Concurrent sound segregation impairments in schizophrenia: The contribution of auditory-specific and general cognitive factors

Spontaneous neural activity underlying neutral and happy speech recognition in noise and its association with psychiatric symptoms in patients with schizophrenia

BACKGROUND

Deficits in speech and emotion perception are intertwined with psychiatric symptoms. How the happy prosody embedded in speech affects target speech-in-noise recognition (TSR) and relates to psychiatric symptoms in patients with schizophrenia (SCHs) remains unclear. This study examined spontaneous brain activity underlying happy TSR and its association with psychiatric symptom dimensions in SCHs.

METHODS

Fifty-four SCHs and 59 healthy control participants (HCs) underwent the TSR task, Positive and Negative Syndrome Scale (PANSS) assessment, and magnetic resonance imaging scanning. Multivariate analyses of partial least squares (PLS) regression were used to explore the associations between whole-brain fractional amplitude of low-frequency fluctuations (fALFF), happy-neutral TSR (target pseudo-sentences were uttered in happy and neutral prosodies), and five PANSS factor scores (excitement/hostility, depression/anxiety, cognition, positive, and negative).

RESULTS

The happy prosody did not alter TSR or TSR changing rates in either SCHs or HCs. SCHs exhibited lower happy and neutral TSR than HCs. A fALFF PLS component (including precentral/postcentral gyrus, Subcallosal Cortex, several temporal regions, and cerebellum) was associated with happy and neutral TSR. SCHs demonstrated higher PLS fALFF scores and PLS TSR scores than HCs. In SCHs, PLS fALFF scores were correlated with the PANSS positive factor score, and PLS TSR scores were correlated with the PANSS cognition factor score.

CONCLUSIONS

The positive-psychiatric-symptoms-related spontaneous activity profile was associated with happy and neutral TSR, contributing to the cognition psychiatric symptoms dimension. The findings suggest the potential to improve positive and cognitive symptoms by enhancing happy and neutral TSR in schizophrenia based on neuroplasticity.

Effects of Memantine on the Auditory Steady-State and Harmonic Responses to 40 Hz Stimulation Across Species

BACKGROUND

Click trains elicit an auditory steady-state response (ASSR) at the driving frequency (1F) and its integer multiple frequencies (2F, 3F, etc.) called harmonics; we call this harmonic response the steady-state harmonic response (SSHR). We describe the 40 Hz ASSR (1F) and 80 Hz SSHR (2F) in humans and rats and their sensitivity to the uncompetitive NMDA antagonist memantine.

METHODS

In humans (healthy control participants, n = 25; patients with schizophrenia, n = 28), electroencephalography was recorded after placebo or 20 mg memantine in a within-participant crossover design. ASSR used 1 ms, 85-dB clicks presented in 250 40/s 500-ms trains. In freely moving rats (n = 9), electroencephalography was acquired after memantine (0, 0.3, 1, 3 mg/kg) in a within-participant crossover design; 65-dB click trains used 5-mV monophasic, 1-ms square waves (40/s).

RESULTS

Across species, ASSR at 1F generated greater evoked power (EP) than the 2F SSHR. 1F > 2F intertrial coherence (ITC) was also detected in humans, but the opposite relationship (ITC: 2F > 1F) was seen in rats. EP and ITC at 1F were deficient in patients and were enhanced by memantine across species. EP and ITC at 2F were deficient in patients. Measures at 2F were generally insensitive to memantine across species, although in humans the ITC harmonic ratio (1F:2F) was modestly enhanced by memantine, and in rats, both the EP and ITC harmonic ratios were significantly enhanced by memantine.

CONCLUSIONS

ASSR and SSHR are robust, nonredundant electroencephalography signals that are suitable for cross-species analyses that reveal potentially meaningful differences across species, diagnoses, and drugs.

Negative-emotion-induced reduction in speech-in-noise recognition is associated with source-monitoring deficits and psychiatric symptoms in mandarin-speaking patients with schizophrenia

BACKGROUND

Patients with schizophrenia (SCH) have deficits in source monitoring (SM), speech-in-noise recognition (SR), and auditory prosody recognition. This study aimed to test the covariation between SM and SR alteration induced by negative prosodies and their association with psychiatric symptoms in SCH.

METHODS

Fifty-four SCH patients and 59 healthy controls (HCs) underwent a speech SM task, an SR task, and the assessment of positive and negative syndrome scale (PANSS). We used the multivariate analyses of partial least squares (PLS) regression to explore the associations among SM (external/internal/new attribution error [AE] and response bias [RB]), SR alteration/release induced by four negative-emotion (sad, angry, fear, and disgust) prosodies of target speech, and psychiatric symptoms.

RESULTS

In SCH, but not HCs, a profile (linear combination) of SM (especially the external-source RB) was positively associated with a profile of SR reductions (induced especially by the angry prosody). Moreover, two SR reduction profiles (especially in the anger and sadness conditions) were related to two profiles of psychiatric symptoms (negative symptoms, lack of insight, and emotional disturbances). The two PLS components explained 50.4% of the total variances of the release-symptom association.

CONCLUSION

Compared to HCs, SCH is more likely to perceive the external-source speech as internal/new source speech. The SM-related SR reduction induced by the angry prosody was mainly associated with negative symptoms. These findings help understand the psychopathology of SCH and may provide a potential direction to improve negative symptoms via minimizing emotional SR reduction in schizophrenia.

Auditory discrimination and frequency modulation learning in schizophrenia patients: amphetamine within-subject dose response and time course

BACKGROUND

Auditory frequency modulation learning ('auditory learning') is a key component of targeted cognitive training (TCT) for schizophrenia. TCT can be effective in enhancing neurocognition and function in schizophrenia, but such gains require significant time and effort and elude many patients.

METHODS

As a strategy to increase and/or accelerate TCT-induced clinical gains, we tested the dose- and time-course effects of the pro-attentional drug, amphetamine (AMPH; placebo, 2.5, 5 or 10 mg po; within-subject double-blind, order balanced) on auditory learning in schizophrenia patients [n = 32; M:F = 19:13; age 42.0 years (24-55)]. To understand predictors and/or mechanisms of AMPH-enhanced TCT, we also measured auditory fidelity (words-in-noise (WIN), quick speech-in-noise (QuickSIN)) and neurocognition (MATRICS comprehensive cognitive battery (MCCB)). Some measures were also acquired from age-matched healthy subjects (drug free; n = 10; M:F = 5:5).

RESULTS

Patients exhibited expected deficits in neurocognition. WIN and QuickSIN performance at low signal intensities was impaired in patients with low v. high MCCB attention/vigilance (A/V) scores; these deficits were corrected by AMPH, maximally at 2.5-5 mg (d's = 0.79-1.29). AMPH also enhanced auditory learning, with maximal effects at 5 mg (d = 0.93), and comparable effects 60 and 210 min post pill. 'Pro-learning' effects of AMPH and AMPH-induced gains in auditory fidelity were most evident in patients with low MCCB A/V scores.

CONCLUSIONS

These findings advance our understanding of the impact of pro-attentional interventions on auditory information processing and suggest dose- and time-course parameters for studies that assess the ability of AMPH to enhance the clinical benefits of TCT in schizophrenia patients.

Neural correlates of concurrent sound perception: A review and guidelines for future research

The perception of concurrent sound sources depends on processes (i.e., auditory scene analysis) that fuse and segregate acoustic features according to harmonic relations, temporal coherence, and binaural cues (encompass dichotic pitch, location difference, simulated echo). The object-related negativity (ORN) and P400 are electrophysiological indices of concurrent sound perception. Here, we review the different paradigms used to study concurrent sound perception and the brain responses obtained from these paradigms. Recommendations regarding the design and recording parameters of the ORN and P400 are made, and their clinical applications in assessing central auditory processing ability in different populations are discussed.

Impaired interaural correlation processing in people with schizophrenia

Detection of transient changes in interaural correlation is based on the temporal precision of the central representations of acoustic signals. Whether schizophrenia impairs the temporal precision in the interaural correlation process is not clear. In both participants with schizophrenia and matched healthy-control participants, this study examined the detection of a break in interaural correlation (BIC, a change in interaural correlation from 1 to 0 and back to 1), including the longest interaural delay at which a BIC was just audible, representing the temporal extent of the primitive auditory memory (PAM). Moreover, BIC-induced electroencephalograms (EEGs) and the relationships between the early binaural psychoacoustic processing and higher cognitive functions, which were assessed by the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), were examined. The results showed that compared to healthy controls, participants with schizophrenia exhibited poorer BIC detection, PAM and RBANS score. Both the BIC-detection accuracy and the PAM extent were correlated with the RBANS score. Moreover, participants with schizophrenia showed weaker BIC-induced N1-P2 amplitude which was correlated with both theta-band power and inter-trial phase coherence. These results suggested that schizophrenia impairs the temporal precision of the central representations of acoustic signals, affecting both interaural correlation processing and higher-order cognitions.

Memantine effects on auditory discrimination and training in schizophrenia patients

The uncompetitive low-affinity NMDA receptor antagonist, memantine, acutely increases electrophysiological measures of auditory information processing in both healthy subjects (HS) and patients with schizophrenia. Memantine effects on functional measures of auditory discrimination performance and learning are not known; conceivably, beneficial effects on these measures might suggest a role for memantine in augmenting the cognitive and functional impact of auditory targeted cognitive training (TCT). Here, carefully characterized HS (n = 20) and schizophrenia patients (n = 22) were tested in measures of auditory discrimination performance (words-in-noise (WIN), quick speech-in-noise (QuickSIN), gaps-in-noise) and auditory frequency modulation learning (a component of TCT) on 2 days about a week apart, after ingesting either placebo or 20 mg memantine po, in a double-blind, within-subject cross-over random order design. Memantine modestly enhanced functional measures of auditory discrimination in both schizophrenia patients (WIN) and HS (WIN and QuickSIN), as well as auditory frequency modulation learning in schizophrenia patients. These findings converge with a growing literature showing that memantine can enhance a range of metrics of auditory function. These properties could contribute to the apparent benefits of memantine as an adjunctive treatment in schizophrenia, and suggest that memantine might augment learning and potentially clinical gains from auditory-based TCT.