Combining ultra-high-field fMRI adaptation and computational modelling to estimate neuronal frequency selectivity in human auditory cortex

Frequency selectivity is a ubiquitous property of auditory neurons. Measuring it in human auditory cortex may be crucial for understanding common auditory deficits, but current non-invasive neuroimaging techniques can only measure the aggregate response of large populations of cells, thereby overestimating tuning width. Here we attempted to estimate neuronal frequency tuning in human auditory cortex using a combination of fMRI-adaptation paradigm at 7T and computational modelling. We measured the BOLD response in the auditory cortex of eleven participants to a high frequency (3.8 kHz) probe presented alone or preceded by adaptors at different frequencies (0.5 to 3.8 kHz). From these data, we derived both the response tuning curves (the BOLD response to adaptors alone as a function of adaptor frequency) and adaptation tuning curves (the degree of response suppression to the probe as a function of adaptor frequency, assumed to reflect neuronal tuning) in primary and secondary auditory cortical areas, delineated in each participant. Results suggested the existence of both frequency-independent and frequency-specific adaptation components, with the latter being more frequency-tuned than response tuning curves. Using a computational model of neuronal adaptation and BOLD non-linearity in topographically-organized cortex, we demonstrate both that the frequency-specific adaptation component overestimates the underlying neuronal frequency tuning and that frequency-specific and frequency-independent adaptation component cannot easily be disentangled from the adaptation tuning curve. By fitting our model directly to the response and adaptation tuning curves, we derive a range of plausible values for neuronal frequency tuning. Our results suggest that fMRI adaptation is suitable for measuring neuronal frequency tuning properties in human auditory cortex, provided population effects and the non-linearity of BOLD response are taken into account.

Parasite egg recognition based on multicomponent cues by green-backed tits (Parus monticolus)

Egg recognition and rejection is a common and effective anti-parasitism adaptation in bird hosts. Hosts reject alien eggs using recognition signals such as egg ground color and maculation. Green-backed tits ( Parus monticolus) have a highly developed capability for recognizing parasite eggs, but the cues used for egg recognition are unclear. We combined avian visual perceptual modeling and field experiments to explore the effects of egg ground color and maculation on the recognition of parasite eggs. P. monticolus uses a multi-cue with possible hierarchical mechanism for egg recognition. The mechanism of egg recognition in P. monticolus appears to be a specific adaptation to the phenotypes of eggs laid by local brood parasites.

Funkcjonowanie nieletnich w ośrodku kuratorskim

The article draws attention to the functioning of juveniles in a probation officer’s centre. The legislator has defined the scope of the centres’ activities quite broadly. Among the tasks carried out, the staff undertake work with juveniles who have been referred by family court for demoralisation or criminal offences. The algorithm of work in the probation officer’s centre defines the actions taken against minors, but the studies lack an idea of the situation from the perspective of the minors themselves. The article also reveals the specific adaptation techniques undertaken by juveniles in a new situation for them, which is undoubtedly directed to the probation officer’s centre, comparing them with those presented by the participants in isolation facilities. The study is complemented by available statistics on the number of minors sent to probation officer’s centres (against the background of statistics on all minors for whom educational measures have been taken); a description of the tasks carried out in the probation officer’s centres, a brief description of the working methodology and conclusions for the practice. The article presents issues from the perspective of both theorist and practice, which allows to capture a broader perspective of the activities of probation officer’s centers.

Lineage Divergence and Vector-Specific Adaptation Have Driven Chikungunya Virus onto Multiple Adaptive Landscapes

Since its introduction into the Caribbean in October 2013, CHIKV has rapidly spread to almost the entire neotropical region. However, its potential to further spread globally, including into more temperate climates, depends in part on its ability to be transmitted efficiently by Aedes albopictus , which can survive colder winters than A. aegypti .

Temporal saliency for motion direction may arise from visual stimulus-specific adaptation in avian midbrain inhibitory nucleus

Food and predators are the most noteworthy objects for the basic survival of wild animals. In nature, both of these are often rare or deviant in both spatial and temporal domains and would soon attract an animal's attention. Although stimulus-specific adaptation (SSA) is considered to be one neural basis of salient sound detection in the temporal domain, related research on visual SSA is lacking. The avian nucleus isthmi pars magnocellularis (Imc), which plays an extremely important role in the selective attention network, is one of the best models for investigating the neural correlate of visual stimulus-specific adaptation (SSA) and detection of salient stimulus in the temporal domain. Here, we used a constant order paradigm to test the existence of SSA in the pigeon's Imc. We found that the strength of response of Imc neurons significantly decreased after repetitive motion stimuli, but recovered when the motion was switched to a novel direction, leading to the saliency detection of the novel motion direction. These results suggest that the inhibitory nucleus Imc shows visual SSA to motion direction, allowing the Imc to implement temporal saliency mapping and to determine the spatial-temporal saliency of the current stimulus. This also implies that pigeons may detect novel spatial-temporal stimuli during the early stage of sensory processing.

Comparative Genomics of Mycobacterium avium Complex Reveals Signatures of Environment-Specific Adaptation and Community Acquisition

Members of the Mycobacterium avium complex (MAC), a group of mycobacteria encompassing M. avium and its closest relatives, are omnipresent in natural environments and emerging pathogens of humans and animals. MAC infections are difficult to treat, sometimes fatal, and increasingly common.

Asymmetries in Perceptual Adjustments to Non-Canonical Pronunciations

This paper examines two plausible mechanisms supporting sound category adaptation: directional shifts towards the novel pronunciation or a general category relaxation of criteria. Focusing on asymmetries in adaptation to the voicing patterns of English coronal fricatives, we suggest that typology or synchronic experience affect adaptation. A corpus study of coronal fricative substitution patterns confirmed that North American English listeners are more likely to be exposed to devoiced /z/ than voiced /s/. Across two perceptual adaptation experiments, listeners in test conditions heard naturally produced devoiced /z/ or voiced /s/ in critical items within sentences, while control listeners were exposed to identical sentences with canonical pronunciations. Perceptual adaptation was tested via a lexical decision test, with devoiced /z/ or voiced /s/, as well as a novel alveopalatalized pronunciation, to determine whether adaptation was targeted in the direction of the exposed variant or reflected a more general relaxation. Results indicate there was directional and word-specific adaptation for /z/-devoicing with no evidence for generalization. Conversely, there was evidence of /s/-voicing generalizing and eliciting general category relaxation. These results underscore the role of perceptual experiences, and support an evaluation stage in perceptual learning, where listeners assess whether to update a representation.

Disturbance of phylogenetic layer-specific adaptation of human brain gene expression in Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder with typical neuropathological hallmarks, such as neuritic plaques and neurofibrillary tangles, preferentially found at layers III and V. The distribution of both hallmarks provides the basis for the staging of AD, following a hierarchical pattern throughout the cerebral cortex. To unravel the background of this layer-specific vulnerability, we evaluated differential gene expression of supragranular and infragranular layers and subcortical white matter in both healthy controls and AD patients. We identified AD-associated layer-specific differences involving protein-coding and non-coding sequences, most of those present in the subcortical white matter, thus indicating a critical role for long axons and oligodendrocytes in AD pathomechanism. In addition, GO analysis identified networks containing synaptic vesicle transport, vesicle exocytosis and regulation of neurotransmitter levels. Numerous AD-associated layer-specifically expressed genes were previously reported to undergo layer-specific switches in recent hominid brain evolution between layers V and III, i.e., those layers that are most vulnerable to AD pathology. Against the background of our previous finding of accelerated evolution of AD-specific gene expression, here we suggest a critical role in AD pathomechanism for this phylogenetic layer-specific adaptation of gene expression, which is most prominently seen in the white matter compartment.