Effect of hyperventilation during resistance exercise on hormonal response in humans

Major depressive disorder (MDD) has been associated with abnormalities in speech and behavioural mimicry. These abnormalities may contribute to the impairments in interpersonal functioning that are often seen in MDD patients. MDD has also been associated with disturbances in the brain serotonin system, but the extent to which serotonin regulates speech and behavioural mimicry remains unclear. In a randomized, double-blind, crossover study, we induced acute tryptophan depletion (ATD) in individuals with or without a family history of MDD. Five hours afterwards, participants engaged in two behavioural-mimicry experiments in which speech and behaviour were recorded. ATD reduced the time participants waited before speaking, which might indicate increased impulsivity. However, ATD did not significantly alter speech otherwise, nor did it affect mimicry. This suggests that a brief lowering of brain serotonin has limited effects on verbal and non-verbal social behaviour. The null findings may be due to low test sensitivity, but they otherwise suggest that low serotonin has little effect on social interaction quality in never-depressed individuals. It remains possible that recovered MDD patients are more strongly affected

Does Signal Degradation Affect Top-Down Processing of Speech?

Speech perception is formed based on both the acoustic signal and listeners' knowledge of the world and semantic context. Access to semantic information can facilitate interpretation of degraded speech, such as speech in background noise or the speech signal transmitted via cochlear implants (CIs). This paper focuses on the latter, and investigates the time course of understanding words, and how sentential context reduces listeners' dependency on the acoustic signal for natural and degraded speech via an acoustic CI simulation. In an eye-tracking experiment we combined recordings of listeners' gaze fixations with pupillometry, to capture effects of semantic information on both the time course and effort of speech processing. Normal-hearing listeners were presented with sentences with or without a semantically constraining verb (e.g., crawl) preceding the target (baby), and their ocular responses were recorded to four pictures, including the target, a phonological (bay) competitor and a semantic (worm) and an unrelated distractor. The results show that in natural speech, listeners' gazes reflect their uptake of acoustic information, and integration of preceding semantic context. Degradation of the signal leads to a later disambiguation of phonologically similar words, and to a delay in integration of semantic information. Complementary to this, the pupil dilation data show that early semantic integration reduces the effort in disambiguating phonologically similar words. Processing degraded speech comes with increased effort due to the impoverished nature of the signal. Delayed integration of semantic information further constrains listeners' ability to compensate for inaudible signals

Elucidating the effects of ageing on remembering perceptually distorted word pairs

We investigated the effects of age, background babble, and acoustic distortion of the word itself on serial position memory in a series of experiments involving six different auditory environments (quiet, and 12-talker background babble presented between, overlapping, or concurrent with word presentation or with two kinds of distortion applied to the words). To control for hearing, the level of babble or distortion was adjusted so that younger and older adults could hear the words equally well. Although the presence of continuous and word-flanking background babble adversely affected memory in the early serial positions in both age groups, only older adults' memory was adversely affected in the later serial positions. Moreover, younger adults' memory was not affected by acoustic word distortion, whereas one of the two types of temporal distortion adversely affected memory for later serial positions in older adults. The exact pattern of impairment and its interaction with age suggests that memory in older adults is more affected than that in younger adults in complex listening situations because they either need more time or have to employ more attentional resources to segregate different auditory streams, thereby depleting the pool of resources available for memory encoding