Selective Attention Increases Both Gain and Feature Selectivity of the Human Auditory Cortex

Background. An experienced car mechanic can often deduce what’s wrong with a car by carefully listening to the sound of the ailing engine, despite the presence of multiple sources of noise. Indeed, the ability to select task-relevant sounds for awareness, whilst ignoring irrelevant ones, constitutes one of the most fundamental of human faculties, but the underlying neural mechanisms have remained elusive. While most of the literature explains the neural basis of selective attention by means of an increase in neural gain, a number of papers propose enhancement in neural selectivity as an alternative or a complementary mechanism. Methodology/Principal Findings. Here, to address the question whether pure gain increase alone can explain auditory selective attention in humans, we quantified the auditory cortex frequency selectivity in 20 healthy subjects by masking 1000-Hz tones by continuous noise masker with parametrically varying frequency notches around the tone frequency (i.e., a notched-noise masker). The task of the subjects was, in different conditions, to selectively attend to either occasionally occurring slight increments in tone frequency (1020 Hz), tones of slightly longer duration, or ignore the sounds. In line with previous studies, in the ignore condition, the global field power (GFP) of event-related brain responses at 100 ms from the stimulus onset to the 1000-Hz tones was suppressed as a function of the narrowing of the notch width. During the selective attention conditions, the suppressant effect of the noise notch width on GFP was decreased, but as a function significantly different from a multiplicative one expected on the basis of simple gain model of selective attention. Conclusions/Significance. Our results suggest that auditory selective attention in humans cannot be explained by a gai

Identifying object categories from event-related EEG: Toward decoding of conceptual representations

Contains fulltext : 99404.pdf (publisher's version ) (Open Access)Multivariate pattern analysis is a technique that allows the decoding of conceptual information such as the semantic category of a perceived object from neuroimaging data. Impressive single-trial classification results have been reported in studies that used fMRI. Here, we investigate the possibility to identify conceptual representations from event-related EEG based on the presentation of an object in different modalities: its spoken name, its visual representation and its written name. We used Bayesian logistic regression with a multivariate Laplace prior for classification. Marked differences in classification performance were observed for the tested modalities. Highest accuracies (89% correctly classified trials) were attained when classifying object drawings. In auditory and orthographical modalities, results were lower though still significant for some subjects. The employed classification method allowed for a precise temporal localization of the features that contributed to the performance of the classifier for three modalities. These findings could help to further understand the mechanisms underlying conceptual representations. The study also provides a first step towards the use of concept decoding in the context of real-time brain-computer interface applications.12 p

Změny kognitivních funkcí měřené pomocí ERPs v časném a pozdním pooperačním období po intravenózní nebo inhalační anestezii

Cíl: Studie zkoumala změny kognitivních funkcí po intravenozní (TIVA) a inhalační (IA) anestézii měřené pomocí sluchových kognitivních evokovaných potenciálů (ERPs). Metoda: Jeden den před operací, první, šestý a čtyřicátý druhý den po operaci byly pacienti vyšetřeni pomocí sluchových ERPs s registrací N1, P3a a P3b komponenty. Výsledky u obou skupin s rozdílnou anestézií byly porovnány. Výsledky: První den po operaci byla prodloužena latence vlny N1 u skupiny po IA anestézii. Signifikantní snížení amplitudy vlny P3a šestý pooperační den s přetrváváním až do čtyřicátého druhého dne bylo zaznamenáno po obou typech anestézie. Snížení amplitudy vlny P3b první pooperační den s normalizací šestý pooperační den bylo zaznamenáno po obou typech anestézie. Závěr: Intravenozní i inhalační anestézie vedou k podobným změnám kognitivních funkcí měřených pomocí ERPs v časném i pozdním pooperačním období. Nemohlo být jasně potvrzeno, zda tyto změny jsou vyvolány anestézií nebo jinými nemonitorovanými perioperačními faktory. Význam: Postanestetické změny reprezentují subklinické poškození, nicméně představují potenciální riziko pro rozvoj následným kognitivním problémům.This study investigated modification in cognitive function following inhalation (IA) and total intravenous (TIVA) anaesthesia measured using auditory ERPs (Event Related Potentials). Methods : Auditory ERPs examination with N1, P3a and P3b component registration was carried out one day before surgery (D-1) and on the first (D+1), sixth (D+6) and 42nd (D+42) days after surgery. Results were compared between two anaesthetic groups. Results: On D+1, N1 latency was increased in the IA group. A significant reduction was observed in amplitude of the P3a component on D+6, which persisted up to D+42 for both IA and TIVA groups. A reduction in the amplitude of P3b on D+1 with normalization by D+6 was found in both groups as well. Conclusions: Intravenous and inhalation anaesthesia lead to similar changes in cognitive function as determined by ERPs, both during the early and late postoperative periods. It cannot be clearly confirmed whether the observed effects are due to anaesthesia or other unmonitored perioperative factors. Significance: Post anaesthetic changes represent a subclinical impairment; nevertheless, they represent a potential risk for subsequent development of cognitive difficulties

The interaction between attention and motor prediction. An ERP study

Performing a voluntary action involves the anticipation of the intended effect of that action. Interaction with the environment also requires the allocation of attention. However, the effects of attention upon motor predictive processes remain unclear. Here we use a novel paradigm to investigate attention and motor prediction orthogonally. In an acquisition phase, high and low tones were associated with left and right key presses. In the following test phase, tones were presented at random and participants attended to only one ear whilst ignoring tones presented in the unattended ear. In the test phase a tone could therefore be presented at the attended or unattended ear, as well as being congruent or incongruent with prior action–effect learning. We demonstrated early and late effects of attention as well as a later independent motor prediction effect with a larger P3a for incongruent tones. Interestingly, we demonstrated an intermediate interaction, showing an action–effect negativity (NAE) for tones which were unattended, whilst no motor prediction effect was found for attended tones. This interaction pattern suggests that attention and motor prediction are not opposing processes but can both operate to modulate prediction, providing valuable new insight into the relationship between attention and the effects of motor prediction