Biomedical subjects

M Kossut

Publications and source records attributed to M Kossut.

At least 55 records · Page 3Linked to original sources

PubMed1991

Loss of gamma-aminobutyric acid (GABA) immunoreactivity from mouse first somatosensory (SI) cortex following neonatal, but not adult, denervation.

Whisker follicles were surgically ablated (lesioned) on two entire rows (B and C) of the left snout of two groups of Swiss mice, in the first 2 days after birth, and in the second group at 8 weeks of age (adults). Two months after surgery GABA-immunoreactivity (GABA-IR) was examined in tangential sections of the first somatosensory (SI) 'barrel' cortex of these two groups (at which time it was also confirmed that the follicles had not regrown). In the adult-lesioned mice all of the barrels appeared intact and visually similar in both the experimental (right) and control (left) hemispheres. The staining pattern of immunopositive cells and puncta was qualitatively similar to that which we have described previously. However, in the neonatally-lesioned mice barrel rows B and C were not visible in the right hemisphere sections and there was a marked reduction in GABA-IR, with fewer immunopositive cells. Many of those that did show GABA-IR stained only weakly and the puncta were also fewer in number than in the left (control) hemisphere where the GABA-IR pattern and staining intensity was normal.

Aging↗

PubMed1991

The effect of short periods of monocular deprivation on excitatory transmission in the striate cortex of kittens: a current source density analysis.

The goal of this study was to assess changes in synaptic activity in the visual cortex of kittens following brief periods of monocular deprivation. Field potentials evoked by electrical stimulation of both optic nerves were registered in vertical penetrations through areas 17 and 18 of 4-5 week-old kittens which had been monocularly deprived for 2-7 days. In order to assess the laminar distribution of synaptic currents these field potentials were subjected to a current source density analysis. Current source density profiles elicited from the deprived eye differed from those induced from the normal eye in several respects: 1) The amplitudes of the responses showed considerable variation at different recording sites across the tangential dimension of cortex. 2) On the average, sinks and sources were markedly reduced, and this reduction was relatively more pronounced in non-granular than in granular layers. 3) However, in 30% of the tracks the layer IV sink showed no attenuation. It was reduced in 48% of the tracks and completely suppressed in 22% of the tracks. These results indicate that a substantial fraction of the deprived thalamocortical synapses remained functional, but that many of these synaptic events remained subthreshold. The significance of these findings is discussed in the context of recovery processes following reverse suture.

Animals↗

PubMed1991

Neuroscience in Poland.

Earlier this year I tried to locate and count the scientists who may possibly want to join the Polish Neuroscience Society. A first rough estimate indicated about 200-250 scientists, including graduate students, who do research on the nervous system. It seemed worthwhile to attempt to highlight their work so that Polish neuroscience might share in the impetus coming from the historical changes sweeping across Europe.

Forecasting↗

PubMed1990

The binding of somatostatin to the mouse retina is altered by the pearl mutation.

Pearl mutants have a night-blind phenotype and abnormal optokinetic nystagmus. Preliminary results from another study showed that the light responses of retinal ganglion cells of pearl mutant mice were affected by bathing the isolated retina with low (less than 1 nM) concentrations of either somatostatin-14 or -28, whereas the responses in wild-type retinas were affected only by somatostatin-28. In order to test the possibility that these physiological differences resulted from alterations in receptor affinity, we studied the binding of 125I-[Tyr11]-somatostatin-14 and 125I-[Leu8,D-Trp22,Tyr25]-somatostatin-28 to frozen, unfixed sections of eyes of wild-type (C57BL/6J +/+) and congenic pearl mutant (C57BL/6J-pin pe(pin)/pe(pin)) mice. As found previously for wild-type mice, specific binding occurred in 3 maxima in pearl mutants: a broad band extending from the retinal ganglion cell to the inner nuclear layer, a narrow and inconstant band over the outer plexiform layer, and a band over the pigment epithelium and choroid. We quantified the label over the inner plexiform layer and found evidence for a single saturable site in both genotypes. However, several results indicate that somatostatin-14 binds more avidly to pearl mutant retinas than to wild-type retinas. In saturation binding studies, Kd for 125I-[Tyr11]-somatostatin-14 was 600 pM in pearl mutants vs 1.5 nM in wild-type; whereas, for 125I-[Leu8,D-Trp22,Tyr25]-somatostatin-28, Kd was nearly equal in the two genotypes (500 and 625 pM, respectively). Bmax was nearly equal for both ligands in both genotypes (63-69 fmol/mg protein).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Cholinergic markers in the plasticity of murine barrel field.

Cholinergic muscarinic receptor binding and acetylcholinesterase (AChE) histochemistry were studied in the barrel cortex of adult, vibrissae deprived and vibrissae denervated mice. In the control barrel field muscarinic receptors labeled with [3H]quinuclidinyl benzilate ([3H]QNB) showed a higher density in the granular cortex and a higher accumulation of label in the barrels. AChE staining revealed a punctuated pattern corresponding to the barrels in the upper part of layer IV and a reverse-image pattern of staining showing only the walls of barrels in the lower part of layer IV. Neonatal denervation of rows of vibrissae lowered both binding of [3H]QNB to the tissue in the shrunken rows and AChE activity in the denervated rows of barrels. Deprivation and late denervation produced no effects on either pattern, or intensity, of [3H]QNB labeling and AChE staining. These observations suggest that the changes in cholinergic markers are related to the altered morphological structure and not to the abnormal functioning of the barrel cortex which received reduced sensory input from the vibrissae.

Acetylcholinesterase↗

PubMed1989

Localization and characterization of somatostatin binding sites in the mouse retina.

We studied the binding of [125I]Tyr11-somatostatin-14 and [125I]Leu8,D-Trp22,Tyr25-somatostatin-28 to frozen, unfixed sections of C57BL/6J mouse eyes with autoradiography. Specific binding of both ligands occurred in 3 maxima, a broad band extending from the retinal ganglion cell to the inner nuclear layers, a narrow and inconstant band over the outer plexiform layer, and a band over the retinal pigment epithelium and choroid. We quantified the label over the inner plexiform layer and found evidence for a single, saturable binding site after Scatchard analysis of saturation binding data. With [125I]Tyr11-somatostatin-14 the dissociation constant (Kd) was 1.48 nM and the total number of binding sites (Bmax) was 68 fmol/mg protein; in competition experiments the inhibitory binding constant (Ki) was 900 pM for somatostatin-14 and 350 pM for somatostatin-28. With [125I]Leu8,D-Trp22,Tyr25-somatostatin-28, Kd was 625 pM and Bmax was 69 fmol/mg protein; in competition experiments Ki was 4.58 nM for somatostatin-14 and 710 pM for somatostatin-28. These results demonstrate the existence of somatostatin receptors in the inner plexiform layer of the retina that appear to have greater specificity for somatostatin-28 than for somatostatin-14.

Animals↗

PubMed1988

Single vibrissal cortical column in SI cortex of rat and its alterations in neonatal and adult vibrissa-deafferented animals: a quantitative 2DG study.

1. A quantitative 2-[14C]deoxy-D-glucose (2DG) autoradiographic study was undertaken to determine the functional (metabolic) organization of an individual column in the first somatosensory cortex (SI) of the awake restrained rat. Manual or mechanically controlled brush stroking of a single vibrissa (typically C3) was used in order to evoke neural activity and increase glucose utilization in a single cortical barrel in lamina IV and in adjacent supra- and infragranular layers in register with the single cortical barrel labeling in lamina IV. 2. The single activated vibrissal column was found to extend from layer I to the superficial half of layer VI of the contralateral SI cortex and was fusiform in shape, being of largest diameter (650-micron) in layer IV and smallest diameter (200 micron) in layer VI. 3. This single metabolic column was not uniform in its density of labeling. The greatest local cerebral metabolic rate of glucose (LCMRG) was found in layer IV (170 mumol.100 g-1.min-1), layers II-III, and V had, on the average, similar LCMRG values (115 mumol.100 g-1.min-1), which decreased with distance from layer IV. 4. The functional (metabolic) columnar activity center situated in layer IV corresponded in size to the appropriate anatomical barrel as determined from thionin-stained sections. Increased metabolic activity was not strictly confined to the candle-pin-shaped column but extended tangentially as radiating fingerlike projections toward the neighboring barrels. 5. In cortical layers other than IV, the metabolic column was less prominently labeled, and the metabolic activity also branched in the tangential plane. The labeling pattern profile in upper layers was characterized by numerous lateral spreading fingerlike projections of increased glucose metabolism. 6. Neonatal follicle lesions sparing only C3 vibrissa caused a great increase (125%) in cortical territory driven by the spared whisker with a concomitant loss of columnar shape and decrease in intensity of metabolic activity in response to its stimulation. 7. Similar lesions in adult rats produced a significant increase (40%) in dimensions of the spared C3 cortical column, which was, however, smaller than that produced after neonatal lesions. The metabolic activation of layer Vb in the spared C3 column was increased (17%) compared with that of the control column.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗

PubMed1988

Modifications of the single cortical vibrissal column.

The anatomy, cytoarchitectonics and unit responses of the vibrissal barrel field make it a good subject for studying the central effects of peripheral receptor manipulations. The paper reviews the properties of the barrel system and the evidence for columnar functioning of the barrel cortex. The plastic changes of the single vibrissal column visualized with 2-deoxyglucose autoradiography are described. Cortical plasticity was evoked by vibrissal receptor lesions, deprivation or repetitive stimulation in neonatal and adult rats. The possible processes participating in changing the appearance of the cortical column are discussed. The role of reshaping of intracortical connections within the barrel field is suggested as an important mechanism of plasticity of the vibrissal cortical columns.

Animals↗

PubMed1986

Single vibrissal cortical column in the mouse labeled with 2-deoxyglucose.

Columnar labeling was found in the primary somatosensory cortex of mice after stimulation of a single mystacial vibrissa following 2-deoxyglucose injection. The cortical vibrissal column had a cylindrical shape, passing through all layers of the cortex and was centered upon the appropriate vibrisal barrel. Columnar labeling extended beyond this barrel onto parts of neighbouring barrels, particularly within the same row. The densest labeling was found in layer IV in the barrel hollow. Removal of the non-stimulated vibrissae resulted in a subsequent lowering of 2DG uptake in the barrelfield surrounding the activated column, but did not affect the dimension of the activated column.

Animals↗

PubMed1986

Autoradiographic localization of GABAergic and muscarinic cholinergic receptor sites in the visual system of the kitten.

The distribution of binding sites for [3H] muscimol (which binds to GABA, receptor) and [3H] QNB (which binds to muscarinic cholinergic receptor) was studied in visual areas of 5 week-old kittens using contact film autoradiography after incubation in vitro of brain sections. A distinct laminar localization of [3H] muscimol receptor sites was observed in young animals with the highest density in layers II/ III and IV of all cortical areas that were investigated. For [3H] QNB binding a laminar pattern of distribution was also found with labeling in layer V exceeding that in adjacent layers. A small intracortical regional variability was noted, for both of the investigated neuroreceptors. [3H] muscimol labeling of the lateral geniculate nucleus and superior colliculus was weaker in comparison to that found in the cortex. The superficial layers of the superior colliculus revealed a high density of [3H] muscimol and [3H] QNB binding sites. The laminar and regional variations in the distribution of [3H] muscimol and [3H] QNB binding sites observed in young kittens, may be related to the possible role of GABAergic and muscarinic receptors in regulation of plastic changes that occur after visual deprivation.

Animals↗

PubMed1985

Changes in thalamic projection to the barrelfield of rat after neonatal lesions sparing one whisker.

The thalamic input to the barrelfield of rats with a solitary mystacial vibrissa (C3) intact was examined using succinic dehydrogenase techniques. Rats were lesioned on postnatal day (PD) 1 and brains examined at either 7, 12, 21 or 28 days later. The resultant segmentation in the hemisphere contralateral to the lesioned muzzle consisted of fused rows (A to E). At all ages row C differed from the other rows in that the center of the row was enlarged and separated from the row on either side of it. Thus the presence of a single vibrissa is sufficient to organize the thalamic input to its barrel.

Afferent Pathways↗

PubMed1985

Decrease in the number of synapses formed by subcortical inputs to the striate cortex of binocularly deprived cats.

The density of synapses was determined from electronmicrographs taken from area 17 of cats binocularly deprived of pattern vision for 6 months and in normally reared litter mates. In each cat the optic radiation was transected on one side 4 days before sacrifice and the density of synapses of subcortical origin was estimated by comparing the density of normal synapses remaining on the lesioned side with the density of synapses on the unlesioned side. In normal animals 36% of the synapses were formed by subcortical afferents, but in the binocularly deprived animals this figure was reduced to only 17%. A decrease found in the total synaptic density in the deprived visual cortex was not statistically significant. Thus, binocular deprivation seems to selectively diminish the subcortical contribution to the synaptic density in the visual cortex.

Animals↗

PubMed1985

Effects of sensory denervation and deprivation on a single cortical vibrissal column studied with 2-deoxyglucose.

The plasticity of a single column in the first somatosensory cortex (SI) was studied with [C14] 2-deoxyglucose (2DG) autoradiography. Columnar labelling of cortical representation of the C3 vibrissa was obtained by stimulating this vibrissa after an injection of 2DG. Plastic changes were caused either by surgical denervation (follicle removal) or deprivation (plucking out) of all vibrissae except C3. The development of changes in the columnar profile of the spared vibrissa cortical representation was studied. Both treatments caused an expansion of the spared whisker column into the surrounding barrel field cortex. Denervation produced an immediate enlargement accompanied later by a loss of columnar shape and a decrease of metabolic activity in the core of the column. Effects of deprivation were visible later and were less pronounced, the columnar shape was retained.

Animals↗

PubMed1984

The development of the vibrissal cortical column: a 2-deoxyglucose study in the rat.

A column of SI cortex responding to stimulation of a single vibrissa can be visualized with [14C]2-deoxyglucose (2-DG) autoradiography. The development of C3 vibrissal column was investigated in rat pups aged 2, 4, 6, 8, 12 and 21 days. A patch of label corresponding to higher glucose utilization appeared at postnatal day (p.d.) 4 to 6 in the cortical plate. Between p.d. 6 and 12 it developed into a spindle-shaped column. The infragranular layers showed metabolic activation later than the upper laminae. The suitability of the 2-DG technique for studies of infant mammalian brain is discussed.

Animals↗

PubMed1984

Early development of changes in cortical representation of C3 vibrissa following neonatal denervation of surrounding vibrissa receptors: a 2-deoxyglucose study in the rat.

The development of changes in cortical representation of a C3 mystacial vibrissa in the rat was studied with [14C]2-deoxyglucose (2-DG) autoradiography after neonatal unilateral ablation of all but the C3 whisker follicle. The 2-DG-labeled column, which was produced by stroking the spared C3 vibrissa, was enlarged (35%) at postnatal day (p.d.) 5 and reached 140% by p.d. 12, as compared to the control C3 vibrissa column in the opposite hemisphere. The diameter of the C3 barrel itself on the involved side was about 40% larger than that of the control side at all ages. Based upon the above postoperative survival times, at least two stages in the altered development of the spared C3 vibrissa column are suggested.

Afferent Pathways↗

PubMed1984

Differential 2-deoxyglucose uptake into chick brain structures during passive avoidance training.

The pattern of [14C]2-deoxyglucose(-6-phosphate) accumulation in the brains of 14 chicks, 24 h post hatch was investigated. Isotope was injected 1 min prior to birds pecking either a water-coated or a methylanthranilate-coated bead (passive avoidance training). Birds were killed following testing for pecking or avoidance of a similar but dry bead 30 min later. Autoradiograms of coronal and parasaggital brain sections were scanned densitometrically and uptake into 12 identified and relatively heavily labelled structures measured. Three of the structures, hyperstriatum ventrale (posterior), palaeostriatum augmentatum and lobus parolfactorius showed significantly enhanced labelling (by 10, 13 and 11%; p less than 0.001, less than 0.05 and less than 0.05 respectively) in the birds which had been trained on the methylanthranilate bead by comparison with those which had pecked at the water-coated bead. The results are discussed in relationship to other observed biochemical changes consequent on passive avoidance training.

Animals↗

PubMed1984

Increase of GABA receptor binding activity after short lasting monocular deprivation in kittens.

GABA receptor activity, as measured by [3H]muscimol binding, was investigated in visual and auditory cortex of 5 weeks old kittens with different visual experience. Binocular deprivation since birth did not affect the GABA receptor binding activity. Three days of monocular vision resulted in an increase of [3H]muscimol binding in the visual cortex of both normally reared (144 percent) and binocularly deprived kittens (149 percent). Neither 3 days of normal binocular vision in deprived animals nor 3 days of binocular deprivation in normally reared ones produced significant changes in GABA receptor binding activity. In all experimental conditions [3H]muscimol binding in auditory cortex was similar. We suggest that activation of the GABA-ergic system is due to asymmetric visual input, possibly connected with mechanisms of ocular dominance shift.

Animals↗

PubMed1984

A single vibrissal column in the first somatosensory cortex of the mouse demonstrated with 2-deoxyglucose.

Single functional column activated by stimulation of C3 vibrissa was visualized in the mouse somatosensory cortex with 2-deo-xyglucose autoradiography. The column was cylindrical in shape and extended through the entire cortical thickness. The darkest labeling was found in layer IV, over the anatomical C3 vibrissal barrel. The functional column stretched horizontally over parts of adjacent barrels. A zone of low 2-deoxyglucose uptake surrounded the densly labeled area and covered the rest of the postero medial barrel subfield.

Afferent Pathways↗