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G Gottlieb

Publications and source records attributed to G Gottlieb.

At least 37 records · Page 2Linked to original sources
PubMed1990

Neophenogenesis: a developmental theory of phenotypic evolution.

An important task for evolutionary biology is to explain how phenotypes change over evolutionary time. Neo-Darwinian theory explains phenotypic change as the outcome of genetic change brought about by natural selection. In the neo-Darwinian account, genetic change is primary; phenotypic change is a secondary outcome that is often given no explicit consideration at all. In this article, we introduce the concept of neophenogenesis: a persistent, transgenerational change in phenotypes over evolutionary time. A theory of neophenogenesis must encompass all sources of such phenotypic change, not just genetic ones. Both genetic and extra-genetic contributions to neophenogenesis have their effect through the mechanisms of development, and developmental considerations, particularly a rejection of the commonly held distinction between inherited and acquired traits, occupy a central place in neophenogenetic theory. New phenotypes arise because of a change in the patterns of organism-environment interaction that produce development in members of a population. So long as these new patterns of developmental interaction persist, the new phenotype(s) will also persist. Although the developmental mechanisms that produce the novel phenotype may change, as in the process known as "genetic assimilation", such changes are not necessary in order for neophenogenesis to occur, because neophenogenetic theory is a theory of phenotypic, not genetic, change.

Animals↗
PubMed1990

Auditory basis of maternal attachment in ducklings (Anas platyrhynchos) under simulated naturalistic imprinting conditions.

The presence of broodmates during the imprinting process results in peer imprinting that interrupts a visually mediated maternal attachment. We sought to determine the conditions in which group-trained mallard ducklings (Anas platyrhynchos) acquire a maternal attachment. At 48 hr of age, ducklings were allowed to follow a vocal, stuffed mallard hen individually or in groups of 4. Individual ducklings showed a preference for the silent, familiar mallard over an unfamiliar pintail. Ducklings trained in groups did not show a preference. When the mallard maternal call was present during testing, group-trained ducklings overwhelmingly responded to it regardless of whether it came from the familiar mallard or an unfamiliar pintail. Training ducklings in groups, which simulates the natural social context of imprinting, results in peer imprinting. Thus, early in development the young become visually imprinted to each other, and the maternal call mediates attachment to the mother.

Animals↗
PubMed1989

Intrathecal baclofen for severe spinal spasticity.

We studied the effect of the intrathecal infusion of baclofen, an agonist of gamma-aminobutyric acid, on abnormal muscle tone and spasms associated with spinal spasticity, in a randomized double-blind crossover study. Twenty patients with spinal spasticity caused by multiple sclerosis or spinal-cord injury who had had no response to treatment with oral baclofen received an intrathecal infusion of baclofen or saline for three days. The infusions were administered by means of a programmable pump implanted in the lumbar subarachnoid space. Muscle tone decreased in all 20 patients (mean [+/- SD] Ashworth score for rigidity, from 4.0 +/- 1.0 to 1.2 +/- 0.4; P less than 0.0001), and spasms were decreased in 18 of the 19 patients who had spasms (mean [+/- SD] score for spasm frequency, from 3.3 +/- 1.2 to 0.4 +/- 0.8; P less than 0.0005). Tests for motor function, neurologic examination, and assessments by the patients correctly indicated when baclofen was being infused in all cases. All patients were then entered in an open long-term trial of continuous infusion of intrathecal baclofen. During a mean follow-up period of 19.2 months (range, 10 to 33), muscle tone has been maintained within the normal range (mean Ashworth score, 1.0 +/- 0.1) and spasms have been reduced to a level that does not interfere with activities of daily living (mean spasm score, 0.3 +/- 0.6). No drowsiness or confusion occurred, one pump failed, and two catheters became dislodged and had to be replaced. No infections were observed. Our observations suggest that intrathecal baclofen is an effective long-term treatment for spinal spasticity that has not responded to oral baclofen.

Adult↗
PubMed1989

Maternal and peer imprinting in mallard ducklings under experimentally simulated natural social conditions.

Previous studies revealed that if socially reared mallard ducklings actively follow a stuffed mallard (Anas platyrhynchos) hen, they later show a visual preference for the familiar mallard hen over an unfamiliar redhead (Aythya americana) hen. The present study determined that the experience of actively following the hen is essential to the induction of a visually controlled, species-typical, maternal preference. Domestic mallard ducklings that had not been given the opportunity to follow the mallard hen were "passively" reared in social groups consisting of a stuffed mallard hen and seven same-aged siblings for either 24, 48, or 72 hr after hatching. These birds were largely unresponsive to the hen in a later choice test, even when they were passively exposed to the mallard hen for as long as 72 hr prior to testing. The question arose as to whether passive exposure to the ducklings induced a preference for them that interfered with establishment of maternal imprinting under these simulated natural nest conditions. Results indicated that socially reared ducklings do prefer stuffed ducklings to a stuffed mallard hen in a simultaneous choice test even when the hen is present and vocalizing during social rearing. Further, even ducklings reared individually with the mallard hen were unresponsive to her in the later choice test. That there is something special about the stimulation provided by ducklings was further demonstrated by the finding that stuffed ducklings were preferred over the mallard hen (1) when the social rearing situation precluded active physical interaction with live ducklings and (2) when reared with inanimate stuffed ducklings. Thus, the ineffectiveness of the stuffed mallard hen in inducing visual imprinting under simulated nesting conditions cannot be attributed to the fact that she was not alive or reciprocally interactive. The present results suggest that mallard ducklings do not become visually imprinted to their hen until after departure from the nest, that the visual component of maternal imprinting likely involves active following subsequent to nest departure, and that early in postnatal development siblings are more visually attractive than is the hen.

Animals↗
PubMed1988

Social specificity: interaction with own species is necessary to foster species-specific maternal preference in ducklings.

Previous studies have shown that if domestic mallard ducklings are allowed social interaction with broodmates after their initial exposure to a stuffed mallard (Anas platyrhynchos) hen, they later show a visual preference for the familiar mallard over an unfamiliar redhead (Aythya americana) hen. Birds kept in social isolation do not make this difficult discrimination. In the present study, we examined whether this social enhancement of imprintability to a natural maternal model is merely the result of social stimulation in its most general sense, or if its effects are specific to social interaction for 30 min (training). This experience resulted in visual preference for the familiar mallard hen over the unfamiliar redhead hen in simultaneous choices tests at 48 hr and 72 hr after hatching only if the birds were allowed social experience with a group of same-age undomesticated mallard hatchings. No visual preference for the familiar mallard hen was found if the ducklings were permitted social experience with a group of same-age chick (Gallus domesticus) hatchlings or muscovy (Cairina moschata) ducklings. Thus, it appears that for ducklings to show a visually imprinted preference for a natural maternal model, they must be allowed social interaction with broodmates of their own species. Social rearing with other precocial bird hatchlings, even other ducklings, is without apparent effect. These results provide further evidence of the importance of nonobvious experimental factors in the development of species-typical behavior. They also suggest that in the evolution of the species-specific learning underlying early species identification, natural selection has operated on the entire (organism-environment) developmental manifold and not merely on genetic, organic, or organismic aspects of that system.

Animals↗
PubMed1988

Development of species identification in ducklings: XV. Individual auditory recognition.

The present experiments examined the ability of domestic mallard ducklings (Anas platyrhynchos) to learn individual mallard maternal calls by either repetition-rate differences or spectral (Hz) differences, both of which are present in such calls recorded in nature. The ducklings could learn both kinds of differences within the first 24 hr after hatching, corresponding to the period prior to the exodus from the nest in nature. The hatchlings were able to learn these differences based upon only 12 min of exposure to the maternal calls during the first day after hatching. They were also able to retain (remember) the familiar call for an additional day after exposure. Embryos, on the other hand, could learn the spectral differences after either 12 or 24 min of exposure but could not retain the information under either exposure condition. An additional difference between the auditory learning competence of hatchlings and embryos was that the hatchlings were capable of learning the spectral features of a maternal call even if it was pulsed at different repetition rates during exposure (familiarization) and the subsequent test for recognition. The evolutionary significance of the results was discussed in terms of the general importance of familiarization as a basic behavioral mechanism underlying not only parental attachment but dietary and habitat preferences and the like.

Animals↗
PubMed1987

Development of species identification in ducklings. XIII: A comparison of malleable and critical periods of perceptual development.

The present experiments sought to determine the relationship of the malleable period--when the mallard duck embryo is most susceptible to alien forms of maternal auditory stimulation--to the critical period, when the embryo must hear its own vocalizations in order to respond normally to the species-typical maternal call after hatching. It was found that a preference for either a wood duck or a chicken maternal call could be induced in devocalized mallard duck embryos by exposing them to either alien call some time between day 24, 0600 to day 26, 0600 hrs. Further experiments showed the height of the malleable period to be between day 24, 1400 hrs and day 25, 0800 hrs of embryonic development. Since the embryonic critical period for maintenance of the species-typical maternal auditory preference spans day 24, 0800 hrs to day 26, 0800 hrs, the malleable period for the induction of a preference for species-atypical maternal stimulation falls inside the critical period. While it is often assumed that malleable and critical periods overlap, this is the first behavioral study to actually demonstrate the temporal relationship of the two periods. It would seem important to further examine malleable and critical periods of development in a broader array of developmental contexts and species to determine whether malleable periods for atypical or abnormal development and critical periods for species-typical or normal development always coincide.

Acoustic Stimulation↗
PubMed1986

Visually imprinted maternal preference in ducklings is redirected by social interaction with siblings.

This study examined the influence of social interaction with broodmates on a visually imprinted maternal preference in domestic mallard ducklings (Anas platyrhynchos) during the first three days of postnatal life. Twenty-four-hour-old ducklings were allowed to follow a stuffed mallard hen for 30 min. This experience resulted in a visually imprinted preference for the familiar stuffed hen over 4 stuffed ducklings in simultaneous choice tests at 48 and 72 hr after hatching, but only if the imprinted birds were kept in social isolation. Imprinted ducklings reared in a social group containing either same-age siblings or the stuffed mallard hen and same-age siblings displayed a visual preference for the stuffed ducklings over the familiar mallard hen at 48 and 72 hr tests. As a first step in the analysis of the features of the social exposure to siblings that are necessary for the redirection of the visually imprinted maternal preference, it was found that direct social interaction is essential to establish the preference for ducklings, but even mere visual exposure to siblings does away with the imprinted maternal preference. These results provide striking evidence of the ready redirection of a species-specific maternal preference in otherwise imprinted ducklings.

Animals↗
PubMed1986

Training ducklings in broods interferes with maternal imprinting.

Under natural conditions, if maternal imprinting is to occur it must occur in a social situation which includes the presence of broodmates. In the laboratory it has been shown that social rearing with siblings prior to maternal imprinting interferes with the establishment of maternal imprinting, whereas social experience with siblings after maternal imprinting enhances the imprinting experience. The present study examined the influence of social experience with broodmates during an imprinting trial on the establishment of a visually imprinted maternal preference in domestic mallard ducklings (Anas platyrhynchos). Twenty-four-hour-old ducklings were allowed to follow a stuffed mallard hen for 30 min either individually or in a brood of four same-aged ducklings. The birds trained alone subsequently showed an imprinted preference for the familiar mallard hen over an unfamiliar pintail hen or four stuffed ducklings in simultaneous choice tests at 48 and 72 hr after hatching. Ducklings trained with broodmates did not show a preference for the familiar mallard hen over the unfamiliar pintail hen and displayed a preference for the stuffed ducklings over the mallard hen at 48 and 72 hr choice tests. These results demonstrate that even brief (30 min) experience with siblings during a maternal imprinting trial results in peer imprinting that interferes with the establishment of maternal imprinting. These and other results of a similar sort render dubious the significance of most laboratory studies of imprinting for an understanding of such events in nature.

Age Factors↗
PubMed1985

Development of visually controlled maternal preferences in Peking ducklings.

The interaction between natural visual and auditory stimulation in the control of filial behavior was studied in domestic mallard (Peking) ducklings during the first 3 days of postnatal life. Visual imprinting at 24 hr resulted in a visual preference for the familiar model over an unfamiliar model in each of two choice tests, one at 48 hr and one at 72 hr, but only if both models were silent. If both models emitted a recording of the mallard maternal call, the visual preference was found only in the later (72-hr) test. Visuomotor experience between training and testing was found to be essential for the development of the visual preference at 72 hr, but the required experience was of a very general nature. Either a choice test with silent models or a period of social rearing (between 24 and 72 hr) provided effective experience. Thus, the ability to show a visual preference in the presence of the maternal call at 72 hr depends on experience, but not necessarily on further exposure to the imprinting object or to any specific aspects of the test situation. These results demonstrate the importance of normal visual, motor and/or social experience to the development of the visual control of filial behavior in ducklings.

Age Factors↗
PubMed1985

Effects of social experience on visually imprinted maternal preferences in Peking ducklings.

If Peking ducklings are given social experience with agemates after their initial exposure to a maternal imprinting model (a stuffed mallard hen) their subsequent maternal preferences in simultaneous choice tests are different from those of isolate-reared ducklings. Early in development (at 48 hr after hatching), they show a visual preference for the mallard over a redhead model, a difficult discrimination that isolated birds do not make (Experiment I). However, later in development (at 72 hr after hatching) the social experience interferes with the birds' maternal preferences, in that socially reared birds do not show a visual preference for the mallard over a pintail model, a preference that isolated birds do show at that age (Experiment II). It was found that it is the later social experience with agemates (between 48 and 72 hr) that actively interferes with the preference for the mallard model, because birds that have had only early social experience with agemates (between 24 and 48 hr) prefer the familiar mallard to the pintail model at both 48 and 72 hr (Experiment III). The conventional view of visual imprinting is that it serves to establish a maternal bond that does not require further experience with the mother to be maintained. Our results suggest that in the natural situation, where potentially interfering social stimulation is provided by siblings, continual exposure to the mother may be necessary to maintain the maternal bond even after it has been established.

Age Factors↗
PubMed1985

Social interaction with siblings is necessary for visual imprinting of species-specific maternal preferences in ducklings (Anas platyrhynchos).

This study was conducted to examine the influence of various social rearing experiences on the development of imprinted visual maternal preferences in domestic mallard ducklings (Anas platyrhynchos) during the first 3 days of postnatal life. Twenty-four-hour-old ducklings were allowed to follow a stuffed mallard hen for 30 min. This experience resulted in a visual preference for the familiar mallard hen over an unfamiliar stuffed redhead (Aythya americana) hen in simultaneous choice tests at 48 hr and 72 hr only if the ducklings were reared in conditions allowing unrestricted social interaction with siblings, as would normally occur in nature. No visual preference for the familiar mallard model was found at 48 hr or at 72 hr if ducklings were reared in social isolation but allowed to see another duckling, reared with one duckling, or reared in a group of ducklings but denied the opportunity for direct social interaction. These results demonstrate the importance of normal social experience in the development of the visual imprinting of filial behavior in ducklings. Imprinting studies have traditionally employed isolation rearing and ignored the precocial bird's natural social context. Thus, the present findings raise doubts about the appropriateness of the usual methods of studying imprinting in the laboratory for an understanding of the process of filial imprinting in nature.

Animals↗
PubMed1984

Development of species identification in ducklings: XII. Ineffectiveness of auditory self-stimulation in wood ducklings (Aix sponsa).

A previous study revealed that wood ducklings vocalize copiously when in auditory isolation. However, such self-stimulation appeared to be ineffective in maintaining their preference for the characteristically descending frequency-modulated (FM) notes of the wood duck maternal call. Only isolated birds that had been exposed to a recording of descending sib calls showed the normal preference for descending maternal notes in a choice test with descending and ascending maternal calls. In this study, the actual vocalizations of stimulated and unstimulated wood ducklings were examined in order to explore the possibility that there is a difference in the kind and/or amount of auditory self-stimulation in the two groups (e.g., the stimulated birds might produce more descending calls). Although the stimulated birds produced more ascending notes than the unstimulated birds, no differences were found in the overall vocal behavior, vocal reactivity, or specific kinds of frequency modulation produced by the birds that preferred the descending maternal call and the other birds that responded in the choice test. The absence of a difference in vocal production between the birds that preferred the descending call and the other responding birds supports the previous conclusion that self-stimulation apparently plays no role in the development or maintenance of the species-typical perceptual preference for the descending FM notes of the wood duck maternal call.

Animals↗
PubMed1983

Development of species identification in ducklings: X. Perceptual specificity in the wood duck embryo requires sib stimulation for maintenance.

A critical acoustic feature of the wood duck maternal assembly call is the descending frequency modulation (FM) of its notes. To determine the role of exposure of wood ducklings to conspecific vocalizations in the development of selective responsiveness to the descending FM of the species maternal call, the behavioral response of embryos to synthetic descending and ascending maternal calls was examined. Previous work indicated that selective responsiveness of newly hatched wood ducklings to the descending FM of the maternal call is dependent upon prior exposure to descending FM calls of siblings. In advance of auditory experience the youngest embryos were responsive to both ascending and descending call notes, but older aurally isolated embryos became selectively responsive to the descending FM. However, even though the wood duck hatching vocalizes considerably in aural isolation, self-stimulation is ineffective in maintaining the perceptual selectivity in the neonate. Unlike the mallard, in which self-stimulation is adequate, the wood duckling must be exposed to sib vocalizations in order to remain selectively responsive to the critical acoustic feature of the maternal call of its species.

Animals↗
PubMed1982

Development of species identification in ducklings: IX. The necessity of experiencing normal variations in embryonic auditory stimulation.

The domestic mallard duck embryo must be exposed to its embryonic contract-contentment call at a repetition rate of 4 notes/sec if the neonate is to show the species-typical preference for the maternal call at its normal rate (3.7 notes/sec) after hatching. Exposing the embryo to the contact call at either 2.1 notes/sec or 5.8 notes/sec is no more effective than no auditory experience at all. To determine if there is a critical period for exposure, embryos were exposed to the 4 notes/sec call either before or after hatching. Both periods proved equally effective provided only that a 48-hr "consolidation" period was allowed to intervene between stimulation and testing. That is, the birds tested 24 hr after prenatal or postnatal stimulation behaved as if they were not stimulated at all. The present study was undertaken to determine whether the curious requirement for a consolidation period is a normal developmental phenomenon or a consequence of limiting the birds to exposure to a call with an abnormally invariant repetition rate of 4 notes/sec. To that end, embryos were stimulated with the same call as before but at variable rates of 2.1, 4, and 5.8 notes/sec, as happens under normal conditions of development. In this case, the neonates had no need for a consolidation period and showed the species-typical preference at 24 hr after hatching. Thus the previous results were a consequence of an abnormally narrow range of embryonic auditory stimulation. A 2nd experiment showed that, if the birds' postnatal perception was to be normal, the embryos could not be merely exposed to the rhythmic component of the contact call, but had to experience the characteristic frequency modulation of the call as well. These results indicate that we require surprisingly detailed information about the sensory stimulation present during the usual course of development of our subject species if we are to give an appropriate interpretation to the results of early experiential and critical period manipulations. Knowledge of usual sensory-stimulative variations has not been a conspicuous feature of developmental psychobiological studies in the past.

Animals↗