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J Mogensen

Publications and source records attributed to J Mogensen.

54 records · Page 3Linked to original sources
PubMed1991

Nonradioactive, sequence-specific detection of RNA in situ by primed in situ labeling (PRINS).

A new method for the detection of RNA in situ is presented. It is based on sequence-dependent annealing of unlabeled specific oligonucleotide primers to intracellular RNA and subsequent chain elongation catalyzed by reverse transcriptase. Under the conditions described, biotin-labeled nucleotides can be incorporated and the cDNA synthesized in situ can thus be detected using fluorescein-conjugated avidin. Compared to traditional in situ hybridization the use of short oligonucleotide primers has the potential advantage of being better to discriminate between closely related RNA transcripts. Compared to in situ transcription with radioactive precursors we find it more attractive to use fluorescein-conjugated avidin as detection system because it allows a more detailed study of cell and signal simultaneously.

Animals↗
PubMed1991

An improved method for chromosome-specific labeling of alpha satellite DNA in situ by using denatured double-stranded DNA probes as primers in a primed in situ labeling (PRINS) procedure.

An improved primed in situ labeling (PRINS) procedure that provides fast, highly sensitive, and nonradioactive cytogenetic localization of chromosome-specific tandem repeat sequences is presented. The PRINS technique is based on the sequence-specific annealing in situ of unlabeled DNA. This DNA then serves as primer for chain elongation in situ catalyzed by a DNA polymerase. If biotin-labeled nucleotides are used as substrate for the chain elongation, the hybridization site becomes labeled with biotin. The biotin is subsequently made visible through the binding of FITC-labeled avidin. Tandem repeat sequences may be detected in a few hours with synthetic oligonucleotides as primers, but specific labeling of single chromosomes is not easily obtained. This may be achieved, however, if denatured double-stranded DNA fragments from polymerase-chain-reaction products or cloned probes are used as primers. In the latter case, single chromosome pairs are stained with a speed and ease (1 h reaction and no probe labeling) that are superior to traditional in situ hybridization. Subsequent high-quality Q banding of the chromosomes is also possible. The developments described here extends the range of applications of the PRINS technique, so that it now can operate with any type of probe that is available for traditional in situ hybridization.

Autoradiography↗
PubMed1990

Long-term retrograde labelling of neurons.

The intensity of labelling of neuronal perikarya with Fluoro-gold or rhodamine microspheres appeared unchanged in rats surviving one year after surgery. These tracers may be used for sequential labelling with long intervals and to study brain connections in precious specimens.

Animals↗
PubMed1988

Strain differences in catecholamine content of pigeon brains.

Concentrations of dopamine, noradrenaline and DOPAC were measured in 6 regions of telencephalon and in the cerebellar cortex of adult white Carneaux, and mixed breed pigeons of either sex. In both groups the regional differences in the amount of dopamine replicated the pattern we published earlier. The absolute values, however, differed in these groups: in all telencephalic regions the amount of dopamine was lower in the Carneaux strain than in the mixed breed specimens; in 4 of these regions the difference was statistically significant. A similar tendency was observed in the noradrenaline concentration but the difference was significant only in two telencephalic samples and the cerebellum. The concentration of DOPAC was significantly smaller in two telencephalic regions of the Carneaux pigeons.

Analysis of Variance↗
PubMed1988

A multipurpose vertical holeboard with automated recording of spatial and temporal response patterns for rodents.

A method is presented for manual or automated recording of rats' spontaneous nose-poking ('visit') behaviors to a vertical holeboard with a matrix of 45 or 54 holes. Several behavior parameters are presented: visit frequency, visit duration, temporal visit pattern, spatial visit pattern, stereotype of visits, diversity of visits and variability of visit patterns. The paper describes the development of the apparatus and some methods of analyzing and presenting the multi-parametric data. The use of the apparatus is illustrated with a one-trial appetitive conditioning task. After 5 min in a single 10-min session, a food pellet is presented, only once in a given hole, to provide reinforcement of a spontaneous visit to that hole. The behavior parameters are compared before and after reinforcement. When the one-trial conditioning effect was challenged with d-amphetamine, the behavior parameters changed in a graded manner depending upon the dose (0.25-6.0 mg/kg). The apparatus has also proven useful for studies of exploratory behavior without using food reinforcement following lesion or drug interventions.

Animals↗
PubMed1988

Differential recovery in measures of exploration/locomotion after a single dosage of reserpine in the rat.

Different aspects of exploration/locomotion were studied in rats injected with reserpine (4 mg/kg i.p.) once and in vehicle injected yoked controls. Fifteen different parameters were measured on 7 sessions - on the 1st, 3rd, 5th, 7th, 11th, 15th and 21st postinjectiorn day. The difference scores (the value obtained from the control animal minus the corresponding value from the yoked reserpinized animal) were subjected to nonparametric analysis of variance across sessions. Of the 15 parameters only 6 revealed significant differences between sessions. Furthermore, for those six parameters which exhibited significant differences between sessions the recovery patterns revealed by differences between sessions were dissimilar. It is concluded that what is usually referred to as exploratianflocomotion must be considered apparatus- and procedure-specific and that the measures obtained in different studies should only be compared when identical procedures have been employed. In addition to the measures of exploration/locomotion the rats were subjected to a parallel series of active avoidance sessions in a shuttle-box. Comparing the reserpinized rats impaired active-avoidance aquisiticm to the recovery patterns in the exploratiodlocomotion tests, it can be tentatively concluded that the lack of recovery in the active-avoidance test is not solely due to impaired motoric abilities.

Animals↗
PubMed1987

The N-CAM D2-protein as marker for synaptic remodelling in the red nucleus.

We have followed the time-course of changes in the concentration of 3 neuronal and one glial antigen in the red nucleus in rats after unilateral lesion of the cerebellorubral connections. The neuronal markers were the neuronal cell adhesion molecule (N-CAM) D2-protein which is prevalent in newly formed neuronal membranes, and the D1- and D3-proteins, which are found mainly in mature neuronal membranes. The glial marker was S-100, a cytoplasmic protein. Six days after the lesion no changes in the concentration of the markers were found in the partially deafferentiated red nucleus. However, 10 days after the lesion the D2-protein concentration was significantly increased, in contrast to the D1-protein concentration which was decreased. After a further 3 days the D2-protein concentration began to decrease, approaching the still significantly decreased D1-protein concentration. Twenty-one days after the lesion the marker protein concentrations were not significantly changed from normal. However, whereas the concentrations of neuronal membrane markers were lower, the glial S-100 concentration showed a tendency to increase. Furthermore, although the changes in D3-protein concentration were unable to reach statistical significance alone they always followed the direction of D1-protein and were significantly in variance with the changes in D2-protein and S-100 concentrations. Our results support the notion of the N-CAM D2-protein as a useful marker for synaptic turnover in adult brain.

Animals↗
PubMed1987

Vertical ascending connections in the isocortex.

Different fluorescent tracers were applied to the surface of the cortex of rats, marmosets and one hedgehog. Irrespective of the kind of tracer and the depth of penetration, some perikarya of layer VI were labelled in each specimen and in all cortical regions. In the rat almost all labelled neurons were packed in sublayer VIb, in the marmoset such cells were dispersed throughout layer VI, whereas in the hedgehog the degree of their segregation to sublayer VIb was intermediate. Additional experiments in the rat indicated that most of the medium-sized neurons in the VIb layer project to layer I, that most of the perikarya projecting to the thalamus are localized in sublayer VIa, that different neurons project to the thalamus and to the surface of the cortex, and that only very few perikarya in deep parts of layers III and V and of sublayer VIa send axons or axon collaterals to layers I and II.

Animals↗
PubMed1987

Protein changes in the rat's prefrontal and "inferotemporal" cortex after exposure to visual problems.

The proteins D2 (N-CAM) and D3, both markers for brain neuronal membranes, MM, a marker for mitochondria, and CM, a cytoplasmic marker protein, were studied in the prefrontal (anteromedial) cortex and "inferotemporal" (Te2) cortex of rats by crossed immunoelectrophoresis. Three experimental groups were investigated: Rats trained to criterion in a visual pattern discrimination test (learning), those run as yoked controls and finally, rats kept in individual cages and not subjected to any training (passive). Statistical analysis indicated that behavioral procedures and marker proteins contributed significantly to the variation. Further analysis indicated that the significant changes occurred in the D3- and MM-protein and that both the learning and yoked control groups had significantly increased concentrations of these two proteins when compared to the passive group. Furthermore, the concentration of D3- and MM-protein in the yoked control group was significantly higher than that of the learning group. The results seem to indicate that changes in concentration of these proteins can be more easily related to the activity of "searching for an adequate behavioral strategy" than to the formation of an "engram".

Animals↗
PubMed1987

On the projections from the neostriatum to the cerebral cortex: the "displaced" neurons.

The entire dorsal and lateral cortex of one cerebral hemisphere of rats was infiltrated with different fluorescent tracers and the neostriatum was examined for labelled perikarya. In spite of the extensive infiltration of the cortex, such neurons were seen only sporadically in the ipsilateral neostriatum and almost only in the vicinity of the globus pallidus and the subcortical white matter. The size and shape of these neurons, and particularly their proximity to some cell groups which surround the neostriatum and project to the cerebral cortex, suggest that these neurons belong to the neighbouring structures such as the magnocellular nuclei of the basal forebrain, the claustrum and the VIb cortical layer.

Animals↗
PubMed1987

Neostriatal lesions impaired rats' delayed alternation performance in a T-maze but not in a two-key operant chamber.

Rats with lesions in the neostriatal region that belongs to the prefrontal system were trained in two versions of delayed alternation. They performed as proficiently as intact animals in a two-key operant chamber. The same operated rats took many more trials to reach criterion when subsequently compared with the same control group in a T-maze. This finding demonstrates that variants of delayed alternation are not equivalent for animals with lesions in the prefrontal system. Observations suggested that delayed alternation in the operant chamber may be mastered by positional mediation.

Animals↗
PubMed1985

The prefrontal 'cortex' in the pigeon. Biochemical evidence.

Concentrations of dopamine and noradrenaline were determined in 6 regions of the telencephalon and in the cerebellum of the pigeon. Noradrenaline was rather evenly distributed. A significant variation was found of the dopamine-noradrenaline ratio (DA:NA), a measure which makes it possible to distinguish dopamine found in dopaminergic fibers from dopamine which is precursor of noradrenaline. The highest ratio was found in the anteroventromedial region (containing the presumed homologue of the mammalian neostriatum), and the next highest in the posteroventrolateral region (containing the archistriatum). Like in mammals, the lowest concentration of the non-precursor dopamine in the pigeon brain seems to be contained in the cerebellum. Among the regions which show physiological and anatomical similarities with the mammalian cerebral cortex, the DA:NA ratio was significantly higher in the posterodorsolateral, than in the posterodorsomedial and anterodorsomedial regions. The two dorsomedial regions contain the equivalents of the hippocampus and sensory cortical areas of mammals. The strong dopamine innervation of the posterodorsolateral region is comparable to that of the mammalian prefrontal cortex.

Animals↗
PubMed1985

The prefrontal "cortex" in the pigeon catecholamine histofluorescence.

The prefrontal cortex of mammals is densely innervated with dopaminergic fibers. We report a comparable, dense network of catecholamine (probably dopamine)-containing fluorescent fibers in the posterodorsolateral neostriatum of the pigeon. This region is clearly separable from paleostriatum augmentatum, lobus parolfactorius, posterior archistriatum, posteromedial corticoid and septum, all of which also show strong catecholamine fluorescence. Parallel biochemical, anatomical and neurobehavioral data support the suggestion that posterodorsolateral neostriatum in the pigeon may be comparable to the mammalian prefrontal cortex. Thus the telencephalic tissue represented as the prefrontal cortex in mammals and the posterodorsolateral neostriatum in the pigeon, may turn out to be a phylogenetically ancient neural device.

Animals↗
PubMed1984

Focal cortical seizures prevent HRP and HRP-WGA labeling only in neurons bidirectionally connected to the cortex.

Intracortical implants of polyacrylamide gel containing horseradish peroxidase labeled cortical efferents and perikarya in some cortical areas and a number of subcortical formations. When epileptogenic penicillin was added to the gel, no labeling was seen in the efferents and cell bodies of the cortex, thalamus, or claustrum, whereas the magnocellular nuclei of the basal forebrain, raphe nuclei and locus coeruleus did contain the label.

Animals↗
PubMed1983

Activity of the auditory system in rats habituated to a test chamber: a 2-deoxyglucose study.

In a number of species, quantitative 2-deoxyglucose method revealed that the auditory system is much more active than any other-neural system. We tested the hypothesis that stressful experimental conditions may be responsible for this hyperactivity. Three rats received transcatheteral injections of [14C] 2 deoxyglucose while exposed to a wide band noise in a sound-shielded chamber in which they had previously spent 17 habituation sessions. In autoradiograms of these animals the auditory system appeared as intensely labelled (active) as in control animals. We conclude that the high activity of the auditory system in the rat does not seem to result from presumably stressful normal laboratory conditions.

Animals↗
PubMed1982

Synaptic proteins in frontal and control brain regions of rats after exposure to spatial problems.

Synaptic proteins D1, D2, D3, synaptin and 14-3-2, as well as the glial protein glutamine synthetase, were measured by crossed immunoelectrophoresis in the anteromedial (prefrontal) cortex, occipital (visual) cortex and the anterior and posterior parts of the neostriatum of rats. The 3 experimental groups consisted of rats trained to criterion in a spatial delayed alternation, those run as yoked controls and, finally, rats kept in individual cages and not subjected to any training. Statistical analysis showed that two variables: behavioral procedures and brain regions, had a significant effect. Their interaction was also significant. Further analysis revealed that only in the prefrontal cortex of the yoked control animals was there a significant decrease of the synaptic membrane proteins D1, D2 and D3. Thus, particular behavioral treatment seems capable of affecting synapses in a specific 'association' cortical area. The change is more easily related to the amount of 'work' than to formation of 'memory trace' within the critical area.

Animals↗
PubMed1982

The prefrontal 'cortex' in the pigeon. Behavioral evidence.

In 3 pigeons ablation of the posterodorsolateral neostriatum impaired delayed alternation without affecting visual discrimination. In mammals the same selective deficit is produced by lesions in the prefrontal system. The presently ablated neostriatal region resembles the mammalian prefrontal cortex also by being richly innervated with dopaminergic fibers. This region is clearly separated from paleostriatum augmentatum and archistriatum which also have a strong dopaminergic innervation. The presence of a prefrontal cortex-like formation in a bird species raises the possibility that all higher vertebrates are equipped with this neural device.

Animals↗