Frontiers in Systems Neuroscience

A fundamental property of the neocortex is its columnar organization in many species. Generally, neurons of the same column share stimulus preferences and have strong anatomical connections across layers. These features suggest that neurons within a column operate as one unified network. Other features, like the different patterns of input and output connections of neurons located in separate layers and systematic differences in feature tuning, hint at a more segregated and possibly flexible functional organization of neurons within a column. To distinguish between these views of columnar processing, we conducted laminar recordings in macaques area V1 while they performed a demanding attention task. We found three separate regions with strong gamma oscillatory current source density (CSD) signals, one each in the supragranular, granular, and infragranular laminar domains. Their characteristics differed significantly in terms of their dominant gamma frequency and attention-dependent modulation of their gramma power and gamma frequency. In line, spiking activity in the supragranular, infragranular, and upper part of the granular domain exhibited strong phase coherence with their domains CSD signals but showed much weaker coherence with the other domains CSD signals. These results indicate that columnar processing involves a certain degree of independence between neurons in the three laminar domains, consistent with the assumption of multiple, separate intracolumnar ensembles. Such a functional organization offers various possibilities for dynamic network configuration, indicating that neurons in a column are not restricted to operate as one unified network. Thus, the findings open interesting new possibilities for future concepts and investigations on flexible, dynamic cortical ensemble formation and selective information processing.

The rodent granular retrosplenial cortex (gRSC), densely interconnected with the hippocampal formation and the anterior thalamic nuclei, plays an important role in learning and memory. We had revealed that small pyramidal neurons in the superficial layers of the rat gRSC exhibit late-spiking (LS) firing properties. It has been suggested that neural circuits containing LS neurons can encode time intervals on the order of seconds, known as "interval timing". To test the possibility that the rat gRSC is involved in the processing of interval timing, we employed a trace fear conditioning paradigm in which the conditioned stimulus (CS) and the unconditioned stimulus (US) were temporally separated. First, we examined the effect of cytotoxic lesions made in the RSC prior to trace fear conditioning. We found that intact rats exhibited freezing behavior after CS tone presentation, whereas lesioned rats did not exhibit such freezing behavior. Next, we conducted in vivo chronic or acute recordings of neural activity from the rat gRSC in a test session conducted one week after the conditioning. In both recordings, we observed a distinct spike activity in which there was a transient increase in the firing rate around the presentation of the CS tone, followed by a rapid suppression and then ramping activity (a gradual elevation of the firing rate) until the next CS presentation. This "ramping activity" is thought to be one way in which interval timing is represented in the brain. Post stimulus histogram analysis revealed the existence of ramping activity in the gRSC, which reached its peak at various time intervals after the onset of the CS tone. Interestingly, this activity was specifically observed in response to the CS tone but not to the non-CS tone. Moreover, in naive rat gRSC (no trace fear conditioning), no such ramping activity was observed. These results indicate that gRSC neurons can encode time information on the order of tens to hundreds of seconds, integrating incoming sensory input with past memory traces.

Neural activity in the olfactory bulb is reflected in local field potentials (LFPs). Functionally, LFPs in the olfactory bulb are categorized into different frequency bands: 1-4 Hz, 6-12 Hz, 25-50 Hz, and 65-130 Hz, which respectively correspond to respiration, sniffing, slow gamma, and fast gamma oscillations. While gamma oscillations in the olfactory bulb are modulated by respiration and sniffing, it remains unknown how and whether the modulation of LFP oscillations is affected by the time of day. To address this question, we recorded LFPs in the olfactory bulb, hippocampus, and neocortex of unrestrained mice for up to 3 d. For each recording site, we calculated the correlation coefficients of normalized LFP powers between pairs of frequency bands in the three regions during the dark and light periods. We then compared these correlations with those generated by surrogate data to investigate whether the correlation was statistically significant. We found that the correlation between sniffing and slow gamma oscillations was higher in the dark period than in the light period. Our finding has the potential to shed light on the coding scheme of olfactory information that is dependent on the light/dark cycle.

The function of the higher-order sensory thalamus remains unresolved. Here, POm nucleus was examined by in vivo extracellular recordings across a range of complex sensory patterns. We found that POm was highly sensitive to multiwhisker stimuli involving complex spatiotemporal interactions. The dynamical spatiotemporal structure of sensory patterns and the different complexity of their parts were accurately reflected in precise POm activity changes. Importantly, POm was also able to respond to ipsilateral stimulation and was implicated in the representation of bilateral tactile events by integrating simultaneous signals arising from both whisker pads. We found that POm nuclei are mutually connected through the cortex forming a functional POm-POm loop. We unravelled the nature and content of the messages travelling through this loop showing that they were structured patterns of sustained activity. These structured messages were transmitted preserving their integrated structure. The implication of different cortical areas was investigated revealing that S1 plays a protagonist role in this functional loop. Our results also demonstrated different laminar implication in the processing of sustained activity in this cortical area and its transmission between hemispheres. We propose a theoretical model in which these structured patterns of sustained activity generated by POm may play important roles in perceptual, motor and cognitive functions. From a functional perspective, this proposal, supported by the results described here, provides a novel theoretical framework to understand the implication of the thalamus in cognition. In addition, a profound difference was found between VPM and POm functioning. The hypothesis of Complementary Components is proposed here to explain it. HighlightsPOm is implicated in the representation of complex sensory patterns. POm is implicated in the encoding of bilateral tactile events. POm nuclei are mutually connected through the cortex forming a functional POm-POm loop. Structured patterns of sustained activity travelling through the loop O_FIG O_LINKSMALLFIG WIDTH=199 HEIGHT=200 SRC="FIGDIR/small/257667v2_ufig1.gif" ALT="Figure 1"> View larger version (51K): org.highwire.dtl.DTLVardef@217b4forg.highwire.dtl.DTLVardef@26a381org.highwire.dtl.DTLVardef@b88b0eorg.highwire.dtl.DTLVardef@1b15904_HPS_FORMAT_FIGEXP M_FIG C_FIG

Gamma rhythms play a major role in many different processes in the brain, such as attention, working memory and sensory processing. While typically considered detrimental, counterintuitively noise can sometimes have beneficial effects on communication and information transfer. Recently, Meng and Riecke showed that synchronization of interacting networks of inhibitory neurons in the gamma band increases while synchronization within these networks decreases when neurons are subject to uncorrelated noise. However, experimental and modeling studies point towards an important role of the pyramidal-interneuronal network gamma (PING) mechanism in the cortex. Therefore, we investigated the effect of uncorrelated noise on the communication between excitatory-inhibitory networks producing gamma oscillations via a PING mechanism. Our results suggest that synaptic noise can have a supporting role in facilitating inter-regional communication and that noise-induced synchronization between networks is generated via a different mechanism than when synchronization is mediated by strong synaptic coupling. Noise-induced synchronization is achieved by lowering synchronization within networks which allows the respective other network to impose its own gamma rhythm resulting in synchronization between networks.

To understand how sensory events are represented in and perceived by the brain, one must understand how varying internal brain states affect neuronal decoding of sensory input. Recent studies indicate global state changes in the brain impact the representation of haptic events in neurons of the primary somatosensory cortex (S1). It could be argued that the manipulations used so far to alter the cortical circuitry behavior were artificial and not reflective of normal information processing in the neocortex. In the present study we therefore wanted to explore if natural visual stimulation also could impact the interpretation of given tactile input patterns. We recorded the unitary extracellular responses to a set of spatiotemporal tactile input patterns presented either alone or together with simultaneously multicolor flashing lights from a large number of neurons in parallel in the rat primary somatosensory cortex (S1). We found that the visual input, mildly but consistently altered the temporal spike outputs to tactile input patterns in S1 neurons. We argue that the visual input change the global cortical state to an extent that it affects the cortical representation of haptic events even within the S1 and that this is an indication that the cortical network in its information processing may be far more reliant on globally distributed network dynamics than traditionally thought.

When we memorize multiple words simultaneously, semantic relatedness among those words assists memory. For example, the information of "apple", "banana" and "orange" will be connected via a common concept of "fruits" and become easy to retain and recall. Neural mechanisms underlying this semantic integration in verbal working memory remain unclear. Here I used electroencephalography (EEG) and investigated neural signals when healthy human participants memorized five nouns semantically related (Sem trial) or not (NonSem trial). The regularity of oscillatory signals (8 - 30 Hz) during the retention period was found to be lower in NonSem than Sem trials, indicating that memorizing words unrelated to each other induced a non-harmonic (irregular) waveform in the temporal cortex. These results suggest that (i) semantic features of a word are retained as a set of neural oscillations at specific frequencies and (ii) memorizing words sharing a common semantic feature produces harmonic brain responses through a resonance or integration (sharing) of the oscillatory signals.

In this research we explore in detail how a phenomenon called "sustained persistent activity" is achieved by circuits of interconnected neurons. Persistent activity is a phenomenon that has been extensively studied (Papoutsi et al. 2013; Kaminski et. al. 2017; McCormick et al. 2003; Rahman, and Berger, 2011). Persistent activity consists of neuron circuits whose spiking activity remains even after the initial stimuli are removed. Persistent activity has been found in the prefrontal cortex (PFC) and has been correlated to working memory and decision making (Clayton E. Curtis and Daeyeol Lee, 2010). We go beyond the explanation of how persistent activity happens and show how arrangements of those basic circuits encode and store data and are used to perform more elaborated tasks and computations. The purpose of the model we propose here is to describe the minimum number of neurons and their interconnections required to explain persistent activity and how this phenomenon is actually a fast storage mechanism required for implementing working memory, task processing and decision making.

Stimulus-driven responses in the cortex reduce due to prior exposure to sensory stimuli, a phenomenon called sensory adaptation. Depression of synaptic supplies and afterhyperpolarization (AHP) following each action potential are the main proposed mechanisms for adaptation. In vitro studies have shown that the neuronal adaptation in the barrel cortex depends on slow AHPs. Such AHPs can be affected by neuromodulators, such as noradrenaline. This evidence suggests that Locus Coeruleus (LC) noradrenergic system may reduce sensory adaptation through this cellular mechanism. We proposed that LC stimulation before whisker deflection can affect the degree of adaptation in the barrel cortex, depending on the nature of noradrenergic interactions in the barrel cortex. We coupled adapted or non-adapted whisker deflections with LC phasic stimulation with a 400 ms interval. A 50ms sinusoidal vibration was applied to the whisker immediately before the test deflection. Neuronal activity was recorded from the barrel cortex (BC) in a urethane anesthetized rat. We quantified the effect of LC stimulation on the degree of adaptation in BC; a lower adaptation index shows lower adaptation. Our result showed that LC stimulation significantly modulated adapted response in 30 % of units with insignificant modulation on the adaptor or non-adapted response. This modulation was in two directions; adaptation decreased in 5 % of units and increased in 25 % of units. In addition to LC modulation on adaptor response in the level of individual units, adaptor response was lower modulated in around 70 % of units, on average. This modulation was not correlated by LC modulation on non-adapted response. Although sensory adaptation in BC was attenuate by LC stimulation in the majority of units, there was a limited number of units that showed significant modulation.

The state of neural oscillation is important for various brain functions. In the basolateral nucleus of amygdala (BA), the oscillation frequency is accelerated in retrieval of conditioned fear memory. The amygdala receives sensory inputs from associated cortex and thalamus. Therefore, we tried to apply the bimodal sensory stimulation at slow frequency (5 Hz, functional frequency in behavioral context) for the entrainment of the BA oscillation. Young adult rats (P24-30) were stimulated by LED illuminator and acoustic speaker at 1 or 5 Hz for 1 hour. Immediately after the stimulus was finished, BA slices were prepared and whole-cell recording was applied to projection neuron. The slow (0.5-2 Hz) rhythmic IPSCs obtained from the pyramidal neuron was accelerated at [~]4 Hz by synchronous opto-acoustic stimulation at 5 Hz. However, the frequency of the neuron at the later recording did not change in the same slice, suggesting that this induced entrainment is transient and reversible phenomenon. As a result, the power distribution was shifted from 0.1-2 to 2-6 Hz by synchronous bimodal 5 Hz stimulation. The regularity of the interval between IPSCs, quantified by rhythm index and the concentration of power around peak frequency in the power spectrum, was not changed by rhythmic sensory stimulation. These results suggest that synchronous bimodal sensory stimuli control the neuronal oscillation frequency by applying with rhythmicity.

Gamma oscillations have been ubiquitously observed across a wide spectrum of brain areas in multiple species. They tend to occur intermittently in the form of bursts, rather than being produced as sustained and continuous rhythmic activity. Recent studies have shown that large visual sinusoidal gratings elicit two distinct gamma rhythms, namely, slow ({approx} 20-35 Hz) and fast gamma ({approx} 40-65 Hz), in the primary visual cortex (V1) of non-human primates. However, their mechanisms of generation and potential functional role in cortical processing remain unclear. Details of their burst signatures could potentially provide crucial insights about how the two rhythms influence network dynamics. Therefore, we computed burst statistics (durations and latencies) of simultaneously induced slow and fast gamma rhythms in the local field potential (LFP) recorded from area V1 of two adult female bonnet monkeys using several burst estimation methods. We found that slow gamma rhythm exhibited significantly longer burst durations and longer latencies as compared to fast gamma. Slow gamma exhibited higher long-range synchrony compared to fast gamma, as estimated by coherence and weighted phase lag index (WPLI), which could aid in enhanced global coordination in neocortex. Interestingly, longer burst length of slow-gamma could be replicated in a recently-developed noisy Wilson-Cowan network model by simply changing the firing-rate time-constant of the corresponding inhibitory interneuronal population, which leads to both slower and longer bursts. These results are consistent with the hypothesis that the two oscillations are generated by different inter-neuronal classes that operate over different temporal and spatial scales of integration. Significance statementSlow ({approx} 20-35 Hz) and fast gamma ({approx} 40-65 Hz) are two distinct rhythms known to be induced by large visual gratings in the primary visual cortex (V1). Interestingly, gamma oscillations manifest in the form of transient and stochastic epochs, generally termed as "bursts". We estimated the durations of stimulus-induced slow and fast gamma bursts generated in the local field potential (LFP) recorded from V1 of monkeys. Slow gamma bursts had significantly longer durations and increased latency to onset compared to fast gamma, which was replicated in a noisy Wilson-Cowan model by changing the time-constant associated with inhibitory neuronal population. These results suggest that slow and fast gamma are generated by different inter-neuronal networks operating at different spatio-temporal scales.

It has been shown recently that the human brain has dedicated networks for perception of human bodies in synchronous motion or in situation of interaction. However, below motion and interaction, how does the brain process a simple plurality of humans in close positioning? We used EEG frequency tagging technique to investigate integration of human dyad elements in a global percept. We presented to participants images of two silhouettes, a man and a woman flickering at different frequencies (5.88 vs.7.14Hz). Clear response at these stimulation frequencies reflected response to dyad parts, both when the dyad was presented upright and inverted. However, an emerging intermodulation component (7.14 + 5.88 = 13.02 Hz), a nonlinear response regarded as an objective signature of holistic representation, was significantly enhanced in upright relatively to inverted position. Inversion effect was significant only for the intermodulation component as opposed to stimulation frequencies revealing that dyad configuration perception overrides structural properties of dyad elements. Inversion effect was not significant for a pair of non-human objects. Our results show that merely facing two humans in close positioning leads to perceptually bind them and suggest that the perception of individuals is of different nature when they form a plurality.

Cross-frequency coupling (CFC) has been proposed as a fundamental mechanism mediating communication between neuronal assemblies through rhythmic interactions across multiple frequency bands, including delta, theta, alpha, beta, and gamma oscillations. Recent findings suggest that slow harmonics in the delta and theta ranges within the brainstem underlie cardiorespiratory rhythms through phase-phase CFC (Kawai, 2023). In contrast, higher-frequency gamma oscillations (>30 Hz) convey information-rich signals via phase-amplitude CFC mechanisms. To date, triple CFC modes have not been characterized in any brain region. Notably, simultaneous delta-theta-gamma coupling--encompassing both phase-phase and phase-amplitude interactions--appears to operate cooperatively, suggesting functional integration through emergent synchrony within the brainstem. Multiple recordings from the nucleus tractus solitarius (NTS) demonstrate that the power and coherence of these synchronized oscillations exhibit distinct spatiotemporal patterns along the dorsoventral axis, reflecting differentiation among large-scale efferent systems and cytoarchitectural domains (Kawai, 2018a; Negishi and Kawai, 2011). Robust gamma activity, phase-coupled with delta and theta oscillations generated by resilient harmonic oscillators within the NTS and the broader brainstem network, may constitute a cooperative mechanism for large-scale homeostatic regulation. The dynamic balance of signal power between slow (delta/theta) and fast (gamma) components could nonlinearly modulate oscillator network dynamics and widespread projection systems throughout the brain. Such integrative neural dynamics likely support adaptive, whole-body responses to fluctuations in the interoceptive environment.

The medial prefrontal cortex (mPFC) and basolateral amygdala (BLA) are involved in the regulation of defensive behavior under threat, but their engagement in flexible behavior shifts remains unclear. Here, we report the oscillatory activities of mPFC-BLA circuit in reaction to a naturalistic threat, created by a predatory robot in mice. Specifically, we found dynamic frequency tuning among two different theta rhythms ([~]5 or [~]10 Hz) was accompanied by agile changes of two different defensive behaviors (freeze or flight). By analyzing flight trajectories, we also found that high beta ([~]30 Hz) is engaged in the top-down process for goal-directed flights and accompanied by a reduction in fast gamma (60-120 Hz, peak near 70 Hz). The elevated beta nested the fast gamma activity by its phase more strongly. Our results suggest that the mPFC-BLA circuit has a potential role in oscillatory gear shifting allowing flexible information routing for behavior switches. HighlightsO_LIWhen threatened, mice take quick defensive behaviors such as freeze or flight. C_LIO_LImPFC-BLA theta tunes its frequency at 5 or 10 Hz for freeze or flight, respectively. C_LIO_LILow and high theta rhythms in mPFC-BLA emerge in a mutually exclusive way. C_LIO_LImPFC-driven beta emerges during goal-directed flights, coordinating fast gamma in BLA. C_LI eTOC BlurbHan et al. presents neural dynamics of mPFC-BLA network for freeze-or-flight defensive behaviors under naturalistic threats. Tuning the theta frequency in the mPFC-BLA network is for fast and agile actions under a naturalistic threat, and mPFC-driven beta oscillatory burst is for strategic action.

Synchrony of oscillatory brain activity has been postulated to be a binding mechanism for cognitive and motor functions. Spectral analysis of human electrocorticogram (ECoG) in sensorimotor cortex has shown that power density of gamma band activity (30-60 Hz) increased and that of alpha-beta band activity (10-20 Hz) decreased during performance of manipulative visuomotor tasks, indicating that amplitude modulation of the gamma band activity occurred in relation to the task performance. Amplitude modulation may provide evidence for synchrony of local neuronal assembly. However, it does not implement the binding mechanisms for distributed networks that are necessary for cognitive and motor functions. To prove that oscillatory activity mediates a binding mechanism, phase modulation of oscillatory activity in a wide range area should be shown. We performed coherence analysis of the ECoG signals in sensorimotor cortex to study if synchrony of the gamma band activity between these areas occurs in relation to manipulative task performance. The ECoGs were recorded from 14 sites in sensorimotor cortex including hand-arm areas with subdural grid electrodes in four subjects. Coherence estimates in all pair-wise sites were calculated in different frequency bands with 10 Hz widths from 10 to 80 Hz. In all subjects, coherence estimates increased in the lower gamma band (20-50 Hz) during the performance of the manipulative tasks. But coherence in the alpha-beta band (10-20 Hz) also increased even though amplitude modulation did not occur in this frequency band. Coherence estimates increased in site pairs within and between sensory and motor areas, many separated by intervening sites. This interregional synchrony of the alpha-beta and the lower gamma activities may play a role in integration of sensorimotor information. Task-dependent increases in coherence estimates, i.e., greater increases during performance of the manipulative tasks than during the simple tasks, suggest another role of synchrony in attention mechanism. Time-series coherence analysis showed that phase modulation occurred in different timings for activities in the alpha-beta and the lower gamma bands. For the activity in higher gamma band (50-80 Hz), power density increased but coherence estimates decreased. Thus, only amplitude modulation occurred in this frequency band. Altogether these results suggest that oscillatory activities in different frequency bands may reflect different functional roles by modulating neural activity in different ways.

Acquaintance to novel environments requires the encoding of spatial memories and the processing of unfamiliar sensory information in the hippocampus. Cholinergic signaling promotes the stabilization of hippocampal long-term potentiation (LTP) and contributes to theta-gamma oscillations balance, which is known to be crucial for learning and memory. However, the oscillatory mechanisms by which cholinergic signals are conveyed to the hippocampus are still poorly defined. We analyzed local field potentials from the basal forebrain (BF), a major source of cholinergic projections to the hippocampus, while rats explored a novel environment, and compared the modulation of BF theta (4-10Hz) and gamma (40-80Hz) frequency bands at distinct stages of spatial exploration. We found that BF theta and gamma display learning stage-related rhythmicity and that theta-gamma coupling is stronger at the later stages of exploration, a phenomenon previously observed in the hippocampus. Overall, our results suggest that the BF-hippocampal cholinergic signaling is conveyed via the stereotypical oscillatory patterns found during mnemonic processes, which questions the origins of the learning-related rhythmic activity found in the hippocampus. KEY-POINTSO_LIBasal forebrain theta oscillations decrease their strength in function of exploration time, as observed in the hippocampus. C_LIO_LIBF gamma ripples (bursting events) are longer after learning. C_LIO_LIBF Theta-gamma coupling increases after initial spatial exploration, suggesting BF cross-frequency coupling relation to the learning stage. C_LI

The default mode network (DMN), a set of transmodal cortical regions, has historically been argued to serve the internal functions of brain. The discovery of this network highlighted the brains intrinsic operations. The DMN generally decreases its activity during tasks and increases its activity during relaxed non-task states. It is important to investigate the nature of the DMN in order to understand the human brain in health and disease. In the current study, we discovered a task-related cortical network we called the Topological Discrimination Network (TDN), which was consistently revealed by contrasting activations from topological discrimination tasks with local geometric discrimination tasks. The TDN and the DMN consist of essentially the same group of brain regions and the fMRI response of topological discrimination in those regions exhibited consistent temporal dynamics with resting state. The robustness of the TDN is supported by multiple experiments performed at different field strengths (3T and 7T MRI scanner) as well as different types of signals measured (BOLD and CBF). The collective results suggest that the process of topological discrimination could almost be considered as a functional "default mode" of our brain. The TDN, like the DMN, could define the functional baseline of brain, with the advantage of functional consistency across participants and experimental sessions.

We introduce a novel perspective in equal and multifrequency coupling derived from considering neuronal synchrony as a possible equivalence relation. The experimental results agree with the theoretical prediction that cross-frequency coupling results in a partition of the brain synchrony state space. We place these results in the framework of the integration and segregation of information in the processing of sensorimotor transformations by the brain cell circuits and propose that equal frequency (1:1) connectivity favours integration of information in the brain whereas cross-frequency coupling (n:m) favours segregation. These observations may provide an outlook about how to reconcile the need for stability in the brains operations with the requirement for diversity of activity in order to process many sensorimotor transformations simultaneously.

In the olfactory bulb (OB), mitral cells (MCs) display a spontaneous firing that is characterized by bursts of action potentials intermixed with silent periods. Burst firing frequency and duration are heterogeneous among MCs and increase with membrane depolarization. By using patch clamp recording on rat slices, we dissected out the intrinsic properties responsible of this activity. We showed that the threshold of action potential (AP) generation dynamically changes as a function of the trajectory of the membrane potential; becoming more negative when the membrane was hyperpolarized and having a recovering rate, inversely proportional to the membrane repolarization rate. Such variations appeared to be produced by changes in the inactivation state of voltage dependent Na+ channels. Thus, the modification AP threshold favours the initiation of the burst following hyperpolarizing event such as negative membrane oscillations or inhibitory transmission. After the first AP, the following afterhyperpolarization (AHP) brought the threshold just below the membrane resting potential or within membrane oscillations and, as a consequence, the threshold was exceeded during the fast repolarization component of the AHP. In this way the fast AHP acts as a regenerative mechanism that sustains the firing. Bursts were stopped by the development of a slow repolarization component of the AHP. The AHP characteristics appeared as determining the bursting properties; AHP with larger amplitudes and faster repolarizations being associated with longer and higher frequency bursts. Thus, the increase of bursts length and frequency upon membrane depolarization would be attributable to the modifications of the AHP and of Na+ channels inactivation.

Interpersonal movement synchrony (IMS) and brain-to-brain coupling play a crucial role in social behavior across species. In humans, IMS is often studied in structured tasks that require specific body movements, while spontaneous, unstructured movements have received less attention. In this study, we investigated both structured and spontaneous motor coordination in mother-child dyads. We recorded upper-body kinematics and dual-EEG from mothers and their preschool children during motor tasks and spontaneous face-to-face interactions. Our findings show that mother-child dyads synchronize their movements and neural activity, particularly in gamma band oscillations. This motor and neural synchrony evolves across task repetitions, with a strong correlation between motor and neural measures. Further, we observed that only motor synchronization was significantly related to the childs motor development stage, as assessed by the Movement Assessment Battery for Children. These results suggest that gamma band brain-to-brain coupling reflects joint motor coordination and mutual adaptation shaped by structured tasks and spontaneous interpersonal interactions.