5-HT1A receptor, 5-HT2A receptor and serotonin transporter binding in the human auditory cortex in depression.

Background: Serotonergic system abnormalities are implicated in many psychiatric disorders, including major depression. The temporal lobe receives a high density of serotonergic afferent projections, and responses in the primary auditory cortex to sound are modulated by serotonergic tone. However, the associations between changes in serotonergic tone, disease state and changes in auditory cortical function remain to be clarified.

Cortisol Stress Response and in Vivo PET Imaging of Human Brain Serotonin 1A Receptor Binding.

Background: Abnormalities in the hypothalamic-pituitary-adrenal axis, serotonergic system, and stress response have been linked to the pathogenesis of major depressive disorder. State-dependent hyper-reactivity of the hypothalamic-pituitary-adrenal axis is seen in major depressive disorder, and higher binding to the serotonin 1A receptor is observed as a trait in both currently depressed and remitted untreated major depressive disorder. Here, we sought to examine whether a relationship exists between cortisol secretion in response to a stressor and serotonin 1A receptor binding throughout the brain, both in healthy controls and participants with major depressive disorder.

Emergence of band-pass filtering through adaptive spiking in the owl's cochlear nucleus.

In the visual, auditory, and electrosensory modalities, stimuli are defined by first- and second-order attributes. The fast time-pressure signal of a sound, a first-order attribute, is important, for instance, in sound localization and pitch perception, while its slow amplitude-modulated envelope, a second-order attribute, can be used for sound recognition. Ascending the auditory pathway from ear to midbrain, neurons increasingly show a preference for the envelope and are most sensitive to particular envelope modulation frequencies, a tuning considered important for encoding sound identity.

Binaural gain modulation of spectrotemporal tuning in the interaural level difference-coding pathway.

In the brainstem, the auditory system diverges into two pathways that process different sound localization cues, interaural time differences (ITDs) and level differences (ILDs). We investigated the site where ILD is detected in the auditory system of barn owls, the posterior part of the lateral lemniscus (LLDp). This structure is equivalent to the lateral superior olive in mammals.

Effect of instantaneous frequency glides on interaural time difference processing by auditory coincidence detectors.

Detecting interaural time difference (ITD) is crucial for sound localization. The temporal accuracy required to detect ITD, and how ITD is initially encoded, continue to puzzle scientists. A fundamental question is whether the monaural inputs to the binaural ITD detectors differ only in their timing, when temporal and spectral tunings are largely inseparable in the auditory pathway.

Difference in response reliability predicted by spectrotemporal tuning in the cochlear nuclei of barn owls.

The brainstem auditory pathway is obligatory for all aural information. Brainstem auditory neurons must encode the level and timing of sounds, as well as their time-dependent spectral properties, the fine structure, and envelope, which are essential for sound discrimination. This study focused on envelope coding in the two cochlear nuclei of the barn owl, nucleus angularis (NA) and nucleus magnocellularis (NM).