Firing rate models for describing the mean-field activities of neuronal ensembles can be used effectively to study network function and dynamics, including synchronization and rhythmicity of excitatory-inhibitory populations. However, traditional Wilson-Cowan-like models, even when extended to include an explicit dynamic synaptic activation variable, are found unable to capture some dynamics such as Interneuronal Network Gamma oscillations (ING). Use of an explicit delay is helpful in simulations at the expense of complicating mathematical analysis. We resolve this issue by introducing a dynamic variable, u, that acts as an effective delay in the negative feedback loop between firing rate (r) and synaptic gating of inhibition (s). In effect, u endows synaptic activation with second order dynamics. With linear stability analysis, numerical branch-tracking and simulations, we show that our r-u-s rate model captures some key qualitative features of spiking network models for ING. We also propose an alternative formulation, a v-u-s model, in which mean membrane potential v satisfies an averaged current-balance equation. Furthermore, we extend the framework to E-I networks. With our six-variable v-u-s model, we demonstrate in firing rate models the transition from Pyramidal-Interneuronal Network Gamma (PING) to ING by increasing the external drive to the inhibitory population without adjusting synaptic weights. Having PING and ING available in a single network, without invoking synaptic blockers, is plausible and natural for explaining the emergence and transition of two different types of gamma oscillations.

BACKGROUND: Impaired gamma band oscillation, specifically 40-Hz auditory steady state response (ASSR) has been robustly found in schizophrenia, while there is relatively little evidence characterizing the ASSR before full-blown psychosis.
OBJECTIVE: To characterize gamma-band ASSR in populations at clinical high-risk for psychosis (CHR).
METHODS: One hundred and seven CHR subjects and sixty-five healthy control (HC) subjects were included and completed clinical assessments, the ASSR paradigm of electroencephalography (EEG) and cognitive assessments. Both indices of event-related spectrum perturbation (ERSP) and intertrial coherence (ITC) in response to 20-Hz, 30-Hz and 40-Hz click sounds were respectively qualified and compared between these two groups, as well as the relationship to clinical psychopathology and cognitive function was assessed.
RESULTS: At 40-Hz click sounds, ERSP in HC group (1.042 ± 0.047) was statistical significantly increased than that in CHR group (0.873 ± 0.036) (p = 0.005)；at 30-Hz, ERSP in HC group (0.536 ± 0.024) was increased than that in CHR group (0.483 ± 0.019), but the difference was trend statistical significance (p = 0.083)；at 20-Hz, ERSP in HC group (0.452 ± 0.017) was not different significantly from CHR group (0.418 ± 0.013) (p = 0.104). ERSP of the HC group was the highest at 40-Hz click sounds, followed by 30-Hz, and the lowest at 20-Hz. The difference between any two of the three ERSP showed statistical significance (30-Hz vs. 40-Hz: p < 0.001; 20-Hz vs. 40-Hz: p < 0.001；20-Hz vs. 30-Hz: p = 0.003). Similarly, ERSP of the CHR group was the highest at 40-Hz click sounds, followed by 30-Hz, and the lowest at 20-Hz. The difference between any two of these three ERSP showed statistical significance (30-Hz vs. 40-Hz: p < 0.001; 20-Hz vs. 40-Hz: p < 0.001；20-Hz vs. 30-Hz: p = 0.002). A statistically significant small positive correlation of 40-Hz ERSP with signal processing speed score was observed in the HC group (ρ = 0.27, p = 0.029). A statistically significant small negative correlation of 40-Hz ERSP with visual learning score was observed in the CHR group (ρ = -0.22, p = 0.023).
CONCLUSIONS: Impaired 40-Hz but undamaged hierarchical organization mode of auditory steady state presented in the CHR populations. Abnormal 40 Hz ASSR for CHR might be associated with cognitive functions, such as information processing speed and visual memory.

Listening to music is a promising and accessible intervention for alleviating symptoms of major depressive disorder. However, the neural mechanisms underlying its antidepressant effects remain unclear. In this study on patients with depression, we used auditory entrainment to evaluate intracranial recordings in the bed nucleus of the stria terminalis (BNST) and nucleus accumbens (NAc), along with temporal scalp electroencephalogram (EEG). We highlight music-induced synchronization across this circuit. The synchronization initiates with temporal theta oscillations, subsequently inducing local gamma oscillations in the BNST-NAc circuit. Critically, the incorporated external entrainment induced a modulatory effect from the auditory cortex to the BNST-NAc circuit, activating the antidepressant response and highlighting the causal role of physiological entrainment in enhancing the antidepressant response. Our study explores the pivotal role of the auditory cortex and proposes a neural oscillation triple time-locking model, emphasizing the capacity of the auditory cortex to access the BNST-NAc circuit.

Children with attention-deficit hyperactivity disorder (ADHD) have difficulties in social interactions. Studying brain activity during social interactions is difficult with conventional artificial stimuli. This pioneering study examined the neural correlates of social perception in children with ADHD and matched controls using naturalistic stimuli. We presented 20 children with ADHD and 20 age-and-sex-matched controls with tailored movies featuring high- or low-level social interactions while recording electroencephalographic signals. Both groups exhibited synchronized gamma-band oscillations, but controls demonstrated greater inter-subject correlations. Additionally, the difference in inter-subject correlations between high- and low-interaction movies was significantly larger in controls compared to ADHD patients. Between 55 and 75 Hz comparing viewing high interaction movies with low interaction moves, controls had a significantly larger weighting in the right parietal lobe, while ADHD patients had a significantly smaller weighting in the left occipital lobe. These findings reveal distinct spatiotemporal neural signatures in social interaction processing among children with ADHD and controls using naturalistic stimuli. These neural markers offer potential for group differentiation and assessing intervention efficacy, advancing our understanding ADHD-related social interaction mechanisms.

Diverse neuron classes in hippocampal CA1 have been identified through the heterogeneity of their cellular/molecular composition. How these classes relate to hippocampal function and the network dynamics that support cognition in primates remains unclear. Here, we report inhibitory functional cell groups in CA1 of freely moving macaques whose diverse response profiles to network states and each other suggest distinct and specific roles in the functional microcircuit of CA1. In addition, pyramidal cells that were grouped by their superficial or deep layer position differed in firing rate, burstiness, and sharp-wave ripple-associated firing. They also showed strata-specific spike-timing interactions with inhibitory cell groups, suggestive of segregated neural populations. Furthermore, ensemble recordings revealed that cell assemblies were preferentially organized according to these strata. These results suggest that hippocampal CA1 in freely moving macaques bears a sublayer-specific circuit organization that may shape its role in cognition.

While recent advancements have been made towards a better understanding of the involvement of the prefrontal cortex (PFC) in the context of cognitive control, the exact mechanism is still not fully understood. Successful behavior requires the correct detection of goal-relevant cues and resisting irrelevant distractions. Frontal parietal networks have been implicated as important for maintaining cognitive control in the face of distraction. The present study investigated the role of gamma-band power in distraction resistance and frontoparietal networks, as its increase is linked to cholinergic activity. We examined changes in gamma activity and their relationship to frontoparietal top-down modulation for distractor challenges and to bottom-up distractor processing. Healthy young adults were tested using a modified version of the distractor condition sustained attention task (dSAT) while wearing an EEG. The modified distractor was designed so that oscillatory activities could be entrained to it, and the strength of entrainment was used to assess the degree of distraction. Increased top-down control during the distractor challenge increased gamma power in the left parietal regions rather than the right prefrontal regions predicted from rodent studies. Specifically, left parietal gamma power increased in response to distraction where the amount of this increase was negatively correlated with the neural activity reflecting bottom-up distractor processing in the visual area. Variability in gamma power in right prefrontal regions was associated with increased response time variability during distraction. This may suggest that the right prefrontal region may contribute to the signaling needed for top-down control rather than its implementation.

BACKGROUND: Recent studies propose 40 Hz neural activity induction as a promising approach for managing Alzheimer\'s dementia (AD). However, traditional flickering light is suboptimal in addressing cognitive and neuropsychiatric symptoms (NPS) of AD. This study aims to investigate the clinical efficacy of a novel multi-luminaire lighting technology, with reduced perceptible flickering, for treating AD NPS.
METHODS: This study is a prospective, convenient sampling, non-randomized case-control investigation involving seventy-eight clinically diagnosed AD patients from 7 daycare centers. Thirty-five were exposed to 40 Hz light through Delta M + BrainCare Light (M +), 4 h daily, 5 days/week, for 12 weeks. The other 43 patients served as controls. Sum of boxes of the Clinical Dementia Rating (CDR-SB) scale, Neuropsychiatric Inventory (NPI), and Zarit Burden Interview (ZBI) were assessed at baseline and the 13th week.
RESULTS: At baseline, the cases had worse cognitive function, lower cognitive score (Mini-Mental State Examination, p = 0.04; Cognitive Abilities Screening Instrument, p = 0.04), and advanced caregiver burden with higher ZBI scores (p < 0.01) than the controls. After the intervention, the cases had significant improvements in NPS as assessed using the NPI (p = 0.02), especially depression and euphoria symptoms (p = 0.04 and < 0.01, respectively) and less caregiver burden (ZBI score, p < 0.01). In global function, the control group showed a significant decline in CDR-SB score (p < 0.01), while the cases did not.
CONCLUSIONS: Results suggest M + may slow global function decline, preserve cognitive function, improve NPS, and reduce caregiver burden in AD patients. Larger studies with biomarkers are needed to explore underlying mechanisms.

UNASSIGNED: This study aimed to investigate gamma oscillations related to face processing of children with autism spectrum disorders and typically developed children using magnetoencephalography.
UNASSIGNED: We developed stimuli that included naturalistic real-time eye-gaze situations between participants and their mothers. Eighteen young children with autism spectrum disorders (62-97 months) and 24 typically developed children (61-79 months) were included. The magnetoencephalography data were analyzed in the bilateral banks of the superior temporal sulcus, fusiform gyrus, and pericalcarine cortex for frequency ranges 30-59 and 61-90 Hz. The gamma oscillation normalized values were calculated to compare the face condition (children gazing at mother\'s face) and control measurements (baseline) using the following formula: (face - control)/(face + control).
UNASSIGNED: The results revealed significant differences in gamma oscillation normalized values in the low gamma band (30-59 Hz) in the right banks of the superior temporal sulcus, right fusiform gyrus, and right pericalcarine cortex between children with autism spectrum disorders and typically developed children. Furthermore, there were significant differences in gamma oscillation normalized values in the high gamma band (61-90 Hz) in the right banks of the superior temporal sulcus, bilateral fusiform gyrus, and bilateral pericalcarine cortex between the groups.
UNASSIGNED: This report is the first magnetoencephalography study revealing atypical face processing in young children with autism spectrum disorders using relevant stimuli between participants and their mothers. Our naturalistic paradigm provides a useful assessment of social communication traits and a valuable insight into the underlying neural mechanisms in children with autism spectrum disorders.

Stimulus size modulation of neuronal firing activity is a fundamental property of the primary visual cortex. Numerous biological experiments have shown that stimulus size modulation is affected by multiple factors at different spatiotemporal scales, but the exact pathways and mechanisms remain incompletely understood. In this paper, we establish a large-scale neuronal network model of primary visual cortex with layer 2/3 to study how gamma oscillation properties are modulated by stimulus size and especially how long-range connections affect the modulation as realistic neuronal properties and spatial distributions of synaptic connections are considered. It is shown that long-range horizontal synaptic connections are sufficient to produce dimensional modulation of firing rates and gamma oscillations. In particular, with increasing grating stimulus size, the firing rate increases and then decreases, the peak frequency of gamma oscillations decreases and the spectral power increases. These are consistent with biological experimental observations. Furthermore, we explain in detail how the number and spatial distribution of long-range connections affect the size modulation of gamma oscillations by using the analysis of neuronal firing activity and synaptic current fluctuations. Our results provide a mechanism explanation for size modulation of gamma oscillations in the primary visual cortex and reveal the important and unique role played by long-range connections, which contributes to a deeper understanding of the cognitive function of gamma oscillations in visual cortex.

The local field potential (LFP) is an extracellular electrical signal associated with neural ensemble input and dendritic signaling. Previous studies have linked gamma band oscillations of the LFP in cortical circuits to sensory stimuli encoding, attention, memory, and perception. Inconsistent results regarding gamma tuning for visual features were reported, but it remains unclear whether these discrepancies are due to variations in electrode properties. Specifically, the surface area and impedance of the electrode are important characteristics in LFP recording. To comprehensively address these issues, we conducted an electrophysiological study in the V1 region of lightly anesthetized mice using two types of electrodes: one with higher impedance (1 MΩ) and a sharp tip (10 μm), while the other had lower impedance (100 KΩ) but a thicker tip (200 μm). Our findings demonstrate that gamma oscillations acquired by sharp-tip electrodes were significantly stronger than those obtained from thick-tip electrodes. Regarding size tuning, most gamma power exhibited surround suppression at larger gratings when recorded from sharp-tip electrodes. However, the majority showed enhanced gamma power at larger gratings when recorded from thick-tip electrodes. Therefore, our study suggests that microelectrode parameters play a significant role in accurately recording gamma oscillations and responsive tuning to sensory stimuli.