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Imaging neuronal activity of auditory thalamus in freely moving mice a Mouse with a head-mounted miniaturized microscope (left). Location of gradient refractive index (GRIN) lens in the medial geniculate body (MGB, right). b Example GCaMP6f expression in MGB. Similarly replicated expression patterns for all animals where GCaMP6f was injected in MGB (N = 24 mice). c High magnification of GCaMP6f-expressing MGB neurons from B. d Individual motion corrected fields of view (maximum intensity projection) of one example animal across a four-day fear conditioning paradigm (Hab, FC, Ext. 1, Ext. 2) as well as the maximum intensity projection across all days. Red circles indicate selected individual components. Replicated for all mice (N = 24) that underwent calcium imaging. e Average number of individual ICs/animal (93 ± 4 neurons, N = 24 mice). Boxplots show median, 2nd, 3rd quartile, minimum and maximum. Cross indicates mean. f Changes in Ca²⁺ fluorescence of five individual neurons during the habituation session. Lines indicate CS tone presentations (red: 12 kHz, blue: 6 kHz). g Tone responses on habituation day 1 of all recorded MGB neurons in fear conditioning experiments (N = 855 neurons, N = 9 mice).
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Cortical and limbic brain areas are regarded as centres for learning. However, how thalamic sensory relays participate in plasticity upon associative learning, yet support stable long-term sensory coding remains unknown. Using a miniature microscope imaging approach, we monitor the activity of populations of auditory thalamus (medial geniculate bod...
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... This proposes that fast deployment, scalability, low cost and specific feature recognition, and the effective implementation of the ad hoc network have been enabled. The static, proactive, hybrid, reactive, and hierarchical analysis is done in the FANET protocol [15]. It features a variety of tools, including cameras, LiDAR, GPS, IMU, thermal imaging, RF, and ultrasonic. ...
Some protocols operated in the MAC layer and the open-source interconnections model to share the packet delivery and the network channel to deliver the packet is done. Transmitting two or more messages through one channel causes problems in packing and information delivery. This causes the lagging of the data to reach the destinations. So, the method of multiple hubs and the host must be created for the packet and the information delivery. This makes the fast transmission of data and messages. Method: The Tunnel monitoring system and the FANET are used for analysis in this study for the research, enabling the mobile radio networks for the examination. The FANET-based flying network system allows the paradigm for accessing human analysis. Then the drone-related data can be helped. The tunnel monitoring system navigates the information purpose and routing of the drone flying and gathering the data. Then based on human analysis, 40% of the data can be analyzed using the system's formation. Result: These results support the coverage and the tunnel monitoring process for detecting the navigation system. Conclusion: Also, some tunnel-based detection using drones is found in this study based on the wireless muometric navigation system that can be enabled using Q-learning.
... Associative learning, a form of behavior plasticity [2], involves associating one behavior or stimulus (conditioned stimulus, CS) with another stimulus (unconditioned stimulus, US) [3]. Various stimuli, including olfactory, gustatory, auditory, visual, and temperature-sensing stimuli, have been identified in associative learning [4][5][6][7][8]. Associative learning, which was first demonstrated by Pavlov (1927), has been reported in a wide range of animals, from snails and Drosophila to nematodes, honeybees, and rats [9][10][11][12][13]. ...
Associative learning is a critical survival trait that promotes behavioral plasticity in response to changing environments. Chemosensation and mechanosensation are important sensory modalities that enable animals to gather information about their internal state and external environment. However, there is a limited amount of research on these two modalities. In this paper, a novel PDMS–agar hybrid microfluidic device is proposed for training and analyzing chemical–mechanical associative learning behavior in the nematode Caenorhabditis elegans. The microfluidic device consisted of a bottom agar gel layer and an upper PDMS layer. A chemical concentration gradient was generated on the agar gel layer, and the PDMS layer served to mimic mechanical stimuli. Based on this platform, C. elegans can perform chemical–mechanical associative learning behavior after training. Our findings indicated that the aversive component of training is the primary driver of the observed associative learning behavior. In addition, the results indicated that the neurotransmitter octopamine is involved in regulating this associative learning behavior via the SER-6 receptor. Thus, the microfluidic device provides a highly efficient platform for studying the associative learning behavior of C. elegans, and it may be applied in mutant screening and drug testing.
... It is well established that the subcortical circuit from the multisensory thalamus, lateral thalamus (LT) to the basolateral amygdala (BLA) is necessary for the acquisition and the recall of auditory learned threat conditioning in rodents (Barsy et al., 2020;Edeline & Weinberger, 1992;Iwata et al., 1986;Lee et al., 2021;LeDoux et al., 1984;Romanski & LeDoux, 1992a;Romanski & LeDoux, 1992b;Taylor et al., 2021). However, the role of the subcortical LT-BLA pathway is underemphasized and understudied in processing innate threats (Kang et al., 2022). ...
... The subcortical pathway comprising the LT inputs to the BLA is known to be essential for the acquisition of threat conditioning (Romanski and LeDoux, 1992 a and b;LeDoux et al., 1984;Campeau & Davis, 1995;Barsy et al., 2020;Taylor et al., 2021;Lee et al., 2021). Therefore, we tested whether these inputs are also required for processing innately aversive threats. ...
... The LT-BLA pathway typically has been evaluated in relation to associative learnings (Janak and Tye, 2015;Tye et al., 2008), especially associative learned threats (Barsy et al., 2020;Taylor et al., 2021). Recent works on associative learned threats have particularly solidified the importance of associative plasticity in the LT (Barsy et al., 2020;Taylor et al., 2021). ...
Behavioral flexibility and timely reactions to salient stimuli are essential for survival. The subcortical thalamic-basolateral amygdala (BLA) pathway serves as a shortcut for salient stimuli ensuring rapid processing. Here, we show that BLA neuronal and thalamic axonal activity mirror the defensive behavior evoked by an innate visual threat as well as an auditory learned threat. Importantly, perturbing this pathway compromises defensive responses to both forms of threats, in that animals fail to switch from exploratory to defensive behavior. Despite the shared pathway between the two forms of threat processing, we observed noticeable differences. Blocking beta-adrenergic receptors impair the defensive response to the innate but not the learned threats. This reduced defensive response, surprisingly, is reflected in the suppression of the activity exclusively in the BLA, as the thalamic input response remains intact. Our side-by-side examination highlights the similarities and differences between innate and learned threat-processing, thus providing new fundamental insights.
... It is well established that the subcortical circuit from the multisensory thalamus, medial geniculate nucleus (MGN) to the basolateral amygdala (BLA) is necessary in the acquisition and processing of auditory learned threat conditioning in rodents (Barsy et al., 2020;Edeline & Weinberger, 1992;Iwata et al., 1986;Lee et al., 2021;LeDoux et al., 1984;Romanski & LeDoux, 1992a;Romanski & LeDoux, 1992b;Taylor et al., 2021). However, the 2 is thought to mimic an approaching aerial predator (Yilmaz & Meister, 2013). ...
... The subcortical pathway comprising the MGN inputs to the BLA is known to be essential for the acquisition of threat conditioning (Romanski and LeDoux, 1992 a and b;LeDoux et al., 1984;Campeau & Davis, 1995;Barsy et al., 2020;Taylor et al., 2021;Lee et al., 2021). Therefore, we tested whether these inputs are also required for Zoomed-in images from the regions outlined in yellow from B and in red from C. Scale bar, 50um. ...
Behavioral flexibility and timely reactions to salient stimuli are essential for survival. The subcortical thalamic-basolateral amygdala (BLA) pathway serves as a shortcut for salient stimuli ensuring rapid processing. Here, we show that BLA neuronal and thalamic axonal activity mirror the defensive behavior evoked by an innate visual threat as well as an auditory learned threat. Importantly, perturbing this pathway compromises defensive responses to both forms of threats, in that animals fail to switch from exploratory to defensive behavior. Despite the shared pathway between the two forms of threat processing, we observed noticeable differences. Blocking beta-adrenergic receptors impair the defensive response to the innate but not the learned threats. This reduced defensive response, surprisingly, is reflected in the suppression of the activity exclusively in the BLA, as the thalamic input response remains intact. Our side-by-side examination highlights the similarities and differences between innate and learned threat-processing, thus providing new fundamental insights.
... However, recent evidence has challenged this view by highlighting a role for the mPFC also during fear memory encoding (Bero et al., 2014;Cho et al., 2017;Cummings and Clem, 2020;Tang et al., 2005;Zelikowsky et al., 2013) as well as for fear memory recall at recent times (Do-Monte et al., 2015;Rajasethupathy et al., 2015). The rich connectivity of the mPFC indeed places it as a potential hub region for memory consolidation, as it receives not only inputs from other cortical areas, including sensory ones, but also from various subcortical areas such as the hippocampal formation, amygdala, and thalamus (Dixsaut and Gräff, 2021;Le Merre et al., 2021), which are all implicated in memory formation (Cho et al., 2017;Nonaka et al., 2014;Ramirez et al., 2013;Reijmers et al., 2007;Taylor et al., 2021). ...
Memory formation and storage rely on multiple interconnected brain areas, the contribution of which varies during memory consolidation. The medial prefrontal cortex, in particular the prelimbic cortex (PL), was traditionally found to be involved in remote memory storage, but recent evidence points toward its implication in early consolidation as well. Nevertheless, the inputs to the PL governing these dynamics remain unknown. Here, we first performed a brain-wide, rabies-based retrograde tracing screen of PL engram cells activated during contextual fear memory formation in male mice to identify relevant PL input regions. Next, we assessed the specific activity pattern of these inputs across different phases of memory consolidation, from fear memory encoding to recent and remote memory recall. Using projection-specific chemogenetic inhibition, we then tested their functional role in memory consolidation, which revealed a hitherto unknown contribution of claustrum to PL inputs at encoding, and of insular cortex to PL inputs at recent memory recall. Both of these inputs further impacted how PL engram cells were reactivated at memory recall, testifying to their relevance for establishing a memory trace in the PL. Collectively, these data identify a spatiotemporal shift in PL inputs important for early memory consolidation, and thereby help to refine the working model of memory formation.
... While corticothalamic projections are excitatory, cortical feedback has both excitatory and inhibitory effects on thalamic neurons through disynaptic connections via the thalamic reticular nucleus (Cruikshank et al., 2010;. Diverse functions have been proposed for corticothalamic feedback in the auditory system, including gating of thalamocortical transmission , supporting thalamic plasticity during learning Taylor et al., 2021), gain control of cortical input (Saldeitis et al., 2021) and switching dynamics of processing to favor detection or discrimination of stimuli . Thalamic sensory processing can also be influenced by altering activity further downstream e.g. ...
... While corticothalamic projections are excitatory, cortical feedback has both excitatory and inhibitory effects on thalamic neurons through disynaptic connections via the thalamic reticular nucleus (Cruikshank et al., 2010;Crandall et al., 2015). Diverse functions have been proposed for corticothalamic feedback in the auditory system, including gating of thalamocortical transmission (Yu et al., 2004;Ibrahim et al., 2021), supporting thalamic plasticity during learning (He, 2003;Suga, 2020;Taylor et al., 2021), gain control of cortical input (Saldeitis et al., 2021) and switching dynamics of processing to favor detection or discrimination of stimuli (Guo et al., 2017). Thalamic sensory processing can also be influenced by altering activity further downstream e.g. ...
The auditory thalamus is the central nexus of bottom-up connections from the inferior colliculus and top-down connections from auditory cortical areas. While considerable efforts have been made to investigate feedforward processing of sounds in the auditory thalamus (medial geniculate body, MGB) of non-human primates, little is known about the role of corticofugal feedback in the MGB of awake non-human primates. Therefore, we developed a small, repositionable cooling probe to manipulate corticofugal feedback and studied neural responses in both auditory cortex and thalamus to sounds under conditions of normal and reduced cortical temperature. Cooling-induced increases in the width of extracellularly recorded spikes in auditory cortex were observed over the distance of several hundred micrometers away from the cooling probe. Cortical neurons displayed reduction in both spontaneous and stimulus driven firing rates with decreased cortical temperatures. In thalamus, cortical cooling led to increased spontaneous firing and either increased or decreased stimulus driven activity. Furthermore, response tuning to modulation frequencies of temporally modulated sounds and spatial tuning to sound source location could be altered (increased or decreased) by cortical cooling. Specifically, best modulation frequencies of individual MGB neurons could shift either toward higher or lower frequencies based on the vector strength or the firing rate. The tuning of MGB neurons for spatial location could both sharpen or widen. Elevation preference could shift toward higher or lower elevations and azimuth tuning could move toward ipsilateral or contralateral locations. Such bidirectional changes were observed in many parameters which suggests that the auditory thalamus acts as a filter that could be adjusted according to behaviorally driven signals from auditory cortex. Future work will have to delineate the circuit elements responsible for the observed effects.
... Because fiber photometry signals arise from populations of neurons, it is impossible to discern whether differences in response amplitude over learning or across different behavioral states reflect the activation of privileged ensembles that were hitherto silent or instead an increased response expressed uniformly across neurons. Conversely, the absence of differences in the population signal could belie striking shifts in the representational dominance of antagonistically related cellular ensembles that would not be captured by changes in net signal amplitude (Grewe et al., 2017;Gründemann, 2021;Taylor et al., 2021). Another caveat in the interpretation of fiberbased GCaMP imaging is that the slow temporal kinetics and poor spatial resolution combines somatic and neuropil-based calcium signals and obscures the relationship to spike rates in distinct types of BFCNs. ...
Basal forebrain cholinergic neurons (BFCNs) project throughout the cortex to regulate arousal, stimulus salience, plasticity, and learning. Although often treated as a monolithic structure, the basal forebrain features distinct connectivity along its rostrocaudal axis that could impart regional differences in BFCN processing. Here, we performed simultaneous bulk calcium imaging from rostral and caudal BFCNs over a one-month period of variable reinforcement learning in mice. BFCNs in both regions showed equivalently weak responses to unconditioned visual stimuli and anticipated rewards. Rostral BFCNs in the horizontal limb of the diagonal band were more responsive to reward omission, more accurately classified behavioral outcomes, and more closely tracked fluctuations in pupil-indexed global brain state. Caudal tail BFCNs in globus pallidus and substantia innominata were more responsive to unconditioned auditory stimuli, orofacial movements, aversive reinforcement, and showed robust associative plasticity for punishment-predicting cues. These results identify a functional topography that diversifies cholinergic modulatory signals broadcast to downstream brain regions.
... Globally, the mPFC functional connectivity has only being partially investigated, and we still lack a comprehensive understanding of the neuronal network involved during fear memory consolidation. Surprisingly, the projections to and from the thalamic nuclei have been little studied, although some of these regions are becoming of high interest in the regulation of the consolidation and the extinction of both recent [78] and remote fear memories [79,80]. This, in addition to the possibility of tracing connections from and to engram cells specifically [13,32], opens up many areas of investigation that will be of high interest in the future. ...
It is becoming increasingly apparent that long-term memory formation relies on a distributed network of brain areas. While the hippocampus has been at the center of attention for decades, it is now clear that other regions, in particular the medial prefrontal cortex (mPFC), are taking an active part as well. Recent evidence suggests that the mPFC—traditionally implicated in the long-term storage of memories—is already critical for the early phases of memory formation such as encoding. In this review, we summarize these findings, relate them to the functional importance of the mPFC connectivity, and discuss the role of the mPFC during memory consolidation with respect to the different theories of memory storage. Owing to its high functional connectivity to other brain areas subserving memory formation and storage, the mPFC emerges as a central hub across the lifetime of a memory, although much still remains to be discovered.
Thalamocortical loops have a central role in cognition and motor control, but precisely how they contribute to these processes is unclear. Recent studies showing evidence of plasticity in thalamocortical synapses indicate a role for the thalamus in shaping cortical dynamics through learning. Since signals undergo a compression from the cortex to the thalamus, we hypothesized that the computational role of the thalamus depends critically on the structure of corticothalamic connectivity. To test this, we identified the optimal corticothalamic structure that promotes biologically plausible learning in thalamocortical synapses. We found that corticothalamic projections specialized to communicate an efference copy of the cortical output benefit motor control, while communicating the modes of highest variance is optimal for working memory tasks. We analyzed neural recordings from mice performing grasping and delayed discrimination tasks and found corticothalamic communication consistent with these predictions. These results suggest that the thalamus orchestrates cortical dynamics in a functionally precise manner through structured connectivity.
