Visual receptive fields and movement fields of visuomovement neurons in the monkey premotor cortex obtained during a visually guided reaching task

Single-neuron activity in the premotor cortex of monkeys was examined while they performed a visually guided reaching task with their eyes fixated. We recorded a total of 177 visually responsive neurons that showed significantly enhanced activity after a presentation of visuospatial cue ('visual response'). Of these neurons, 57% (n = 101) also showed significantly enhanced activity after an onset of the go-signal and before movement ('movement-associated response'). These were designated as 'visuomovement neurons'. The visual response latencies of 81% of the visuomovement neurons were between 60 and 160 ms (median = 100 ms) and the response durations were less than 240 ms in 80% of the neurons. The preferred direction of the visual response (PDV) was toward the contralateral side in 57% and the ipsilateral side in 20% of the neurons. The preferred direction of the movement-associated response (PDM) was toward the contralateral side in 50% of the neurons. In most of the neurons (74/101, 73%), the PDV and the PDM corresponded to approximately the same direction. These results suggest that premotor visuomovement neurons play a role in receiving visuospatial information for visually guided reaching, and commanding reaching movements.

Neuronal activity in the frontal eye field of the monkey is modulated while attention is focused on to a stimulus in the peripheral visual field, irrespective of eye movement

We tested the hypothesis that the frontal eye field (FEF) is involved in attention to the peripheral visual field (PVF). Neuronal activity was recorded in the FEF of two monkeys while they were performing three oculomotor tasks. In the visual attention task (VAT), the monkeys released a lever when a test stimulus (TS) presented in the PVF dimmed while they were looking at a central fixation point (FP). In the visual saccade task (VST), the monkeys exhibited saccadic eye movements when the FP was extinguished. In the visual fixation task (VFT), the monkeys released the lever when the FP dimmed. Overall, the activities of 80 FEF neurons were examined. The responses to visual stimuli of 41 of these neurons (51%) were modulated during the VAT. Twenty-five neurons showed pre-saccadic activity. Of these, 13 neurons (52%) exhibited activity modulation during the VAT. Eighteen neurons showed no pre-saccadic activity. Of these, 10 neurons (56%) exhibited activity modulation during the VAT. These results suggest that the FEF is involved in selecting the visual stimuli relevant to performing a task irrespective of eye movements.

Conventional molecular diagnosis of steroid 21-hydroxylase deficiency using mismatched primers and polymerase chain reaction

We tested a conventional method based on polymerase chain reaction (PCR) and specific primers with one mismatched base at the 3' end to introduce restriction enzyme sites in order to detect mutations of the CYP21 gene without radioisotope. Using this method, the intron 2 mutation causing aberrant splicing of mRNA (In2G) and the exon 4 mutation (Ile->Asn, Ex4) in the CYP21 gene were analyzed. The nonsense mutation in exon 8 (Ex8NON) of the CYP21 gene was also investigated by PCR and subsequent restriction enzyme digestion. The mismatched primers successfully amplified the CYP21 gene containing the In2G and the Ex4 mutation sites, and the presence of these two mutations could be determined by restriction enzyme digestion after PCR. We used this new method to study 33 patients. Twenty-five of these patients were found to have at least one mutation (In2G and/or Ex4 mutation). By enzyme digestion after PCR, the Ex8NON mutation was also identified (7 out of 33 patients). In conclusion, we have developed a new method to detect point mutations in the CYP21 gene. This method was proved to be sensitive and rapid for the detection of the mutations studied. Therefore, this method is suitable for clinical genetic diagnosis.

A new isopatulin derivative pintulin produced by Penicillium vulpinum F-4148 taxonomy, isolation, physico-chemical properties, structure and biological properties

During our screening program of natural products from fungal metabolites for drugs effective against tumor cell lines, we discovered a new isopatulin derivative, pintulin, from the fermentation broth of Penicillium vulpinum F-4148. Pintulin shows weak activity against tumor cell lines, compared to that of adriamycin.

Multiple mouse chromosomal loci for dynein-based motility

Dyneins are multisubunit mechanochemical enzymes capable of interacting with microtubules to generate force. Axonemal dyneins produce the motive force for ciliary and flagellar beating by inducing sliding between adjacent microtubules within the axoneme. Cytoplasmic dyneins translocate membranous organelles and chromosomes toward the minus ends of cytoplasmic microtubules. Dynactin is an accessory complex implicated in tethering cytoplasmic dynein to membranous organelles and mitotic kinetochores. In the studies described here, we have identified a number of new dynein genes and determined their mouse chromosomal locations by interspecific backcross analysis. We have also mapped several dynein and dynactin genes cloned previously. Our studies provide the first comprehensive attempt to map dynein and dynactin genes in mammals and provide a basis for the further analysis of dynein function in development and disease.

In vitro motility from recombinant dynein heavy chain

The dyneins are a class of motor protein involved in ciliary and flagellar motility, organelle transport, and chromosome segregation. Because of their large size and subunit complexity, relatively little is known about their mechanisms of force production and regulation. We report here on the expression and analysis of the entire rat cytoplasmic dynein heavy chain (Mr 532,000). Full-length cDNAs were constructed from a series of partial clones and tagged at the C terminus with either a FLAG-epitope tag or a His6-tag. The recombinant polypeptides were expressed either in insect cells by baculovirus infection or in COS-7 cells by transient transfection. The recombinant protein was mostly soluble and showed good microtubule binding. It exhibited a broad sedimentation profile, indicative of the formation of dimers as well as higher order multimers. Good microtubule gliding motility activity was observed in assays of heavy chain expressed in either insect or COS-7 cells. Average microtubule gliding velocities of 1.2-1.8 microm/sec were observed, comparable with the rates determined for calf brain cytoplasmic dynein. These results represent the first indication that recombinant heavy chain alone is capable of force production, and should lead to rapid progress in defining the dynein motor domain.

Visual neurons with higher selectivity can retain memory in the monkey temporal cortex

Activities of individual neurons were recorded from the superior temporal sulcus (STS) of rhesus monkeys during the performance of a visual discrimination and memory task. Of 174 neurons analyzed in detail, 19 neurons showed sustained changes in discharge rates during the delay period (D neurons). All the D neurons showed responses during the presentation of the same stimulus and had higher selectivity compared to the remaining non-D neurons. The data indicated that a subgroup of highly selective visual neurons in the STS participate in short-term retention of these stimuli.

Local injection of bicuculline into area 8 and area 6 of the rhesus monkey induces deficits in performance of a visual discrimination GO/NO-GO task

While performing a symmetrically reinforced visual discrimination GO/NO-GO task, five monkeys were injected with a GABAA antagonist, bicuculline methiodide (BMI), into Brodmann's area 9, 8, 6, or 4. The task consisted of five periods: START, OFF, CUE, RESPONSE, and an inter-trial interval. The monkey was trained to make either the GO response (lever release) or the NO-GO response (continued pressing of the lever), depending on the color of the cue, during the RESPONSE period. Analysis was limited to 102 sites in which muscle convulsions of the forelimb and/or shoulder did not result from BMI injections. Errors in performance increased 10-60 min after injection into 10 of 33 sites in area 9, 9 of 25 sites in area 8, 20 of 34 sites in area 6, and 2 of 10 sites in area 4. The number of trials finished in a 120-min session decrease. Injections induced PRE-RESPONSE errors (release of the lever in either the OFF or CUE periods), GO RESPONSE errors (failure to release the lever when signaled), and NO-GO RESPONSE errors (release of the lever despite a signal not to release). The results suggest that both areas 8 and 6 are involved in correct performance of the GO/NO-GO task.

Effect of transcranial magnetic stimulation on cerebral function in a monkey model

The effect of transcranial magnetic stimulation on higher cerebral function was studied using 3 monkeys. They were trained in a delayed response task which required spatial short-term memory. The task was presented by a computer on a cathode-ray tube and results of the delayed response task, which consisted of the percentage of correct choices, reaction time and trial number, were analyzed. For stimulation, small and large round coils were used as well as a figure 8 configuration. Their maximal B-fields were 3.3 T, 1.9 T and 2.4 T, respectively. A total of more than 7000 stimuli were given to each monkey in various patterns. There was no deficit in the delayed response. Further complications such as epileptic seizures were not observed either. In conclusion, transcranial magnetic stimulation does not appear to have any effect on higher cerebral functions in monkeys.

Visual response properties of single neurons in the temporal pole of behaving monkeys

1. The responses of single neurons in the anterior part of the temporal cortex in monkeys, mainly the temporopolar cortex, area 36, and the most anterior part of area TE of von Bonin and Bailey (1947) (these areas were designated here as the temporal pole), were examined during the performance of a visual recognition memory task. The visual stimulus (sample stimulus) was presented when the monkey pressed a lever. The same sample stimulus was presented one to four times and, thereafter, a new stimulus was presented. The monkeys were trained to discriminate the new stimulus from the sample stimulus and to release the lever in response to the new stimulus. We used colored photographs of natural objects (human faces, monkeys, foods, and non-food objects) as complex visual stimuli or computer-generated two-dimensional shapes (a red square, a green circle, etc.) as simple visual stimuli. 2. In total, the activity of 311 neurons was recorded, and 225 of these responded to at least one visual stimulus. All visually responsive neurons were located in the ventral part of the temporal pole including the banks of the superior temporal sulcus. 3. The relationship between the monkey's eye movements and visual responses was investigated. Visual response properties, such as the number of spikes, onset latency, and response duration, were stable regardless of the monkey's eye positions and movements if the eyes were directed to the display. We also examined the receptive field property of neurons (n = 3). The neurons tested in the temporal pole tended to have a large receptive field (24 x 24 degrees). 4. The neurons tended to respond to different stimuli in different magnitudes. In each case, the maximal responses were elicited by complex, colored photographs, whereas simple, two-dimensional colored shapes elicited little or no responses. In 21% of the cases (47/225), the magnitude of the maximal response was significantly larger than for any of the other responses. 5. An achromatic version of the stimulus that induced the maximal response was tested in 53 neurons. About 80% of the neurons (41/53) responded to the achromatic stimulus at a magnitude that was not significantly different from the response to the original stimulus. In 12 neurons, the removal of color did significantly decrease the magnitude of the response. When other colors were tested, 3 of 9 neurons were found to code for color. 6. In 21 of these 53 neurons, a portion (the left-, right-, upper-, or lower-half) of the stimulus was also tested.(ABSTRACT TRUNCATED AT 400 WORDS)

Neuronal responses to photographs in the superior temporal sulcus of the rhesus monkey

The activity of a total of 174 visual neurons in the superior temporal sulcus (mostly area TE) of rhesus monkeys was examined quantitatively using complex visual stimuli. Colored photographs of human faces (n = 411), monkeys (n = 308), and non-face objects (n = 35), as well as computer-generated graphics were presented as visual stimuli during a performance of a visual discrimination task. All neurons responded to a limited number of photographs. We quantified these stimulus-selective responses, using two kinds of selectivity indices. With the first index (SI1), we attempted to estimate how many stimuli produced a significant response. The mean value of SI1 was 0.63. About 31% of neurons had values of SI1 greater than 0.8. With the second index (SI2), we attempted to estimate how many stimuli could be distinguished from the stimulus that elicited the strongest activity. The mean value of the SI2 was 0.71. About 51% of neurons had values of SI2 greater than 0.8. About 66% of neurons had values of either SI1 or SI2 that were greater than 0.8, a value that corresponds to a selectivity of one out of five stimuli. We designated these neurons as stimulus-selective (SS) neurons. Of these SS neurons, 45% showed the best response to human faces. Similarly, 28.8% showed the best response to a photograph of monkeys. 7.5% to food, 8.8% to non-food and 10% to simple graphics, such as, a colored square or a circle.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular cloning of the retrograde transport motor cytoplasmic dynein (MAP 1C)

Overlapping cDNAs encoding the entire heavy chain of cytoplasmic dynein (MAP 1C) have been obtained. A 4644 amino acid polypeptide containing four ATP-binding consensus sequences is predicted. Homology with the sea urchin flagellar outer arm dynein beta heavy chain is observed within the C-terminal two-thirds of the protein. The N-terminal third of the two polypeptides shows no clear relationship, suggesting that this region of MAP 1C is responsible for its association with retrograde organelles and other functions. Northern blot analysis reveals a 16.5 kb band in brain and other tissues. Southern blot analysis is consistent with a single cytoplasmic dynein gene. Thus, in contrast with cilia and flagella, which contain numerous forms of dynein, our results are consistent with the existence of only a single cytoplasmic dynein heavy chain gene, which appears to produce only a single transcript.

Homology of the 74-kD cytoplasmic dynein subunit with a flagellar dynein polypeptide suggests an intracellular targeting function

In previous work we found cytoplasmic dynein to be a complex of two catalytic heavy chains and at least seven co-purifying polypeptides of unknown function. The most prominent of these is a 74-kD electrophoretic species which can be resolved as two to three bands by SDS-PAGE. We have now selected a series of overlapping rat brain cDNAs encoding the 74-kD species. The deduced sequence of a full-length cDNA predicts a 72,753 D polypeptide which includes the amino acid sequences of nine peptides determined by NH2-terminal microsequencing. PCR performed on first strand rat brain cDNA together with the sequence of a partially matching tryptic peptide indicated the existence of at least three isoforms of the 74-kD cytoplasmic dynein subunit. Comparison with known sequences revealed that the carboxyl-terminal half of the polypeptide is 26.4% identical and 47.7% similar to the product of the Chlamydomonas ODA6 gene, a 70-kD intermediate chain of flagellar outer arm dynein. Immunoblot analysis with a monoclonal antibody to the 74-kD species indicated a widespread tissue distribution, as expected for a cytoplasmic dynein subunit. Nonetheless, the antibody recognized a 67-kD species in ram sperm flagella and pig tracheal cilia, supporting the existence of distinct but related cytoplasmic and axonemal polypeptides in mammals. In view of evidence for a role for the ODA6 gene product in anchoring flagellar dynein to the A subfiber microtubule in the axoneme, we predict an analogous role for the 74-kD polypeptide, perhaps in mediating the interaction of cytoplasmic dynein with membranous organelles and kinetochores.

Development of the ability to detect visual motion in infant macaque monkeys

A preferential looking technique was used to measure detection of visual motion by 12 infant macaque monkeys (10 Macaca fuscata and 2 Macaca mulatta at ages between 1 and 100 days). A 0.25 cycles/deg square-wave grating was presented at speeds from 40 to 0.4 deg/s. The threshold was determined by a two-alternative forced-choice preferential looking method, in conjunction with a staircase procedure. The threshold for detection of visual motion decreased exponentially with age over the first 100 days of life. At each age there was substantial variability among the individual infants tested, but each monkey's ability to detect visual motion improved with age.

Activity of single neurons in the monkey amygdala during performance of a visual discrimination task

1. The activity of single neurons was recorded extracellularly from the monkey amygdala while monkeys performed a visual discrimination task. The monkeys were trained to remember a visual stimulus during a delay period (0.5-3.0 s), to discriminate a new visual stimulus from the stimulus, and to release a lever when the new stimulus was presented. Colored photographs (human faces, monkeys, foods, and nonfood objects) or computer-generated two-dimensional shapes (a yellow triangle, a red circle, etc.) were used as visual stimuli. 2. The activity of 160 task-related neurons was studied. Of these, 144 (90%) responded to visual stimuli, 13 (8%) showed firing during the delay period, and 9 (6%) responded to the reward. 3. Task-related neurons were categorized according to the way in which various stimuli activated the neurons. First, to evaluate the proportion of all tested stimuli that elicited changes in activity of a neuron, selectivity index 1 (SI1) was employed. Second, to evaluate the ability of a neuron to discriminate a stimulus from another stimulus, SI2 was employed. On the basis of the calculated values of SI1 and SI2, neurons were classified as selective and nonselective. Most visual neurons were categorized as selective (131/144), and a few were characterized as nonselective (13/144). Neurons active during the delay period were also categorized as selective visual and delay neurons (6/13) and as nonselective delay neurons (7/13). 4. Responses of selective visual neurons had various temporal and stimulus-selective properties. Latencies ranged widely from 60 to 300 ms. Response durations also ranged widely from 20 to 870 ms. When the natures of the various effective stimuli were studied for each neuron, one-fourth of the responses of these neurons were considered to reflect some categorical aspect of the stimuli, such as human, monkey, food, or nonfood object. Furthermore, the responses of some neurons apparently reflected a certain behavioral significance of the stimuli that was separate from the task, such as the face of a particular person, smiling human faces, etc. 5. Nonselective visual neurons responded to a visual stimulus, regardless of its nature. They also responded in the absence of a visual stimulus when the monkey anticipated the appearance of the next stimulus. 6. Selective visual and delay neurons fired in response to particular stimuli and throughout the subsequent delay periods. Nonselective delay neurons increased their discharge rates gradually during the delay period, and the discharge rate decreased after the next stimulus was presented. 7. Task-related neurons were identified in six histologically distinct nuclei of the amygdala.(ABSTRACT TRUNCATED AT 400 WORDS)

Oscillatory neuronal activity related to visual short-term memory in monkey temporal pole

The activity of single neurons was recorded extracellularly from the temporal pole of monkeys while they were performing a visual short-term memory task. Neurons in the ventral part of the temporal pole showed sustained firing during the memorization delay period of the task when the monkey was remembering particular visual stimuli. The presence and absence of the firing were correlated with the correct and incorrect performance of the task, respectively. The sustained firing showed oscillation. The data suggest that visual information was stored as sustained firing among certain group of neurons producing oscillations.

Spatiotemporal characteristics of direction-selective neurons in the middle temporal visual area of the macaque monkeys

In an attempt to elucidate the mechanisms of directional selectivity in the neurons of the middle temporal visual area (MT) of macaque monkeys, we presented small numbers of sequentially flashed stimuli with various temporal and spatial intervals within the receptive field (RF) of direction-selective MT neurons. Experiments were performed using awake macaque monkeys trained to fixate on a set of short stationary lines. Stimuli were presented on a CRT screen under computer control. In two-flash experiments, responses to a test flash presented in the center of the RF were examined following a conditioning flash presented in various locations within the RF. Inhibition in the null direction was observed in about 78% of MT neurons, while facilitation was relatively weak in this group of neurons. In most of these neurons, the ranges of temporal and spatial intervals that produced directional selectivity in two-flash experiments were within half the values and double the values, respectively of those in multi-flash experiments. In the remaining 22% of direction-selective MT neurons, several flashed stimuli were necessary to produce directional selectivity. Most of these neurons showed facilitation in the preferred direction. It appears that the inhibitory mechanisms in the null direction are sufficiently strong to be induced by a single conditioning flash whereas the facilitatory mechanisms are weaker and several stimuli are required for production of the direction-selective response.

Direction selective neurons respond to short-range and long-range apparent motion stimuli in macaque visual area MT

To examine the involvement of macaque visual area MT in the short-range process and the long-range process of visual motion (Braddick 1974), direction selective MT neurons responding to alternating slits and alternating random dots were analyzed. Experiments were performed in awake macaque monkeys trained to fixate a pair of small stationary lines. Visual stimuli were presented on a CRT display screen. About 82% of direction selective MT neurons showed directional responses to alternating slits and/or alternating random dots. The maximum spatial separation for eliciting directional responses (Dmax) was determined for each neuron. In most of cases, Dmax for the alternating random dots was smaller than Dmax for the alternating slits. The Dmax for both alternating random dots and alternating slits increased when retinal eccentricity increased. It is suggested that MT neurons might be involved in the long-range process rather than the short-range process of the apparent motion.

Transformation of 25- and 1 alpha-hydroxyvitamin D3 to 1 alpha, 25-dihydroxyvitamin D3 by using Streptomyces sp. strains

To enzymatically synthesize vitamin D derivatives, we screened about 300 Streptomyces sp. strains. Streptomyces sclerotialus FERM BP-1370 and Streptomyces roseoporus FERM BP-1574 were found to have the ability to convert 25-hydroxyvitamin D3 and 1 alpha-hydroxyvitamin D3, respectively, to 1 alpha, 25-dihydroxyvitamin D3. The average rates of 1 alpha hydroxylation of 25-hydroxyvitamin D3 were 6.9 micrograms liter-1 min-1 with FERM BP-1370 and 7.0 micrograms liter-1 min-1 with FERM BP-1574. The specific cytochrome P-450 inhibitors carbon monoxide, SKF-525-A, and metyrapone inhibited the hydroxylation of 1 alpha- and 25-hydroxyvitamin D3 to 1 alpha, 25-dihydroxyvitamin D3 by FERM BP-1370 and FERM BP-1574. The cytochromes P-450 of these strains were detected by reduced CO difference spectra in the whole-cell suspensions. The appearance of cytochrome P-450 suggests that the cytochromes P-450 of FERM BP-1370 and FERM BP-1574 carry out the hydroxylation of 25- and 1 alpha-hydroxyvitamin D3 to 1 alpha, 25-dihydroxyvitamin D3.

Unique oscillatory activity related to visual processing in the temporal pole of monkeys

To examine the role of the temporal pole of monkeys in visual processing, the activity of single neurons was extracellularly recorded while the monkey performed a visual discrimination task. Various colored photographs were used as visual stimuli. We found neurons with oscillatory activity coupled to visual stimuli in the ventral part of the temporal pole. Oscillatory activity tended to be elicited by objects familiar to the monkey, such as familiar human faces, familiar foods and familiar non-food objects related to the experiment. The frequencies of oscillations changed depending upon the nature of the visual stimulus. The results suggest that oscillatory activity generated by the activation of a certain circuit is involved in the recognition of complex visual stimuli, leading to the production of certain psychological states.

Primary structure and functional expression from complementary DNA of a brain calcium channel

The primary structure of a voltage-dependent calcium channel from rabbit brain has been deduced by cloning and sequencing the complementary DNA. Calcium channel activity expressed from the cDNA is dramatically increased by coexpression of the alpha 2 and beta subunits, known to be associated with the dihydropyridine receptor. This channel is a high voltage-activated calcium channel that is insensitive both to nifedipine and to omega-conotoxin. We suggest that it is expressed predominantly in cerebellar Purkinje cells and granule cells.

Intramembrane charge movement restored in dysgenic skeletal muscle by injection of dihydropyridine receptor cDNAs

The skeletal muscle dihydropyridine (DHP) receptor is essential in excitation-contraction (EC) coupling. The receptor is postulated to be the voltage sensor giving rise to the intramembrane current, termed charge movement. We have now tested this hypothesis using myotubes from mice with the muscular dysgenesis mutation, which alters the skeletal muscle DHP receptor gene and prevents its expression. Our results indicate that charge movement is deficient in dysgenic myotubes but is fully restored following injection of an expression plasmid carrying the rabbit skeletal muscle DHP receptor complementary DNA, strongly supporting the hypothesis that the DHP receptor is the voltage sensor for EC coupling in skeletal muscle. Additionally, our data obtained for normal and chimaeric DHP receptor constructs demonstrate that DHP receptors with widely differing abilities to function as calcium channels and to mediate EC coupling produce very similar charge movements.

Cardiac-type excitation-contraction coupling in dysgenic skeletal muscle injected with cardiac dihydropyridine receptor cDNA

There are dihydropyridine (DHP)-sensitive calcium currents in both skeletal and cardiac muscle cells, although the properties of these currents are very different in the two cell types (for simplicity, we refer to currents in both tissues as L-type). The mechanisms of depolarization-contraction coupling also differ. As the predominant voltage-dependent calcium current of cardiac cells, the L-type current represents a major pathway for entry of extracellular calcium. This entry triggers the subsequent large release of calcium from the sarcoplasmic reticulum (SR). In contrast, depolarization of skeletal muscle releases calcium from the SR without the requirement for entry of extracellular calcium through L-type calcium channels. To investigate the molecular basis for these differences in calcium currents and in excitation-contraction (E-C) coupling, we expressed complementary DNAs for the DHP receptors from skeletal and cardiac muscle in dysgenic skeletal muscle. We compared the properties of the L-type channels produced and showed that expression of a cardiac calcium channel in skeletal muscle cells results in E-C coupling resembling that of cardiac muscle.

Primary structure and functional expression of the cardiac dihydropyridine-sensitive calcium channel

In cardiac muscle, where Ca2+ influx across the sarcolemma is essential for contraction, the dihydropyridine (DHP)-sensitive L-type calcium channel represents the major entry pathway of extracellular Ca2+. We have previously elucidated the primary structure of the rabbit skeletal muscle DHP receptor by cloning and sequencing the complementary DNA. An expression plasmid carrying this cDNA, microinjected into cultured skeletal muscle cells from mice with muscular dysgenesis, has been shown to restore both excitation-contraction coupling and slow calcium current missing from these cells, so that a dual role for the DHP receptor in skeletal muscle transverse tubules is suggested. We report here the complete amino-acid sequence of the rabbit cardiac DHP receptor, deduced from the cDNA sequence. We also show that messenger RNA derived from the cardiac DHP receptor cDNA is sufficient to direct the formation of a functional DHP-sensitive calcium channel in Xenopus oocytes. Furthermore, higher calcium-channel activity is observed when mRNA specific for the polypeptide of relative molecular mass approximately 140,000 (alpha 2-subunit) associated with skeletal muscle DHP receptor is co-injected.

Induction of mRNA for low-density lipoprotein receptors in heterozygous Watanabe heritable hyperlipidemic rabbits treated with CS-514 (Pravastatin) and cholestyramine

We administered CS-514, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, alone and in combination with cholestyramine to heterozygous Watanabe heritable hyperlipidemic rabbits. This rabbit model for heterozygous familial hypercholesterolemia has hepatic low-density lipoprotein receptors that are assumed to be half as many as in normal rabbits. CS-514 alone lowered plasma low-density lipoprotein cholesterol levels by 50%, and in combination with cholestyramine, it lowered levels by 80%. The membrane-binding assay showed these drugs caused 1.5- and 1.8-fold increases in the number of hepatic low-density lipoprotein receptors, respectively. We also measured the amount of mRNA for low-density lipoprotein receptor by S1 nuclease protection assay in the same livers as above. These drugs induced mutant mRNA for the low-density lipoprotein receptor, which has an in-flame deletion of 12 nucleotides, as well as normal receptor mRNA. CS-514 alone produced a 1.8-fold increase in the amount of mRNA for the normal receptor and a 2.3-fold increase for the mutant mRNA, whereas CS-514 in combination with cholestyramine produced 1.9- and 3.1-fold increases, respectively. We conclude that CS-514 induces mRNA for the low-density lipoprotein receptor, subsequently increasing the receptor protein in the liver, and then reduces the levels of plasma cholesterol, and that the induction is augmented when the drug is administered in combination with cholestyramine.

Directionally selective response of cells in the middle temporal area (MT) of the macaque monkey to the movement of equiluminous opponent color stimuli

Based on the fact that a great majority of cells in the middle temporal (MT) area of the macaque respond to movement of luminance contours with directional selectivity, this area has been thought to be concerned with the analysis of visual motion. However, objects can be discriminated from the background not only by differences in luminance but also by differences in color. It is possible that color signals are also used for motion analysis in MT. In the present study, we examined whether MT cells respond to movement of a pattern composed of pure color-contours. Using a color TV system, a moving color bar was displayed on a uniform background whose color was opponent with that of the bar. The main bar/background color combination we examined was magenta/cyan. Yellow/blue and cyan/magenta combinations were also examined for some cells. The response of MT cells to movements of opponent-color stimuli was recorded while the bar/background luminance ratio was changed from 1/10 to 10/1. In half of 89 cells tested in 3 monkeys, the response decreased considerably (disappeared completely in some cells) at a luminance ratio close to the human equiluminous condition. In the other half, a directional response persisted at any bar/background luminance ratio, though the response decreased to a varied extent (30-90% of the maximum response) near the ratio 1 (human equiluminous condition). The average magnitude of the equiluminous response to the magenta/cyan stimulus for the overall population was about 35% of the maximal response when the length of the bar (0.5 degrees in width) and the movement amplitude were set to be optimal for individual cells, i.e. smaller than 15 degrees and 10 degrees of visual angle, respectively. This fall to 23% when the bar length and movement amplitude were limited to 2 degrees. The same cell responded to pure color-contours of yellow/blue as well as of cyan/magenta combinations. Thus, MT can detect the direction of movement of pure color-contours, although the sensitivity is less than for luminance contours.

The concentration of serum lipids in Zen monks and control males in Japan

The concentrations of total, low density lipoprotein (LDL), and high density lipoprotein (HDL) cholesterol, triglyceride and apoprotein B have been examined in Zen monks whose intake of animal products was almost negligible for 2 to 8 years, and in age-matched (24 to 35 years) control Japanese males who eat Western style food. The mean levels of total, LDL- and HDL-cholesterol, and apoprotein B were 135.1 +/- 16.7, 73.0 +/- 11.6, 50.4 +/- 9.6, and 70.6 +/- 15.6 mg/dl, respectively in Zen monks. These levels were 28.5, 32.8, 18.8, and 23.9% lower in Zen monks than in control Japanese males. These values are statistically significant compared to those of the controls (p less than 0.01). There were no significant changes in the level of triglyceride in both groups.

Primary structure of the receptor for calcium channel blockers from skeletal muscle

The complete amino-acid sequence of the receptor for dihydropyridine calcium channel blockers from rabbit skeletal muscle is predicted by cloning and sequence analysis of DNA complementary to its messenger RNA. Structural and sequence similarities to the voltage-dependent sodium channel suggest that in the transverse tubule membrane of skeletal muscle the dihydropyridine receptor may act both as voltage sensor in excitation-contraction coupling and as a calcium channel.

[A case report of hereditary angioedema and studies on the serum components of complement, C1-inactivator and proteinase inhibitors during edema attack]

Sixteen years old girl was admitted because of for the past ten years' frequent edema attack and abdominal pain. Laboratory examination revealed hypocomplementemia, marked depletion of the fourth component of complement and low level of C1-inactivator. Familial studies revealed that her mother was also hypocomplementemic and in low level of C1-inactivator. Serial studies performed on the alterlation of components of complement, C1-inactivator, alpha 1-antitrypsin, antithrombin III, and alpha 2-macroglobulin during edema attack. The fourth component of complement and C1-inactivator were markedly depleted in remission and attack. Remarkable depletion was found in antithrombin III and esterase inhibition activity of C1-inactivator during attack. In contrast, alpha 1-antitrypsin and alpha 2-macroglobulin did not change. The present study may explain that Hageman factor fragments, activated by C1s, promotes kinin generation via kalikrein activation. And the condition that complete functional deficiency of C1-inactivator was main role in this circuit. Fibrynolysis and late components of complement was less influence on edema attack.

Primary structure of porcine cardiac muscarinic acetylcholine receptor deduced from the cDNA sequence

The complete amino acid sequence of the porcine cardiac muscarinic acetylcholine receptor has been deduced by cloning and sequencing the cDNA. The tissue location of the RNA hybridizing with the cDNA suggests that this muscarinic receptor species represents the M2 subtype.

Cloning, sequencing and expression of complementary DNA encoding the muscarinic acetylcholine receptor

Cloning and sequence analysis of DNA complementary to porcine cerebral messenger RNA encoding the muscarinic acetylcholine receptor predict the complete amino-acid sequence of this protein. Expression of the complementary DNA produced functional muscarinic receptor in Xenopus oocytes. The muscarinic receptor is homologous with the beta-adrenergic receptor and rhodopsin in both amino-acid sequence and suggested transmembrane topography.

Discharges of neurons in the dorsal paraflocculus of monkeys during eye movements and visual stimulation

Extracellular recordings were obtained from 319 input units and 304 Purkinje cells (P-cells) in the dorsal paraflocculus of alert monkeys trained to fixate a visual target. They changed discharge rates with either eye movement, eye position, or visual stimulus movement. Of the 319 input units, recorded in the granular layer or white matter, most were mossy fibers (MFs), but 90 (28%) showed characteristic cellular spikes. The latter units were probably granular cells (p-GC). Of the 319 input units, 163 (51%) showed bursts with saccades (burst units) and 62 (19%) showed a prelude on the average 124 ms prior to the onset of saccade (long-lead burst units). Sixty-five (20%) had tonic activity related to eye position and also showed bursts with saccades (burst-tonic units), and the remaining 29 (9%) showed only tonic activity (tonic units). MFs and p-GCs showed no significant differences in the proportion of each type of unit or in their response properties. The majority of burst units (63%) were pan directional, whereas all long-lead burst units had directional selectivity. The preferred directions of long-lead burst, burst tonic, and directionally selective burst units were found in all four quadrants. Position-related activity was found in 48% of the burst-tonic and tonic units to be linearly related to eye position and to show position threshold. The other units also had position thresholds but their activity was not monotonically related to fixation position. Six climbing fibers (CFs), 32 input units (including 13 p-GC), and 8 P-cells showed cyclic responses during sinusoidal movements of a visual pattern. One class of MF units (57%) responded only to the direction, whereas the others responded to both the direction and retinal-slip velocity. Both CF and P-cell units responded to sinusoidal retinal-slip velocity. Of 67 input units, 23 showed cyclic modulation in firing during sinusoidal eye movements in the horizontal plane. Nineteen were burst-tonic and four were tonic units. They also showed position sensitivity. The phase of the cyclic responses tended to lag behind the eye velocity during low-frequency trackings. Of 237 P-cells, 163 (68.8%) discharged with saccades (burst P-cells), 42 (17.7%) paused with saccades (pause P-cells), and 32 (13.5%) discharged with saccades in one direction and paused in the other (burst-pause P-cells). Position sensitivity was found in 38 P-cells; 12 were burst, 5 were pause, and 10 were burst-pause P-cells. Eleven did not respond with saccades.(ABSTRACT TRUNCATED AT 400 WORDS)

Motion selectivity in macaque visual cortex. III. Psychophysics and physiology of apparent motion

We have conducted physiological and psychophysical experiments to identify possible neural substrates of the perception of apparent motion. We used identical sequences of flashed stimuli in both sets of experiments to better compare the responses of cortical neurons and psychophysical observers. Physiological data were obtained from two cortical visual areas, striate cortex (V1) and the middle temporal area (MT). In the previous paper we presented evidence that neuronal thresholds for direction selectivity in extrastriate area MT were similar to psychophysical thresholds for motion perception at the largest effective interflash interval, and thus speed, for a given eccentricity. We now examine physiological and psychophysical thresholds for a broad range of speeds to determine whether such a correspondence exists for speeds below the upper threshold considered in the previous paper. Stimuli were presented in stroboscopic motion of constant apparent speed while the spatial and temporal interflash intervals were systematically varied. For each neuron we measured the largest spatial interval that elicited directionally selective responses at each of several apparent speeds. We calculated the composite performance of neurons in both MT and V1 by averaging the spatial interval necessary for direction selectivity at each apparent speed. We employed the same apparent-motion stimuli for psychophysical experiments with human subjects in which we measured the spatial interval necessary for the perception of motion over a similar range of apparent speeds. We obtained a composite profile of psychophysical performance by averaging thresholds across subjects at each apparent speed. For high apparent speeds, physiological data from MT, but not V1, corresponded closely to the psychophysical data as suggested in the preceding paper. For low apparent speeds, however, physiological data from MT and V1 were similar to each other and to the psychophysical data. It would appear, therefore, that neurons in either V1 or MT could mediate the perceptual effect at low speeds, whereas MT is a stronger candidate for this role at high speeds. We suggest that the neuronal substrate for apparent motion may be distributed over multiple cortical areas, depending upon the speed and spatial interval of the stimulus.

Motion selectivity in macaque visual cortex. I. Mechanisms of direction and speed selectivity in extrastriate area MT

Mechanisms of direction selectivity and speed selectivity were studied in single neurons of the middle temporal visual area (MT) of behaving macaque monkeys. Visual stimuli were presented in both smooth and stroboscopic motion within a neuron's receptive field as the monkey fixated a stationary point of light. Direction selectivity, speed selectivity, and the spontaneous discharge characteristics of MT neurons in behaving monkeys were similar to those reported in previous studies in anesthetized monkeys. Stroboscopic motion stimuli were sequences of flashes characterized by the spatial and temporal intervals between each flash. The spatial and temporal intervals were systematically varied so that suppressive and facilitatory interactions could be studied in both the preferred and null directions. Suppression and facilitation were measured by subtracting the peak discharge rate elicited by a single flash from the peak discharge rate elicited by a stroboscopic train of flashes. The dominant mechanism of direction selectivity in MT was a pronounced suppression of discharge for motion in the null direction which we interpreted as inhibition. The inhibition was sufficiently potent to abolish the responses to single flashed stimuli when they were embedded in a series of flashes in the null direction, and it frequently reduced the neuronal discharge to a level below the spontaneous firing rate. Facilitation in the preferred direction was a prominent feature of the responses of some, but not all, MT neurons. The peak discharge rate for stroboscopic motion in the preferred direction was more than twice the peak rate to a single flash for approximately 50% of the neurons in our sample. The direction selectivity of most MT neurons showed the effects of both inhibitory and facilitatory mechanisms, and it was not possible to segregate MT neurons into distinct groups on the basis of these measures. Suppressive mechanisms contributed to speed tuning as well as direction tuning. The low-speed cutoff for motion in the preferred direction resulted from suppression in 82% of the neurons tested. The high-speed cutoff resulted from suppression in 32% of the neurons tested. The latter mechanism appeared to be distinct from the inhibitory mechanism which acted in the null direction in that large spatial intervals were required for its activation.

Motion selectivity in macaque visual cortex. II. Spatiotemporal range of directional interactions in MT and V1

We measured the spatial and temporal limits of directional interactions for 105 directionally selective middle temporal (MT) neurons and 26 directionally selective striate (V1) neurons. Directional interactions were measured using sequentially flashed stimuli in which the spatial and temporal intervals between stimuli were systematically varied over a broad range. A direction index was employed to determine the strength of directional interactions for each combination of spatial and temporal intervals tested. The maximum spatial interval for which directional interactions occurred in a particular neuron was positively correlated with receptive-field size and with retinal eccentricity in both MT and V1. The maximum spatial interval was, on average, three times as large in MT as in V1. The maximum temporal interval for which we obtained directional interactions was similar in MT and V1 and did not vary with receptive-field size or eccentricity. The maximum spatial interval for directional interactions as measured with flashed stimuli was positively correlated with the maximum speed of smooth motion that yielded directional responses. MT neurons were directionally selective for higher speeds than were V1 neurons. These observations indicate that the large receptive fields found in MT permit directional interactions over longer distances than do the more limited receptive fields of V1 neurons. A functional advantage is thereby conferred on MT neurons because they detect directional differences for higher speeds than do V1 neurons. Recent psychophysical studies have measured the spatial and temporal limits for the perception of apparent motion in sequentially flashed visual displays. A comparison of the psychophysical results with our physiological data indicates that the spatiotemporal limits for perception are similar to the limits for direction selectivity in MT neurons but differ markedly from those for V1 neurons. These observations suggest a correspondence between neuronal responses in MT and the short-range process of apparent motion.

Comparison of sulfide oxygenation mechanism for liver microsomal FAD-containing monooxygenase with that for cytochrome P-450

Mechanistic mode for the oxygenation of sulfides with the pig liver microsomal FAD-containing monooxygenase(EC 1.14.13.8) has been conveniently distinguished from that with the phenobarbital induced liver microsomal cytochrome P-450 by analyzing products of the oxygenation of phenacyl phenyl sulfide. Upon oxygenation of phenacyl phenyl sulfide, the FAD-containing monooxygenase gave solely phenacyl phenyl sulfoxide in contrast to the cytochrome P-450 promoted oxygenation which is known to give substantial amounts of C-S bond fission products. The observation suggests that the oxygenation of sulfide with FAD-containing monooxygenase involves the nucleophilic attack of the divalent sulfur on the reactive oxygen atom involved at the enzyme active site, namely electrophilic oxygenation of sulfide, though the oxygenation with the cytochrome P-450 is initiated by a single electron transfer from the sulfide to the enzyme active species.

Punctate chemical lesions of striate cortex in the macaque monkey: effect on visually guided saccades

Chemical agents which reversibly or irreversibly disrupt neural processing offer several advantages over traditional techniques for behavioral studies of the central nervous system. In order to evaluate the utility of chemical agents for a behavioral analysis of visual cortical function in primates, we have tested the effects of muscimol and ibotenic acid on the function of striate cortex in awake, behaving monkeys. We studied the monkey's ability to generate saccadic eye movements to visual targets at various locations in the visual field following an injection of one or the other chemical solution into a topographically identified location in striate cortex. Our results show that deficits in the generation of visually guided saccades following such injections are similar to those that result from surgical ablation of striate cortex, although recovery is more rapid following the injections. The experiments indicate that, with certain restrictions, chemical inactivation is a useful technique for behavioral analysis of visual cortical function.

Deficits in visual motion processing following ibotenic acid lesions of the middle temporal visual area of the macaque monkey

Physiological experiments have produced evidence that the middle temporal visual area (MT) of the monkey is selectively involved in the analysis of visual motion. We tested this hypothesis by studying the effects of small chemical lesions of MT on eye movements made in response to moving as opposed to stationary visual targets. We observed two deficits for eye movements made to moving targets: a monkey's ability to match the speed of his smooth pursuit eye movements to the speed of the moving target was impaired, and a monkey's ability to adjust the amplitude of a saccadic eye movement to compensate for target motion was impaired. In contrast, saccades to stationary targets were unaffected by the MT lesions, suggesting that monkeys with MT lesions had more difficulty responding to moving than to stationary stimuli. These results provide the first behavioral evidence that neural processing in MT contributes to the cortical analysis of visual motion.

Posterior inferotemporal neuron activities during a visual fixation task and a visual tracking task

Single neuron activities were recorded from the posterior inferotemporal cortex (PIT) while a monkey was fixating or tracking a target spot. Of 168 recorded neurons, 86 were activated by the extrafoveal slit stimuli; 48 were activated during eye fixation. Twenty were activated only during tracking, and not by fixation or a extrafoveal slit stimuli. It was suggested the PIT participates not only in the perception mechanisms but also in the foveation mechanisms such as fixation or tracking.

[Inferotemporal neuron activities of monkey during Konorski's task (author's transl)]

In order to search inferotemporal (IT) neuron activities related to processes of visual discrimination and visual short-term memory, the monkeys were trained to do so called Konorski's task. In the task, the monkey was seated in a primate chair and a pair of color stimuli (red or green) was presented from the same two colored light-emitting-diode (LED) before and after a fixed delay interval of 1-5 sec. The monkey was rewarded for pressing one of two levers when two stimuli were the same in color, and the other side when two stimuli were different. A total of 101 neurons were recorded from the anterior IT (between A3-A15). About 80% of recorded neurons activated by LED and about 60% of them showed different discharge rates to different colors (color selectivity). About 80% of color selective neurons showed stronger responses to the second visual stimuli than the first stimuli. These color selective neurons were recorded from the posterior part of the anterior IT (between A3-A10). No color dependent activities were observed during delay period. The data suggested that the IT neurons were related to a process of visual discrimination so that a physically identical stimulus which had a different meaning in the behavioral context would be differentiated.