[The effect of acute alcohol administration on auditory evoked potentials in altricial nestlings during the development of natural behavior]. / Vliianie ostrogo vvedeniia alkogolia na slukhovye vyzvannye potentsialy u nezrelorozhdaiushchikhsia ptentsov v period formirovaniia estestvennogo povedeniia.

Acute ethanol influence on field L auditory evoked potentials (AEP) was studied in 4-8-days-old altricial nestlings of pied flycatcher. Nestlings were presented with tone pips related with the realization of natural behaviour (2.0 and 5.0 kHz) and bearing no meaning for the behaviour of the young of the age under study (3.0 kHz). Ethanol ingestion was found to reduce the maturity index (MI) of AEP in response to "behavioural" but not to control frequencies; this effect was first observed at day 5, when nestlings eyes opened and defence behaviour appeared, while previously formed feeding behaviour was significantly modified. During the next 2 days alcohol had a greater effect upon the AEP in response to 2.0 kHz tone pips, related with feeding behaviour of increasing complexity than upon the AEP in response to 5.0 kHz, related with the defence behaviour that remained relatively constant. The previous data concerning the effect of alcohol on unit activity are used to support the view that MI increase during the early postembryonic ontogeny is due to the involvement of neurons with newly formed behavioural specializations into the subserving of new behavioural patterns while the decrease of MI under alcohol is due to the depression of activity in these neurons.

[Role of a species-specific acoustic environment in the development of hearing in nestlings]. / Rol' vidospetsificheskoi akusticheskoi sredy v razvitii slukha ptentsov.

Main parameters were studied of the acoustic evoked potentials (EPs) from L field of the caudal neostriatum of altricial nestlings of 2-8 days to pure tones in the range of species-specific signals. It has been established that auditory EPs to the tones of different frequencies differ by the terms of appearance and the degree of maturity. At every of the revealed stages of the auditory ontogenesis, including the stage of completely formed auditory sensitivity, such parameters of auditory EPs, as latencies of different phases, amplitude-temporal pattern and the course of recovery curve are different for the tones of different frequencies. The earliest to appear are the responses to the tones 0.2-4.0 kHz, corresponding to the energy of alimentary signals. Responses to tones of higher frequencies corresponding to the spectrum of other species-specific signals appear later, but the speed of their formation is higher than in the responses to the tones of low frequencies. It is suggested that the higher speed of sensitivity maturation in the high-frequency region is determined by ecologically conditioned afferentation, the function of which is fulfilled by nestlings own vocalization.

[Age dynamics of visually guided behavior and visual evoked potentials of altricial nestlings]. / Vozrastnaia dinamika zritel'no napravliaemogo povedeniia i zritel'nykh vyzvannykh potentsialov nezrelorozhdaiushchikhsia ptentsov.

Comparative study has been carried out of factors of organization of visually guided feeding behaviour (observation method) and the degree of maturity of the visual mechanisms by the criterion of Wulst EPs formation and of their recovery cycles in normally developing and visually deprived nestlings. In has been established that during the period following the opening of the eyes (5-9th day) the feeding behaviour is connected with diffuse photo-sensitivity of visual mechanisms. Diffuse photo-sensitivity fully provides for natural feeding behaviour at the corresponding stage of development of visual functions. Complete visual deprivation during the whole period of diffuse photo-sensitivity does not influence subsequent development of the visual system.

[Formation of visual evoked potentials and development of visually guided behavior in the Ficedula hypoleuca nestling]. / Formirovanie zritel'nykh vyzvannykh potentsialov i razvitie zritel'no napravliaemogo povedeniia ptentsov duplognezdnikov.

Age dynamics of evoked potentials (EPs) of Wulst area of the dorsal hyperstriatum (functional analogue of mammalian visual cortex) was investigated in 2-7 days old nestlings. EPs in response to light stimuli, with the duration and intensity imitating natural alimentary signals for 5-7 days-old nestlings, were recorded parallel with the behaviour. It was found that the development of the visual system in precocious nestlings became completed in postembryonal ontogenesis. The most essential changes in the parameters of visual EPs occur between 2.5 and 4 days of nest life. By the end of the 4-th day the EPs parameters resemble those of the definite EPs. During the same period the visually directed form of the alimentary behaviour appears for the first time. Both the visual EPs and the visually directed alimentary behaviour first appear in the ontogenesis in response to the second component of two-fold luminosity change--the natural signal of alimentary behaviour.

[Auditory evoked potentials and acoustically-directed behavior of nestlings]. / Slukhovye vyzvannye potentsialy i akusticheski-napravliaemoe povedenie ptentsov.

Characteristics of auditory evoked potentials (EP) were studied in 1.5 to 7.5 days old Pied Flycatchers nestlings (Ficedula hypoleuca) with chronically implanted electrodes in the field L (analogue of the mammal's auditory cortex). EPs simultaneously with behaviour were recorded in nestlings under conditions similar to natural, in response to "feeding" calls and pure tones of different frequency and intensity. It was found that EP generation thresholds do not depend on the sum total of factors which influence the organization of feeding behaviour. The EP generation threshold is by 13-36 dB (for different frequencies) below that of the appearance of feeding responses in nestling with a maximum high motivation. It is suggested that the realization of inborn behaviour with a signal basis needs not only an integration (formed in the process of embryogenesis) of a definite sensory input with a complex of structures of the "feeding centre", but also the presence of a massive modality-specific inflow.

[Visual evoked potentials of fledglings to ecologically significant stimuli]. / Zritel'nye vyzvannye potentsialy ptentsov na ékologicheski znachimye stimuly.

A study was made of the structure of evoked potentials in the Wulst of the dorsal hyperstriatum in five- to eight-day old nestlings in response to ecologically determined visual stimuli significant for the alimentary behaviour, within the range of their intensity natural fluctuation. It was established that the parameters of the visual evoked potentials correlate with the rate of behaviour manifestation, which depends on the level of alimentary motivation. At a low motivation level (and under Nembutal anaesthesia), latencies of all response components depend on the energetic parameters of the stimuli and to a maximum degree so -- the primary component latencies. At a high level of alimentary motivation, dependence of the response components latencies on the stimuli parameters is pronounced to a much lesser degree, and still less for the primary component. It is assumed that when the subsequent behavioral response is present, evoked potentials are more linked to the processes of organization and realization of behaviour than to the parameters of affective stimulation.

[Development of species specific acoustic sensitivity in hole-nester fledgelings]. / Razvitie vidospetsificheskoi zvukovoi chuvstvitel'nosti u ptentsov duplognezdnikov.

A study was made of acoustic sensibility of hole nestlings to species-specific signals of adult birds. It has been established that the final formation of sensibility to such signals is not completed in the embrional period of development, but continues, at least during the first half of life in the nest. In the embrional period, the formation of sensibility is concluded only within the spectrum of the "alimentary" signal complex, providing for adequate alimentary behaviour of the nestlings immediately after hatching. In the early postembrional period, the formation of acoustic sensibility in the spectrum of other species-specific signals (alarm signals) is completed in parallel with the organization of behavioral reactions controlled by these stimuli.

[Role of natural sensory factors in organization of feeding behavior using fledgling development as an example]. / Rol' estestvennykh sensornykh faktorov v organizatsii pishchevogo povedeniia na primere razvitiia ptentsov

A change in the composition of natural sensory stimuli, triggers of the alimentary functional system of Muscicapa hypoleuca nestlings, was studied throughout their nest life. In the first five days the alimentary reaction is elicited by a complex of acoustic stimuli. From the fifth to the eighth day the reaction appears in response to a momentary change of illumination. From the ninth to the thirteenth day two stimuli are involved in the organization of the alimentary reaction: a trigger stimulus-a momentary change of illumination, and a directional stimulus-a mobile silhouette of the bird. On the thirteenth to the fifteenth day the alimentary reaction appears only in response to the bird's movement. It is assumed that the successive change of trigger stimuli in one and the same alimentary functional system is determined by a successive involvement of increasingly complicated sensory mechanisms. The time periods of involvement may vary with a change of environmental factors.