Influence of Natural Asymmetric Embryonic Visual Afferentation on the Neuronal Activations in the Caudomedial Mesopallium during the Freezing Response in Altricial Nestlings.

The study was designed to investigate the role of asymmetric prenatal visual stimulation on the activation of caudomedial mesopallium (CMM) neurons in nine-day-old pied flycatcher nestlings during auditory-guided freezing. Four groups of nestlings were studied: groups 1 and 2 included nestlings with normal vision and visually deprived, respectively, that were incubated and hatched in normal light environment; groups 3 and 4, nestlings with normal vision and visually deprived, respectively, that were incubated and hatched in the dark. The eyes of visually deprived nestlings were covered with non-transparent cups 2 h before the experiment. C-Fos expression was studied. It was shown that densities of neurons activated during freezing response differed in right vs. left CMM only in the group of visually deprived nestlings incubated under light. This suggests that the presence or absence of the asymmetric embryonic visual afferentation may result in the development of different strategies of the visual system integration into defense behavior.

[Wulst Activation in Pied Flycatcher Nestlings in Feeding Behavior Induced by Patterned Visual Stimulus].

Immunohistochemical detection of c-Fos was used to study the transcriptional activation in two higher visual centers (Wulst area and Entopallium) of 12-day-old pied flycatcher (Ficedula hypoleuca) during the realization of feeding behavior guided by patterned visual stimulus, simulating the species-specific one. Activation was compared in 4 groups of nestlings. Control group was not subjected to any experimental influence. In binocular, right-field (deprivation of the left eye) and left-filed (deprivation of the right eye) groups the vision feeding responses were provoked, reinforced and evaluated. It was shown that the visual afferentation from the right eye was more significant for the organization of early feeding behavior guided by a moving patterned visual stimulus as compared with the afferentation from the left eye. Feeding behavior induced activation of c-Fos expression only in neurons of the higher center of thalamofugal system--Wulst area. The comparison of transcriptional activation in different groups revealed the significant increase of c-Fos induction related with feeding behavior only in the left hemisphere and only in binocular and right-field groups.

[Visual input affects the expression of the early genes c-Fos and ZENK in auditory telencephalic centers of pied flycatcher nestlings during the acoustically-guided freezing].

The present study analyzed expression of transcriptional factors c-Fos and ZENK in 9-day-old pied flycatcher nestlings' (Ficedula hypoleuca) telencephalic auditory centers (field L, caudomedial nidopallium and caudomedial mesopallium) involved in the acoustically-guided defense behavior. Species-typical alarm call was presented to the young in three groups: 1--intact group (sighted control), 2--nestlings visually deprived just before the experiment for a short time (unsighted control) 3--nestlings visually deprived right after hatching (experimental deprivation). Induction of c-Fos as well as ZENK in nestlings from the experimental deprivation group was decreased in both hemispheres as compared with intact group. In the group of unsighted control, only the decrease of c-Fos induction was observed exclusively in the right hemisphere. These findings suggest that limitation of visual input changes the population of neurons involved into the acoustically-guided behavior, the effect being dependant from the duration of deprivation.

[Activation of tectofugal visual system of the pied flycatcher nestlings at early developmental stages of feeding behavior guided by diffuse photosensitivity].

Immunohistochemical detection of c-Fos in serial frontal sections of the brain of Pied flycatcher nestlings was used to map the sensory structures involved in early forms of feeding behavior. The c-Fos content was quantitatively analyzed in the higher structures of thalamofugal (Wulst area) and tectofugal (entopallium) visual pathways during visually-guided feeding behavior in 6-day-old nestlings at the stage of diffuse photosensitivity. Induction of c-Fos was not observed in the Wulst area which is known to be involved in the feeding integration in adult bifoveal birds. Induction of c-Fos was detected in the ventral area of entopallium containing neurons that are, according to literature, sensitive to a luminosity change. In the entopallium of 6-day-old nestlings, asymmetry in the evoked c-Fos expression was observed, probably reflecting the asymmetry of the visual projections originating in the embryonic period.

Effects of visual deprivation on the development of auditory sensitivity during formation of the freezing reaction in pied flycatcher nestlings.

Recording of evoked potentials from the higher center of the auditory system - field L of the nidopallidum - was used to study the formation of auditory sensitivity in normally developing and visually deprived pied flycatcher nestlings aged 6-9 days. Restriction of visual afferentation was found to produce significant reductions in the absolute threshold of auditory evoked potentials in the frequency range of the species-specific food call (1-3 kHz) during the period at which vision acquires a role in providing sensory support for feeding behavior in control nestlings (six days). In the frequency range of the species-specific alarm call (4-5 kHz), the thresholds of auditory evoked potentials were significantly lower than those in controls during the period at which vision acquires a role in providing sensory support for defensive behavior (8-9 days). Taking account of previous data showing decreases in the efficiency of acoustic signals in evoking freezing reactions in visually deprived nestlings, it is suggested that defensive behavior develops not simply as a response to the acoustic alarm call or tones imitating it, but as a system whose complete formation and functioning require integration of a series of factors, including visual afferentation.

[Visual deprivation affects the development of auditory sensitivity during the period of maturation of freezing response in pied flycatcher nestlings].

Recording of evoked potentials (EP) from the higher auditory center of birds field L of the nidopallium was used to study the development of the auditory sensitivity in normally developing vs visually deprived pied flycatcher nestlings aged 6-9 days. The visual deprivation was shown to induce a significant decrease in the absolute auditory EP thresholds in the frequency range of species-typical food call (1-3 kHz) during the period corresponding to the time of the vision involvement into the feeding behavior in the normal young (6 days post-hatching). In the frequency range of species-typical alarm call (4-5 kHz), EP thresholds in visually deprived nestlings were significantly lower than in the control birds during the period corresponding to the time of the vision involvement into the defense behavior of the latter (8-9 days post-hatching). With account made for the previous data demonstrating the decrease of efficiency of acoustic signals provoking freezing in visually-deprived nestlings, it is reasonable to suggest that defense behavior develops not just as a response to alarm call or imitating tone pips, but as a whole system, whose norma maturation and functioning requires integration of numerous factors visual afferentation being one of them.

[Prenatal acoustic stimulation and feeding behavior of Japanese quail chicks (Coturnix coturnix japonica)].

Effects of a prenatal rhythmic tone on behavior of Japanese quail chicks were studied on the next days after hatching. The acoustically stimulated chicks demonstrated a significantly more frequent following response, feeding reaction and comfortable behavior when hearing the tone as compared with their controls. Bandwidths stimulating this or another behavior were determined.

[The role of visual afferentation in the development of early defense behavior of pied flycatcher nestlings].

The development of defense behavior in normal and visually deprived pied flycatcher nestlings was studied in the wild. It was demonstrated that the young deprived of the visual afferentation did not develop the freezing posture. In the majority of cases, specific alarm call suppressed begging in visually deprived nestlings less effectively than in the control ones. Visually deprived nestlings could not discriminate between the alarm call and other rhythmically organized acoustic signals even though the latter effectively suppressed begging.

[Increasing selectivity of defense behavior during development of pied flycatcher nestlings]. / Rost selektivnosti oboronitel'nogo povedeniia v ontogeneze ptentsov mukholovki-pestrushki.

The development of defense reaction was studied in the wildlife and experimentally in 7 broods of altricial pied flycatcher (Ficedula hypoleuca) nestlings. Field studies demonstrated that passive-defense response first appeared on the 4th day of the nest life. It developed from the cessation of begging in young relatively satiated nestlings to characteristic freezing response independent of the level of feeding motivation in older nestlings. Older nestlings also acquire the defense reaction in response to novel visual stimuli. The efficiency of the natural stimulus for defense behavior (species-specific alarm call) nongradually changes during the nest life attaining the 100% level only on the 11th posthatching day. During the initial phase of defense behavior development, the reaction can be induced by different rhythmically organized stimuli. Later it becomes considerably more selective and other rhythmic and acoustic signals become much less effective than the alarm call.

The minimal provision principle of functional systems. Neuronal mechanisms.

An important characteristic of the developing nerve cell is its ability to function long before maturity. At this time, the neuron has the basic properties of an excitable membrane, an incompletely developed dendritic tree, and a low level of afferent input. All of these factors hinder the initiation of synaptic and spike potentials. It is proposed that the functional potential of neurons at the early stages of development are provided by an adaptive system, which may include: 1) the excess phenomenon, i.e., increases in the numbers of nerve cells, their processes, spines, and synapses; 2) factors increasing the chances of meeting the expected afferentation, i.e., the orientation and growth of dendrites towards the afferent input and the structure and localization of branch points; 3) factors facilitating the initiation of nerve spikes i.e., juvenile channels for ion current generation, electrical interactions between cells. and additional trigger zones. These groups of properties solve a single common problem: that of facilitating cells to respond to single or weak signals. This is the basic condition supporting the operation of interneuron interactions at the early stages of brain development.

[Visual afferentation deficit during diffuse photosensitivity period in nestlings affects morphogenesis in Wulst neurons]. / Defitsit zritel'noi afferentatsii v period diffuznoi fotochuvstvitel'nosti ptentsov vliiaet na morfogenez neironov Wulst.

Golgi-stained preparations were processed with computerized morphometry to study the effect of the deprivation (eyes covered with nontransparent caps) on the development of neurons in the Wulst (the structure analogous to mammalian visual cortex) of pied flycatcher nestlings. Six-day-old nestlings that have only one form of the visual perception--diffuse photosensitivity--were studied. In the previous paper [Korneeva et al., 1994] in was shown that the Wulst of 6-day-old nestlings consisted of non-differentiated neurons and stellate-like cells at different stages of maturation; the latter group was subdivided into more- and less-mature cells. This work proved that even a 1.5-day-long deprivation (actual duration being counted off from the moment of appearance of the first retinal photoreceptors at the age of 4.5 days) resulted in significant changes in the geometry of stellate-like neurons. The changes in less-mature cells were predominantly destructive (decline of all quantitative indices of a cell, including the significant decrease in the total length of dendrites, maximal radius of the dendritic field and cell branching index), while the changes in more-mature cells were constructive (increase in all quantitative cell indices, including statistically significant increase in the soma section area, total length of dendrites, maximal radius of dendritic field and the number of foci of maximal branching). Different reactions of these cell types to the limitation of visual afferentation may be connected with differences in the afferent inflow to less- and more-mature cells or/and with different maturational stages of these neurons at the onset of deprivation.

[The 3-dimensional organization of the sensory epithelium of the cochlea in birds]. / Trekhmernaia organizatsiia sensornogo épiteliia ulitki ptits.

Using authors' original approach to studying histoarchitecture of cellular layers three-dimensional structure of bird helix sensory epithelium was studied theoretically and experimentally. The composition of its elementary morphofunctional unit, AB3 (one sensory cell per three supporting cells) was established. Three dimensional model of this unit was worked out that described shape and arrangement of cells at apical, basal and intermediate levels of the layer. The presence of its translation symmetry was demonstrated. Comparison of theoretical model and results of morphological research of sensory epithelium allowed to conclude that the model corresponds with the real tissue. The model assists in three-dimensional reconstruction of sensory epithelium. And allows to deal with minimum number of sections and also gives an opportunity to forecast its developmental changes.

Sensory information--the major factor of ontogeny.

On the basis of their own data authors postulate that the increase in sensory input during early ontogeny results in a delay in the development of the sensory systems formed earlier. In connection with this, the sensory basis of behavioral patterns becomes ineffective, causing their reorganization and the appearance of new forms of behavior. Limitation of sensory input during during the critical periods of development stimulates the accelerated manifestation of behavioral patterns. However, this acceleration also has long-lasting negative effects - alterations in the process of learning and memory in adult animals.

[Sensory information--an important factor in ontogeny]. / Sensornaia informatsiia--vazhnyi faktor ontogeneza.

Ontogenetic process reveals a row of consecutive stages characterized by the gradual increase in complexity and by the changing specificity of sensory mechanisms basic for the adaptive behavior of the young. The study examines the mechanisms of interaction among different sensory systems during the formation of early behavioral patterns and analyzes why, at a certain stage of development, a particular sensory stimulus loses its efficacy in the organization of a given behavior and is substituted by another one, previously ineffective. A special attention is paid to formation of behavior based on sensory information within the limits of ontogenetically fixed developmental critical periods and to the role of the early sensory experience in learning in adult animals.

[Acoustically guided behavior in the early ontogeny of the long-eared owl: the characteristics of its feeding behavior and the parameters of the acoustic signal important for its stimulation]. / Akusticheski napravliaemoe povedenie v rannem ontogeneze ushastoi sovy: osobennosti pishchevogo povedeniia i znachimye dlia ego stimuliatsii parametry akusticheskogo signala.

Feeding behaviour of nestlings of long-eared owls (Asio otus) is manifested as a complex of two components, i. e., the vocal reaction (uttering of begging calls) and specific motor response. Exposure to the appropriate acoustic signals resulted in an increase in the number of begging calls and approaching reaction to the source of acoustic signals. The range of monotonal signals effective for eliciting feeding behaviour was 0.2--1.5 kHz, the most effective were the tones of 0.3--0.7 kHz. The approaching reaction to acoustic signals was rather weak up to the 5th day after hatching, clearly pronounced in the 6--11th days, and later on was abruptly substituted for the response of following the visual stimulus provoked by the acoustic stimulation. Specific acoustic afferentation is the sole stimulus for begging in nestlings up to 11 days of age, and it remains a triggering stimulus for feeding behaviour in owl nestlings throughout the period of artificial feeding under laboratory conditions (up to the 40th day after hatching.