Pre-attentive Mismatch Response and Involuntary Attention Switching to a Deviance in an Earlier-Than-Usual Auditory Stimulus: An ERP Study

An acoustic stimulus elicits an electroencephalographic response called auditory event-related potential (ERP). When some members of a stream of standard auditory stimuli are replaced randomly by a deviant stimulus and this stream is presented to a subject who ignores the stimuli, two different ERPs to deviant and standard stimuli are recorded. If the ERP to standard stimuli is subtracted from the ERP to deviant stimuli, the difference potential (DP) waveform typically exhibits a series of negative-positive-negative deflections called mismatch negativity (MMN), P3a, and reorienting negativity (RON), which are associated with pre-attentive change detection, involuntary attention switching, and reorienting of attention, respectively. The aim of the present study was to investigate how these pre-attentive processes are affected if the change occurs earlier than its usual timing implied by isochronous standard stimuli. In the MMN paradigm employed, 15% of the standards were randomly replaced by deviant stimuli which differed either in their pitch, their earlier onset time, or in both. Event-related responses to these three deviants [timely pitch change (RTP), earlier onset (REO), earlier pitch change (REP)] and to standards (RS) were recorded from 10 reading subjects. To maintain identical stimulation histories for the responses subtracted from each other, “deviant-standard” difference potentials (DP) for “timely” and “early” pitch deviances were derived as follows: DPTP = RTP − RS and DPEP = REP − REO. Interestingly, the MMN components of the DPs to timely and early pitch deviances had similar amplitudes, indicating that regularity of stimulus timing does not provide any benefit for the pre-attentive auditory change detection mechanism. However, different scalp current density (SCD) dynamics of the MMN/P3a complexes, elicited by timely and early pitch deviances, suggested that an auditory change in a stimulus occurring earlier-than-usual initiates a faster and more effective call-for-attention and causes stronger attention switching than a timely change. SCD results also indicated that the temporal, frontal, and parietal MMN components are simultaneously present rather than emerging sequentially in time, supporting the MMN models based on parallel deviance processing in the respective cortices. Similarity of the RONs to timely and early pitch deviances indicated that reorienting of attention is of the same strength in two cases

The Effects of Concurrent Cognitive Tasks on Postural Sway in Healthy Subjects

Introduction: Keeping balance of the upright stance is a highly practiced daily task for healthy adults and is effectively performed without overt attentional control in most. Objective: The purpose of this study was to examine the influence of concurrent cognitive tasks on postural sway in healthy participants. Methods: This was a prospective study. 20 healthy volunteer subjects were included. The cognitive and balance tasks were performed separately and then, concurrently. Postural control task consisted of 6 conditions (C) of the Sensory Organization Test. The cognitive task consisted of digit rehearsal task of varying presentation and varying levels of difficulty. Results: A statistically significant difference was noted between dual task and no task for C1, C2, C3 and C4 Sensory Organization Test scores (p 0.05). Conclusion: During dual task, increase has been determined in postural sway for C1, C2, C3 and C4 for all presentation modes and difficulty levels of the cognitive tasks. (C) 2015 Associacao Brasileira de Otorrinolaringologia e Cirurgia Cervico-Facial. Published by Elsevier Editora Ltda. All rights reserved.WoSScopu

Comparison of Regularity Detection between Individuals with and without Speech-in-Noise Problems using Electrophysiological Methods

OBJECTIVE: To analyze the cortical representations of auditory regularities and the relation between these representations and speech-in-noise (SIN) abilities and to compare two groups of participants with different SIN abilities on these cortical measures. MATERIALS and METHODS: In total, 22 participants aged 20-40 years with normal hearing and without noise exposure, brain stem level-processing issues, neurological/psychiatric issues, or related medication were presented with three different stimuli resembling auditory regularities appearing after random sounds as well as a random series of sounds. Participants received a total of 480 stimuli in passive and active phases each (in which they actively detected regularities). Evoked responses were recorded via 20-channel standard electroencephalography (EEG) cap. RESULTS: The groups were not significantly different in terms of evoked potential parameters. A significant negative correlation was observed between amplitudes of responses evoked by decreasing the frequency regularity in the active phase and SIN scores. Response parameters were significantly different between the stimuli. Active phase latencies were shorter and amplitudes were higher than passive phase ones, except for two stimuli. CONCLUSION: Cortical representations of decreasing frequency regularity are promising for revealing the link between SIN and representations of regularity detection. This paradigm is suggested to applicable to individuals with clinical-level SIN problems [hearing aid (HA) and cochlear implant (CI) users, normal-hearing individuals, children with learning problems, children with dyslexia, and others] to reveal which process of SIN mechanism is defective; this is a complicated process with many sub-mechanisms. These results may be utilized in designing CI and HA algorithms (for more robust representations of auditory regularities) and rehabilitation programs

Accuracy in Archery Shooting is linked to the Amplitude of the ERP N1 to the Snap of Clicker

An archer requires a well-balanced and highly reproducible release of the bowstring to attain high scores in competition. Recurve archers use a mechanical device called the "clicker" to check the draw length. The fall of the clicker that generates an auditory stimulus should evoke a response in the brain. The purpose of this study is to evaluate the event-related potentials during archery shooting as a response to the fall of the clicker. Fifteen high-level archers participated. An electro cap was placed on the archers' scalps, and continuous EEG activity was recorded (digitized at 1000 Hz) and stored for off-line analysis. The EEG data were epoched beginning 200 ms before and lasting 800 ms after stimulus marker signals. An operational definition has been developed for classifying hits corresponding to hit and/or miss areas. The hit area enlarged gradually starting from the centre of the target (yellow: 10) to blue (6 score) by creating ten hit area indexes. It is found that the snap of the clicker during archery shooting evokes N1-P2 components of long-latency evoked brain potentials. N1 amplitudes are significantly higher in hit area than that of miss areas for the 2nd and 4th indexes with 95% confidence intervals and 90% confidence intervals for the 1st and 3rd indexes with 90% confidence intervals. We conclude that the fall of the clicker in archery shooting elicits an N1 response with higher amplitude. Although evoked potential amplitudes were higher in successful shots, their latencies were not significantly different from the unsuccessful ones

Ankle clonus and its relationship with the medium-latency reflex response of the soleus by peroneal nerve stimulation

Ankle clonus and soleus medium-latency reflex are stretch-induced responses. Clonus is traditionally considered to be the result of oscillation in the group Ia mediated spinal stretch reflex but the soleus medium-latency reflex response originates mainly from the activation of group II afferents

Can Global Field Power Be An Objective Tool To Assess Cortical Responses To Acoustic Change? A Study with Cochlear Implant Users

Introduction: The aim of the present study was to record and analyse acoustic change complex (ACC) response with Global Field Power (GFP) in cochlear implant users. Materials and Methods: Event-related potentials were recorded from 12 CI users. Study participants were tested in sound-treated electrically shielded test booth in the Auditory Electrophysiology Laboratory at the Hacettepe University. For acoustic change complex recording/ui/stimulus was used. The magnitude of the acoustic change complex was expressed as the ratio of GFP amplitude of ACC response to GFP amplitude of onset response and GFP measures. Results: Recordings from each participant's 20 electrodes were plotted as butterfly plots and GFPs were computed. The GFP waveform of each subject was analyzed in terms of the peaks corresponding to suspected latency ranges of onset, ACC and off-set responses. Moreover ratio of GFP amplitude of ACC response to GFP amplitude of onset response was computed for each subject. Discussions: In this study a new tool for adding objectivity to ACC response identification was applied, which was GFP measures. In addition, ratio of GFP peak amplitude corresponding to suspected ACC and onset response was computed, in order to find a cut-off score that differentiates a clear ACC response from a questionable one.Wo