Search results for "Negativity"
showing 10 items of 301 documents
Atomistic Modeling of a New Storage
2008
It was observed that Me/Li2O and Me/LiF nanocomposites (Me is a metal that does not alloy with lithium) are able to exhibit an extra Li storage typically beyond the uptake of stoichiometric Li in the potential window 1.2 0.02 V, with pseudo-capacitive behavior and high-rate performance. Among the composites, the Ru/Li2O exhibits a high extra Li storage at this low potential. Moreover, the Li2O matrix allows one a higher storage in contact with transition metal than the LiF matrix [1,2]. To clarify the mechanism of the Li interfacial storage anomaly, we have performed comparative first principles calculations on the atomic and electronic structure of polar Ti/Li2O(111) and nonpolar Cu/LiF(00…
Visual mismatch negativity (vMMN): A review and meta-analysis of studies in psychiatric and neurological disorders
2015
The visual mismatch negativity (vMMN) response is an event-related potential (ERP) component, which is automatically elicited by events that violate predictions based on prior events. VMMN experiments use visual stimulus repetition to induce predictions, and vMMN is obtained by subtracting the response to rare unpredicted stimuli from those to frequent stimuli. One increasingly popular interpretation of the mismatch response postulates that vMMN, similar to its auditory counterpart (aMMN), represents a prediction error response generated by cortical mechanisms forming probabilistic representations of sensory signals. Here we discuss the physiological and theoretical basis of vMMN and review…
Auditory cortical and hippocampal-system mismatch responses to duration deviants in urethane-anesthetized rats.
2013
Any change in the invariant aspects of the auditory environment is of potential importance. The human brain preattentively or automatically detects such changes. The mismatch negativity (MMN) of event-related potentials (ERPs) reflects this initial stage of auditory change detection. The origin of MMN is held to be cortical. The hippocampus is associated with a later generated P3a of ERPs reflecting involuntarily attention switches towards auditory changes that are high in magnitude. The evidence for this cortico-hippocampal dichotomy is scarce, however. To shed further light on this issue, auditory cortical and hippocampal-system (CA1, dentate gyrus, subiculum) local-field potentials were …
Rapid categorization of sound objects in anesthetized rats as indexed by the electrophysiological mismatch response
2014
It is not known whether animals can, similarly to humans, categorize auditory objects based on an abstract rule in combining their physical features. We recorded local-field potentials from the dura above the primary auditory cortex in urethane-anesthetized rats presented with sound series occasionally violating a rule (e.g., "the higher the frequency, the weaker the intensity"). In a separate control condition, the same frequency and intensity levels were applied in the sound objects, but they obeyed no rule. Responses found selectively to the violations of the rule suggest that an abstract rule was represented in the rat brain, enabling auditory categorization.
Modulated neural processing of Western harmony in folk musicians
2013
A chord deviating from the conventions of Western tonal music elicits an early right anterior negativity (ERAN) in inferofrontal brain regions. Here, we tested whether the ERAN is modulated by expertise in more than one music culture, as typical of folk musicians. Finnish folk musicians and nonmusicians participated in electroencephalography recordings. The cadences consisted of seven chords. In incongruous cadences, the third, fifth, or seventh chord was a Neapolitan. The ERAN to the Neapolitans was enhanced in folk musicians compared to nonmusicians. Folk musicians showed an enhanced P3a for the ending Neapolitan. The Neapolitan at the fifth position was perceived differently and elicited…
Do categorical representations modulate early perceptual or later cognitive visual processing? An ERP study.
2021
Abstract Encoding of perceptual categorical information has been observed in later cognitive processing like memory encoding and maintenance, starting around 300 ms after stimulus onset (P300). However, it remains open whether categorical information is also encoded in early perceptual processing steps (reflected in the mismatch negativity component; vMMN). The main goal of this study was to assess the influence of categorical information on both early perceptual (i.e., vMMN component) and later cognitive (i.e., P300 component) processing within one paradigm. Hence, we combined an oddball paradigm with a delayed memory task. We used five-dot patterns belonging to different categories even t…
Musical training facilitates the neural discrimination of major versus minor chords in 13-year-old children
2012
Music practice since childhood affects the development of hearing skills. An important classification in Western music is the chords’ major-minor dichotomy. Its preattentive auditory discrimination was studied here using a mismatch negativity (MMN) paradigm in 13-year-olds with active hobbies, music-related (music group) or other (control group). In a context of root major chords, root minor chords and inverted major chords were presented infrequently. The interval structure of inverted majors differs more from root majors than the interval structure of root minors. However, the identity of the chords is the same in inverted and root majors (major), but different in root minors. The deviant…
Practiced musical style shapes auditory skills
2012
Musicians' processing of sounds depends highly on instrument, performance practice, and level of expertise. Here, we measured the mismatch negativity (MMN), a preattentive brain response, to six types of musical feature change in musicians playing three distinct styles of music (classical, jazz, and rock/pop) and in nonmusicians using a novel, fast, and musical sounding multifeature MMN paradigm. We found MMN to all six deviants, showing that MMN paradigms can be adapted to resemble a musical context. Furthermore, we found that jazz musicians had larger MMN amplitude than all other experimental groups across all sound features, indicating greater overall sensitivity to auditory outliers. Fu…
ERP qualification exploiting waveform, spectral and time-frequency infomax
2008
The present contribution briefly introduces an event related potential (ERP) detector. The specified detector includes three kinds of features of ERP. They are the ERP waveform feature, ERP spectral feature and ERP time-frequency feature respectively. According to these characteristics, two parameters are defined to reflect the timing feature of ERP. The mismatch negativity (MMN) is taken as the example to design an exact qualification detector. The experiment validates that the computer can automatically detect the raw trace to reflect the quality of the dataset, qualify the filtered trace to test whether the artifacts have been filtered out, and select the ERP-like component to reject art…
Relation between the Fukui function and the Coulomb hole
2005
By using a coarse-grain representation of the molecular electronic density, we demonstrate that the value of the condensed Fukui function at an atomic site is directly related to the polarization charge (Coulomb hole) induced by a test electron removed (or added) from (at) the atom. The link between the formation of an electron-hole pair and the condensed Fukui function provides insights on the possible negativity of the Fukui function which is interpreted in terms of two phenomena: overscreening and over-strengthening.