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At least 253 records · Page 14Linked to original sources

PubMed1984

Gestural communication in deaf children: the effects and noneffects of parental input on early language development.

We previously reported that deaf children of hearing parents can develop a gestural communication system with some of the observed properties of early child language. In the present study, this phenomenon of gesture creation was replicated in four deaf children aged 1-4 to 3-1 at the time of the first interview. Each child, despite his atypical language-learning conditions (in particular his lack of usable conventional linguistic input, either oral or manual), developed a gesture system comparable in semantic content and structure (specifically, constructional ordering of elements, differential probabilities of production of elements, and recursive concatenation of semantic relations) to the gestural systems of the six deaf children of hearing parents in our original study and comparable as well to the spoken and sign systems of children acquiring conventional languages under typical learning conditions. This phenomenon suggests that the human child has strong biases to communicate in language-like ways. Nevertheless, it is possible that the deaf child's hearing parents, and not the child himself, were responsible for the emergence of the child's structured (yet idiosyncratic) gesture system. To investigate this possibility, we considered three possible parental influences on the child's sentence structures. First, we entertained the hypothesis that the children's sign sentences were merely imitations (perhaps even uncomprehending imitations) of a hearing adult's immediately preceding gestures. Second, we considered the possibility that the regularities underlying the deaf children's structured sign sentences were induced from their hearing parents' gestures taken in toto. Finally, we considered the possibility that the deaf children's sign sentences had been shaped by their parents' responses to those sentences. We found no evidence to support any of these hypotheses. The data reported in this series of studies confirm that deaf children lacking a conventional linguistic input can develop a gestural communication system that shows some of the structural regularities characteristic of early child language. The results suggest that communication with a number of language-like properties can develop in a markedly atypical language-learning environment, even without a tutor's modeling or shaping the structural aspects of the communication. The data are consistent with the hypothesis that the deaf child himself plays a seminal role in the emergence of the structural aspects of these communication systems.

Child, Preschool↗

PubMed1982

[Effects of post-weaning rearing conditions on learning performance in "dwarf" mice (author's transl)].

The effects of different environments on learning ability were investigated in mice homozygous for the locus "dwarf," characterized by a primary deficiency of the anterior hypophysis. Two experiments were conducted; they differed from one another in several aspects such as sex and age at entry into different environments. In both experiments, half the "dwarf" (homozygous dw/dw) and control mice of the same strain (heterozygous dw/+ or homozygous +/+) were placed in either an "enriched" or "impoverished" environment. After 31 days of rearing in these conditions, animals were then pretrained and tested with the standard 12 Hebb-Williams problems. Results from both experiments revealed that (1), independently of environment, "dwarf" mice made significantly more errors than controls (p less than 0.001); (2) mice of the "enriched" groups made significantly less errors than those of the "impoverished" groups (p less than 0.05); (3) environmental effects tended to be larger in "dwarf" mice than in controls. The results are discussed in the light of previous observations on the level of locomotor activity and on the degree of interaction of "dwarf" mice with their physical environment; they are compared to those reported for hypothyroid animals and to those of animals with hippocampal lesions.

Animals↗

PubMed1992

A simple, single, trial-learning paradigm for conditioned increase in natural killer cell activity.

A change in natural killer (NK) cell activity can be conditioned with one trial learning when conditioned stimulus (CS) precedes the unconditioned stimulus (US). To avoid the problems associated with two reexposures in our earlier studies, we have developed a reliable and simple conditioning protocol utilizing the one trial learning and one reexposure to the odor CS. The conditioned change in NK cell activity was significantly different (P less than 0.05) from the control groups of mice. The paradigm is short and simple in that the conditioned change could be demonstrated within 3 days. We have also compared the effects of temporal association of CS and US on conditioned increase in NK cell activity. Forward conditioning (CS preceded the US) demonstrated a conditioned change, but the backward conditioning protocol did not. The paradigm provides a reliable approach to the study of mechanisms of the phenomenon of odor-NK conditioning.

Administration, Inhalation↗

PubMed2003

Alcohol-induced memory impairment in trace fear conditioning: a hippocampus-specific effect.

It has been hypothesized that the amnesic effects of alcohol are through selective disruption of hippocampal function. Delay and trace fear conditioning are useful paradigms to investigate hippocampal-dependent and independent forms of memory. With delay fear conditioning, learning of explicit cues does not depend on normal hippocampal function, whereas learning explicit cues in trace fear conditioning does. In both delay and trace fear conditioning, the hippocampus is involved in learning to contextual cues, but it may not be entirely necessary. The present study investigates the effects of alcohol on the acquisition of delay and trace fear conditioning in mice, using freezing as a measure of learning. Male C57BL/6J mice were injected with 0.8 or 1.6 g/kg of 20% v/v alcohol and were immediately exposed to eight tone-footshock pairings in which the conditional stimulus (CS) either coterminated with a footshock unconditional stimulus (US) (delay conditioning) or was separated from the footshock by a 30-s trace interval (trace conditioning). During trace, but not delay fear conditioning, 0.8 g/kg alcohol impaired learning to a tone CS. This dose also impaired context-dependent learning in both procedures (although only slightly for trace fear conditioning). The 1.6 g/kg alcohol exerted a nonselective impairment on learning. The impairment by alcohol of learning to a tone CS when it is hippocampus-dependent, but not when it is hippocampus-independent provides further support for the hypothesis that alcohol exerts a selective effect on hippocampus-dependent learning.

Acoustic Stimulation↗

PubMed2005

Activation of the precuneus is related to reduced reaction time in serial reaction time tasks.

Multiple brain areas are activated during serial reaction time (RT) tasks (SRTTs), but the part of the brain that facilitates reductions in RT remains unclear. The present study attempted to determine the brain region contributing most to improved RTs during explicit SRTTs. Subjects comprised 18 healthy volunteers who were instructed to press one of four buttons corresponding to visual stimuli as quickly as possible and with minimal errors during functional MRI. Stimuli were presented either in random order (control condition) or in a repeated six-item sequence (learning condition). Conventional analysis contrasting learning and control conditions revealed activation in the prefrontal-parietal area, which shifted to motor area. Subjects with high RT reduction showed more prominent activation in the precuneus than subjects with low RT reduction. Intra-subject correlation analysis revealed that time course of precuneus activation was unrelated to time-course of RT reduction. However, inter-subject correlation analysis revealed that RT changes correlate only with precuneus activation, meaning that subjects showing more prominent RT reduction revealed more prominent activation of the precuneus, which is known to play critical roles in controlling finger movements with reference to buffered memory.

Adult↗

PubMed1983

Visual discrimination learning under conditions of interocular conflict in hooded and albino rats.

Hooded and albino rats were trained on a paradigm of interocular conflict, in which the animals were trained on a discrimination of vertically inverted triangles with one eye, and on the reversed discrimination with the other eye on alternate days. Albino rats acquired the conflicting tasks as quickly as a single monocularly trained task. Hooded rats required considerably longer training on the conflicting discriminations. The role of some non-visual behavioral strategies in the performance of the conflicting tasks was explored, and possible mechanisms are discussed with reference to the different size of the ipsilateral optic projection in hooded and albino rats.

Animals↗

PubMed1983

Effects of apomorphine and methamphetamine on a quickly-learned conditioned-suppression response in rats.

Rats exhibited a marked suppression of motor activity when placed in the same chamber where they had been given electric shocks. Administration of apomorphine-HCl (0.1, 0.5 and 1.0 mg/kg, i.p.) attenuated the conditioned suppression, dose-dependently, but did not facilitate motor activity of control (i.e. non-shocked) rats. Methamphetamine-HCl (0.1, 0.5 and 1 mg/kg, i.p.) increased motor activity of both the shocked and non-shocked rats, in a dose-related manner. Haloperidol (0.3 and 1 mg/kg, i.p.), but not chlorpromazine-HCl (5 mg/kg, i.p.), enhanced the conditioned-suppression response. Atropine-sulfate (5 and 10 mg/kg, i.p.), p-chlorophenylalanine (300 mg/kg, i.p.) and alpha-methyl-p-tyrosine (100 mg/kg, i.p.) were slightly effective in reducing the conditioned-suppression response. Apomorphine- and methamphetamine-induced reduction of the conditioned-suppression response was inhibited by pretreatment with haloperidol. When catecholamine-synthesizing processes in rats were inhibited by pretreatment with alpha-methyl-p-tyrosine, or alpha-adrenergic receptor sites were blocked by pretreatment with phenoxybenzamine, the effect of methamphetamine, but not that of apomorphine, was reduced. Therefore, enhancement of dopaminergic neurotransmission may be responsible for attenuation of the conditioned-suppression response.

Animals↗

PubMed1985

Effects of antidepressant drugs on a quickly-learned conditioned-suppression response in mice.

Mice experienced to electric shock, exhibited a marked suppression of motor activity when placed in the same cage 24 hr after administration of shocks. Acute administration of imipramine-HCl (10 mg/kg, i.p.), desipramine-HCl (5 and 10 mg/kg, i.p.) and amitriptyline-HCl (5 and 10 mg/kg, i.p.) caused marked reduction of the conditioned suppression of shocked mice, but reduced the motor activity of the non-shocked mice. Maprotiline, mianserin and dimetacrine did not cause reduction of the conditioned suppression. Nialamide (100 mg/kg, i.p.) and pargyline-HCl (100 and 200 mg/kg, i.p.) caused marked reduction of the conditioned suppression but did not increase the motor activity of the non-shocked mice, and tranylcypromine-HCl (10 and 20 mg/kg, i.p.) did not cause reduction of the conditioned suppression. Diphenhydramine-HCl (10 and 20 mg/kg, i.p.) reduced the conditioned suppression of shocked mice in a dose-related manner. Chronic administration of imipramine-HCl (1 and 5 mg/kg, i.p.) for 14 days significantly reduced the conditioned suppression but did not influence the motility rate of the non-shocked mice. Also, chronic administration of amitriptyline (1 mg/kg, i.p.), desipramine (5 mg/kg, i.p.) and dimetacrine (10 mg/kg, i.p.), for 10 days, significantly reduced the conditioned suppression, but did not influence the motility rate of the non-shocked mice. Chronic administration of maprotiline reduced the conditioned suppression. On the other hand, chronic administration of mianserin (5 mg/kg, i.p.) and diphenhydramine (10 mg/kg, i.p.) did not cause a reduction of the conditioned suppression.

Acridines↗

PubMed2000

Effects of acute nicotine on several operant behaviors in rats.

The present experiment assessed nicotine's effects on complex cognitive processes using a variety of operant tasks in rats, including incremental repeated acquisition (IRA) to assess learning; conditioned position responding (CPR) to assess auditory, visual, and position discrimination; progressive ratio (PR) to assess motivation; temporal response differentiation (TRD) to assess timing; and differential reinforcement of low response rates (DRL) to assess timing and response inhibition. Acute nicotine administration (0.0, 0.3, 0.42, 0.56, 0.75, and 1.0 mg/kg, IP) increased IRA and CPR response rate without significantly altering accuracy. Nicotine had similar effects on response rate for PR. For TRD, nicotine had a U-shaped dose effect on accuracy, but failed to shift the mode of the TRD response distribution. For DRL, nicotine reduced accuracy and also shifted the mode of the DRL response initiation time distribution to the left. Nicotine produced an inverted U-shaped dose-effect curve for the overall number of "bursting" responses under both of these schedules. The results of this experiment suggest that nicotine can impair performance on some aspects of cognitive-behavioral performance, while simultaneously improving performance on others.

Animals↗

PubMed2005

'Word-learning wizardry' at 1;6.

This article explores whether infants are able to learn words as rapidly as has been reported for preschoolers. Sixty-four infants aged 1;6 were taught labels for either two moving images or two still images. Each image-label pair was presented three times, after which comprehension was assessed using an adaptation of the intermodal preferential looking paradigm. Three repetitions of each label were found to be sufficient for learning to occur, fewer than has previously been reported for infants under two years. Moreover, contrary to a previous finding, learning was equally rapid for infants who were taught labels for moving versus still images. The findings indicate that infants in the early stages of acquiring a vocabulary learn new word-referent associations with ease, and that the learning conditions that allow such learning are less restricted that was previously believed.

Child Language↗

PubMed1968