Response-related potentials during semantic priming: the effect of a speeded button response task on ERPs

This study examines the influence of a button response task on the event-related potential (ERP) in a semantic priming experiment. Of particular interest is the N400 component. In many semantic priming studies, subjects are asked to respond to a stimulus as fast and accurately as possible by pressing a button. Response time (RT) is recorded in parallel with an electroencephalogram (EEG) for ERP analysis. In this case, the response occurs in the time window used for ERP analysis and response-related components may overlap with stimulus-locked ones such as the N400. This has led to a recommendation against such a design, although the issue has not been explored in depth. Since studies keep being published that disregard this issue, a more detailed examination of influence of response-related potentials on the ERP is needed. Two experiments were performed in which subjects pressed one of two buttons with their dominant hand in response to word-pairs with varying association strength (AS), indicating a personal judgement of association between the two words. In the first experiment, subjects were instructed to respond as fast and accurately as possible. In the second experiment, subjects delayed their button response to enforce a one second interval between the onset of the target word and the button response. Results show that in the first experiment a P3 component and motor-related potentials (MRPs) overlap with the N400 component, which can cause a misinterpretation of the latter. In order to study the N400 component, the button response should be delayed to avoid contamination of the ERP with response-related components

Sentence context prevails over word association in aphasia patients with spared comprehension : evidence from N400 event-related potential

Behavioral and event-related potential (ERP) studies on aphasia patients showed that lexical information is not lost but rather its integration into the working context is hampered. Studies have been conducted on the processing of sentence-level information (meaningful versus meaningless) and of word-level information (related versus unrelated) in aphasia patients, but we are not aware of any study that assesses the relationship between the two. In healthy subjects the processing of a single word in a sentence context has been studied using the N400 ERP. It was shown that, even when there is only a weak expectation of a final word in a sentence, this expectation will dominate word relatedness. In order to study the effect of semantic relatedness between words in sentence processing in aphasia patients, we conducted a crossed design ERP study, crossing the factors of word relatedness and sentence congruity. We tested aphasia patients with mild to minimum comprehension deficit and healthy young and older (age-matched with our patients) controls on a semantic anomaly judgment task when simultaneously recording EEG. Our results show that our aphasia patient's N400 amplitudes in response to the sentences of our crossed-design study were similar to those of our age-matched healthy subjects. However, we detected an increase in the N400 ERP latency in those patients, indicating a delay in the integration of the new word into the working context. Additionally, we observed a positive correlation between comprehension level of those patients and N400 effect in response to meaningful sentences without word relatedness contrasted to meaningless sentences without word relatedness

Fixed point rules for heteroscedastic Gaussian kernel-based topographic map formation

We develop a number of fixed point rules for training homogeneous, heteroscedastic but otherwise radially-symmetric Gaussian kernel-based topographic maps. We extend the batch map algorithm to the heteroscedastic case and introduce two candidates of fixed point rules for which the end-states, i.e., after the neighborhood range has vanished, are identical to the maximum likelihood Gaussian mixture modeling case. We compare their performance for clustering a number of real world data sets

Fixed point rules for heteroscedastic Gaussian kernel-based topographic map formation

We develop a number of fixed point rules for training homogeneous, heteroscedastic but otherwise radially-symmetric Gaussian kernel-based topographic maps. We extend the batch map algorithm to the heteroscedastic case and introduce two candidates of fixed point rules for which the end-states, i.e., after the neighborhood range has vanished, are identical to the maximum likelihood Gaussian mixture modeling case. We compare their performance for clustering a number of real world data sets

Penerapan Kampanye Penggalangan Dana oleh Perusahaan Penyiaran Televisi untuk Mendukung Kegiatan Kemanusiaan (Studi Deskriptif Kulitatif Program Jembatan Asa Sctv)

Turut berkontribusi terhadap masa depan masyarakat agar menjadi lebih baik merupakan salah satu kewajiban Perusahaan, tak terkecuali Perusahaan yang bergerak dalam bidang industri penyiaran. Penelitian ini membahas kampanye penggalangan dana oleh PT Surya Citra Televisi (SCTV) melalui program Jembatan Asa, sebuah program kemanusiaan untuk membangun jembatan rusak di berbagai daerah di Indonesia. Tujuan penelitian ini adalah untuk mengetahui penerapan kampanye penggalangan dana kemanusiaan Program Jembatan Asa oleh SCTV dengan menggunakan model kampanye Nowak dan Warneryd. Pada model ini terdapat delapan elemen kampanye yang harus diperhatikan: efek yang diharapkan; persaingan komunikasi; obyek komunikasi; populasi target dan kelompok penerima; saluran; pesan; komunikator/pengirim pesan; efek yang dicapai. Pendekatan penelitian yang digunakan adalah kualitatif, dengan sifat penelitian deskriptif. Prosedur pengumpulan data melalui dokumentasi iklan dan berita serta wawancara mendalam dari key informan, yakni Ketua Penyelenggara program CSR Jembatan Asa, Manajer Produksi Berita, Produser Program Liputan 6 dan Video Journalist di Divisi Pemberitaan SCTV. Hasil dan analisis temuan data memperlihatkan bahwa kampanye dilakukan dengan menggandeng stakeholder internal SCTV yaitu departemen pemberitaan, programming, promosi, IT dan media online www.liputan6.com. Sedangkan dari pihak eksternal dilakukan kerja sama dengan Yayasan Relawan Kampung dan Kementerian Sosial Republik Indonesia. Target khalayak yang dituju mengalami Perubahan dari awalnya masyarakat ekonomi kelas A,B,C, diperluas menjadi kelas D dan E, serta kaum muda yang memanfaatkan media online dan media sosial dalam keseharian. Media yang digunakan dalam kampanye terdiri dari traditional media dan new media. Traditional media yang digunakan yaitu program berita Liputan 6, program infotainmen Was-was dan Halo Selebriti, serta program hiburan Inbox yang semuanya tayang di SCTV. Kampenye melalui new media, dilakukan dengan cara publikasi di media online, www.liputan6.com dan www.sctv.co.id. Sedangkan publikasi media sosial dilakukan melalui facebook https://www.facebook.com/Surya.Citra.TV dan twitter @SCTV_. Dengan menggunakan kampanye tersebut, SCTV mampu memperoleh sumbangan dana masyarakat sebesar Rp 4.546.241.368, yang digunakan untuk membangun 10 jembatan, melebihi target awal kampanye yang direncanakan hanya membangun 3 jembata

High-gamma oscillations precede visual steady-state responses : a human electrocorticography study

The robust steady-state cortical activation elicited by flickering visual stimulation has been exploited by a wide range of scientific studies. As the fundamental neural response inherits the spectral properties of the gazed flickering, the paradigm has been used to chart cortical characteristics and their relation to pathologies. However, despite its widespread adoption, the underlying neural mechanisms are not well understood. Here, we show that the fundamental response is preceded by high-gamma (55-125 Hz) oscillations which are also synchronised to the gazed frequency. Using a subdural recording of the primary and associative visual cortices of one human subject, we demonstrate that the latencies of the high-gamma and fundamental components are highly correlated on a single-trial basis albeit that the latter is consistently delayed by approximately 55 ms. These results corroborate previous reports that top-down feedback projections are involved in the generation of the fundamental response, but, in addition, we show that trial-to-trial variability in fundamental latency is paralleled by a highly similar variability in high-gamma latency. Pathology- or paradigm-induced alterations in steady-state responses could thus originate either from deviating visual gamma responses or from aberrations in the neural feedback mechanism. Experiments designed to tease apart the two processes are expected to provide deeper insights into the studied paradigm

Language Model Applications to Spelling with Brain-Computer Interfaces

Within the Ambient Assisted Living (AAL) community, Brain-Computer Interfaces (BCIs) have raised great hopes as they provide alternative communication means for persons with disabilities bypassing the need for speech and other motor activities. Although significant advancements have been realized in the last decade, applications of language models (e.g., word prediction, completion) have only recently started to appear in BCI systems. The main goal of this article is to review the language model applications that supplement non-invasive BCI-based communication systems by discussing their potential and limitations, and to discern future trends. First, a brief overview of the most prominent BCI spelling systems is given, followed by an in-depth discussion of the language models appli

Semantic Features Reveal Different Networks During Word Processing: An EEG Source Localization Study

The neural principles behind semantic category representation are still under debate. Dominant theories mostly focus on distinguishing concrete from abstract concepts but, in such theories, divisions into categories of concrete concepts are more developed than for their abstract counterparts. An encompassing theory on semantic category representation could be within reach when charting the semantic attributes that are capable of describing both concept types. A good candidate are the three semantic dimensions defined by Osgood (potency, valence, arousal). However, to show to what extent they affect semantic processing, specific neuroimaging tools are required. Electroencephalography (EEG) is on par with the temporal resolution of cognitive behavior and source reconstruction. Using high-density set-ups, it is able to yield a spatial resolution in the scale of millimeters, sufficient to identify anatomical brain parcellations that could differentially contribute to semantic category representation. Cognitive neuroscientists traditionally focus on scalp domain analysis and turn to source reconstruction when an effect in the scalp domain has been detected. Traditional methods will potentially miss out on the fine-grained effects of semantic features as they are possibly obscured by the mixing of source activity due to volume conduction. For this reason, we have developed a mass-univariate analysis in the source domain using a mixed linear effect model. Our analyses reveal distinct networks of sources for different semantic features that are active during different stages of lexico-semantic processing of single words. With our method we identified differences in the spatio-temporal activation patterns of abstract and concrete words, high and low potency words, high and low valence words, and high and low arousal words, and in this way shed light on how word categories are represented in the brain

A new insight into sentence comprehension : the impact of word associations in sentence processing as shown by invasive EEG recording

The effect of word association on sentence processing is still a matter of debate. Some studies observe no effect while others found a dependency on sentence congruity or an independent effect. In an attempt to separate the effects of sentence congruity and word association in the spatio-temporal domain, we jointly recorded scalp- and invasive-EEG (iEEG). The latter provides highly localized spatial (unlike scalp-EEG) and high temporal (unlike fMRI) resolutions. We recorded scalp- and iEEG in three patients with refractory epilepsy. The stimuli consisted of 280 sentences with crossed factors of sentence congruity and within sentence word-association. We mapped semantic retrieval processes involved in sentence comprehension onto the left temporal cortex and both hippocampi, and showed for the first time that certain localized regions participate in the processing of word association in sentence context. Furthermore, simultaneous recording of scalp- and iEEG gave us a direct overview of signal change due to its propagation across the head tissues