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M Griswold

Publications and source records attributed to M Griswold.

6 recordsLinked to original sources
PubMed1999

Silent functional magnetic resonance imaging demonstrates focal activation in rapid eye movement sleep.

Functional imaging of human sleep has been performed with nuclear medicine methods, but MRI has been difficult to implement, in part because of the noise associated with echo-planar imaging as well as the difficulty in reading physiologic signals in the MRI environment. We describe a silent MR sequence that can record brain activation over many hours with simultaneous acquisition of an EEG. This shows activation of occipital cortex and deactivation of frontal cortex during REM sleep, in agreement with previous studies using other techniques. MRI-Sleep-REM sleep.

Adult↗
PubMed1998

Functional burst imaging.

A quiet magnetic resonance (MR) imaging technique for detecting changes in cerebral activity functions is presented. This single-shot method, functional Burst imaging (FBI), combines elements of Burst imaging with an offset technique known as asymmetric spin echo (ASE). The FBI sequence has the unique feature of being nearly silent, because of the low number of gradient switching steps involved. Furthermore, this approach has the key advantage that it can be implemented on conventional MR systems. Established auditory and visual paradigms were used to evaluate whether FBI can detect changes in cerebral activity using a 1.5 Tesla MR system. In a second set of experiments, the FBI technique was used to evaluate cerebral activity changes during different sleep stages in humans. The results obtained demonstrate that the FBI sequence provides an alternative approach for functional imaging of brain activity in primary and secondary sensory areas of the human brain. Furthermore, in using this quiet MR technique, it was possible to scan continuously during different stages of human sleep without acoustic noise perturbation.

Acoustic Stimulation↗
PubMed1987

Regulation of levels of specific Sertoli cell mRNAs by vitamin A.

The regulation of Sertoli cell transferrin and sulfated glycoprotein-2 (SGP-2) mRNA levels by vitamin A was studied in vitamin A deficient rats. Vitamin A deficiency differentially affected the levels of these mRNAs. Sertoli cells from vitamin A deficient rats contained 3-fold less transferrin mRNA and 1.8-fold more SGP-2 mRNA than Sertoli cells from normal rats. Vitamin A deficiency did not result in changes in the amount of transferrin mRNA per liver cell. When vitamin A deficient rats were fed a retinol supplemented diet, Sertoli cell transferrin and SGP-2 mRNA levels returned to normal. In contrast, dietary retinoic acid did not support recovery of the levels of the two mRNAs. The regulation of transferrin and SGP-2 mRNA levels was further examined in vitamin A deficient rats that had received subcapsular testicular injections of vitamin A and in vitamin A supplemented cultures of Sertoli cells from vitamin A deficient rats. Under these conditions, retinol and retinoic acid both stimulated transferrin mRNA levels but did not affect SGP-2 mRNA levels. Retinol did not inhibit the turnover of transferrin mRNA in Sertoli cell cultures suggesting that the stimulation of transferrin mRNA levels by retinol is due to increased transcription of the transferrin gene. A mathematical correlation between the Sertoli cell transferrin mRNA levels and the weight of the testes or the number of germinal cells was observed.

Animals↗