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J Hassmannová

Publications and source records attributed to J Hassmannová.

At least 19 recordsLinked to original sources
PubMed1991

Ontogeny of ribonucleic acid content in rat cortical neurons influenced by early stimulation.

Developmental changes in the total RNA content were studied in pyramidal cells of the frontal, parietal (somesthetic), temporal (auditory) and occipital (visual) cortical areas in Wistar rats aged 13, 14, 15, 21, 28, 35 and 56 days, and compared with those after complex, visual and acoustic stimulation. In all areas neuronal RNA content reached peak values at the age of 3 weeks, except the parietal cortex, where the values were highest as early as at 15 days (in 21-day pups they were only insignificantly lower). Between the age of 3 and 4 weeks, RNA content of cortical neurons decreased in all three projection areas, whereas in the frontal cortex a significant decline came later--in the 5th week. In the occipital cortex neuronal RNA at 8 weeks reached reliably lower values than in 13-day pups. Neuronal RNA increased at the time of eye-lid opening (13-15 days), highly significantly in the visual cortex. Complex visual and acoustic stimulation raised neuronal RNA content in projection areas of modality involved in stimulation and, moreover, acoustic stimulation did so in the frontal and occipital cortex. On the contrary, complex and visual stimulation decreased RNA contents in the frontal cortex. Developmental dependence, stimulation contingency, and specificity vs. nonspecificity of the observed changes are discussed, and compared with other biochemical, morphological and functional changes that have been found in the period of peaking RNA content, or immediately thereafter.

Acoustic Stimulation↗
PubMed1991

Impact of prenatal low-dose diazepam or chlorpromazine on reflex and motor development and inhibitory-learning.

Long-term behavioral effects of a low dose of diazepam (1 mg/kg body weight) or chlorpromazine (2.5 mg/kg) administered 2-3 times during the last week of pregnancy i.m. were studied in Wistar rats and compared with sequelae of analogously applied saline as well as with normal ontogeny in controls. Inhibitory learning-and-memory ontogeny was assessed by 3 types of passive avoidance (PA) at 3 different life periods: neonatal, 2 months, 4 months. Also were investigated: development of righting, air righting, hanging on a thin horizontal bar, eye-lid opening, somatic development and mortality. Prenatal application of diazepam had adverse effects in all parameters except of eye-lid opening. The reflex and motor development was retarded, and so was body weight. The high mortality in the diazepam treated progeny was due to increased death rate in males. In all PA paradigms investigated no memory was established in rats given diazepam prenatally. Chlorpromazine exhibited a lesser effect. I.m. saline had doubtless a character of prenatal-stress. The impact of diazepam was therefore the result of its proper action and only of a partial, if any, after-effect of prenatal stressful manipulation of the dam.

Animals↗
PubMed1991

Step-down passive avoidance in the rat ontogeny.

Ontogeny of step-down passive avoidance (PA) was studied in 174 Wistar rats at the age of 2, 3, 4, 6, 8 and 13 weeks. Latency to the first descent from the safe bench (DL), number of descents (DN), time to criterion meeting (TC) and time during which animals were shocked (TS), were evaluated within learning (L) and two consecutive retention tests (R1 and R2); R1 took place at short to intermediate intervals (5 min-6 h), R2 24 h after learning. None of 2-week pups mastered the task. The most efficient learning was in 6-week pups, and also three indices of R1 (DN, TC and TS) were best at this age. However, the longest DL (most commonly used memory index in PA) was found in R1 and R2 of 3-week pups, due probably to high fear motivation. In 3-month animals DL was zero in R1. It is emphasized that the development of learning and memory is non-monotonous, which was also seen in our previous studies. There were differences between DL recalled from memory and other three indices (DN, TC and TS) in which further reinforcement within the retention test facilitated the retrieval.

Age Factors↗
PubMed1990

Early inhibitory learning in the rat. I. Learning and memory development.

The present status of knowledge on early inhibitory learning and memory is presented. The inhibitory learning (passive avoidance) can be mastered by rat pups several hours after parturition, provided specific characteristics of the newborn organism and its neurobehavioral capabilities are respected. The curve of numbers of trials to criterion displays, as already reported earlier, a generally decreasing trend which is, however, interrupted by a temporary inversion in both strains studied, but at different time, taking place in Long Evans between postnatal day 1 and 2, which is shifted in Wistar pups one day later. Present data show significant learning differences between strains at postnatal days 1-4; from day 5 onward no significant differences are evidenced up to postnatal day 11. A reliable 24-hour memory shown by positive values of the retention index (RI) is revealed from postnatal day 4, having in Long Evans higher RI values. Moreover, high positive RIs of 24-hour memory are found in animals trained on the day just before the inversion of the learning development. It is conjectured that the indirect development of the early inhibitory learning is due to the developmental reorganization within CNS, and the necessity to find out its underlying mechanisms is emphasized.

Aging↗
PubMed1987

Differential ontogenetic peaks and drops in various conditioned reactions.

A survey of results obtained by the authors was compared with the body of recent data of the literature on the development of learning and memory. The following conclusions were pointed out: The development of learning and memory is not a monotonous process; one or more peaks followed by temporary drops or lasting decay are characteristic for it. There is no coincidence in time between learning and memory peaks, both are greatly dependent on the experimental design and conditions. Learning of more complex reactions and prolonged retention intervals shift the peaks toward later age periods. Early learning and memory that occurs at earlier age periods than thought before may be proved in the very first postnatal days in altricial mammals for inhibitory conditioning as well, if neurobiological and developmental specificities of this age are respected.

Animals↗
PubMed1979

Ontogeny of active avoidance in the rat: learning and memory.

Ontogenetic development of active avoidance learning, extinction and retention was studied in rats. The learning of a 1-way active avoidance was most rapid between Weeks 4 and 6, although some slight gender-related differences were evident. No such unambiguous development was detected in forced extinction. The 24-hr retention of avoidance peaked at the age of 4 weeks whereas 1-month retention was best in animals trained at the age of 8 weeks. The retrieval of memory trace also had best values at these ages. Retention of forced extinction was found to peak in 6-week animals. The existence of developmental "critical periods" must be considered cautiously as various functions have different time courses depending upon the chosen parameters in assessment.

Animals↗
PubMed1977

Role of the claustrum in sensory activation.

The functional organization of the claustrum was studied in acute experiments in cats from birth to adulthood. No somatotopic organization was found, but, on the contrary, multisensory convergence was confirmed. The significance of the claustrum for somesthetic and acoustic afferentation is emphasized. The claustrum is activated mainly by a "cortical loop", along the following route: the diencephalic nuclei (the relevant modality system) leads to cortical projection areas (including secondary and probably association areas) leads to the claustrum. All the correlations described exist from the very first period of postnatal development.

Animals↗
PubMed1975

Evoked potential correlates of early conditioning in the rat ontogeny.

In rats aged 2-8 weeks cortical EP to CS (20 flash - tone combinations, 0,9/sec, reinforced since the 10th application by electric shocks to the hind leg) were studied within different kinds of behavioral responses during avoidance learning and extinguishing. In contrast to our results in freely moving rats no developmental trend was found in this kind of avoidance (lifting of the hind leg). Average EP within reinforced trials (with escape or no reactions) differed in isolated application of CS from those when both CS and US were acting together. In younger animals the EP to CS combined with US were characterized by an evident late negative wave which shifted later (5-6 weeks toward the early negative complex. The EP changes in the auditory cortex were more pronounced, whereas visual EP with CS-US combination were rather decreased. In the youngest animals (2 weeks) the auditory EP within trials with avoidance were characterized by a distinct short latency deflection of the first positive wave, whereas in EP to extinguished CS the second deflection of the first positive wave prevailed. Also in these phenomena, the typical changes were clearly revealed in the auditory cortex. At later developmental stages (starting the 3rd, more prominently the 4th and 5th week) the wave following primary positive - negative complex was shifted toward the negativity if the animal responded by an avoidance; on the contrary an ample positive, often a double-peak wave arose if the response was extinguished. The stimulus and reaction dependence in the cortical EP showed the role of not yet fully mature cerebral cortex in avoidance learning. Both, fast as well as with some delay running processes participated in the observed phenomena during the ontogenetical development.

Animals↗