PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Strigiformes”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources
PubMed2004

Owls' eyes move.

Explore the source record for details and available documents.

Animals↗
PubMed2003

Double crossed.

Explore the source record for details and available documents.

Animals↗
PubMed2004

Use of endoscopy and renal biopsy for the diagnosis of kidney disease in free-living birds of prey and owls.

Eighty-nine free-living birds of prey and owls were examined and blood samples and radiographs were taken. In addition, 126 specimens of renal tissue were obtained without complications, with a mean postbiopsy haemorrhage time of 67 seconds. On average, the samples were 2.2 mm long, 1.3 mm wide and 1.0 mm deep and they all contained proximal and distal tubuli and from one to 89 glomeruli; 49 of them contained from one to four intralobular veins, and on average each sample contained 10.7 per cent air sac tissue; 113 of the 126 samples could be evaluated histologically.

Animals↗
PubMed2005

Ophthalmological findings in free-living tawny owls (Strix aluco) examined at a wildlife veterinary hospital.

Detailed ophthalmological examinations were made on 128 of the 216 free-living tawny owls (Strix aluco) examined at a wildlife hospital in the south west of England during the years 2000 to 2002. There were significant lesions in the eyes of 96 (75 per cent) of the birds examined. There were 147 adult birds admitted, of which 89 (60.5 per cent) were due to road traffic accidents; only 13 of these birds (14.6 per cent) were normal. Sixty-nine juvenile birds were admitted, 36 (52 per cent) of them as 'orphans'. Only 25 of the juvenile birds were examined ophthalmologically, and of these 13 (52 per cent) were normal. The ophthalmological examination included a Schirmer tear test the results of which were consistently lower than is normal for some other families of birds.

Animals↗
PubMed2006

Chronic ocular lesions in tawny owls (Strix aluco) injured by road traffic.

The chronic ocular lesions suffered by 50 tawny owls (Strix aluco) injured by road traffic were investigated. They included non-healing corneal erosions, cataracts and retinal scarring, and periretinal membrane formation. The intraocular pressure was significantly lower in the eyes with intraocular inflammatory pathology and higher in the eyes with irido- or cyclodialysis than in ophthalmically normal eyes. Cicatritial retinal lesions were not associated with high titres of antibodies to Toxoplasma species. The findings correlate with those observed in human beings with eye injuries due to high-speed blunt trauma.

Animals↗
PubMed2003

Coding of auditory space.

Behavioral, anatomical, and physiological approaches can be integrated in the study of sound localization in barn owls. Space representation in owls provides a useful example for discussion of place and ensemble coding. Selectivity for space is broad and ambiguous in low-order neurons. Parallel pathways for binaural cues and for different frequency bands converge on high-order space-specific neurons, which encode space more precisely. An ensemble of broadly tuned place-coding neurons may converge on a single high-order neuron to create an improved labeled line. Thus, the two coding schemes are not alternate methods. Owls can localize sounds by using either the isomorphic map of auditory space in the midbrain or forebrain neural networks in which space is not mapped.

Animals↗
PubMed2006

Combined auditory and visual stimuli facilitate head saccades in the barn owl (Tyto alba).

The barn owl naturally responds to an auditory or visual stimulus in its environment with a quick head turn toward the source. We measured these head saccades evoked by auditory, visual, and simultaneous, co-localized audiovisual stimuli to quantify multisensory interactions in the barn owl. Stimulus levels ranged from near to well above saccadic threshold. In accordance with previous human psychophysical findings, the owl's saccade reaction times (SRTs) and errors to unisensory stimuli were inversely related to stimulus strength. Auditory saccades characteristically had shorter reaction times but were less accurate than visual saccades. Audiovisual trials, over a large range of tested stimulus combinations, had auditory-like SRTs and visual-like errors, suggesting that barn owls are able to use both auditory and visual cues to produce saccades with the shortest possible SRT and greatest accuracy. These results support a model of sensory integration in which the faster modality initiates the saccade and the slower modality remains available to refine saccade trajectory.

Acoustic Stimulation↗
PubMed2006

Passive soma facilitates submillisecond coincidence detection in the owl's auditory system.

Neurons of the avian nucleus laminaris (NL) compute the interaural time difference (ITD) by detecting coincident arrivals of binaural signals with submillisecond accuracy. The cellular mechanisms for this temporal precision have long been studied theoretically and experimentally. The myelinated axon initial segment in the owl's NL neuron and small somatic spikes observed in auditory coincidence detector neurons of various animals suggest that spikes in the NL neuron are generated at the first node of Ranvier and that the soma passively receives back-propagating spikes. To investigate the significance of the "passive soma" structure, we constructed a two-compartment NL neuron model, consisting of a cell body and a first node, and systematically changed the excitability of each compartment. Here, we show that a neuron with a less active soma achieves higher ITD sensitivity and higher noise tolerance with lower energy costs. We also investigate the biophysical mechanism of the computational advantage of the "passive soma" structure by performing sub- and suprathreshold analyses. Setting a spike initiation site with high sodium conductance, not in the large soma but in the small node, serves to amplify high-frequency input signals and to reduce the impact and the energy cost of spike generation. Our results indicate that the owl's NL neuron uses a "passive soma" design for computational and metabolic reasons.

Action Potentials↗
PubMed2002

Computational diversity in the cochlear nucleus angularis of the barn owl.

The cochlear nucleus angularis (NA) is widely assumed to form the starting point of a brain stem pathway for processing sound intensity in birds. Details of its function are unclear, however, and its evolutionary origin and relationship to the mammalian cochlear-nucleus complex are obscure. We have carried out extracellular single-unit recordings in the NA of ketamine-anesthetized barn owls. The aim was to re-evaluate the extent of heterogeneity in NA physiology because recent studies of cellular morphology had established several distinct types. Extensive characterization, using tuning curves, phase locking, peristimulus time histograms and rate-level functions for pure tones and noise, revealed five major response types. The most common one was a primary-like pattern that was distinguished from auditory-nerve fibers by showing lower vector strengths of phase locking and/or lower spontaneous rates. Two types of chopper responses were found (chopper-transient and a rare chopper-sustained), as well as onset units. Finally, we routinely encountered a complex response type with a pronounced inhibitory component, similar to the mammalian typeIV. Evidence is presented that this range of response types is representative for birds and that earlier conflicting reports may be due to methodological differences. All five response types defined were similar to well-known types in the mammalian cochlear nucleus. This suggests convergent evolution of neurons specialized for encoding different behaviorally relevant features of the auditory stimulus. It remains to be investigated whether the different response types correlate with morphological types and whether they establish different processing streams in the auditory brain stem of birds.

Acoustic Stimulation↗
PubMed2006

Comparison of midbrain and thalamic space-specific neurons in barn owls.

Spatial receptive fields of neurons in the auditory pathway of the barn owl result from the sensitivity to combinations of interaural time (ITD) and level differences across stimulus frequency. Both the forebrain and tectum of the owl contain such neurons. The neural pathways, which lead to the forebrain and tectal representations of auditory space, separate before the midbrain map of auditory space is synthesized. The first nuclei that belong exclusively to either the forebrain or the tectal pathways are the nucleus ovoidalis (Ov) and the external nucleus of the inferior colliculus (ICx), respectively. Both receive projections from the lateral shell subdivision of the inferior colliculus but are not interconnected. Previous studies indicate that the owl's tectal representation of auditory space is different from those found in the owl's forebrain and the mammalian brain. We addressed the question of whether the computation of spatial cues in both pathways is the same by comparing the ITD tuning of Ov and ICx neurons. Unlike in ICx, the relationship between frequency and ITD tuning had not been studied in single Ov units. In contrast to the conspicuous frequency independent ITD tuning of space-specific neurons of ICx, ITD selectivity varied with frequency in Ov. We also observed that the spatially tuned neurons of Ov respond to lower frequencies and are more broadly tuned to ITD than in ICx. Thus there are differences in the integration of frequency and ITD in the two sound-localization pathways. Thalamic neurons integrate spatial information not only within a broader frequency band but also across ITD channels.

Acoustic Stimulation↗