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A Markowska

Publications and source records attributed to A Markowska.

At least 73 records · Page 4Linked to original sources
PubMed1988

Cue distinctiveness and response-to-change in scopolamine injected or hippocampal rats.

Our previous findings indicated that hippocampal lesions (H) or scopolamine' injections (Sc) affected stimulus information acquired by distant observation of the white-black T-maze arms (the passive test), but left the information intact when it was gained by T-maze exploration (the active test). Because this difference might reflect the attentional deficit in H or Sc rats, in the present experiment we attempted to investigate the effect of lowered distinctiveness of cues (dark grey vs black T-maze arms) on the performance of rats in the active test. A total of 75 rats were assigned to four groups: (i) damaged in the dorsal hippocampus (H); (ii) sham operated (C); (iii) scopolamine (Sc) injected (1.0 mg/kg i. p.) and (iv) saline injected (NaCL). Each group showed a significant preponderance of choices of the arm which was changed in brightness between the two consecutive trials, separated by 1 min break. The groups did not differ markedly among themselves in the percentage of changed arm choices (H group, 85 percent; C, 74 percent; Sc -72 percent; NaCL, 72 percent). This result indicates that H or Sc rats are able to perceive a slight difference of brightness and to retain it over a period of 1 min. Therefore, the different performance of H as well as Sc rats in the passive and active test, observed previously, cannot be accounted for by the attentional deficit hypothesis.

Animals↗
PubMed1987

[Preservation of the blood of slaughter animals by the non-diaphragmatic use of solidified carbon dioxide. II. Blood preservation-related changes in plasma proteins].

The preservation effectivity of slaughter animal blood for consumptive purposes was studies by a method of non-phrenic action with solidified CO2. The material for studies was full pig blood stabilized with sodium citrate. The course of the changes in plasma proteins caused by storage has been described by regression equations. It was found that non-phrenic contact of blood with solidified CO2 caused slight, statistically insignificant changes in plasma proteins. Moreover, the changes of the protein quality factors showed a smaller dynamics in the blood stabilized with solidified CO2 than in the control blood. The changes observed in the plasma proteins analysed were highly correlated with increasing parallel decomposition of morphological elements and the resulting increase of the level of hemocyte proteins in plasma.

Animals↗
PubMed1986

Behavioral effects after ibotenic acid, 6-OHDA and electrolytic lesions in the central amygdala nucleus of the rat.

Selective lesions of central amygdaloid neurons with ibotenic acid and electrolytic destruction of the nucleus both led to marked increases in open field activity and activity during passive avoidance conditioning. However, electrolytic lesions of both neurons and fibers resulted in the most pronounced passive avoidance impairments and it is suggested that this lesion effect should be attributed to a combined destruction of intrinsic neurons and neurons located outside the central amygdala nucleus. The 6-OHDA lesions resulted in no significant changes in the behavioral parameters under investigation or in plasma corticosterone levels. The lack of reduced corticosterone levels in any of the lesioned groups do not indicate that general fear arousal is critically dependent on intact central amygdala neurons in the rat. The behavioral data are, however, still compatible with a hypothesis of a temporary reduction in fear arousal during the initial phase of the passive avoidance conditioning.

Amygdala↗
PubMed1985

Comparison of electrolytic and ibotenic acid lesions in the lateral hypothalamus.

Electrolytic lesions in the lateral hypothalamus (LH) seriously affect ingestive behavior and sensorimotor functions in the rat. We here report that bilateral infusions of the neurotoxin, ibotenic acid (IBO) in the LH yield a decrease in body weight, but not to the same extent as electrolytic lesions. The sensorimotor impairments were most severe after electrolytic lesions. When tested in a residential maze on days 5-7 and 18-20 after surgery, both lesioned groups showed no lack of motivation to seek food and water. Histological examination of the LH following IBO exposure revealed extensive degeneration of neuronal cell bodies with little evidence of non-specific damage. Biochemical analysis of the rostral forebrain content of norepinephrine (NE) and serotonin (5-HT) revealed that the fibers passing through the LH remained largely intact in the IBO treated rats. The results suggest that the observed aphagia and adipsia is not due to a lack of motivation, but rather reflects changes in the process which operate to initiate eating and drinking. Furthermore, selective neuronal degeneration induced the same behavioral changes as the electrolytic ones, though not to the same extent.

Animals↗
PubMed1983

An attempt to account for controversial estimates of working memory persistence in the radial maze.

Factors affecting performance in the radial maze were examined to explain widely differing estimates of the persistence of spatial working memory. In Experiment 1, two groups of 10 rats each, trained in the 8-arm elevated maze (EM) or two-level maze (TLM), showed after 30 trials 0.66 and 0.34 errors per eight choices, respectively. In Experiment 2 insertion of a delay between choices 4 and 5 increased error incidence in choices 5 to 8 from 0.8 and 1.0 at 2-min delay to 1.8 and 1.9 at the 1-hr delay in the EM and TLM, respectively. (Chance level is 2.0 errors in choices 5 to 8). In Experiment 3, omission of the masking food odor sources improved performance in the EM at the 1-hr (1.1 error) but not at the 4-hr delay (1.85 error). In Experiment 4, elimination of trail marking by replacement of maze A, used in choices 1 to 4, by maze B in choices 5 to 8 caused a significant deterioration of delayed performance in the TLM but not in the EM. In Experiment 5, a continuous series of 15 trials with the 40-min delay improved performance in the EM from 1.60 to 1.35 errors in choices 5 to 8. High error incidence (0.41) on choice 5 was due to rat's preference for channels visited on choices 1 and 2. Significant decrease of errors on choice 6 (to 0.25) indicates that the rats responded to incorrect choice 5 by activation of an error-correcting strategy. Examples of such strategies are given which increase delayed performance well above chance level even in the absence of working memory. Error-induced change of response pattern is indicated by the observation that the interchoice distances 1--2 and 5--6 are the same after correct, but differ by 0.83 channel after incorrect choice 5. Possible reasons for the failure to confirm the long persistence (more than 4 hr) of spatial working memory reported by Beatty and Shavalia (Behavioral and Neural Biology, 28, 454--462, 1980) are discussed. It is argued that longevity of the working memory record gives the rat no advantage in foraging and must be, therefore, carefully checked against possible alternative explanations.

Animals↗
PubMed1983

Response to stimulus change: amygdalar lesion elicits similar deficit as hippocampal damage.

We attempted to test whether the effect of amygdaloid lesion on the response-to-change would be similar to that observed previously after hippocampal damage. Twelve rats with lesions in the cortico-basomedial region of the amygdala (CBM) and 20 sham operated controls were used. The experiment was conducted in a T-maze under two different conditions of stimulus presentation in trial 1. In the passive test the rat was allowed to inspect the white-black maze arms, but was prevented from entering them by transparent partitions. In the active test the rat was permitted to explore the entire T-maze. In both tests, the brightness of one arm was changed in trial 2, so that the two arms were alike. Control rats showed a statistically significant pre-ponderance of choices of the changed arm in both tests. CBM rats responded on a chance level in the passive test, while in the active one they performed like controls. These results, replicating closely the previous findings on rats with hippocampal damage, indicate the involvement of both the amygdala and hippocampus in the passive version of the response-to-change test. The postoperative disturbance might be interpreted as an attentional deficit or a selective impairment of information processing in the passive version of the test.

Amygdala↗
PubMed1982

Response to stimulus change following observation or exploration by the rat: a confirmation of differential effects of hippocampal damages.

The experiment attempted to confirm the previous finding that hippocampal lesions in rats affected the information acquired by distant observation of the brightness difference of the T-maze arms, but left the information intact when it was gained by maze exploration. An alteration was introduced in the latter procedure allowing a complete elimination of olfactory stimuli, which might be utilized as nonmemorial cues. Despite this alteration the results were virtually the same as previously. Following maze exploration the hippocampally lesioned rats tended to enter the arm that had been subsequently changed in brightness, similarly to control rats. However, unlike the controls, they responded on the chance level after distant observation. This finding is not compatible with Olton’s hypothesis postulating the involvement of the hippocampus in the working memory, or with the O’Keefe-Nadel theory of processing spatial information by the hippocampus.

Animals↗
PubMed1981

Open-field behavior in rats with frontomedial cortical, neostriatal or hippocampal lesions.

The effects of lesions in four structures corresponding to the main components of dorsal prefrontal system of the monkey were studied in a total of 165 rats. In a homogeneous open-field apparatus, rats with frontomedial cortical (FM) or anteromedial neostriatal (NC) lesions showed more ambulations than their respective sham operated controls. Posteroventral (VH) and anterodorsal (DH) hippocampal damages did not affect ambulations. The introduction of a novel stimulus produced transient suppression of open-field activity in all lesioned and control groups. Exploratory responses to the stimulus, assessed by the number of direct contacts and the time spent near the stimulus, were fewer in rats with VH or DH lesions than in rats with FM or NC lesions, that in turn did not differ from controls in this respect. Fear, indicated by defecations during the entire open-field test and by prolonged activity suppression in response to the presence of the novel stimulus, was observed in FM or VH lesioned rats, but not in those subjects with NC or DH lesions. Functional interrelations among these structures are discussed relative to their participation in a common functional system.

Animals↗
PubMed1981

Response to stimulus change following observation or exploration by the rat: differential effects of hippocampal damages.

The tendency of the rat to approach the place that had been changed between two successive trials was studied in a total of 118 rats. The experiment was conducted in an enclosed T-maze under two different conditions of stimuli presentation on trial 1. In the "passive" test the rat was allowed to inspect the white-black maze arms but prevented from entering them by transparent partitions, in the "active" test the rat was permitted to explore the entire T-maze. On trial 2 of both tests, the color of one arm was changed, so that the arms were either both white or both black. Sham operated controls showed a preponderance of choosing the changed arms in 75-80 percent in both tests. Rats with lesions of the anterodorsal or the posteroventral hippocampal region showed no arm preference in the passive test, while in the active test, the same groups displayed significant preference for the changed arm. Since performance in both tests relies m memory required for detection of the place of change, the behavioral dissociation following the hippocampal damage cannot be explained by recent hypotheses postulating involvement of the hippocampus in recognition memory, working memory or construction and execution of cognitive spatial maps.

Animals↗
PubMed1981

Conditioned emotional response after dorsohippocampal, ventrohippocampal or entorhinal cortical lesions in rats.

Acquisition and extinction of the conditioned emotional response (CER) was studied in 24 male hooded rats which, prior to training, received small electrolytical lesions in the dorsal hippocampus, the ventral hippocampus, the entorhinal cortex, or were given sham operations. The rate of the on-going bar-pressing behavior for food pellets was highest in rats with lesions in the ventral hippocampus and the lowest after lesions in the entorhinal cortex. CER acquisition was markedly retarded and suppression was the weakest only in rats with dorsal hippocampal lesions. When compared with the level of suppression established toward the end of training, the greatest resistance to extinction of the CER was observed after entorhinal cortical lesions. The results of the experiment indicate functional heterogenity of the hippocampal formation.

Animals↗
PubMed1980

Emotional reactivity after frontomedial cortical, neostriatal or hippocampal lesions in rats.

Emotional reactivity following lesions in structures corresponding to the main components of dorsal prefrontal system of the monkey was evaluated in a total of 165 rats by a six-categorial rating scale. Frontomedial cortical damage (FM) and lesions in anterodorsal (DH) or posteroventral (VH) hippocampal regions elicited marked increases in emotional reactivity, relative to sham operated controls. The most profound effect was observed in FM rats. VH rats were somewhat more emotional than DH ones. Anteromedial neostriatal lesions (NC) evoked increased emotionality only on the first day of testing. Damage to different structures differentially affected the various categories examined. The magnitude of overall reactivity and the pattern of changes indicate a similarity of effects from frontomedial and hippocampal lesions. This similarity was stronger between FM and VH than DH lesions. The negligible eff.ect of NC damage on emotional reactivity suggests a functional dissociation between the enteromedial neostriatum and the anatomically related frontomedial cortex.

Animals↗
PubMed1980

Emotionality and exploratory behavior following cortico-basomedial amygdala lesion in rat.

Twelve rats with amygdaloid lesion (CBM group) and 20 sham operated (Control group) were tested. Emotional reactivity evaluated by six category scale showed transient decrease in CBM group with respect to Control one. The CBM lesion enhanced the locomotor activity in electromagnetic activity meter in the initial phase of confinement in the apparatus. Open-field ambulation was higher in CBM rats than in controls on the first day of examination, while on the second day both groups showed similar locomotor activity. No between group differences were found in response to introduction of novel object. Both groups preferred to stay in box placed in open-field than move around the field. However, CBM rats were engaged in box exploration, whereas controls spent major proportion of time sitting motionless. These results indicate that CBM lesion increases some components of response to novelty. The pattern of changes and their transitory character suggest that cortico-basomedial region of the amygdala is involved in the control of processes underlying the initial phase of responding to novel environment.

Amygdala↗