bulb. In addition, the sensitivity to three series of n-aliphatic odorants with an added amino group was examined. Sensitivity became higher as the electronegativity of the functional groups increased, suggesting that a hydrogen bond might partly mediate affinity in one type of non-nFA/nAA discriminating ORNs. 5. The diversity in odorant tuning specificity and sensitivity of the individual ORNs indicated that their receptor sites were finely tuned to the stereochemical structures of numerous odorants by changes in the three-dimensional size and intermolecular positions of the hydrophobic domains for hydrophobic bond, as well as the proton-acceptor or donor for the hydrogen bond and the electrical charge for the ionic bond. 6. The subpopulation of ORNs tuned to an individual odorant increased as the length of carbon chain of the odorant increased from three to nine. This tendency was more marked for nFA than for nAA in the case of non-nFA/nAA discriminating ORNs. 7. Data obtained by the in vitro approach using the tissue-printing method suggested that three or more subtypes of ORNs, which were similar in some cases and significantly different in other cases, were located within close proximity to one another.

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PubMed1992

Simultaneous recording of [Ca2+]i increases in isolated olfactory receptor neurons retaining their original spatial relationship in intact tissue.

A new method is described for isolating olfactory receptor neurons suitable for simultaneous recording of odorant responses in several cells. This method, called "tissue printing" by Cassab and Varner, was used to isolate cells for measurement of odorant-induced increases in cytosolic-free calcium concentration ([Ca2+]i) using the Ca2+ indicator dye fura-2. A large number of receptors could be isolated from a piece of olfactory epithelium (about 300 microns square), preserving their normal morphology and relative local topology to that in the intact olfactory tissue. The probability that there are one or more receptor cells with odorant-induced responses in [Ca2+]i per preparation was 4 times higher with cells isolated by the tissue printing than with those obtained by the pipetting method. The responses of 2 receptor cells separated by 28 microns in the recording chamber differed for 2 odorants: isoamyl acetate and citralva. The method was useful for isolating receptor neurons without losing their morphological features and for investigating the spatial distribution of odorant responsiveness of each receptor over the olfactory epithelium.

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PubMed1991

Two types of increases in free Ca2+ evoked by odor in isolated frog olfactory receptor neurons.

Olfactory transduction involves second messenger-related enzymes and cAMP-gated, K+ and Ca2+ channels, which are known to be regulated by Ca2+. We report here that cytosolic free Ca2+ concentration ([Ca2+]i) in olfactory receptor neuron was increased by odorants or forskolin and Ca2+ influx contributed to the adaptation. The increases in [Ca2+]i were below two to three-fold of resting level and transient for 26 s (mean value, n = 18). The increases were due to two pathways: Ca2+ influx and release. The slow increases in [Ca2+]i by forskolin resembled those by citralva. It was suggested that the responses to citralva were accompanied by increases in intracellular cAMP and Ca2+ influx or release leading to transient increases in [Ca2+]i.

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PubMed1980

Neuronal activity in the monkey dorsolateral prefrontal cortex during a discrimination task with delay.

Ninety-nine single neuron activities of the dorsolateral prefrontal cortex of 3 monkeys were recorded during performance of a Konorski task. Green or red lights were presented successively with a separation of fixed delay interval. The monkey responded as soon as the second stimulus was presented. If the two stimuli were color-matched, the 'YES' lever press was rewarded; if the two stimuli were not, the 'NO' lever press was rewarded. In the second task, after paired color stimuli, a tone pip was presented as the 'GO' signal for lever presses. During sample and matching periods 50 neurons increased their discharge rates and 10 decreased. In 86% of increasing type neurons rate increase occurred during both periods. During auditory GO periods, 27 neurons increased their rates and 11 decreased. Discharge peak was before or at the moment of hold key release. In 60% of these neurons were also observed the rate changes to sample and matching stimuli. Differential activations between left and right levers were found in 20%. It was suggested that the prefrontal cortex is related to a sensorial attention mechanism to the visual stimulus which enables correct choice of the behavior to be rewarded.

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