Objective: The current study evaluates the efficacy of a P300-based brain-computer interface (BCI) communication device for individuals with advanced ALS. Methods: Participants attended to one cell of a N x N matrix while the N rows and N columns flashed randomly. Each cell of the matrix contained one character. Every flash of an attended character served as a rare event in an oddball sequence and elicited a P300 response. Classification coefficients derived using a stepwise linear discriminant function were applied to the data after each set of flashes. The character receiving the highest discriminant score was presented as feedback. Results: In Phase I, six participants used a 6 x 6 matrix on 12 separate days with a mean rate of 1.2 selections/min and mean online and offline accuracies of 62% and 82%, respectively. In Phase II, four participants used either a 6 x 6 or a 7 x 7 matrix to produce novel and spontaneous statements with a mean online rate of 2.1 selections/min and online accuracy of 79%. The amplitude and latency of the P300 remained stable over 40 weeks. Conclusions: Participants could communicate with the P300-based BCI and performance was stable over many months. Significance: BCIs could provide an alternative communication and control technology in the daily lives of people severely disabled by ALS.

This study examines the effects of expanding the classical P300 feature space on the classification performance of data collected from a P300 speller paradigm [Farwell LA, Donchin E. Talking off the top of your head: toward a mental prosthesis utilizing event-related brain potentials. Electroenceph Clin Neurophysiol 1988;70:510-23]. Using stepwise linear discriminant analysis (SWLDA) to construct a classifier, the effects of spatial channel selection, channel referencing, data decimation, and maximum number of model features are compared with the intent of establishing a baseline not only for the SWLDA classifier, but for related P300 speller classification methods in general. By supplementing the classical P300 recording locations with posterior locations, online classification performance of P300 speller responses can be significantly improved using SWLDA and the favorable parameters derived from the offline comparative analysis.

To date, only one study has situationally bolstered attentional resources in an effort to improve P300-BCI performance. The current study implements a 4-week Mindfulness Meditation Training Program (MMTP) as a nonmedicinal means to increase concentrative attention and to reduce lapses of attention; MMTP is expected to improve P300-BCI performance by enhancing attentional resources and reducing distractibility. A second aim is to test the efficacy of the checkerboard paradigm (CBP) against the standard row-column paradigm (RCP). Online results show that MMTP had greater accuracies than CTRL and that CBP outperformed the RCP. MMTP participants provided greater amplitude positive target responses, but these differences were not statistically significant. CBP had greater positive amplitude peaks and negative peaks than RCP. The discussion focuses on potential benefits of MMTP for P300-based BCIs, provides further support for the construct validity of mindfulness, and addresses future directions of the translational applicability of MMTP to in-home settings.

The purpose of this study was to compare event-related potential (ERP) effects of speech processing and effects in sentence reading elicited by sentences containing gapping structures, or a "missing" verb. N400 and P600 waveforms were collected in 20 adults between 18 and 30 years of age. Two experiments were conducted with each participant. In the two experiments ERP recordings were collected as sentences, some containing gapping structures, were presented to the subjects. In one experiment sentences were presented through headphones in sentences spoken at normal rate and with normal intonation. In the second experiment sentences with the same gapping structures were presented on a computer screen word by word at a rate of four words per second. Results suggest that all gapping structures are processed at approximately the same time. Amplitude and topography differences were seen between stimuli types and modalities.

Many questions remain unanswered regarding the intricacies of the human brain, especially with regard to the complexities of language processing. One essential component of human sentence processing is the ability to detect, decipher, and recover from errors in the interpretation of both verbal and written language. This process of repair of ungrammatical sentences and revision or reinterpretation of ambiguous sentences has been studied extensively in recent years. A variety of tools have been developed, including the use of event-related potentials (ERPs) in order to assess how language is processed and developed, and to help better identify the nature of these processes. The purpose of this study was to compare event-related potential effects of speech processing of spoken and written sentences containing both incorrect and correct semantic and syntactic information. Specifically, sentences containing correct and incorrect gapping structures, each with a "missing" verb, were presented along with other grammatical and ungrammatical sentences in order to elicit and measure the P300, N400, and P600 amplitudes and latencies. The aim was to determine some of the commonalities and differences in these electrophysiological responses via the auditory and visual modalities. Two experiments were conducted with each participant, one in the auditory modality, and one within the visual using two sets of stimuli. Amplitude and topography differences were noted within and between modalities for each of the components (P300, N400, and P600), as well as between stimulus types. Significant findings suggest that in the adolescent population, incorrect gapping structures are generally processed as semantic errors, as evidenced by the N400 response, followed by the P600 response in both the auditory and visual modalities. The exact nature of the P600 component within gapping structures remains unclear. Of particular interest was the involvement of the occipital area of the brain for the processing of gapping structures. Minimal differences were noted overall between adolescents and the adult populations.

Infants 6-8 months old are able to identify nearly every speech sound contrast on which they have been tested, regardless of whether that contrast represents an across-category (two different phonemes) phonetic change in their native language or not. A child's ability to identify non-native consonant contrasts greatly diminishes by 11-12 months of age. The present study examined speech sound discrimination in three groups of listeners. Adult second language (L2) listeners of Spanish were compared with native English listeners with no knowledge of Spanish and native Mexican listeners to determine if they would show the ability to discriminate phonetic distinctions that are present in Spanish and not English. Behavioral and Electrophysiological measures were obtained in response to a continuum of bilabial consonant-vowel (CV) stimuli that differed in voice onset time (VOT) from -50 to 30 ms VOT (/ba/ to /pa/). The -50 ms VOT stimulus was paired with each of the others to form stimulus pairs with varying degrees of acoustic difference. Behavioral data showed that L2 listeners of Spanish perceived a transition from /ba/ to /pa/ later than native Spanish listeners but earlier than English only listeners. Electrophysiological data using the mismatch negativity revealed that the both L2 Spanish and native Spanish listeners perceived a distinction between stimuli in the stimulus pairs 20 ms earlier than English only listeners. These results support the theory that underlying neural-sensory representations of speech may be altered by linguistic experiences, and that the loss of non-native speech sound discrimination abilities in infancy and the regaining of these abilities in adulthood is not due merely to attentional bias.

This study examined the electrophysiological activity of two children with Specific Language Impairment (SLI) and two aged-matched peers while listening to syntactically correct sentences versus syntactically incorrect sentences. The study specifically analyzed the N400 and P600 components. The N400 component is a negative wave occurring approximately 400 ms post-stimulus and is elicited by semantically incorrect stimuli. The P600 component is a positivity that occurs approximately 600 ms post-stimulus and reflects processing of syntactically incorrect stimuli. The participants in the study included a 7-year-old child and a 9-year-old child with SLI and two age-matched peers with typically developing language. Each participant listened to a series of syntactically correct and incorrect stimuli. The results of this study indicate that children with SLI present with an N400 while listening to both syntactically correct and incorrect stimuli. This suggests that these participants have greater lexical and semantic processing demands while listening to sentence stimuli. The study also suggests that 7-year-olds have greater syntactic processing demands as seen by the presence of the P600 in both the correct and incorrect conditions. This was likely due to the complexity of the sentence stimuli which included irregular past tense and irregular plural forms. Further research is still needed in order to better understand the role of the N400 and P600 in children with SLI, which will provide useful information regarding the neurological basis for language impairments.

Studying language development through event-related potentials provides specific information regarding how the brain processes specific aspects of language over time. In this study, the P600 component, a positive wave occurring approximately 600 ms post-stimulus and known for detecting syntactic errors, was specifically analyzed. Thirty children between the ages of 5 and 12 years listened to linguistically correct, syntactically incorrect, and semantically incorrect sentences in three ear conditions: monaurally to the right ear, monaurally to the left ear, and binaurally. The participants were instructed to judge the sentences to be correct or incorrect. Comparisons were then made of the latency and amplitude of the P600 between the age groups, sentence types, and ear conditions. The results of this study indicate that younger children exhibit later latencies and higher amplitudes than do adults. The study also suggests that syntactic processing becomes fully established around the age of 8 to 9 years. In reference to ear condition, this study found that ear condition may be a factor in a child's ability to recognize syntax. This was the first study that investigated developmental ERPs and ear condition. Therefore, this finding is a result of interest that needs to be further explored in future studies. The current study also suggests that the right ear advantage (REA) phenomenon may exist neurologically in older ages with monotic sentences. This is another area that would benefit from additional research as this phenomenon has not been previously described.

This study investigated the neurophysiology of semantic language processing in children, ages 5 to 12 years. A well-established marker of semantic processing, the N400 event related potential (ERP), was analyzed within and across child age groups. Child N400s were recorded in response to correct sentences, semantically incorrect sentences, and syntactically incorrect sentences. N400s were also recorded across ear condition to examine potential processing differences. Children across all age groups consistently demonstrated N400s in the semantic error condition. N400s were also regularly observed in the syntactic error condition; especially, for younger children. Younger children also demonstrated N400s even in response to correct sentence types. Interestingly, clear N400 effects (i.e. N400 amplitude differences between correct and semantically incorrect sentences) were only observed for one age group. While these findings indicate that children across all age groups detect semantic errors, the ability to consistently parse error types develops later.

The examination of Event Related Potentials during language processing tasks provides valuable information of how the brain processes language over time. In the current study, the development of the early left anterior negativity (ELAN) was analyzed in young children. Previous research has described the ELAN as a negative waveform elicited during syntactic processing between 200 and 500 ms post linguistic stimuli. Thirty children from 5 to 12 years of age listened to sentences that were linguistically correct, syntactically incorrect, or semantically incorrect. Sentences were presented for right monaural, left monaural, and binaural ear conditions to determine possible differences related to right ear advantage (REA). An ELAN-like component in regards to latency and amplitude was observed in children 8 years of age and older; however, comparison between linguistic conditions suggest that the ability to differentiate between linguistically correct, syntactically incorrect, and semantically incorrect stimuli is not established until 12 years of age. Results suggest that adult-like syntactic processing of morphosyntactic errors is not established until after 12 years of age. Comparison between ear conditions suggests that the REA effect may exist in older children, a finding that has not been reflected in previous behavioral research.