Familiarity of environmental sounds is used to establish auditory rules

This study addressed the extraction of long-term sound familiarity as a higher-order feature of complex, environmental sounds. Physically variable, familiar animal sounds and spectrotemporally matched, unfamiliar control sounds were presented. Participants ignored the acoustic stimuli. Infrequent deviant sounds violated the familiarity status established by the standard sounds, but no regularity on the basis of physical features. In the auditory event-related potential, deviants elicited a negative-going deflection over parietal scalp areas around 230 ms. This effect occurred for familiar deviants among unfamiliar standards and for unfamiliar deviants among familiar standards. The results indicate the establishment of an auditory regularity based on sound familiarity. This reflects the extraction of sound familiarity outside the focus of attention.     

Event-related oscillations in structural and semantic encoding of faces

ObjectiveThe ability to perceive faces is acquired through an interaction between species-specific biological mechanisms and social experience. To elucidate the mechanisms of the cognitive system underlying face recognition, we investigated cerebral oscillations related to encoding in ‘person identity nodes’.MethodsEEG was measured in nine healthy adults during perception of their own face, familiar face and unfamiliar face images.ResultsEvent-related synchronization (ERS) in theta, alpha and beta bands was initially induced in occipito-temporal areas within 0–200 ms of the presentation of facial stimuli. In addition, delta ERS over parietal and left temporal areas was greater in response to familiar faces around 0–800 ms compared with unfamiliar faces. Beta ERS over the right prefrontal area was significantly greater in response to a participant’s own face compared with a familiar face at 400–800 ms post-stimulus.ConclusionsERS within 0–200 ms reflects structural encoding of faces (i.e., N170 of the event related potential). Delta ERS within 0–800 ms suggests an association with memory retrieval. Beta ERS within 400–800 ms is consistent with the cortical areas reported to be strongly related to self-face perception in previous fMRI studies.SignificanceThe delta and beta bands ERS might provide an index of familiarity and self-recognition, respectively.     

Familiarity affects the processing of task-irrelevant auditory deviance

The effects of familiarity on auditory change detection on the basis of auditory sensory memory representations were investigated by presenting oddball sequences of sounds while participants ignored the auditory stimuli. Stimulus sequences were composed of sounds that were familiar and sounds that were made unfamiliar by playing the same sounds backward. The roles of frequently presented stimuli (standards) and infrequently presented ones (deviants) were fully crossed. Deviants elicited the mismatch negativity component of the event-related brain potential. We found an enhancement in detecting changes when deviant sounds appeared among familiar standard sounds compared when they were delivered among unfamiliar standards. Familiarity with the deviant sounds also enhanced the change-detection process. We suggest that tuning to familiar items sets up preparatory processes that affect change detection in familiar sound sequences.     

Memory-based mismatch response to changes in duration of auditory stimuli: An MEG study

ObjectiveDifferences in physical features and occurrence probability between standards and deviants in oddball paradigms provide contributions to magnetic mismatch negativity (MMNm). We aimed to reduce these influential factors and extract memory-based MMNm by adding a control paradigm.MethodsMagnetoencephalographic responses were recorded in 13 healthy adults with an oddball paradigm (125-ms standard and 50-ms deviant tones) and an equiprobable control paradigm (50-ms control and four other duration-varying tones). The stimulus onset asynchrony was 500 ms. Controlled MMNm was obtained by subtracting control-evoked responses from deviant-evoked responses.ResultsWith respect to the onset of stimulus difference, the peak latency of controlled MMNm was compatible with previous intracranial MMN recordings. Both controlled and traditional MMNm were generated around the superior temporal cortex, whereas the controlled MMNm amplitude was about 70% of traditional MMNm amplitude. Right-hemispheric dominance was observed in traditional MMNm but not in controlled MMNm. N100m amplitude was smaller in standard-evoked than in deviant- or control-evoked responses.ConclusionsControlled MMNm reflects memory-based processing of duration changes, whereas traditional MMNm additionally involves non-memory activations related to differential refractoriness states and physical properties between standard and deviant stimuli.SignificanceThe memory-based processing of auditory deviants may be preferentially extracted by adding a control paradigm.     

The dynamics of language-related high-gamma activity assessed on a spatially-normalized brain

ObjectiveWe developed a novel technique of spatial normalization of subdural electrode positions across subjects and assessed the spatial–temporal dynamics of high-gamma activity (HGA) in the dominant hemisphere elicited by three distinct language tasks.MethodsThe normalization process was applied to 1512 subdural electrodes implanted in 21 patients with intractable epilepsy. We projected each task-related HGA profile onto a normalized brain.ResultsThe word interpretation task initially elicited HGA augmentation in the bilateral fusiform gyri at 100 ms after stimulus onsets, subsequently in the left posterior middle temporal gyrus, in the left ventral premotor cortex at 200 ms and in the left middle and left inferior frontal gyri at 300 ms and after. The picture naming task elicited HGA augmentation in few sites in the left frontal lobe. The verb generation task elicited HGA in the left superior temporal gyrus at 100–600 ms. Common HGA augmentation elicited by all three tasks was noted in the left posterior-middle temporal and left ventral premotor cortices.ConclusionsThe spatial–temporal dynamics of language-related HGA were demonstrated on a spatially-normalized brain template.SignificanceThis study externally validated the spatial and temporal dynamics of language processing suggested by previous neuroimaging and electrophysiological studies.     

Timely event-related synchronization fading and phase de-locking and their defects in migraine

ObjectiveTo investigate the characteristics of event-related synchronization (ERS) fading and phase de-locking of alpha waves during passive auditory stimulation (PAS) in the migraine patients.MethodsThe subjects were 16 adult women with migraine and 16 normal controls. Electroencephalographic (EEG) data obtained during PAS with standard (SS) and deviant stimuli (DS) were used. Alpha ERS fading, the phase locking index (PLI) and de-locking index (DLI) were evaluated from the 10 Hz complex Morlet wavelet components at 100 ms (t100) and 300 ms (t300) after PAS.ResultsAt t100, significant ERS was found with SS and DS in the migraineurs and controls (P = 0.000). At t300 in the controls, ERS faded to zero for DS while in the migraineurs there was no fading for DS. In both groups the PLI for SS and DS was significantly reduced, i.e. de-locked, at t300 compared to t100 (P = 0.000). In the migraineurs, the DLI for DS was significantly lower than in the controls (P = 0.003).ConclusionThe alpha ERS fading and phase de-locking are defective in migraineurs during passive auditory cognitive processing.SignificanceThe defects in timely alpha ERS fading and in de-locking may play a role in the different attention processing in migraine patients.     

Effects of social context on endocrine function and Zif268 expression in response to an acute stressor in adolescent and adult rats

There is a paucity of studies comparing social buffering in adolescents and adults, despite their marked differences in social behavior. We investigated whether greater effects of social buffering on plasma corticosterone concentrations and expression of Zif268 in neural regions after an acute stressor would be found in adolescent than adult rats. Samples were obtained before and after 1 h of isolation stress and after either 1 or 3 h of recovery back in the colony with either a familiar or unfamiliar cage partner. Adolescent and adult rats did not differ in plasma concentrations of corticosterone at any time point. Corticosterone concentrations were higher after 1 h isolation than at baseline (p < 0.001), and rats with a familiar partner during the recovery phase had lower corticosterone concentrations than did rats with an unfamiliar partner (p = 0.02). Zif268 immunoreactive cell counts were higher in the arcuate nucleus in both age groups after isolation (p = 0.007) and in the paraventricular nucleus of adolescents than adults during the recovery phase irrespective of partner familiarity. There was a significant decrease in immunoreactive cell counts after 1 h isolation compared to baseline in the basolateral amygdala, central nucleus of the amygdala, and in the pyramidal layer of the hippocampus (all p < 0.05). An effect of partner familiarity on Zif268 immunoreactive cell counts was found in the granule layer of the dentate gyrus irrespective of age (higher in those with a familiar partner, p = 0.03) and in the medial prefrontal cortex in adolescents (higher with an unfamiliar partner, p = 0.02). Overall, the acute stress and partner familiarity produced a similar pattern of results in adolescents and adults, with both age groups sensitive to the social context.     

Mismatch Negativity (MMN) evoked by sound duration contrasts: An unexpected major effect of deviance direction on amplitudes

ObjectiveVerify and explore unexpected results suggesting an effect of deviance direction (shorter or longer deviants) on the amplitude of MMNs evoked by sound duration contrasts.MethodsMMNs were recorded using the oddball paradigm on ten adults. Four standard stimulus durations (100, 150, 200 and 250 ms) were used and deviants were 50% shorter or longer. Behavioral data (hit rates, d′, and reaction times) were collected after the electrophysiological sessions.ResultsMMNs were larger for short than for long deviants. There was no effect on MMN latencies. Hit rates and d′ data were almost at ceiling level for all conditions even for the longest standard – long deviant combination in which the MMN was abolished.ConclusionsWe argue that the deviance direction effect on MMN amplitudes can be explained by the delay between the moment of deviance detection and the end of the deviance quantification process.SignificanceA major effect of deviance direction on amplitudes was confirmed. This effect, which was confined to electrophysiological data, is to be taken into account when using duration contrasts to probe the processing of temporal information.     

Parameter-specific modulation of the mismatch negativity to duration decrement and increment: Evidence for asymmetric processes

ObjectiveThe mismatch negativity (MMN) component of event-related potentials (ERPs) reflects a change-detection process in the brain. The present study investigated whether stimulus parameters (sound type and duration) exert a differential influence on the MMN for a duration decrement and increment of an equal magnitude. Some asymmetries were reported in the previous studies; yet no systematical study has been conducted.MethodsERPs were recorded from 16 healthy adults presented with repetitive standard sounds interspersed with duration changes (deviant sounds). In separate sequences, stimuli were vowels, music chord, sinusoid, or band-pass filtered white noise. The stimulus durations (standard/deviant) were either 200/120 ms or 400/240 ms for decrements, and vice versa for increments.ResultsThe MMN for the increments was abolished in the 400/240 ms condition, whereas the MMN for decrements was significant irrespective of the sound duration. The amplitude of the increment MMN paralleled with the spectral complexity of the stimulus sound, whereas that of the decrement MMN was larger for natural sounds than artificial sounds.ConclusionsThe observed interactions demonstrated asymmetries in the MMN for duration increment and decrement.SignificanceThe present findings suggest that the effects of stimulus parameters should be taken into account when comparing different studies, especially where clinical populations are involved, with one another.     

Neonatal frequency discrimination in 250–4000-Hz range: Electrophysiological evidence

ObjectiveThe precision of sound frequency discrimination in newborn infants in the 250–4000-Hz frequency range was determined using the neonatal electrophysiological mismatch response (MMR), the infant equivalent of adult mismatch negativity (MMN).MethodsThe electroencephalogram (EEG) was recorded in 11 full-term sleeping newborn infants mostly in active sleep (67% of the time). Pure tones were presented through loudspeakers in an oddball paradigm with a 800-ms stimulus onset asynchrony (SOA). Each stimulus block contained a standard (p = 0.76) of 250, 1000, or 4000 Hz in frequency (in separate blocks) and deviants with a frequency change of either 5% or 20% of the standard (p = 0.12 of each).ResultsA positive ERP deflection was found at 200–300 ms from stimulus onset in response to the 20% deviation from the 250, 1000, and 4000 Hz standard frequencies. The amplitude of the response in the 200–300 ms time window was significantly larger for the 20% than 5% deviation.ConclusionsWe observed in newborn infants automatic frequency discrimination as reflected by a positive MMR. The newborns were able to discriminate frequency change of 20% in the 250–4000-Hz frequency range, whereas the discrimination of the 5% frequency change was not statistically confirmed.SignificanceThe present data hence suggest that the neonatal frequency discrimination has lower resolution than that in adult and older children data.     

Children’s brain responses to sound changes in pseudo words in a multifeature paradigm

ObjectiveThe multifeature mismatch negativity (MMN) paradigm has previously been used to study MMN responses to changes in tones or isolated syllables. We tested 4–12 year old children’s MMNs to changes in a naturally produced pseudo word context.MethodsWe studied preschoolers’ (under the age of 7 years, N = 15, mean age 5 years 4 months) and school childrens’ (over the age of 7 years, N = 15, mean age 9 years 3 months) MMNs to five types of changes (vowel duration, fundamental frequency, gap, intensity, vowel identity) in the middle syllable of a pseudo word [tɑtɑtɑ] using a multifeature paradigm.ResultsVowel duration and gap changes elicited larger frontocentral MMN responses than other change types and the vowel identity change also produced an early positive p-MMR. The presence of the MMN was also determined at the individual level, and it was found that vowel duration and gap deviants produced MMNs in most of the participants.ConclusionsThe current study shows that children’s neural speech sound discrimination can be assessed in a word context in a short recording time (30 min) by using the multifeature paradigm.SignificanceA paradigm which can be used to investigate the discrimination of several change types of speech-sounds in a natural context can be useful for investigating speech development and deficits.     

Change detection in newborns using a multiple deviant paradigm: A study using magnetoencephalography

ObjectiveMismatch responses are elicited to changes in sound streams in healthy newborns. In the ideal case, these responses can predict cognitive problems later in life. We employed a multiple deviant paradigm for a fast assessment of the ability of the newborn brain to respond to various types of acoustic changes.MethodsIn 12 healthy newborns, we recorded an electroencephalogram (EEG) and magnetoencephalogram while presenting auditory stimuli. Between repeated stimuli, four types of acoustic changes (frequency, intensity, duration, and a gap) were presented, varying in deviance magnitude.ResultsOne major response was present in the neonatal evoked potentials and fields at 250–260 ms. Magnetic mismatch responses were elicited to all change types except for the duration deviant and they were positive in polarity. The frequency deviant elicited more positive EEG amplitudes than the standard, whereas the response to the duration deviant was more negative.ConclusionsThese results show that newborns can detect changes to at least four types of deviances within a sound stream. Furthermore, the use of magneto- and electroencephalography is complementary in newborns, since the methods may reveal different outcomes.SignificanceFurther studies are warranted to determine whether the present study design can play a role in testing auditory function in clinical infant populations.     

Event-related potential measures of gap detection threshold during natural sleep

ObjectiveThe minimum time interval between two stimuli that can be reliably detected is called the gap detection threshold. The present study examines whether an unconscious state, natural sleep affects the gap detection threshold.MethodsEvent-related potentials were recorded in 10 young adults while awake and during all-night sleep to provide an objective estimate of this threshold. These subjects were presented with 2, 4, 8 or 16 ms gaps occurring in 1.5 duration white noise.ResultsDuring wakefulness, a significant N1 was elicited for the 8 and 16 ms gaps. N1 was difficult to observe during stage N2 sleep, even for the longest gap. A large P2 was however elicited and was significant for the 8 and 16 ms gaps. Also, a later, very large N350 was elicited by the 16 ms gap. An N1 and P2 was significant only for the 16 ms gap during REM sleep.SignificanceERPs to gaps occurring in noise segments can therefore be successfully elicited during natural sleep. The gap detection threshold is similar in the waking and sleeping states.     

Auditory selective attention and processing in children with attention-deficit/hyperactivity disorder

ObjectiveThis study sought to better characterize the contributions of deficits in attention allocation and distracter inhibition to the poor performance on attention tasks often seen in children with ADHD.MethodsElectrophysiological (Nd, P3b) and behavioral measures (speed and accuracy) were examined during an auditory selective attention task in children with ADHD, children with typical development (TD), and adults. Thirty children (15 ADHD; 13 females) between the ages of 7 and 13 and 16 adults (8 females) participated.ResultsNd waveforms were elicited from adults and children with TD, but not from children with ADHD. Further, those with ADHD exhibited significantly smaller auditory responses at 100 ms (Ta). P3bs were elicited in all three groups by targets but not by unattended deviants. Performance was significantly poorer in children with ADHD than TD and RTs were more variable.ConclusionsChildren with ADHD evidenced poorer attention allocation, as measured by Nd and hits, but were not more distracted by unattended deviants, as measured by P3b and false alarms, than children with TD.SignificanceFindings for Nd, P3b, and Ta considered together suggest that deficits in auditory selective attention in children with ADHD may be attributable to reduced information early in the processing stream.     

Neurophysiologic markers in laryngeal muscles indicate functional anatomy of laryngeal primary motor cortex and premotor cortex in the caudal opercular part of inferior frontal gyrus

ObjectiveThe aim of this study was to identify neurophysiologic markers generated by primary motor and premotor cortex for laryngeal muscles, recorded from laryngeal muscle.MethodsTen right-handed healthy subjects underwent navigated transcranial magnetic stimulation (nTMS) and 18 patients underwent direct cortical stimulation (DCS) over the left hemisphere, while recording neurophysiologic markers, short latency response (SLR) and long latency response (LLR) from cricothyroid muscle. Both healthy subjects and patients were engaged in the visual object-naming task. In healthy subjects, the stimulation was time-locked at 10–300 ms after picture presentation while in the patients it was at zero time.ResultsThe latency of SLR in healthy subjects was 12.66 ± 1.09 ms and in patients 12.67 ± 1.23 ms. The latency of LLR in healthy subjects was 58.5 ± 5.9 ms, while in patients 54.25 ± 3.69 ms. SLR elicited by the stimulation of M1 for laryngeal muscles corresponded to induced dysarthria, while LLR elicited by stimulation of the premotor cortex in the caudal opercular part of inferior frontal gyrus, recorded from laryngeal muscle, corresponded to speech arrest in patients and speech arrest and/or language disturbances in healthy subjects.ConclusionIn both groups, SLR indicated location of M1 for laryngeal muscles, and LLR location of premotor cortex in the caudal opercular part of inferior frontal gyrus, recorded from laryngeal muscle, while stimulation of these areas in the dominant hemisphere induced transient speech disruptions.SignificanceDescribed methodology can be used in preoperative mapping, and it is expected to facilitate surgical planning and intraoperative mapping, preserving these areas from injuries.     

Pure word deafness due to left subcortical lesion: Neurophysiological studies of two patients

ObjectiveThis study investigated the auditory processing in two patients with pure word deafness (PWD) using neurophysiological experimental methods.MethodsWe recorded the auditory brainstem response (ABR), the middle latency auditory-evoked response (MLR) and the auditory-evoked event-related potentials (ERPs) in two patients with PWD after subcortical hemorrhage in the left temporal lobe.ResultsBoth patients showed normal response in ABR and abnormality in MLR. The latency of P300 evoked by right-ear stimulation was 51 ms longer in one patient and 26 ms longer in the other patient than that evoked by left-ear stimulation.ConclusionsOur results suggested that the prolongation of P300 latency could be caused by the deterioration of auditory stimulus processing and supported the hypothesis that the defect in auditory temporal resolution was an important factor in the development of PWD.SignificanceThis study demonstrated that recordings of ERP with auditory-evoked response such as ABR and MLR are useful to elucidate the deterioration of auditory stimulus processing in patients with PWD.     

Cortical rhythm of No-go processing in humans: An MEG study

ObjectiveWe investigated the characteristics of cortical rhythmic activity in No-go processing during somatosensory Go/No-go paradigms, by using magnetoencephalography (MEG).MethodsTwelve normal subjects performed a warning stimulus (S1) – imperative stimulus (S2) task with Go/No-go paradigms. The recordings were conducted in three conditions. In Condition 1, the Go stimulus was delivered to the second digit, and the No-go stimulus to the fifth digit. The participants responded by pushing a button with their right thumb for the Go stimulus. In Condition 2, the Go and No-go stimuli were reversed. Condition 3 was the resting control.ResultsA rebound in amplitude was recorded in the No-go trials for theta, alpha, and beta activity, peaking at 600–900 ms. A suppression of amplitude was recorded in Go and No-go trials for alpha activity, peaking at 300–600 ms, and in Go and No-go trials for beta activity, peaking at 200–300 ms.ConclusionThe cortical rhythmic activity clearly has several dissociated components relating to different motor functions, including response inhibition, execution, and decision-making.SignificanceThe present study revealed the characteristics of cortical rhythmic activity in No-go processing.     

Neuromagnetic activation of primary and secondary somatosensory cortex following tactile-on and tactile-off stimulation

ObjectiveMagnetoencephalography (MEG) recordings were performed to investigate the cortical activation following tactile-on and tactile-off stimulation.MethodsWe used a 306-ch whole-head MEG system and a tactile stimulator driven by a piezoelectric actuator. Tactile stimuli were applied to the tip of right index finger. The interstimulus interval was set at 2000 ms, which included a constant stimulus of 1000 ms duration.ResultsProminent somatosensory evoked magnetic fields were recorded from the contralateral hemisphere at 57.5 ms and 133.0 ms after the onset of tactile-on stimulation and at 58.2 ms and 138.5 ms after the onset of tactile-off stimulation. All corresponding equivalent current dipoles (ECDs) were located in the primary somatosensory cortex (SI). Moreover, long-latency responses (168.7 ms after tactile-on stimulation, 169.8 ms after tactile-off stimulation) were detected from the ipsilateral hemisphere. The ECDs of these signals were identified in the secondary somatosensory cortex (SII).ConclusionsThe somatosensory evoked magnetic fields waveforms elicited by the two tactile stimuli (tactile-on and tactile-off stimuli) with a mechanical stimulator were strikingly similar. These mechanical stimuli elicited both contralateral SI and ipsilateral SII activities.SignificanceTactile stimulation with a mechanical stimulator provides new possibilities for experimental designs in studies of the human mechanoreceptor system.     

Finding the right control: The mismatch negativity under investigation

ObjectiveWhen investigating auditory perceptual regularity processing, mismatch negativity (MMN) is commonly used. MMN is computed as a difference signal between the event-related potentials (ERPs) elicited by repeated standard tones and rarely occurring deviant tones. This procedure leads to an underestimation of the N1 component elicited by standards compared to the N1 to deviants which might affect the MMN. Consequently, a random control design was previously introduced. This design, however, overestimates the N1 to the deviant. Here, we developed a new paradigm that avoids previous drawbacks.MethodsWe designed a regular cascadic sequence as a control to the deviant. ERPs were measured while presenting conventional oddball blocks (standards, deviants), random control blocks and a cascadic control block.ResultsMMN was observed in each difference signal. Regarding the N1, standards elicited smallest amplitudes. The N1 for the deviant and the cascadic control was comparable. The largest N1 was elicited by the random control.ConclusionStandards underestimate N1 refractoriness effects in the responses to deviants, while random control tones overestimate. Cascadic control tones, however, provide a reasonable estimation for the N1.SignificanceThe new cascadic control design is suitable to investigate auditory perceptual regularity processes while controlling for N1 refractoriness effects.     

The effects of healthy aging on auditory processing in humans as indexed by transient brain responses

ObjectiveThe aim of the study was to investigate the effects of aging on human cortical auditory processing of rising-intensity sinusoids and speech sounds. We also aimed to evaluate the suitability of a recently discovered transient brain response for applied research.MethodsIn young and aged adults, magnetic fields produced by cortical activity elicited by a 570-Hz pure-tone and a speech sound (Finnish vowel /a/) were measured using MEG. The stimuli rose smoothly in intensity from an inaudible to an audible level over 750 ms. We used both the active (attended) and the passive recording condition. In the attended condition, behavioral reaction times were measured.ResultsThe latency of the transient brain response was prolonged in the aged compared to the young and the accuracy of behavioral responses to sinusoids was diminished among the aged. In response amplitudes, no differences were found between the young and the aged. In both groups, spectral complexity of the stimuli enhanced response amplitudes.ConclusionsAging seems to affect the temporal dynamics of cortical auditory processing. The transient brain response is sensitive both to spectral complexity and aging-related changes in the timing of cortical activation.SignificanceThe transient brain responses elicited by rising-intensity sounds could be useful in revealing differences in auditory cortical processing in applied research.