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T Tateno

Publications and source records attributed to T Tateno.

At least 19 recordsLinked to original sources
PubMed2007

Phase resetting curves and oscillatory stability in interneurons of rat somatosensory cortex.

Synchronous oscillations in neural activity are found over wide areas of the cortex. Specific populations of interneurons are believed to play a significant role in generating these synchronized oscillations through mutual synaptic and gap-junctional interactions. Little is known, though, about the mechanism of how oscillations are maintained stably by particular types of interneurons and by their local networks. To obtain more insight into this, we measured membrane-potential responses to small current-pulse perturbations during regular firing, to construct phase resetting curves (PRCs) for three types of interneurons: nonpyramidal regular-spiking (NPRS), low-threshold spiking (LTS), and fast-spiking (FS) cells. Within each cell type, both monophasic and biphasic PRCs were observed, but the proportions and sensitivities to perturbation amplitude were clearly correlated to cell type. We then analyzed the experimentally measured PRCs to predict oscillation stability, or firing reliability, of cells for a complex stochastic input, as occurs in vivo. To do this, we used a method from random dynamical system theory to estimate Lyapunov exponents of the simplified phase model on the circle. The results indicated that LTS and NPRS cells have greater oscillatory stability (are more reliably entrained) in small noisy inputs than FS cells, which is consistent with their distinct types of threshold dynamics.

Action Potentials↗
PubMed2006

Rate coding and spike-time variability in cortical neurons with two types of threshold dynamics.

Neurons and dynamical models of spike generation display two different classes of threshold behavior: type 1 [firing frequency vs. current (f-I) relationship is continuous at threshold] and type 2 (discontinuous f-I). With steady current or conductance stimulation, regular-spiking (RS) pyramidal neurons and fast-spiking (FS) inhibitory interneurons in layer 2/3 of somatosensory cortex exhibit type 1 and type 2 threshold behaviors, respectively. We compared the postsynaptic firing variability of type 1 RS and type 2 FS cells, during naturalistic, fluctuating conductance input. In RS neurons, increasing the level of independently random, shunting inhibition caused a monotonic increase in spike reliability, whereas in FS interneurons, there was an optimum level of shunting inhibition for achieving the most reliable spike generation and the most precise spike-time encoding. This was observed over a range of different degrees of synchrony, or correlation, in the input. RS cells displayed a progressive rise in spike jitter during natural-like transient burst inputs, whereas for FS cells, jitter was mostly kept low. Furthermore, RS cells showed encoding of the input level in the spike shape, whereas FS cells did not. These differences between the two cell types are consistent with a role of RS neurons as rate-coding integrators, and a role of FS neurons as resonators controlling the coherence of synchronous firing.

Action Potentials↗
PubMed2005

Spatio-temporal cholinergic modulation in cultured networks of rat cortical neurons: spontaneous activity.

Activation of the cholinergic innervation of the cortex has been implicated in sensory processing, learning, and memory. At the cellular level, acetylcholine both increases excitability and depresses synaptic transmission, and its effects on network firing are hard to predict. We studied the effects of carbachol, a cholinergic agonist, on network firing in cultures of rat cortical neurons, using electrode arrays to monitor the activity of large numbers of neurons simultaneously. These cultures show stable spontaneous synchronized burst firing which propagates through dense synaptic connections. Carbachol (10-50 microM), acting through muscarinic receptors, was found to induce a switch to asynchronous single-spike firing and to result in a loss of regularity and fragmentation of the burst structure. To obtain a quantitative measure of cholinergic actions on cortical networks, we applied a cluster Poisson-process model to sets of paralleled spike-trains in the presence and absence of carbachol. This revealed that the time series can be well-characterized by such a simple model, consistent with the observed 1/f(b)-like spectra (0.04<b<2.08). After applying higher concentrations of carbachol the property of the spectra shifted toward a Poisson-process (white) spectrum. These results indicate that cholinergic neurotransmitters have a strong and reliable desynchronizing action on cortical neural activity.

Animals↗
PubMed2005

Spatio-temporal cholinergic modulation in cultured networks of rat cortical neurons: evoked activity.

We studied the effects of carbachol, a cholinergic agonist, on extracellularly evoked firing of networks in mature cultures of rat cortical neurons, using multi-electrode arrays to monitor the activity of large numbers of neurons simultaneously. These cultures show evoked burst firing which propagates through dense synaptic connections. When a brief voltage pulse was applied to one extracellular electrode, spiking electrical responses were evoked in neurons throughout the network. The response had two components: an early phase, terminating within 30-80 ms, and a late phase which could last several hundreds of milliseconds. Action potentials evoked during the early phase were precisely timed, with only small jitter. In contrast, the late phase characteristically showed clusters of electrical activity with significant spatio-temporal fluctuations. The late phase was suppressed by applying a relatively small amount of carbachol (5 microM) in the external solution, even though the spontaneous firing rate was not significantly changed. Carbachol increased both the spike-timing precision and the speed of propagation of population spikes, and selectively increased the firing coincidence in a subset of neuron pairs in the network, while suppressing late variable firing in responses. Hence, the results give quantitative support for the idea that cholinergic activation in the cortex has a general role of focusing or enhancing significant associative firing of neurons.

Animals↗
PubMed2004

Threshold firing frequency-current relationships of neurons in rat somatosensory cortex: type 1 and type 2 dynamics.

Neurons and dynamical models of spike generation display two different types of threshold behavior, with steady current stimulation: type 1 [the firing frequency vs. current (f-I) relationship is continuous at threshold) and type 2 (discontinuous f-I)]. The dynamics at threshold can have profound effects on the encoding of input as spikes, the sensitivity of spike generation to input noise, and the coherence of population firing. We have examined the f-I and frequency-conductance (f-g) relationships of cells in layer 2/3 of slices of young (15-21 DIV) rat somatosensory cortex, focusing in detail on the nature of the threshold. Using white-noise stimulation, we also measured firing frequency and interspike interval variability as a function of noise amplitude. Regular-spiking (RS) pyramidal neurons show a type 1 threshold, consistent with their well-known ability to fire regularly at very low frequencies. In fast-spiking (FS) inhibitory interneurons, although regular firing is supported over a wide range of frequencies, there is a clear discontinuity in their f-I relationship at threshold (type 2), which has not previously been highlighted. FS neurons are unable to support maintained periodic firing below a critical frequency fc, in the range of 10 to 30 Hz. Very close to threshold, FS cells switch irregularly between bursts of periodic firing and subthreshold oscillations. These characteristics mean that the dynamics of RS neurons are well suited to encoding inputs into low-frequency firing rates, whereas the dynamics of FS neurons are suited to maintaining and quickly synchronizing to gamma and higher-frequency input.

Action Potentials↗
PubMed2002

Absence of microdeletions in the Y chromosome in patients with Prader-Willi syndrome with cryptorchidism.

Unilateral or bilateral cryptorchidism is found in 80-100% of male patients with Prader-Willi syndrome (PWS). Recently, the relationship between Yq deletions and cryptorchidism has been assessed. However, the relationship between Yq deletions and PWS patients with cryptorchidism remains unclear. Polymerase chain reaction (PCR) amplification of 51 DNA loci encompassing all of the regions for azoospermia factor (AZF) of the Y chromosome, including the deleted in azoospermia (DAZ) and ribonucleic acid-binding motif (RBM) genes, were examined for microdeletions in 10 PWS males with cryptorchidism and 20 healthy control male subjects. No microdeletions of 51 loci were found in any of the PWS males. The present study therefore suggests that microdeletions in the AZF regions of the Y chromosome do not relate to the occurrence of cryptorchidism in PWS patients.

Adolescent↗
PubMed2001

Mutation screening and CAG repeat length analysis of the androgen receptor gene in Klinefelter's syndrome patients with and without spermatogenesis.

BACKGROUND: Mutations of the androgen receptor (AR) gene give rise to a wide array of phenotypic abnormalities. A systematic analysis of the AR gene in patients with 47,XXY has not previously been performed. METHODS: Mutations of the AR gene and expansion of the CAG repeats in exon 1 of the AR gene were studied in 13 patients with Klinefelter's syndrome either with (n = 1) or without (n = 12) spermatogenesis. RESULTS: No abnormalities in the AR gene were detected by single strand conformational polymorphism analysis. The CAG lengths ranged from 17 to 27 (mean +/- SD 22.8 +/- 3.3, median 23) for Klinefelter patients or from 17 to 28 (mean +/- SD 23.2 +/- 2.6, median 23) for control subjects. X-inactivation analysis for the methylation status of the AR gene was performed in seven patients who were heterozygous for CAG repeats of different length, showing that the longer CAG repeat alleles underwent random but more frequent inactivation in five patients and skewed inactivation in two. CONCLUSIONS: An AR gene abnormality does not constitute an important factor for impaired spermatogenesis in patients with Klinefelter's syndrome.

Adult↗
PubMed2000

Posterior retroperitoneoscopic partial adrenalectomy using ultrasonic scalpel for aldosterone-producing adenoma.

BACKGROUND: Posterior retroperitoneoscopic adrenalectomy has become a standard procedure, but removal of the entire gland is not necessary in all cases. PATIENTS AND METHODS: We performed 10 posterior retroperitoneoscopic partial adrenalectomies for aldosterone-producing adenoma (APA) using an ultrasonic scalpel to divide the normal adrenal gland and the adenoma. RESULTS: The mean operation time and blood loss were 154 (110-231) minutes and 11 (5-32) mL, respectively. The mean weight of removed tissue was 5.7 g (2.3-10.2 g). Subcutaneous emphysema occurred in three patients, but there were no serious operative complications. CONCLUSION: Posterior retroperitoneoscopic partial adrenalectomy using the ultrasonic scalpel may be a valuable treatment for typical solitary APA.

Adenoma↗
PubMed2000

CAG repeat length of the androgen receptor gene in Japanese males with cryptorchidism.

We have analysed the CAG repeat length in exon 1 of the androgen receptor gene in 48 Japanese males with cryptorchidism and 100 fertile Japanese males. The CAG repeat length was 23.4 +/- 0.48 (mean +/- SE) (range 16-32, median 23) in cryptorchid patients and 23.5 +/- 0.29 (range 15-32, median 23) in normal males. There was no significant difference between the two groups. The expansion of the CAG repeats in exon 1 of the androgen receptor gene is unlikely to constitute a major cause of cryptorchidism.

Adolescent↗
PubMed1999

Expression of plasminogen-related gene B varies among normal tissues and increases in cancer tissues.

We previously found that the promoter activity of plasminogen (PLG)-related gene B (PRGB) was 5-fold that of PLG. We have since examined the transcript levels of PRGB among various normal human tissues, and compared these findings with those of PLG. Reverse transcription-PCR analysis revealed that the PRGB expression varied widely among different tissues, while PLG was expressed only in the liver and kidney. RNA samples obtained from cultured cell lines also demonstrated differing PRGB expression. Furthermore, increased PRGB expression was observed in several fresh samples of cancer tissue obtained from cancer patients when compared with surrounding normal tissues.

Base Sequence↗
PubMed1999

Activity-dependent enhancement in the reliability of correlated spike timings in cultured cortical neurons.

To study the use-dependent modification of activity in neural networks, we investigated the spike timing by simultaneously recording activity at multiple sites in a network of cultured cortical neurons. We used dynamical analysis to study the temporal structure of spike trains and the activity-dependent changes in the reliability and reproducibility of spike patterns evoked by a stimulus. We also used cross-correlation analysis to evaluate the interactions of neuron pairs. Our main conclusions are that even when no obvious change in spike numbers can be seen, use-dependent modification occurs, either enhancing or reducing in the reliability and reproducibility of spike trains evoked by a stimulus, and the fine temporal structure of stimulus-evoked spike trains and interactions between neurons are also modified by tetanic stimulation.

Action Potentials↗
PubMed1999

Simultaneous induction of pathway-specific potentiation and depression in networks of cortical neurons.

Activity-dependent modification of synaptic efficacy is widely recognized as a cellular basis of learning, memory, and developmental plasticity. Little is known, however, of the consequences of such modification on network activity. Using electrode arrays, we examined how a single, localized tetanic stimulus affects the firing of up to 72 neurons recorded simultaneously in cultured networks of cortical neurons, in response to activation through 64 different test stimulus pathways. The same tetanus produced potentiated transmission in some stimulus pathways and depressed transmission in others. Unexpectedly, responses were homogeneous: for any one stimulus pathway, neuronal responses were either all enhanced or all depressed. Cross-correlation of responses with the responses elicited through the tetanized site revealed that both enhanced and depressed responses followed a common principle: activity that was closely correlated before tetanus with spikes elicited through the tetanized pathway was enhanced, whereas activity outside a 40-ms time window of correlation to tetanic pathway spikes was depressed. Response homogeneity could result from pathway-specific recurrently excitatory circuits, whose gain is increased or decreased by the tetanus, according to its cross-correlation with the tetanized pathway response. The results show how spatial responses following localized tetanic stimuli, although complex, can be accounted for by a simple rule for activity-dependent modification.

Animals↗
PubMed1999

Microdeletion of the DAZ (deleted in azoospermia) gene or the YRRM (Y chromosome ribonucleic acid recognition motif) gene does not occur in patients with Klinefelter's syndrome with and without spermatogenesis.

OBJECTIVE: To evaluate the occurrence of microdeletions of the Y chromosome involving the DAZ and YRRM genes in patients with Klinefelter's syndrome with and without spermatogenesis. DESIGN: Controlled clinical study. SETTING: Yamagata University Hospital, Yamagata, Japan. PATIENT(S): Patients with Klinefelter's syndrome with spermatogenesis (n = 1) and without spermatogenesis (n = 20) and a control group of men of proven fertility (n = 10). INTERVENTION(S): Blood and semen sampling and testicular biopsy. MAIN OUTCOME MEASURE(S): Semen analysis, polymerase chain reaction amplification of 32 DNA loci on the long arm of the Y chromosome involving the DAZ (deleted in azoospermia) and YRRM (Y chromosome ribonucleic acid recognition motif) genes, and measurement of plasma FSH, LH, and testosterone levels. RESULT(S): No microdeletions of 32 loci were found in any of the patients with Klinefelter's syndrome, either with or without spermatogenesis. Plasma LH and FSH levels were abnormally high and testosterone levels were reduced in all the patients with Klinefelter's syndrome. American Society for Reproductive Medicine.) CONCLUSION(S): Severe impairment of spermatogenesis in patients with Klinefelter's syndrome is not caused by microdeletions of the Y chromosome involving the DAZ and YRRM genes.

DNA↗
PubMed1999

Long arm deletion of chromosome 10 in a boy with monorchidism.

We report on a boy with long-arm deletion of chromosome 10 and compare this case to 10 previously reported patients. He had right cryptorchidism and absence of the left testis, but the size of his penis was normal. Cytogenetic analysis of the case showed the deficiency of 10q26.1-26.3 and the presence of 10qter. Four of 10 previously reported patients had an intersex phenotype, and all others had combinations of cryptorchidism, micropenis and hypospadias. These facts indicate that the terminal of chromosome 10q is strongly associated with abnormal male development.

Child↗
PubMed1998

Pulmonary function after posterior retroperitoneoscopic surgery.

Pulmonary function tests were performed in 12 patients who underwent posterior retroperitoneoscopic surgery, before and on the 3rd and 7th days after operation. Forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), FEV1/FCV, vital capacity (VC), total lung capacity (TLC), residual volume (RV) and functional residual capacity (FRC) were not significantly different between before and after surgery. It is assumed that posterior retroperitoneoscopic surgery could be performed without impairment of pulmonary function after surgery.

Adrenalectomy↗