Comparison of sensory gating to mismatch negativity and self-reported perceptual phenomena in healthy adults

The mismatch negativity (MMN) in basic research of central auditory processing: a review

In the present article, the basic research using the mismatch negativity (MMN) and analogous results obtained by using the magnetoencephalography (MEG) and other brain-imaging technologies is reviewed. This response is elicited by any discriminable change in auditory stimulation but recent studies extended the notion of the MMN even to higher-order cognitive processes such as those involving grammar and semantic meaning. Moreover, MMN data also show the presence of automatic intelligent processes such as stimulus anticipation at the level of auditory cortex. In addition, the MMN enables one to establish the brain processes underlying the initiation of attention switch to, conscious perception of, sound change in an unattended stimulus stream.

Genetic and environmental influences on sensory gating of mid-latency auditory evoked responses: a twin study

A deficit in sensory gating measured by the suppression of P50 auditory event-related potential (ERP) has been implicated in the biological bases of schizophrenia and some other psychiatric disorders and proposed as a candidate endophenotype for genetic studies. More recently, it has been shown that gating deficits in schizophrenics extend to ERP components reflecting early attentive processing (the N1/P2 complex). However, evidence for heritability of sensory gating in the general population is very limited. Heritability of P50, N1, and P2 amplitudes and gating was estimated in 54 monozygotic and 55 dizygotic twin pairs using a dual-click auditory paradigm. Genetic model-fitting analysis showed high heritability of peak amplitudes of P50, N1, and P2 waves. Genetic influences on P50 gating (S2/S1) were modest, while heritability of N1 and P2 gating was high and significant. The alternative gating measure (S1-S2 difference) showed significant heritability for all three ERP components. Weak genetic influences on P50 gating ratio can be related to its poor test-retest reliability demonstrated in previous studies. These results suggest that gating measures derived from the N1/P2 wave complex may be useful endophenotypes for population-based genetic studies of the sensory gating function and its impairments in psychopathology.

Effects of nicotine vary across two auditory evoked potentials in the mouse

BACKGROUND

Schizophrenia patients display sensory processing deficits, reduced alpha7-nicotine receptor expression, and increased incidence of smoking, prompting investigation of nicotine receptor agonists as possible treatments. We evaluated the effects of acute and chronic nicotine, using an animal model that incorporates genetic variation for sensory processing and nicotine sensitivity.

METHODS

C57BL/6J and DBA/2Hsd mice received 2 weeks of 4.2 mg/kg chronic nicotine or saline. Auditory evoked potentials were recorded before and after acute nicotine injection of 1.05 mg/kg on day 14, with a paired-click paradigm (S1/S2). Amplitude and gating of the P20 and N40 were compared between conditions.

RESULTS

Acute nicotine increased the amplitude and gating of the P20 and decreased the amplitude and gating of the N40 across all groups, primarily by acting on S1. Chronic nicotine attenuated the effects of acute nicotine on the N40.

CONCLUSIONS

Our data support the notion that the mouse P20 shares pharmacological response properties with the human P50. In addition, findings suggest that nicotine might increase the initial sensory response (S1), with a resulting improvement in gating of some components.

Detection threshold for inspiratory resistive loads and respiratory-related evoked potentials

The relationship between detection threshold of inspiratory resistive loads and the peaks of the respiratory-related evoked potential (RREP) is unknown. It was hypothesized that the short-latency and long-latency peaks of the RREP would only be elicited by inspiratory loads that exceeded the detection threshold. The detection threshold for inspiratory resistive loads was measured in healthy subjects with inspiratory-interruption or onset load presentations. In a separate protocol, the RREPs were recorded with resistive loads that spanned the detection threshold. The loads were presented in stimulus attend and ignore sessions. Onset and interruption load presentations had the same resistive load detection threshold. The P1, Nf, and N1 peaks of the RREP were observed with loads that exceeded the detection threshold in both attend and ignore conditions. The P300 was present with loads that exceeded the detection threshold only in the attend condition. No RREP components were elicited with subthreshold loads. The P1, Nf, and P300 amplitudes varied with resistive load magnitude. The results support the hypothesis that there is a resistive load threshold for eliciting the RREPs. The amplitude of the RREP peaks vary as a function of load magnitude. The cognitive P300 RREP peak is present only for detectable loads and when the subject attends to the stimulus. The absence of the RREP with loads below the detection threshold and the presence of the RREP elicited by suprathreshold loads are consistent with the gating of these neural measures of respiratory mechanosensory information processing.

Gamma and beta neural activity evoked during a sensory gating paradigm: effects of auditory, somatosensory and cross-modal stimulation

OBJECTIVE

Stimulus-driven salience is determined involuntarily, and by the physical properties of a stimulus. It has recently been theorized that neural coding of this variable involves oscillatory activity within cortical neuron populations at beta frequencies. This was tested here through experimental manipulation of inter-stimulus interval (ISI).

METHODS

Non-invasive neurophysiological measures of event-related gamma (30-50 Hz) and beta (12-20 Hz) activity were estimated from scalp-recorded evoked potentials. Stimuli were presented in a standard "paired-stimulus" sensory gating paradigm, where the S1 (conditioning) stimulus was conceptualized as long-ISI, or "high salience", and the S2 (test) stimulus as short-ISI, or "low salience". Three separate studies were conducted: auditory stimuli only (N = 20 participants), somatosensory stimuli only (N = 20), and a cross-modal study for which auditory and somatosensory stimuli were mixed (N = 40).

RESULTS

Early (20-150 ms) stimulus-evoked beta activity was more sensitive to ISI than temporally-overlapping gamma-band activity, and this effect was seen in both auditory and somatosensory studies. In the cross-modal study, beta activity was significantly modulated by the similarity (or dissimilarity) of stimuli separated by a short ISI (0.5 s); a significant cross-modal gating effect was nevertheless detected.

CONCLUSIONS

With regard to the early sensory-evoked response recorded from the scalp, the interval between identical stimuli especially modulates beta oscillatory activity.

SIGNIFICANCE

This is consistent with developing theories regarding the different roles of temporally-overlapping oscillatory activity within cortical neuron populations at gamma and beta frequencies, particularly the claim that the latter is related to stimulus-driven salience.

Reduced Suppression or Labile Memory? Mechanisms of Inefficient Filtering of Irrelevant Information in Older Adults

Cognitive aging theories emphasize the decrease in efficiency of inhibitory processes and attention control in normal aging, which, in turn, may result in reduction of working memory function. Accordingly, some of these age-related changes may be due to faster sensory memory decay or to inefficient filtering of irrelevant sensory information (sensory gating). Here, event-related brain potentials and the event-related optical signal were recorded in younger and older adults passively listening to tone trains. To determine whether age differentially affects decay of sensory memory templates over short intervals, trains were separated by delays of either 1 or 5 sec. To determine whether age affects the suppression of responses to unattended repeated stimuli, we evaluated the brain activity elicited by successive train stimuli. Some trains started with a shorter-duration stimulus (deviant trains). Results showed that both electrical and optical responses to tones were more persistent with repeated stimulation in older adults than in younger adults, whereas the effects of delay were similar in the two groups. A mismatch negativity (MMN) was elicited by the first stimulus in deviant trains. This MMN was larger for 1- than 5-sec delay, but did not differ across groups. These data suggest that age-related changes in sensory processing are likely due to inefficient filtering of repeated information, rather than to faster sensory memory decay. This inefficient filtering may be due to, or interact with, reduced attention control. Furthermore, it may increase the noise levels in the information processing system and thus contribute to problems with working memory and speed of processing.

Neuropsychological and sensory gating deficits related to remote alcohol abuse history in schizophrenia

Recent evidence suggests that changes in brain structure associated with alcohol abuse are compounded in individuals dually diagnosed with alcohol abuse and schizophrenia. To investigate the separate, and possibly interacting, effects of these diagnoses, an event-related brain potential (ERP) measure of auditory information processing (P50 sensory gating paradigm) and neuropsychological measures were administered to healthy control participants with either (1a) no history of alcohol abuse/dependence, or (1b) a remote history of alcohol abuse/dependence, and patients with schizophrenia with either (2a) no history of alcohol abuse/dependence, or (2b) a remote history of alcohol abuse/dependence. Schizophrenia was associated with impaired P50 sensory gating and poorer performance across neuropsychological scores compared to measurements in healthy control participants. Those with a positive alcohol history had impaired gating ratios in contrast to those with a negative alcohol history. There were additive effects of schizophrenia diagnosis and alcohol history for P50 sensory gating and for neuropsychological scores: attention, working memory, and behavioral inhibition. For executive attention and general memory there was an interaction, suggesting that the combination of schizophrenia and history of alcohol abuse results in greater impairment than that predicted by the presence of either diagnosis alone.

Age-related change in neural processing of time-dependent stimulus features

Aging is associated with changes in automatic processing of task-irrelevant stimuli, and this may lead to functional disturbances including repeated orienting to nonnovel events and distraction from task. The effect of age on automatic processing of time-dependent stimulus features was investigated by measurement of the auditory mismatch negativity (MMN) in younger (18-23) and older (55-85) adults. Amplitude of MMN recorded during a paradigm involving low-probability deviation in interstimulus interval (from 500 ms to 250 ms) was found to be reduced in the older group at fronto-central sites. This effect was paralleled by, and correlated to, decreased sensory gating efficiency for component N1 recorded during a separate paradigm involving alternate presentation of auditory stimuli at long (9 s) and short (0.5 s) interstimulus intervals. Further, MMN amplitude was correlated to behavioral performance on a small subset of neuropsychological tests, including the Rey Auditory Verbal Learning Test, within a group of healthy older adults. The results support the hypothesis that aging is associated with declines in automatic processing of time-dependent stimulus features, and this is related to cognitive function. These conclusions are considered in the context of age-related declines in prefrontal cortex function and associated increases in susceptibility to task-irrelevant stimuli.

Sensory gating impairment in development of post-concussive symptoms in mild head injury

Post-concussive symptoms reported by mild head injury (MHI) patients have been inadequately understood. Post-concussive symptoms reported by patients with MHI have so far been explained in terms of impairment in neurocognitive functions or deficits in modulation of flow of information. There are no studies that have looked into sensory gating impairment in MHI and its relation to post-concussive symptoms. The purpose of the present paper was to investigate the role of sensory gating impairment in post-concussive symptoms in mild head injury patients. Thirty MHI patients were evaluated for their neuropsychological functions, sensory gating deficits, and post-concussive symptoms. Neuropsychological functions were in the domain of attention, executive functions, and learning and memory. Sensory gating was assessed by Structured Interview for Assessing Perceptual Anomalies and post-concussive symptoms were assessed using the Neurobehavioral Rating Scale. Multiple regression method was used to identify predictors for post-concussive symptoms. Post-concussive symptoms were predicted by sensory gating deficits when sensory gating deficit was one of the predictors along with neuropsychological functions. Post-concussive symptoms were predicted by scores of Digit Vigilance and Digit Symbol Substitution Test, when predictors were restricted to neuropsychological functions. Sensory gating deficits were correlated with performance on Digit Symbol Substitution test. Post-concussive symptoms reported by MHI patients are the result of poor modulation of incoming sensory information.

Auditory recovery cycle dysfunction in schizophrenia: a study using event-related potentials

Previous event-related potential (ERP) studies reported evidence of impaired auditory information processing in patients with schizophrenia. The recovery cycle of the auditory N1 ERP component was measured in 17 patients with schizophrenia and 17 age- and sex-matched healthy volunteers. Subjects performed a visual distraction task while listening to 80-dB SPL, 1000-Hz tone pairs, presented with intra-pair intervals of 1, 3, 5 or 7 s, with inter-pair intervals of 9-13 s. Patients with schizophrenia had significantly reduced N1 amplitudes for S1 stimuli compared with healthy volunteers. For N1 amplitudes elicited by S2 stimuli, there was a significant group effect whilst the main effect of intra-pair interval was not significant. These results provide additional evidence of inhibitory auditory processing deficits in schizophrenia.

Distinct M50 and M100 auditory gating deficits in schizophrenia

The time course of the schizophrenia auditory gating deficit may provide clues to mechanisms of impaired cognition. Magnetoencephalography was recorded during a standard paired-click paradigm. Using source strength of the M50 and M100 components for each click, calculated from dipole locations identified as underlying each component for the first click, a ratio of the second divided by the first was used to measure gating. Patients showed a left-hemisphere gating deficit in M50 and a bilateral gating deficit in M100. Hypothesizing that an early deficit may affect later processing, hierarchical regression was used to examine variance shared between the components. A left-hemisphere M100 gating deficit was coupled with the left M50 gating deficit. In contrast, a right-hemisphere M100 gating deficit was unrelated to M50 gating in either hemisphere. Investigations of interhemisphere gating relations may clarify group differences in regional connectivity and their role in gating.

Auditory inhibitory gating in the amygdala: Single-unit analysis in the behaving rat

Inhibitory sensory gating has been proposed to be a fundamental physiological process that filters neural input. Its temporal properties could allow for a rapid influence on vigilance and attention processes. Inhibitory mechanisms are reflected by reductions in neural responsiveness to repeated and well-predicted stimuli; for auditory gating, this translates into an inhibition of the neural activation to subsequent tone stimuli embedded within sequential and identical tone presentations. Here we expand previous neurophysiological data on inhibitory gating by examining gating in the amygdala using single-unit recording in freely moving animals. Previous data have shown the amygdala to be important in mediating rapid auditory sensory processing involved in emotional conditioning. We measured inhibitory gating with two matching auditory tones presented in a repetitive fashion (10 ms tones, ISI = 500 ms and 10 s between pairs) for 1 h (360 pairs). The majority of the tone responsive units showed inhibitory gating (78/95 units) located in both the medial and lateral subnuclei of the amygdala. Different types of tone responses were gated, including both shorter- and longer-duration excitatory tone responses as well as inhibitory tone responses. Different degrees of gating were found ranging from 100% inhibition (complete gating category) to 25% inhibition (graded gating category). The degree of gating varied over short-term and long-term time intervals. These findings demonstrate the existence of inhibitory gating in the amygdala and provide a detailed description of the basic properties of this rapid neural inhibition that could play an important role in filtering stimulus input.