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W S Hall

Publications and source records attributed to W S Hall.

At least 19 recordsLinked to original sources
PubMed2001

Distribution of iron in the parrot brain: conserved (pallidal) and derived (nigral) labeling patterns.

The distribution of iron in the brain of a vocal learning parrot, the budgerigar (Melopsittacus undulatus), was examined using iron histochemistry. In mammals, iron is a highly specific stain for the dorsal and ventral pallidal subdivision as well as specific cell groups in the brainstem, including the substantia nigra pars reticulata [Neuroscience 11 (1984) 595-603]. The purpose of this study was to compare the distribution of iron in the mammalian and avian brain focusing on pallidal and nigral cell groups. The results show that in the avian brain, iron stains oligodendrocytes, neurons and the neuropil. Cell staining changes dramatically along the rostrocaudal axis, with neuronal labeling confined to regions caudal to the thalamus and oligodendrocyte labeling denser in regions rostral to the dorsal thalamus. Many sensory forebrain regions contain appreciable iron labeling, including telencephalic vocal control nuclei. The dorsal and ventral subdivision of the avian pallidum, along with the basal ganglia component of the vocal control circuit, the magnicellular nucleus of the lobus parolfactorius, stain heavily for iron. Several brainstem regions, including nucleus rotundus, the medial spiriform nucleus (SpM), the principle nucleus of the trigeminal nerve, nucleus laminaris and scattered cell groups throughout the isthmus and pontine reticular formation stain intensely for iron. Within SpM neuronal labeling is more intense in the medial division while oligodendrocyte labeling is more intense in the lateral division. surprisingly no nigral iron staining was observed. Our results imply that iron is a conserved marker for the pallidum in birds and mammals, but that patterns of nigral staining have diverged in birds and mammals. Differences in iron staining patterns between birds and mammals may also reflect the relatively greater importance of the collothalamic visual pathways, pretectal-cerebellar pathways and specialized vocal learning circuitry in avian sensory and motor processing.

Animals↗
PubMed2001

Distribution of tyrosine hydroxylase-containing neurons and fibers in the brain of the budgerigar (Melopsittacus undulatus): general patterns and labeling in vocal control nuclei.

The distribution of tyrosine hydroxylase (TH) was mapped out in cells and fibers of the budgerigar (Melopsittacus undulatus) brain. Special attention was given to vocal control and auditory nuclei because budgerigars are a psittacine species in which both males and females are capable of lifelong vocal learning (Farabaugh et al. [1994] J. Comp. Psychol 108:81-92). The results show that TH staining in the central nucleus of the anterior archistriatum (AAc) resembled that of surrounding archistriatal fields, except for portions of the ventral archistriatum, which exhibited substantially more TH+ fibers. Fewer fibers and fiber baskets are present in the central nucleus of the lateral neostriatum (NLc) than in surrounding fields. Both the oval nuclei of the ventral hyperstriatum (HVo) and anterior neostriatum (NAo) exhibit less fiber staining than surrounding fields whereas fiber staining in the medial NAo (NAom) and magnicellular nucleus of the parolfactory lobe (LPOm) resemble that of surrounding fields. Staining in primary telencephalic auditory nuclei was extremely low. The only sex difference observed was slightly increased TH staining in LPOm of females compared with surrounding fields on some tissue sections. These findings are in contrast to previous findings in zebra finch (Poephila guttata), a close ended vocal learning songbird in which TH staining in vocal nuclei increases during development and remains greater than surrounding fields throughout adulthood. The present results therefore support the view that catecholamines act to inhibit vocal plasticity in adult vocal learning species. Several unique features of TH-immunoreactive (ir) cell groups were observed in the brainstem including sparsely scattered TH-ir somata immediately adjacent to the third ventricle, within the tectum, basal forebrain, archistriatum, and caudal neostriatum, and in the hippocampus. These latter populations have not been described in other avian species and resemble features of the catecholamine system generally found in either reptiles or mammals.

Animals↗
PubMed1999

Cytoarchitecture of vocal control nuclei in nestling budgerigars: relationships to call development.

Changes in the cytoarchitecture of vocal control nuclei were investigated in nestling budgerigars (Melopsittacus undulatus) from hatching to fledging (five to six weeks) in relation to changes in vocalizations produced by nestlings during this period. The nuclei investigated were the hypoglossal nucleus, dorsomedial nucleus of the intercollicular midbrain, central nucleus of the archistriatum, central nucleus of the lateral neostriatum, oval nucleus of the hyperstriatum ventrale, medial division of the oval nucleus of the anterior neostriatum, and magnocellular nucleus of the lobus parolfactorius. These nuclei have been shown to form functional circuits in adults related to vocal learning. Consistent with previously reported results, we found that call development could be described in terms of five different phases based on changes in the duration and segmentation of single and multiple segment food begging calls and the appearance of the first socially learned contact calls around the time of fledging. We also found that call segment duration exhibited an inverted U-shaped developmental function during the nestling period, as has been found for total call duration. Cytoarchitectonic studies revealed striking changes in the cellular architecture of vocal control nuclei during the first four weeks posthatching. At hatching the hypoglossal nucleus exhibits adult-like cytoarchitecture, and the central nucleus of the archistriatum and the central nucleus of the lateral neostriatum are distinguishable from surrounding fields. By one week posthatch, the central nucleus of the archistriatum exhibits an adult-like appearance, while other telencephalic vocal control nuclei do not exhibit adult-like cytoarchitecture until three to four weeks posthatching. By two weeks posthatching, the dorsomedial nucleus of the intercollicular midbrain also exhibits adult-like cytoarchitecture. We observed substantial decreases in the thickness of ventricular proliferation zones during this period, with decreases in ventricular zones occurring at about the same point that nuclei at corresponding levels come to exhibit adult-like cytoarchitectonic features. Of interest is the fact that cytoarchitectural development occurs asynchronously in different brain regions, with the appearance of adult-like characteristics in the hindbrain and midbrain occurring before the appearance of adult-like cytoarchitectonic characteristics in telencephalic nuclei. These results are consistent with recent lesion studies indicating that neither auditory feedback nor telencephalic vocal control nuclei are necessary for the production of food begging and other nestling calls until three to four weeks posthatching.

Animals↗
PubMed1997

Functional anatomy of forebrain vocal control pathways in the budgerigar (Melopsittacus undulatus).

Budgerigars throughout life are capable of learning to produce many different sounds including those of human speech. Like humans, budgerigars use multiple craniomotor systems and coordinate both orosensory and auditory feedback in specialized forebrain nuclei. Although budgerigar auditory-vocal learning has a different evolutionary origin from that of human speech, both the human and budgerigar systems can control F0 and can alter the distribution of energy in spectral bands by adjusting the filter properties of the vocal tract. This allows budgerigars to produce an extremely diverse array of calls including many broadband and highly complex sounds.

Animals↗
PubMed1997

Molecular analysis of episomal human papillomavirus type 16 DNA in a cervical carcinoma cell line.

Integration of human papillomavirus type 16 DNA sequences into host DNA is a frequent event in cervical carcinogenesis. However, recent studies showing that HPV16 is present exclusively in an episomal form in many primary cervical cancers suggest that HPV16 can transform target cells by mechanisms that do not require viral integration. We have established a cervical carcinoma cell line that harbors episomal copies of HPV16 DNA of approximately 10 kb. Restriction enzyme and two-dimensional gel analysis confirmed that HPV16 DNA was extrachromosomal with both monomeric and multimeric forms present. HPV16 was maintained as episomes with passage both in culture and after subcutaneous growth in nude mice. The 10 kb viral genome, consisting of a full-length copy of HPV16 and a partial duplication of the long control region and the L1 open reading frame, exhibited transforming activity comparable to prototype HPV16. This cell line should provide a useful model system for studying the biological significance of the physical state of the HPV16 genome in cervical carcinoma cells.

Animals↗
PubMed1997

Acquisition of the mental state verb know by 2- to 5-year-old children.

The production of the cognitive internal state word know by four 2- to 5-year-old children and their parents was examined. The levels of meaning of cognitive words can be categorized hierarchically along the dimensions of conceptual difficulty and abstractness (see Booth & Hall, 1995). The present study found that children and their parents expressed low levels of meaning less frequently, whereas they expressed high levels of meaning more frequently as a function of age. The children's use of know was also correlated positively with (1) their number of different words produced suggesting that cognitive words are related to more general semantic processes, and (2) with parental use of those same cognitive words suggesting that parental linguistic input may be an important mechanism in cognitive word acquisition. Finally, young children tended to use know more to refer to themselves than to refer to others, whereas their parents tended to use know equally to refer to self and others. The importance of cognitive words in a theory of language acquisition is discussed.

Adult↗
PubMed1996

Distribution of choline acetyltransferase and acetylcholinesterase in vocal control nuclei of the budgerigar (Melopsittacus undulatus).

The present study used histochemical methods to map the distributions of choline acetyl transferase (ChAT) and acetylcholinesterase (AChE) in the vocal control nuclei of a psittacine, the budgerigar (Melopsittacus undulatus). The distributions of ChAT and AChE in budgerigars appeared similar to that in oscine songbirds despite evidence that these systems have evolved independently. The magnicellular nucleus of the lobus parolfactorius in budgerigars, like the area X in songbirds, contained many ChAT labeled somata, fibers, and varicosities and stained densely for AChE. In contrast, the robust nucleus of the archistriatum (RA) and the supralaminar area of the frontal neostriatum in budgerigars, like the RA and the magnicellular nucleus of the neostriatum (MAN) in songbirds, respectively, contained few or no ChAT labeled somata, fibers, and varicosities and stained lightly for AChE. The central nucleus of the lateral neostriatum in budgerigars, like the higher vocal center (HVC) in songbirds, contained no ChAT labeled somata, moderate densities of ChAT labeled fibers and varicosities, and moderate levels of AChE staining. Two nuclei, the oval nucleus of the hyperstriatum ventrale (HVo) and the oval nucleus of the anterior neostriatum (NAo), contained no ChAT labeled somata, dense ChAT labeled fibers and varicosities, and moderate to high levels of AChE staining. The HVo and the NAo have no counterparts in songbirds but may be important vocal control nuclei in the budgerigar. Cholinergic enzymes are also described in other regions which may be involved in budgerigar vocal behavior, including the basal forebrain, the torus semicircularis, and the hypoglossal nuclei (nXII).

Acetylcholinesterase↗
PubMed1994

Functional anatomy of forebrain auditory pathways in the budgerigar (Melopsittacus undulatus).

Interconnections of forebrain auditory and vocal control nuclei were mapped in the budgerigar using pathway tracing techniques. The anatomical results indicate four circuits by which auditory information may influence the vocal motor system: (1) direct auditory thalamic projections from nucleus dorsomedialis posterior (DMP) to both the neostriatal higher vocal center (HVC) and robust archistriatal nucleus (RA); (2) direct projections from a neostriatal projection field of DMP (i.e., MAN, the magnocellular nucleus of the neostriatum) to HVC and RA; (3) projections from DMP and other 'accessory' auditory thalamic nuclei to the ventral paleostriatum (VP), which in turn projects to MAN and RA; (4) projections to HVC from the lateral hyperstriatum ventrale (HV), which receives input from nucleus basalis (Bas) as well as from the oval nucleus of the HV (HVo), which receives direct input from RA. Lesion methods were used to evaluate the roles of auditory pathways in call learning and production. The results show that pathways associated with Bas are essential for call production in both adult and unfledged budgerigars, while VP efferents influence vocalization only in young, unfledged budgerigars. Lesions centered in either the primary auditory neostriatum (Field L2a) or the neostriatal area in receipt of Field L input (the ventrolateral neostriatum intermedium or NIVL) did not affect vocalization in juvenile or adult budgerigars.

Animals↗
PubMed1994

Comparison of the effects of lesions in nucleus basalis and field 'L' on vocal learning and performance in the budgerigar (Melopsittacus undulatus).

Lesions were placed in either nucleus basalis (Bas) or the primary thalamorecipient portion of Field 'L' (i.e. centered in Field L2a) in budgerigars at 3-5 weeks posthatching and as adults. The calls of birds sustaining Bas lesions before fledging, or as adults, were markedly abnormal in that they showed little frequency modulation and individual distinctiveness. Call durations, however, were similar for lesioned and unlesioned birds. In contrast, the calls of Field 'L' lesioned birds were similar to those of siblings and cagemates. This implies that the roles of the isthmofrontal (i.e., direct projections from the ventrolateral nucleus of the lateral lemniscus to Bas) and thalamotelencephalic (i.e., direct projections from nucleus ovoidalis thalami to Field L2a) auditory pathways in providing auditory feedback during vocal learning and performance are different and that the isthmofrontal pathway plays an essential role in these processes throughout the life of the animal.

Animals↗
PubMed1993

Auditory projections to the anterior telencephalon in the budgerigar (Melopsittacus undulatus).

The connections of a higher order auditory area in the neostriatum intermedium pars ventrolateralis (NIVL) were mapped with pathway tracing techniques in order to elucidate possible pathways by which auditory feedback may influence vocal learning in the budgerigar (Melopsittacus undulatus). Previous research has shown that NIVL receives projections from Field 'L' as well as adjacent portions of the dorsolateral neostriatum intermedium (NIDL) and hyperstriatum ventrale (HV) and, therefore, may be homologous to previously described auditory centers in the dorsal and lateral portions of the auditory neostriatum of songbirds. The efferent connections of NIVL terminate within a small portion of the rostromedial archistriatum as well as a more rostrally situated area within the medial neostriatum intermedium (NI) and HV. Near by (but not overlapping) fields in NI and HV receive input from the nucleus dorsomedialis posterior thalami (DMP), the archistriatum and ectostriatum. Interestingly, only the DMP projection field overlaps a neural field known to be related to the vocal motor system. The DMP projection field corresponds to that previously described as the magnocellular nucleus of the anterior neostriatum; this nucleus is known to project to the higher vocal center in the budgerigar. In addition to projections from NIVL to medial NI and HIV, auditory information is relayed to the anterolateral telencephalon directly from the brainstem via the ventrolateral nucleus of the lateral lemniscus (VLV). This latter pathway appears comparable to that described in pigeons derived from the intermediate nucleus of the lateral lemniscus. The projection field of VLV overlaps a restricted portion of the caudal and medial aspect of nucleus basalis. These results support the notion that many aspects of telencephalic auditory pathways in birds are primitive characters, although a direct connection between auditory and vocal motor circuits was not found in the present study.

Animals↗
PubMed1989

Acute toxicity of industrial surfactants to Mysidopsis bahia.

Three- to eight-day old Mysidopsis bahia were used to evaluate the acute toxicities of 17 industrial surfactants having a wide range of physiochemical characteristics. LC50s based on nominal concentrations covered approximately three orders of magnitude (less than 1 to greater than 4,000 mg/L). The base structure of the surfactants (i.e., aromatic or aliphatic, branched or linear) was not a factor controlling toxicity. Low solubility surfactants with low ethylene oxide (EO) molar ratios were the most toxic surfactants tested. Ethylene oxide chain length was the best predictor of toxicity, and would be a good parameter to use to "screen" for surfactant toxicity in hazard assessment. Substitution of terminal OH with SO3 or PO4 reduced toxicity of a selected group of surfactants. Sensitivity of M. bahia up to 26 days old was not significantly different from that of 3- to 8-day old animals. Use of one surfactant as a reference toxicant demonstrated that sensitivity of M. bahia was consistent throughout the various tests.

Animals↗
PubMed1981

Combination therapy of a mouse sarcoma using razoxane and electron irradiation.

The combination of a single dose of razoxane (ICRF 159) with a single dose of electron radiation has been studied with the murine sarcoma S180. A drug dose of 30 mg/kg combined with radiation produced a greater tumour response than either agent alone, but it was not possible to establish whether the effect was more than additive. Direct measurements of tumour and s.c. oxygen concentrations and studies of tumour-cell respiration were carried out after various razoxane treatments in an attempt to elucidate mechanisms of action. There were no indications at the drug dose levels used in the radiation studies of any significant changes in tissue oxygenation or cellular respiration.

Animals↗