Stress-Induced Alterations of Norepinephrine Release in the Bed Nucleus of the Stria Terminalis of Mice

Stress can drive adaptive changes to maintain survival during threatening stimuli. Chronic stress exposure, however, may result in pathological adaptations. A key neurotransmitter involved in stress signaling is norepinephrine. Previous studies show that acute stress elevates norepinephrine levels in the bed nucleus of the stria terminalis (BNST), a critical node regulating anxiety and upstream of stress responses. Here, we use mice expressing channelrhodopsin in norepinephrine neurons to selectively activate terminals in the BNST, and measure norepinephrine release with optogenetics-assisted fast-scan cyclic voltammetry (FSCV). We demonstrate that while corticosterone habituates to chronic restraint stress, cFos activation of medullary norepinephrine neurons shows equivalent activation under both acute and chronic stress conditions. Mice exposed to a single restraint session show an identical optically stimulated norepinephrine release profile compared to that of unexposed mice. Mice experiencing 5 days of restraint stress, however, show elevated norepinephrine release across multiple stimulation parameters, and reduced sensitivity to the α₂-adrenergic receptor (AR) antagonist idazoxan. These data are the first to examine norepinephrine release in the BNST to tonic and phasic stimulation frequencies, and confirm that repeated stress alters autoreceptor sensitivity.

Hypocretin/orexin knock-out mice display disrupted behavioral and dopamine responses to cocaine

The hypocretin/orexin (HCRT) system is implicated in reward and reinforcement processes through actions on the mesolimbic dopamine (DA) system. Here we provide evidence for the relationship between HCRT and DA in vivo in anesthetized and freely moving mice. The ability of cocaine to elicit reward-related behaviors in mice lacking the HCRT prepro-peptide (HCRT knock-out; KO) and wild-type controls was determined using conditioned place preference. Using a combination of microdialysis and in vivo fast scan cyclic voltammetry in anesthetized and freely moving mice, we investigated the underlying role of HCRT in the regulation of DA release and uptake. We show that, unlike wild-type mice, HCRT KO mice fail to develop characteristic conditioned place preference for cocaine. These mice also demonstrated reduced DA release and uptake under baseline conditions in both anesthetized and freely moving experiments. Further, diminished DA signaling in HCRT KO mice persists following administration of cocaine. These findings indicate that HCRT is essential for the expression of behaviors associated with the rewarding effects of cocaine, and suggest that HCRT regulation of reward and reinforcement may be related to disruptions to DA neurotransmission.

Biased agonists of the kappa opioid receptor suppress pain and itch without causing sedation or dysphoria

Agonists targeting the kappa opioid receptor (KOR) have been promising therapeutic candidates because of their efficacy for treating intractable itch and relieving pain. Unlike typical opioid narcotics, KOR agonists do not produce euphoria or lead to respiratory suppression or overdose. However, they do produce dysphoria and sedation, side effects that have precluded their clinical development as therapeutics. KOR signaling can be fine-tuned to preferentially activate certain pathways over others, such that agonists can bias signaling so that the receptor signals through G proteins rather than other effectors such as βarrestin2. We evaluated a newly developed G protein signaling-biased KOR agonist in preclinical models of pain, pruritis, sedation, dopamine regulation, and dysphoria. We found that triazole 1.1 retained the antinociceptive and antipruritic efficacies of a conventional KOR agonist, yet it did not induce sedation or reductions in dopamine release in mice, nor did it produce dysphoria as determined by intracranial self-stimulation in rats. These data demonstrated that biased agonists may be used to segregate physiological responses downstream of the receptor. Moreover, the findings suggest that biased KOR agonists may present a means to treat pain and intractable itch without the side effects of dysphoria and sedation and with reduced abuse potential.

Social isolation rearing increases nucleus accumbens dopamine and norepinephrine responses to acute ethanol in adulthood

BACKGROUND

Early-life stress is associated with increased vulnerability to alcohol addiction. However, the neural substrates linking chronic childhood/adolescent stress and increased risk of alcohol addiction are not well understood. In the nucleus accumbens (NAc), dopamine (DA) and norepinephrine (NE) signaling can be profoundly influenced by stress, anxiety, and drugs of abuse, including ethanol (EtOH). Here, we employed a rodent model of early-life stress that results in enduring increases in behavioral risk factors of alcoholism to gain a better understanding of how chronic adolescent stress may impact the EtOH sensitivity of DA and NE release in the NAc.

METHODS

Male Long-Evans rats were either group housed (GH; 4 rats/cage) or socially isolated (SI; 1 rat/cage) for 6 weeks beginning on postnatal day 28. SI and GH rats were tested in adulthood for anxiety-like behaviors (elevated plus maze), and the effects of EtOH (1 and 2 g/kg; intraperitoneally.) on NAc DA and NE were assessed by microdialysis.

RESULTS

SI animals showed increased anxiety-like behavior compared to GH animals. Although SI had no effect on baseline levels of DA or NE, baseline DA levels were positively correlated with anxiety measures. In addition, while no significant differences were observed with 1 g/kg EtOH, the 2 g/kg dose induced significantly greater DA release in SI animals. Moreover, EtOH (2 g/kg) only elevated NAc NE levels in SI rats.

CONCLUSIONS

These results suggest that chronic early-life stress sensitizes accumbal DA and NE release in response to an acute EtOH challenge. A greater EtOH sensitivity of DA and NE release dynamics in the NAc may contribute to increases in behavioral risk factors of alcoholism, like greater EtOH self-administration, that are observed in SI rats.

Moderate Alcohol Exposure during the Rat Equivalent to the Third Trimester of Human Pregnancy Alters Regulation of GABAA Receptor-Mediated Synaptic Transmission by Dopamine in the Basolateral Amygdala

Fetal ethanol (EtOH) exposure leads to a range of neurobehavioral alterations, including deficits in emotional processing. The basolateral amygdala (BLA) plays a critical role in modulating emotional processing, in part, via dopamine (DA) regulation of GABA transmission. This BLA modulatory system is acquired during the first 2 weeks of postnatal life in rodents (equivalent to the third trimester of human pregnancy) and we hypothesized that it could be altered by EtOH exposure during this period. We found that exposure of rats to moderate levels of EtOH vapor during the third trimester-equivalent [postnatal days (P) 2-12] alters DA modulation of GABAergic transmission in BLA pyramidal neurons during periadolescence. Specifically, D1R-mediated potentiation of spontaneous inhibitory postsynaptic currents (IPSCs) was significantly attenuated in EtOH-exposed animals. However, this was associated with a compensatory decrease in D3R-mediated suppression of miniature IPSCs. Western blot analysis revealed that these effects were not a result of altered D1R or D3R levels. BLA samples from EtOH-exposed animals also had significantly lower levels of the DA precursor (L-3,4-dihydroxyphenylalanine) but DA levels were not affected. This is likely a consequence of reduced catabolism of DA, as indicated by reduced levels of 3,4-dihydroxyphenylacetic acid and homovanillic acid in the BLA samples. Anxiety-like behavior was not altered in EtOH-exposed animals. This is the first study to demonstrate that the modulatory actions of DA in the BLA are altered by developmental EtOH exposure. Although compensatory adaptations were engaged in our moderate EtOH exposure paradigm, it is possible that these are not able to restore homeostasis and correct anxiety-like behaviors under conditions of heavier EtOH exposure. Therefore, future studies should investigate the potential role of alterations in the modulatory actions of DA in the pathophysiology of fetal alcohol spectrum disorders.

Effects of early life stress on drinking and serotonin system activity in rhesus macaques: 5-hydroxyindoleacetic acid in cerebrospinal fluid predicts brain tissue levels

Early childhood stress is a risk factor for the development of substance-abuse disorders. A nonhuman primate model of early life stress, social impoverishment through nursery-rearing rather than mother-rearing, has been shown to produce increased impulsive and anxiety-like behaviors, cognitive and motor deficits, and increased alcohol consumption. These behavioral changes have been linked to changes in cerebrospinal fluid (CSF) levels of 5-hydroxyindoleacetic acid (5-HIAA), a serotonin (5-HT) metabolite. The effects of different rearing conditions on ethanol drinking and three measures of 5-HT function in the central nervous system were evaluated, including CSF 5-HIAA levels and tissue levels of 5-HT and 5-HIAA in brain samples. Brain samples were taken from the dorsal caudate, putamen, substantia nigra (SN) pars reticulata, SN pars compacta and hippocampus. There was a clear effect of rearing condition on the 5-HT system. Overall 5-HIAA and 5-HIAA/5-HT ratio measures of 5-HT turnover were significantly lower in nursery reared compared to mother-reared animals. In addition, there was a strong within-subject correlation between CSF and brain tissue 5-HIAA levels. Ethanol drinking was greater in nursery reared monkeys, consistent with previous results. These findings show that CSF 5-HIAA measurements can be used to predict brain 5-HT activity that may be involved in behavioral outcomes such as anxiety and alcohol consumption. Thus, CSF sampling may provide a minimally invasive test for neurochemical risk factors related to alcohol abuse.

The hypocretin-orexin system regulates cocaine self-administration via actions on the mesolimbic dopamine system

Recent evidence suggests that the hypocretin-orexin system participates in the regulation of reinforcement processes. The current studies examined the extent to which hypocretin neurotransmission regulates behavioral and neurochemical responses to cocaine, and behavioral responses to food reinforcement. These studies used a combination of fixed ratio, discrete trials, progressive ratio and threshold self-administration procedures to assess whether the hypocretin 1 receptor antagonist, SB-334867, reduces cocaine self-administration in rats. Progressive ratio sucrose self-administration procedures were also used to assess the extent to which SB-334867 reduces responding to a natural reinforcer in food-restricted and food-sated rats. Additionally, these studies used microdialysis and in vivo voltammetry in rats to examine whether SB-334867 attenuates the effects of cocaine on dopamine signaling within the nucleus accumbens core. Furthermore, in vitro voltammetry was used to examine whether hypocretin knockout mice display attenuated dopamine responses to cocaine. Results indicate that when SB-334867 was administered peripherally or within the ventral tegmental area, it reduced the motivation to self-administer cocaine and attenuated cocaine-induced enhancement of dopamine signaling. SB-334867 also reduced the motivation to self-administer sucrose in food-sated but not food-restricted rats. Finally, hypocretin knockout mice displayed altered baseline dopamine signaling and reduced dopamine responses to cocaine. Combined, these studies suggest that hypocretin neurotransmission participates in reinforcement processes, likely through modulation of the mesolimbic dopamine system. Additionally, the current observations suggest that the hypocretin system may provide a target for pharmacotherapies to treat cocaine addiction.

A theory of neurolinguistic development

This article offers a developmental theory of language and the neural systems that lead to and subserve linguistic capabilities. Early perceptual experience and discontinuities in linguistic development suggest that language develops in four phases that occur in a fixed, interdependent sequence. In each phase of language, a unique ontogenetic function is accomplished. These functions have proprietary neural systems that vary in their degree of specialization. Of particular interest is an analytical mechanism that is responsible for linguistic grammar. This mechanism is time-locked and can only be turned on in the third phase. Confirming evidence is provided by children who are delayed in the second phase of the language learning process. These children store insufficient lexical material to activate their analytic mechanism. Inactivation behaves like damage, shifting language functions to homologous mechanisms in the nondominant hemisphere, thereby increasing functional and anatomical symmetry across the hemispheres. This atypical assembly of neurolinguistic resources produces functional but imperfect command of spoken language and may complicate learning of written language. The theory thus offers a different role for genetics and early experience, and a different interpretation of neuroanatomic findings, from those entertained in most other proposals on developmental language disorders.

A fatality due to alprazolam intoxication

Alprazolam is one of the most widely prescribed benzodiazepines in the United States. It is generally considered a safe and effective drug for the treatment of anxiety disorders and panic attacks. Few overdoses that are due to the sole ingestion of alprazolam have been reported. This paper documents a fatality due to alprazolam intoxication and describes the distribution of alprazolam and an active metabolite, alpha-hydroxyalprazolam, in tissues obtained at autopsy. Qualitative identification of the drugs was achieved by full-scan gas chromatography-mass spectrometry, and quantitative analysis was performed by high-performance liquid chromatography. High concentrations of alprazolam were found in all specimens analyzed, but the metabolite was detected only in subclavian blood, urine, bile, and liver. A postmortem heart blood alprazolam concentration of 2.1 mg/L is the highest reported in the literature to date.

Why do infants begin to talk? Language as an unintended consequence

Scholars have addressed a range of questions about language development, but for some reason have neglected to ask why infants begin to talk. Biologists often prefer 'how' to 'why' questions, but it is possible to ask about the immediate consequences of developing behaviours--an acceptable strategy for attacking causation--and psycholinguists can study the immediate consequences to the infant of behaviours that lead to linguistic competence. This process is demonstrated with a series of illustrative proposals as to the short- and long-term consequences of vocal learning and utterance storage, two developmental phases that lead to talking, as well as the act of talking itself. The goal is to encourage investigation of behavioural dispositions that nudge the child, by degrees, towards proficiency in the use of spoken language.

Emergent control of manual and vocal-motor activity in relation to the development of speech

Babbling typically precedes, resembles, and conceivably facilitates development of speech, and yet there is no accepted neurobiological characterization of babbling. Here we report a study of infants' developing control of vocal behavior in relation to manual activity performed under differing conditions of audibility. We hypothesized that babbling is associated with the onset of left-lateralized motor control, as expressed in repetitive right-handed activity, and that audibility facilitates such activity. Sixty-one normally developing infants were seen before (N = 21) or at various intervals following (N = 40) the onset of babbling. In experimental trials, audible or inaudible rattles were placed in left or right hands equally often. Analysis of manual activity revealed little shaking movement in the youngest and vocally least differentiated infants, and a sharp increase in shaking in slightly older infants who had recently begun to babble. Surprisingly, audibility only marginally enhanced shaking activity. A dextral bias was evident in the shaking of infants who had recently begun to babble, but not in younger or older infants. These and other findings suggest that the left cerebral hemisphere may be disproportionately involved in the production of repetitive vocal-motor activity as occurs in babbling.

Gradual emergence of developmental language disorders

This article presents a theory of normal and delayed development of language. According to the theory, linguistic capacity develops in critically timed phases that occur gradually and sequentially. Normally, the rapid accumulation of stored utterances activates analytical mechanisms that are needed for the development of linguistic grammar. Children with slowly developing brains have delays in the socially cognitive systems that store utterances, and a critical period for activation of experience-dependent grammatical mechanisms declines without optimal result. Continuing efforts to speak induct species-atypical allocations of neural resources into linguistic service. It is speculated that this compensatory activity leads to compensatory growth, which may ultimately be revealed as volumetric symmetry of perisylvian areas. Because rate of brain maturation is under genetic as well as environmental control, the stage is thus set for an impairment that will seem to be specific and a brain that will appear to be abnormal.

Thirty years of research on developmental neurolinguistics

A body of medically important work has accumulated in the field of developmental neurolinguistics in the 30 years since Lenneberg set forth a research agenda for that field, consisting of the following: (1) the physiologic specialization or endowment for speech; (2) the genetic origin or natural history of vocalization and speech; (3) the nature of prelinguistic behavior, making possible the detection of any environmental (social) influences; (4) the development of motor-speech organization from birth; and (5) the limiting effects of deficient intelligence, hearing, and environmental stimulation. Subsequent study of these questions has established a genetic, neuroanatomic, and functional basis for such outwardly disparate disorders as dyslexia, stuttering, autism, and delayed language. Studies of emergent motor behavior suggest that babbling may index a state of neural maturation favoring expression of spoken languages. Based on studies of the congenitally deaf, mentally retarded, and other clinical populations it is now considered possible to detect early warning signs of developmental language disorders during the first year of life based on analyses of vocal turn-taking, gesturing, and utterance complexity.

Structure and stimulation in the ontogeny of spoken language

Linguistic innateness is a fundamentally physical notion, which ultimately requires independent physical evidence. For spoken language, it is relevant to consider babbling, components of which are unaffected by ambient stimulation and are predicted by models of vocal tract function. Links between babbling and speech point to innate factors in the ontogeny of spoken language and invite attention to central control mechanisms. These neural capabilities enable oral language learning by providing children with control over an initial stock of speech-like movements and by directing their attention to salient linguistic patterns. Dispositions to attend to some cues are so strong that little stimulation is required. In other cases, predispositions are weak, and acquisition requires correspondingly more experience. To understand the ontogeny of language, we need to learn which cases are which and to know how these interactions occur and change over the course of acquisition.

Angiosarcoma of the axillary vein

Angiosarcoma is a malignant tumor of vascular origin. Malignant primary vein tumors are rare. The case of a 64-year-old patient who underwent a left forequarter amputation for angiosarcoma arising from the left axillary vein, a site not previously described, is presented. Also, the literature is reviewed.

Segmental infarct of the testis due to hypersensitivity angiitis

We present a case of hypersensitivity angiitis causing a segmental infarction of the testis. The lesion presented as a discrete, palpable mass that led to orchiectomy. Hypersensitivity angiitis has not been reported previously to affect the testes or to produce a segmental infarct in any solid organ. A discussion is given of the vasculitides, especially periarteritis nodosa, that may involve the testes.

Stress-related rib and vertebral changes

In the course of routine chest examination, 80 asymptomatic patients were observed to have localized hyperostosis of the posterior ribs and articulating transverse processes. The authors studied the distributions of lesions in these 80 patients, and records were reviewed in the 50 cases in which they were available. The occupational histories, male-to-female ratio (5:1), and ratio of right-to-left rib involvement (9:1)--in addition to results of electromyographic and histologic studies and the principles of bone remodeling--suggest that this hyperostosis occurs at sites most stressed with bending and rotation of the thorax. The authors hypothesize that this stress-related change occurs due to the pull of the iliocostalis thoracis muscle and is of no clinical significance.

The processing of printed language by aphasic adults: some phonological and syntactic effects

Eight aphasic and eight brain-damaged nonaphasic patients silently "read" a short passage while performing an internal search for specified consonant letters of varying phonological and syntactic salience. The nonaphasic patients showed the phonological and syntactic effects customarily achieved by normal readers. For example, they were more likely to find a letter if it were pronounced than if it were silent, and they were more likely to find a letter if it were in a content word than in a function word. The aphasics had reliable phonological effects but no observable syntactic effects. Those aphasics with relatively large phonological effects performed better on a separate task requiring the oral reading of isolated words. For reading theory, the primary message from this study is that phonological recoding may occur between word recognition and the completion of semantic analysis, and that recoding may not by itself be sufficient to reading for meaning. For aphasia theory, the main implication of this study is that aphasics read by applying the appropriate phonological strategies, but that such strategies are limited in the face of ineffective syntactic and semantic processing, as occurs in aphasia.

The inference of speech perception in the phonologically disordered child. Part II: Some clinically novel procedures. Their use, some findings

Several procedures used to assess speech perception of children with disorders at the phonological level of language are described. In most cases of segmental substitution, children discriminated target and substitution phonemes regardless of whether both were spoken by an adult, or one form was produced by an adult and the other was the child's internal representation of the target phoneme. However, in about a third of the cases there was consistent failure to discriminate the target phoneme from the substituted phoneme. Perceptual approaches to the treatment of sound production problems are questioned when perception is inferably differential. Certain phonetic effects, and their implications for theories of phonological acquisition and disorder, are discussed.

The inference of speech perception in the phonologically disordered child. Part I: A rationale, some criteria, the conventional tests

This paper considers the rationale and presents some criteria for assessing the speech perception of children with disorders at the phonological level of language. An examination of conventional test procedures suggests that none is useful in identifying clinically relevant perceptual disorders. However, readers are encouraged to inspect Part II (Locke, 1980), which describes procedures with more clinical promise.

Large auditory and small visual effects in the recall of consonant letters

Eighty-six adults serially recalled lists of visually presented consonant letters similar in auditory or visual features or dissimilar in both feature sets. There were significantly more errors at every auditory list position than at the corresponding visual and neutral list positions, which did not themselves differ. There was a positive correlation between the tendency toward phonetic coding and overall performance, with 75 subjects making more errors on the auditory list than either of the other lists. The eight subjects who made more errors on the visual list showed poor performance in the recall of all lists. Factors governing the perceivability of stimuli apparently do not continue to operate significantly in controlling their recallability, at least in the case of veridical visual input.

Memory for speech and speech for memory

Thirty kindergarteners, 15 who substituted /w/ for /r/ and 15 with correct articulation, received two perception tests and a memory test that included /w/ and /r/ in minimally contrastive syllables. Although both groups had nearly perfect perception of the experimenter's productions of /w/ and /r/, misarticulating subjects perceived their own tape-recorded w/r productions as /w/. In the memory task these same misarticulating subjects committed significantly more /w/-/r/ confusions in unspoken recall. The discussion considers why people subvocally rehearse; a developmental period in which children do not rehearse; ways subvocalization may aid recall, including motor and acoustic encoding; an echoic store that provides additional recall support if subjects rehearse vocally, and perception of self- and other- produced phonemes by misarticulating children-including its relevance to a motor theory of perception. Evidence is presented that speech for memory can be sufficiently impaired to cause memory disorder. Conceptions that restrict speech disorder to an impairment of communication are challenged.

Children's phonetic learning in the laboratory: judgmental or real?

To determine whether an “expectation-of-learning” effect was operative in judging a child’s phonetic imitation, two techniques for scoring were used to evaluate sequentially one child’s phonetic imitations. A tape of this child attempting, in 20 trials, to imitate a novel syllable [′e ⊣ Ʒ ə] was played forward (Trials 1 to 20) to six judges. Of these six, one group of three judges used a seven-point rating scale to evaluate the adequacy of the child’s imitation of the syllable, while the other three used a phonemic-classification system. A reverse tape (Trials 20 to 1) also was evaluated similarly by two different groups of three judges. Judges assigned lower scores to “early” rather than “late” responses only if initial responses were heard first. The phonetic learning of the child in this experiment was real, but judgmental bias radically enhanced it in forward-order and nearly destroyed it in reverse-order listening.

Ease of articulation

Two tasks required adults to estimate the muscular ease of articulating word-initial consonant phonemes. Ease ratings were positively correlated with Templin’s data (1957) on three-year-old children’s degree of mastery of these same phonemes. Three-year-olds' phoneme perception data (Koenigsknecht) were not correlated with phoneme production, lending mild support to a motor ease hypothesis of phonological development. Children’s articulatory substitutions (Snow, 1963) also were found to be explainable on the basis of ease of articulation, with substituted phonemes receiving “easier” ratings than the target phonemes for which they were substituted. Adult ease ratings and children’s articulatory mastery of manner, place, and voicing features generally were in fairly close agreement. The significance of these findings is discussed, as well as certain problems presented by the use of adult ease ratings and data from disparate sources and populations.

Phonetic correlates of graphic recall

A previous paper (Locke & Fehr, in press a) reported analyses of EMG recordings from a chin-lip sire of 24 adults during their perception and rehearsal of word lists, with the general finding that lip activity was substantially greater when Ss processed lip-articulated compared to nonlabial words. This paper reports a subsequent analysis of phonetic activity during Ss' recall of the word lists, which was effected orally or graphically, with the finding that Ss' written reports were accompanied by as much motor-phonetic activity as spoken recall. The primary difference between overt and covert forms of speech appears not to lie in the nature of labial-nonlabial tracing relationships but in the absolute magnitude of EMG values.

Phonemic processing in silent reading

6 adults silently read short passages containing a high, medium, or low frequency of words whose pronunciation requires labial movement. Analysis of electromyographic recordings at a chin-lip site showed significantly higher tracings for the high- than for the low-labial passages, suggesting that covert oral activity during silent reading is a form of speech and can be measured.

Phoneme perception in two- and three-year-old children

20 2- and 3-yr.-old children were given a phoneme perception task in which they were to point to one of two pictures whose labels differed by minimally discriminable phonetic features. Results suggested that picture identification testing can be used successfully to test phoneme perception in Ss as young as 2 yr., that place-of-articulation cues are not difficult for young children to distinguish, and that children's acquisition of expressive phonology must not be wholly dependent on their ability to process phonetic cues from the environment.

Short-term auditory memory, oral perception, and experimental sound learning

Ten children with high scores on an auditory memory span task were significantly better at imitating three non-English phones than 10 children with low auditory memory span scores. An additional 10 children with high scores on an oral stereognosis task were significantly better at imitating two of the three phones than 10 children with low oral stereognosis scores. Auditory memory span and oral stereognosis appear to be important subskills in the learning of new articulations, perhaps explaining their appearance in the literature as “etiologies” of disordered articulation. Although articulation development and the experimental acquisition of non-English phones have certain obvious differences, they seem to share some common processes, suggesting that the sound learning framework may be an efficacious technique for revealing otherwise inaccessible information.

Discriminative learning in children's acquisition of phonology

The theories of acquired equivalence and acquired distinctiveness of cues are presented as particularly effectual models in terms of their capacity to explain certain normal and deviant articulation learning. Articulation therapy is discussed as an application of the acquired distinctiveness model. Both theories generate basic, clinically pertinent, testable questions.

Oral perception and articulation learning

10 children with inaccurate oral perception were less able to learn new consonant articulations than 10 Ss with accurate oral perception. Oral stereognosis was discussed as a substrate of articulation skill. The linguistic significance of experimental sound learning was pondered.

Long Base Line Interferometry: A New Technique

The technique of using magnetic-tape recorders and atomic frequency standards to operate two widely separated radio telescopes as a phase-coherent interferometer when the stations have no radio-frequency connecting link has been successfully tested at the National Research Council of Canada's Algonquin Radio Observatory.