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PubMed2002

[The dysplastic nevus. An Ariadne's thread through a conceptual labyrinth].

The concept of the dysplastic nevus is flawed by inconsistencies regarding the clinical presentation, histological features and biological considerations. With regard to basic mechanisms of malignancy, dysplastic nevi exhibit neither increased proliferation indices nor elevated telomerase activity. These traits denote a benign lesion that is highly prevalent among Caucasians. In rare cases, the distinction from malignant melanoma may pose problems.

Cell Division↗
PubMed2001

The ontogenetic development of auditory sensitivity, vocalization and acoustic communication in the labyrinth fish Trichopsis vittata.

The anabantoid fish Trichopsis vittata starts vocalizing as 8-week-old juveniles. In order to determine whether juveniles are able to detect conspecific sounds, hearing sensitivities were measured in six size groups utilizing the auditory brainstem response-recording technique. Results were compared to sound pressure levels and spectra of sounds recorded during fighting. Auditory evoked potentials were present in all size groups and complete audiograms were obtained starting with 0.18 to 0.30 g juveniles. Auditory sensitivity during development primarily increased between 0.8 kHz and 3.0 kHz. The most sensitive frequency within this range shifted from 2.5 kHz to 1.5 kHz, whereas thresholds decreased by 14 dB. Sound production, on the other hand, started at 0.1 g and sound power spectra at dominant frequencies increased by 43 dB, while dominant frequencies shifted from 3 kHz to 1.5 kHz. Comparisons between audiograms and sound power spectra in similar-sized juveniles revealed no clear match between most sensitive frequencies and dominant frequencies of sounds. This also revealed that juveniles cannot detect conspecific sounds below the 0.31 to 0.65 g size class. These results indicate that auditory sensitivity develops prior to the ability to vocalize and that vocalization occurs prior to the ability to communicate acoustically.

Acoustics↗
PubMed2004

Efferent actions in the chinchilla vestibular labyrinth.

Efferent fibers were electrically stimulated in the brain stem, while afferent activity was recorded from the superior vestibular nerve in barbiturate-anesthetized chinchillas. We concentrated on canal afferents, but otolith afferents were also studied. Among canal fibers, calyx afferents were recognized by their irregular discharge and low rotational gains. In separate experiments, stimulating electrodes were placed in the efferent cell groups ipsilateral or contralateral to the recording electrode or in the midline. While single shocks were ineffective, repetitive shock trains invariably led to increases in afferent discharge rate. Such excitatory responses consisted of fast and slow components. Fast components were large only at high shock frequencies (200-333/s), built up with exponential time constants <0.1 s, and showed response declines or adaptation during shock trains >1 s in duration. Slow responses were obtained even at shock rates of 50/s, built up and decayed with time constants of 15-30 s, and could show little adaptation. The more regular the discharge, the larger was the efferent response of an afferent fiber. Response magnitude was proportional to cv*b, a normalized coefficient of interspike-interval variation (cv*) raised to the power b = 0.7. The value of the exponent b did not depend on unit type (calyx vs. bouton plus dimorphic, canal vs. otolith) or on stimulation site (ipsilateral, contralateral, or midline). Responses were slightly smaller with contralateral or midline stimulation than with ipsilateral stimulation, and they were smaller for otolith, as compared to canal, fibers. An anatomical study had suggested that responses to contralateral afferent stimulation should be small or nonexistent in irregular canal fibers. The suggestion was not confirmed in this study. Contralateral responses, including the large responses typically seen in irregular fibers, were abolished by shallow midline incisions that should have severed crossing efferent axons.

Afferent Pathways↗
PubMed2007

"It's like being in a labyrinth:" Hispanic immigrants' perceptions of depression and attitudes toward treatments.

This study aimed to describe Hispanic immigrants' perceptions of depression and attitudes toward treatments and to examine how demographics, acculturation, clinical factors, and past service use were associated with their perceptions and attitudes. A convenience sample of 95 Hispanic immigrant patients was presented a vignette depicting an individual with major depression. Structured interviews that included standardized instruments and open-ended questions were used to query patients about their views of depression and its treatments. Findings showed that Hispanic immigrants perceived depression as a serious condition caused by interpersonal and social factors. Consistent with existing literature, most patients endorsed positive attitudes toward depression treatments yet reported apprehensions toward antidepressants. Demographic factors, acculturation, depressive symptoms, and past mental health service use were related to patients' views of depression and attitudes toward care. This study emphasizes the need to incorporate Hispanic immigrants' perceptions and attitudes into depression treatments.

Acculturation↗
PubMed1991

Effect of T2 spinal transection on compensation of horizontal canal related activity in the medial vestibular nucleus following unilateral labyrinth ablation in the decerebrate gerbil.

The effects of spinal transection at T2 upon static and dynamic responses of type I and II neurons in the medial vestibular nucleus after vestibular compensation were investigated in decerebrate Mongolian gerbils (Meriones unguiculatus). Spinal transection in compensated animals resulted in bilaterally depressed spontaneous activity and asymmetry in the response gain of type I neurons, suggesting that tonic spinal inputs contribute to vestibular compensation through effects upon type I neurons.

Adaptation, Physiological↗
PubMed1981

Efferent neurons to the labyrinth of Salamandra salamandra as revealed by retrograde transport of horseradish peroxidase.

Application of horseradish peroxidase to the severed VIIIth nerve of Salamandra salamandra resulted in heavy bilateral labeling of neurons of the medullary reticular formation. These neurons closely resemble the Mauthner neuron in their widespread dendritic ramification. In most preparations axon collaterals are seen to leave the medulla via the contralateral VIIIth nerve. It is suggested that these neurons are labyrinthine efferents.

Animals↗