Representation Of Cues Research Articles

Investigating the Interrelationship between the Desire for a Cohesive Community and Opioid Abuse: A Neuropsychological Study of Demon Copperhead

Abstract Foregrounding the increasing global crisis of opioids as the “leading cause of deaths in fatal overdoses,” the World Drug Report 2023, published by the United Nations Office on Drugs and Crime (UNODC), mentioned that in 2021 more than 80,000 people died due to opioid overdose in the United States of America. The Centers for Disease Control and Prevention (CDC), the national public health protection agency in the United States, has reported that “the predicted number of drug overdose deaths showed an increase of 0.5% from the 12 months ending in December 2021 to the 12 months ending in December 2022, from 109,179 to 179,680” (“Provisional Data”). Although the trajectory of opioid use disorders (OUDs) has affected different sociodemographic groups in the country since its first wave in the 1990s, teenagers in poverty-stricken rural areas are more vulnerable to such addiction (Keyes et al.). Poor parental guidance, impoverishment, troubled childhoods, detrimental familial structure, scarce opportunities, and accessibility to opioids are often considered to be the primary risk factors for unprivileged teenagers to develop a psychic reliance on opioids for engendering a perpetual sense of contentment. According to the incentive sensitization theory, the persistent desire to transcend physical and psychical limitations for a sense of relief, triggered by chronic drug misuse, often evokes a sense of “wanting” or incentive salience, a compulsive inclination towards drug-associated stimuli (Berridge and Robinson, “Drug Addiction” 22). This intense desire of “wanting” often generates a perpetual sensitization of the mesolimbic systems in the brain which is also activated by mental representations of drug-associated cues (Robinson and Berridge 3139). Focusing on drug-induced changes in the brain such as hypersensitization and neuroadaptation, this study analyzes Barbara Kingsolver’s Demon Copperhead, a modern reimagining of David Copperfield by Charles Dickens. The selected text addresses primarily some pertinent socio-political crises, such as the poor foster care system, poverty, and the engrossing opioid endemic in Southern Appalachia. However, this study attempts to analyze the precarious state of some characters, who become addicted to opioids seeking recognition from peer groups and perpetual psychic stability, in the selected text from a neuropsychological perspective.

Divergent reward cue representations in prefrontal cortex underlie differences in reward motivation between adolescents and adults.

A prevailing view on postnatal brain development is that brain regions gradually acquire adult functions as they mature. The medial prefrontal cortex (mPFC) regulates reward learning, motivation, and behavioral inhibition, and undergoes a protracted postnatal maturation. During adolescence, reward-seeking behavior is heightened compared to adulthood - a developmental difference that may be driven by a hypoactive mPFC, with decreased top-down control of impulsive reward-seeking. However, this hypothesis has been difficult to test directly, due in part to technical challenges of recording neuronal activity in vivo across this developmental period. Here, using a novel 2-photon imaging-compatible platform for recording mPFC activity during an operant reward conditioning task beginning early in life, we show that the adolescent mPFC is hyper-responsive to reward cues. Distinct populations of mPFC neurons encode reward-predictive cues across development, but representations of no-reward cues and unrewarded outcomes are relatively muted in adolescence. Chemogenetic inhibition of GABAergic neurons decreased motivation in adolescence but not in adulthood. Together, our findings indicate that reward-related activity in the adolescent mPFC does not gradually increase across development. On the contrary, adolescent mPFC neurons are hyper-responsive to reward-related stimuli and encode reward-predictive cues and outcomes through qualitatively different mechanisms relative to the adult mPFC, opening avenues to developing distinct, developmentally informed strategies for modulating reward-seeking behavior in adolescence and adulthood.

Distinct codes for environment structure and symmetry in postrhinal and retrosplenial cortices

Complex sensory information arrives in the brain from an animal’s first-person (‘egocentric’) perspective. However, animals can efficiently navigate as if referencing map-like (‘allocentric’) representations. The postrhinal (POR) and retrosplenial (RSC) cortices are thought to mediate between sensory input and internal maps, combining egocentric representations of physical cues with allocentric head direction (HD) information. Here we show that neurons in the POR and RSC of female Long-Evans rats are tuned to distinct but complementary aspects of local space. Egocentric bearing (EB) cells recorded in square and L-shaped environments reveal that RSC cells encode local geometric features, while POR cells encode a more global account of boundary geometry. Additionally, POR HD cells can incorporate egocentric information to fire in two opposite directions with two oppositely placed identical visual landmarks, while only a subset of RSC HD cells possess this property. Entorhinal grid and HD cells exhibit consistently allocentric spatial firing properties. These results reveal significant regional differences in the neural encoding of spatial reference frames.

Hippocampal neuronal activity is aligned with action plans.

Neurons in the hippocampus are correlated with different variables, including space, time, sensory cues, rewards, and actions, where the extent of tuning depends on ongoing task demands. However, it remains uncertain whether such diverse tuning corresponds to distinct functions within the hippocampal network or if a more generic computation can account for these observations. To disentangle the contribution of externally driven cues versus internal computation, we developed a task in mice where space, auditory tones, rewards, and context were juxtaposed with changing relevance. High-density electrophysiological recordings revealed that neurons were tuned to each of these modalities. By comparing movement paths and action sequences, we observed that external variables had limited direct influence on hippocampal firing. Instead, spiking was influenced by online action plans modulated by goal uncertainty. Our results suggest that internally generated cell assembly sequences are selected and updated by action plans toward deliberate goals. The apparent tuning of hippocampal neuronal spiking to different sensory modalities might emerge due to alignment to the afforded action progression within a task rather than representation of external cues.

Similar Quality of Visual Working Memory Representations between Negative and Positive Attentional Templates.

Visual working memory (VWM) plays an important role during visual search, with some theories suggesting an equivalence between working memory representations and guidance from attentional templates. However, recent work has shown that participants can also use 'negative templates', the foreknowledge of distractor-features stored in VWM, to guide attention away from distractors during visual search. These negative templates must also be represented in working memory, but the question remains whether the quality of the working memory representations underlying negative and positive templates are similar, in spite of their opposite impacts on attention. In this study, participants (N = 33) engaged in a visual search task for a shape-defined target after receiving a positive cue (target color), negative cue (distractor color) or neutral cue (non-informative). In 20% of the trials, a color-wheel probe was presented instead of a search array to measure the quality of the cue representation stored in VWM. Our results revealed that participants were more likely to guess in response to neutral cues than negative cues. Yet, the comparison between positive and negative cues showed no significant differences. However, we found no difference in memory precision for the three cue types. More interestingly, the more the VWM quality is boosted by the negative cue, the greater the ability to guide attention away from distractors. Such a pattern of results might map to recent evidence of between-individuals differences in utilization of negative cues. These findings highlight the distinction between attentional templates and simple maintenance in working memory.

The Neural Representation of Binaural Sound Localization Cues Across Different Subregions of the Chicken's Inferior Colliculus.

The sound localization behavior of the nocturnally hunting barn owl and its underlying neural computations is a textbook example of neuroethology. Differences in sound timing and level at the two ears are integrated in a series of well-characterized steps, from brainstem to inferior colliculus (IC), resulting in a topographical neural representation of auditory space. It remains an important question of brain evolution: How is this specialized case derived from a more plesiomorphic pattern? The present study is the first to match physiology and anatomical subregions in the non-owl avian IC. Single-unit responses in the chicken IC were tested for selectivity to different frequencies and to the binaural difference cues. Their anatomical origin was reconstructed with the help of electrolytic lesions and immunohistochemical identification of different subregions of the IC, based on previous characterizations in owl and chicken. In contrast to barn owl, there was no distinct differentiation of responses in the different subregions. We found neural topographies for both binaural cues but no evidence for a coherent representation of auditory space. The results are consistent with previous work in pigeon IC and chicken higher-order midbrain and suggest a plesiomorphic condition of multisensory integration in the midbrain that is dominated by lateral panoramic vision.

Rapid emergence of latent knowledge in the sensory cortex drives learning.

Rapid learning confers significant advantages to animals in ecological environments. Despite the need for speed, animals appear to only slowly learn to associate rewarded actions with predictive cues1-4. This slow learning is thought to be supported by a gradual expansion of predictive cue representation in the sensory cortex2,5. However, evidence is growing that animals learn more rapidly than classical performance measures suggest6-8, challenging the prevailing model of sensory cortical plasticity. Here, we investigated the relationship between learning and sensory cortical representations. We trained mice on an auditory go/no-go task that dissociated the rapid acquisition of task contingencies (learning) from its slower expression (performance)7. Optogenetic silencing demonstrated that the auditory cortex (AC) drives both rapid learning and slower performance gains but becomes dispensable at expert. Rather than enhancement or expansion of cue representations9, two-photon calcium imaging of AC excitatory neurons throughout learning revealed two higher-order signals that were causal to learning and performance. First, a reward prediction (RP) signal emerged rapidly within tens of trials, was present after action-related errors only early in training, and faded at expert levels. Strikingly, silencing at the time of the RP signal impaired rapid learning, suggesting it serves an associative and teaching role. Second, a distinct cell ensemble encoded and controlled licking suppression that drove the slower performance improvements. These two ensembles were spatially clustered but uncoupled from underlying sensory representations, indicating a higher-order functional segregation within AC. Our results reveal that the sensory cortex manifests higher-order computations that separably drive rapid learning and slower performance improvements, reshaping our understanding of the fundamental role of the sensory cortex.

Speech Emotion Recognition Using Dual-Stream Representation and Cross-Attention Fusion

Speech emotion recognition (SER) aims to recognize human emotions through in-depth analysis of audio signals. However, it remains challenging to encode emotional cues and to fuse the encoded cues effectively. In this study, dual-stream representation is developed, and both full training and fine-tuning of different deep networks are employed for encoding emotion patterns. Specifically, a cross-attention fusion (CAF) module is designed to integrate the dual-stream output for emotion recognition. Using different dual-stream encoders (fully training a text processing network and fine-tuning a pre-trained large language network), the CAF module is compared to other three fusion modules on three databases. The SER performance is quantified with weighted accuracy (WA), unweighted accuracy (UA), and F1-score (F1S). The experimental results suggest that the CAF outperforms the other three modules and leads to promising performance on the databases (EmoDB: WA, 97.20%; UA, 97.21%; F1S, 0.8804; IEMOCAP: WA, 69.65%; UA, 70.88%; F1S, 0.7084; RAVDESS: WA, 81.86%; UA, 82.75.21%; F1S, 0.8284). It is also found that fine-tuning a pre-trained large language network achieves superior representation than fully training a text processing network. In a future study, improved SER performance could be achieved through the development of a multi-stream representation of emotional cues and the incorporation of a multi-branch fusion mechanism for emotion recognition.

Dissociated Representation of Binaural Cues in Single-Sided Deafness: Implications for Cochlear Implantation.

Congenital single-sided deafness (SSD) leads to an aural preference syndrome that is characterized by overrepresentation of the hearing ear in the auditory system. Cochlear implantation (CI) of the deaf ear is an effective treatment for SSD. However, the newly introduced auditory input in congenital SSD often does not reach expectations in late-implanted CI recipients with respect to binaural hearing and speech perception. In a previous study, a reduction of the interaural time difference (ITD) sensitivity has been shown in unilaterally congenitally deaf cats (uCDCs). In the present study, we focused on the interaural level difference (ILD) processing in the primary auditory cortex. The uCDC group was compared with hearing cats (HCs) and bilaterally congenitally deaf cats (CDCs). The ILD representation was reorganized, replacing the preference for the contralateral ear with a preference for the hearing ear, regardless of the cortical hemisphere. In accordance with the previous study, uCDCs were less sensitive to interaural time differences than HCs, resulting in unmodulated ITD responses, thus lacking directional information. Such incongruent ITDs and ILDs cannot be integrated for binaural sound source localization. In normal hearing, the predominant effect of each ear is excitation of the auditory cortex in the contralateral cortical hemisphere and inhibition in the ipsilateral hemisphere. In SSD, however, auditory pathways reorganized such that the hearing ear produced greater excitation in both cortical hemispheres and the deaf ear produced weaker excitation and preserved inhibition in both cortical hemispheres.

The representation of contextual cue is stimulus-specific yet its expression is flexible.

Contextual cueing refers to the phenomenon in which individuals utilize frequently encountered environmental contexts, comprised of distractors, as cues to expedite a target search. Due to the conflict between the widespread occurrence of contextual cue transfer and the observed impact of changing the identity of distractors on contextual cue learning, the content of contextual cue representations remains contentious. Considering the independent nature of contextual cue learning and expression, our proposition is twofold: (1) Contextual cue representations are stimulus-specific, and (2) their expression is highly flexible. To validate the model, two experiments were conducted. Experiment 1 aimed to confirm the hypothesis that contextual cue representations are stimulus-specific. We manipulated the identity consistency of distractors within repeated scenes during contextual cue learning. Difficulty in contextual cue learning under the identity-changing condition would suggest the necessity of identity within contextual cue representation, indicating the stimulus-specific nature of these representations. Experiment 2 was designed to affirm the conclusion of Experiment 1 and explore the flexibility in the expression of contextual cue representations. This experiment comprised two phases: learning and testing. During the learning phase, participants were exposed to two sets of repeated scenes in different colors under two learning conditions: load and no-load. Working memory load was introduced to interfere with the expression to prevent it from becoming automatic. In the subsequent testing phase, the colors of the two scene sets were interchanged to impede retrieval based on identity. If both load and no-load conditions demonstrate similar levels of contextual cue effects during the testing phase, it implies the flexibility in the expression of contextual cue representations and confirms the conclusion of Experiment 1. In Experiment 1, a notable contextual cue learning effect was observed under the identity-consistent condition (p = 0.001). However, this effect was not evident under the identity-changing condition (p = 0.286). This finding strongly supports the stimulus-specific nature of contextual cue representation. In Experiment 2, the contextual cueing effect appeared but did not show a significant difference between the two conditions (t(23) = 0.02, p = 0.987, BF10 = 0.215), indicating the cognitive system's ability to flexibly redefine retrieval cues. This adaptability aligns with our hypothesis and confirms the high flexibility in the expression process of contextual cue representations and confirms the conclusion of Experiment 1.

Effect of inter-aural temporal envelope differences on inter-aural time difference thresholds for amplitude modulated noise.

The inter-aural time difference (ITD) and inter-aural level difference (ILD) are important acoustic cues for horizontal localization and spatial release from masking. These cues are encoded based on inter-aural comparisons of tonotopically matched binaural inputs. Therefore, binaural coherence or the interaural spectro-temporal similarity is a pre-requisite for encoding ITD and ILD. The modulation depth of envelope is an important envelope characteristic that helps in encoding the envelope-ITD. However, inter-aural difference in modulation depth can result in reduced binaural coherence and poor representation of binaural cues as in the case with reverberation, noise and compression in cochlear implants and hearing aids. This study investigated the effect of inter-aural modulation depth difference on the ITD thresholds for an amplitude-modulated noise in normal hearing young adults. An amplitude modulated high pass filtered noise with varying modulation depth differences was presented sequentially through headphones. In one ear, the modulation depth was retained at 90% and in the other ear it varied from 90% to 50%. The ITD thresholds for modulation frequencies of 8 Hz and 16 Hz were estimated as a function of the inter-aural modulation depth difference. The Friedman test findings revealed a statistically significant increase in the ITD threshold with an increase in the inter-aural modulation depth difference for 8 Hz and 16 Hz. The results indicate that the inter-aural differences in the modulation depth negatively impact ITD perception for an amplitude-modulated high pass filtered noise.

Cue predictiveness and uncertainty determine cue representation during visual statistical learning.

This study investigated how humans process probabilistic-associated information when encountering varying levels of uncertainty during implicit visual statistical learning. A novel probabilistic cueing validation paradigm was developed to probe the representation of cues with high (75% probability), medium (50%), low (25%), or zero levels of predictiveness in response to preceding targets that appeared with high (75%), medium (50%), or low (25%) transitional probabilities (TPs). Experiments 1 and 2 demonstrated a significant negative association between cue probe identification accuracy and cue predictiveness when these cues appeared after high-TP but not medium-TP or low-TP targets, establishing exploration-like cue processing triggered by lower-uncertainty rather than high-uncertainty inputs. Experiment 3 ruled out the confounding factor of probe repetition and extended this finding by demonstrating (1) enhanced representation of low-predictive and zero-predictive but not high-predictive cues across blocks after high-TP targets and (2) enhanced representation of high-predictive but not low-predictive and zero-predictive cues across blocks after low-TP targets for learners who exhibited above-chance awareness of cue-target transition. These results suggest that during implicit statistical learning, input characteristics alter cue-processing mechanisms, such that exploration-like and exploitation-like mechanisms are triggered by lower-uncertainty and higher-uncertainty cue-target sequences, respectively.

Multiple Risk Factors Precipitate Smoking Relapse: a Demonstration Using a Rat Model of Nicotine Addiction

Relapse to drug addiction behavior in abstinent subjects could be attributable to re-exposure to relevant environments (i.e., environmental cues), drug priming, and stressful life events. In particular, it is common for the abstinent subjects to be imposed with more than one risk factors at any social circumstance. Using a rat model of nicotine addiction, we demonstrated the behavioral effect of exposure to a combination of risk factors on relapse to nicotine-seeking behavior. Male Sprague-Dawley rats were trained to press a level to intravenously self-administer nicotine at a unit dose of 0.03 mg/kg/infusion. In the daily 60-min session, an auditory/visual stimulus was paired with each nicotine infusion so that the stimulus become a nicotine-conditioned cue. After the administration responses were extinguished without nicotine infusion, the reinstatement tests were conducted under five conditions: cue representation, nicotine priming, stress, cue/priming, and cue/stress. The results showed that nicotine priming, pharmacological stressor and re-presentation of the cue respectively reinstated lever responses. The combined presentation of these factors seemed to produce stronger effect. These laboratory findings confirmed the motivational effect of re-exposure to nicotine-associated environmental cues, nicotine priming and confrontation with stressful life events in abstinent smokers. This work would support for behavioral management, in addition to medications, to eliminate exposure to these risk factors.

Aging alters across-hemisphere cortical dynamics during binaural temporal processing.

Differences in the timing and intensity of sounds arriving at the two ears provide fundamental binaural cues that help us localize and segregate sounds in the environment. Neural encoding of these cues is commonly represented asymmetrically in the cortex with stronger activation in the hemisphere contralateral to the perceived spatial location. Although advancing age is known to degrade the perception of binaural cues, less is known about how the neural representation of such cues is impacted by age. Here, we use electroencephalography (EEG) to investigate age-related changes in the hemispheric distribution of interaural time difference (ITD) encoding based on cortical auditory evoked potentials (CAEPs) and derived binaural interaction component (BIC) measures in ten younger and ten older normal-hearing adults. Sensor-level analyses of the CAEP and BIC showed age-related differences in global field power, where older listeners had significantly larger responses than younger for both binaural metrics. Source-level analyses showed hemispheric differences in auditory cortex activity for left and right lateralized stimuli in younger adults, consistent with a contralateral activation model for processing ITDs. Older adults, however, showed reduced hemispheric asymmetry across ITDs, despite having overall larger responses than younger adults. Further, when averaged across ITD condition to evaluate changes in cortical asymmetry over time, there was a significant shift in laterality corresponding to the peak components (P1, N1, P2) in the source waveform that also was affected by age. These novel results demonstrate across-hemisphere cortical dynamics during binaural temporal processing that are altered with advancing age.

Targeted memory reactivation during sleep influences social bias as a function of slow-oscillation phase and delta power.

To understand how memories are reactivated and consolidated during sleep, experimenters have employed the unobtrusive re-presentation of memory cues from a variety of pre-sleep learning tasks. Using this procedure, known as targeted memory reactivation (TMR), we previously found that reactivation of counter-social-bias training during post-training sleep could selectively enhance training effects in reducing unintentional social biases. Here, we describe re-analyses of electroencephalographic (EEG) data from this previous study to characterize neurophysiological correlates of TMR-induced bias reduction. We found that TMR benefits in bias reduction were associated with (a) the timing of memory-related cue presentation relative to the 0.1-1.5Hz slow-oscillation phase and (b) cue-elicited EEG power within the 1-4Hz delta range. Although cue delivery was at a fixed rate in this study and not contingent on the slow-oscillation phase, cues were found to be clustered in slow-oscillation upstates for those participants with stronger TMR benefits. Similarly, higher cue-elicited delta power 250-1000 ms after cue onset was also linked with larger TMR benefits. These electrophysiological results substantiate the claim that memory reactivation altered social bias in the original study, while also informing neural explanations of these benefits. Future research should consider these sleep physiology parameters in relation to TMR applications and to memory reactivation in general.

Effects of Temporal Envelope Cutoff Frequency, Number of Channels, and Carrier Type on Brainstem Neural Representation of Pitch in Vocoded Speech.

The objective of this study was to determine if and how the subcortical neural representation of pitch cues in listeners with normal hearing is affected by systematic manipulation of vocoder parameters. This study assessed the effects of temporal envelope cutoff frequency (50 and 500 Hz), number of channels (1-32), and carrier type (sine-wave and noise-band) on brainstem neural representation of fundamental frequency (f o) in frequency-following responses (FFRs) to vocoded vowels of 15 young adult listeners with normal hearing. Results showed that FFR f o strength (quantified as absolute f o magnitude divided by noise floor [NF] magnitude) significantly improved with 500-Hz vs. 50-Hz temporal envelopes for all channel numbers and both carriers except the 1-channel noise-band vocoder. FFR f o strength with 500-Hz temporal envelopes significantly improved when the channel number increased from 1 to 2, but it either declined (sine-wave vocoders) or saturated (noise-band vocoders) when the channel number increased from 4 to 32. FFR f o strength with 50-Hz temporal envelopes was similarly small for both carriers with all channel numbers, except for a significant improvement with the 16-channel sine-wave vocoder. With 500-Hz temporal envelopes, FFR f o strength was significantly greater for sine-wave vocoders than for noise-band vocoders with channel numbers 1-8; no significant differences were seen with 16 and 32 channels. With 50-Hz temporal envelopes, the carrier effect was only observed with 16 channels. In contrast, there was no significant carrier effect for the absolute f o magnitude. Compared to sine-wave vocoders, noise-band vocoders had a higher NF and thus lower relative FFR f o strength. It is important to normalize the f o magnitude relative to the NF when analyzing the FFRs to vocoded speech. The physiological findings reported here may result from the availability of f o-related temporal periodicity and spectral sidelobes in vocoded signals and should be considered when selecting vocoder parameters and interpreting results in future physiological studies. In general, the dependence of brainstem neural phase-locking strength to f o on vocoder parameters may confound the comparison of pitch-related behavioral results across different vocoder designs.

Depressioner: Facial dynamic representation for automatic depression level prediction

Physiological studies have shown that facial changes can be seen as a biomarker to analyze the severity of depression. Therefore, this study proposes a Depressioner model to predict the depression level by examining facial changes. Our method is mainly to solve two problems in the previous works: (1) each channel in the tensor obtained by the convolution layer can be regarded as a pattern extraction result related to depression. However, previous works rarely explore the relationship among channels, which is limited in integrating the advantages of various channels; (2) the average (or max) pooling is often used to vectorize the tensor, which is not conduction to capturing the depression cues from tensors with temporal attribute. To this end, this study designs two novel blocks namely Graph Convolution Embedding (GCE) block and Multi-Scale Vectorization (MSV) block. The GCE block treats each channel as a node in the graph and constructs the corresponding adjacency matrix. Furthermore, the GCE block adopts the graph convolution operation to examine the relationship among channels to take advantage of each channel and highlight useful elements. The MSV block combines the dilated convolution and attention mechanism to process each channel to extract the multi-scale representation of depression cues along temporal dimension. Moreover, it aggregates these representations into the vectorization result of tensor along channel dimension. Experimental results on AVEC 2013 (RMSE = 7.49, MAE = 6.12) and AVEC 2014 (RMSE = 7.56, MAE = 6.01) depression databases illustrate the effectiveness of our method, which may promote the auxiliary diagnosis of depression screening in the future. Meanwhile, these results also show that the proposed Depressioner model can capture the differences of facial changes among individuals with different depression levels.

Estimating How Sounds Modulate Orientation Representation in the Primary Visual Cortex Using Shallow Neural Networks.

Audiovisual perception results from the interaction between visual and auditory processing. Hence, presenting auditory and visual inputs simultaneously usually improves the accuracy of the unimodal percepts, but can also lead to audiovisual illusions. Cross-talks between visual and auditory inputs during sensory processing were recently shown to occur as early as in the primary visual cortex (V1). In a previous study, we demonstrated that sounds improve the representation of the orientation of visual stimuli in the naïve mouse V1 by promoting the recruitment of neurons better tuned to the orientation and direction of the visual stimulus. However, we did not test if this type of modulation was still present when the auditory and visual stimuli were both behaviorally relevant. To determine the effect of sounds on active visual processing, we performed calcium imaging in V1 while mice were performing an audiovisual task. We then compared the representations of the task stimuli orientations in the unimodal visual and audiovisual context using shallow neural networks (SNNs). SNNs were chosen because of the biological plausibility of their computational structure and the possibility of identifying post hoc the biological neurons having the strongest influence on the classification decision. We first showed that SNNs can categorize the activity of V1 neurons evoked by drifting gratings of 12 different orientations. Then, we demonstrated using the connection weight approach that SNN training assigns the largest computational weight to the V1 neurons having the best orientation and direction selectivity. Finally, we showed that it is possible to use SNNs to determine how V1 neurons represent the orientations of stimuli that do not belong to the set of orientations used for SNN training. Once the SNN approach was established, we replicated the previous finding that sounds improve orientation representation in the V1 of naïve mice. Then, we showed that, in mice performing an audiovisual detection task, task tones improve the representation of the visual cues associated with the reward while deteriorating the representation of non-rewarded cues. Altogether, our results suggest that the direction of sound modulation in V1 depends on the behavioral relevance of the visual cue.

Dynamic Distortion of Orientation Representation after Learning in the Mouse Primary Visual Cortex.

Learning is an essential cognitive mechanism allowing behavioral adaptation through adjustments in neuronal processing. It is associated with changes in the activity of sensory cortical neurons evoked by task-relevant stimuli. However, the exact nature of those modifications and the computational advantages they may confer are still debated. Here, we investigated how learning an orientation discrimination task alters the neuronal representations of the cues orientations in the primary visual cortex (V1) of male and female mice. When comparing the activity evoked by the task stimuli in naive mice and the mice performing the task, we found that the representations of the orientation of the rewarded and nonrewarded cues were more accurate and stable in trained mice. This better cue representation in trained mice was associated with a distortion of the orientation representation space such that stimuli flanking the task-relevant orientations were represented as the task stimuli themselves, suggesting that those stimuli were generalized as the task cues. This distortion was context dependent as it was absent in trained mice passively viewing the task cues and enhanced in the behavioral sessions where mice performed best. Those modifications of the V1 population orientation representation in performing mice were supported by a suppression of the activity of neurons tuned for orientations neighboring the orientations of the task cues. Thus, visual processing in V1 is dynamically adapted to enhance the reliability of the representation of the learned cues and favor generalization in the task-relevant computational space.SIGNIFICANCE STATEMENT Performance improvement in a task often requires facilitating the extraction of the information necessary to its execution. Here, we demonstrate the existence of a suppression mechanism that improves the representation of the orientations of the task stimuli in the V1 of mice performing an orientation discrimination task. We also show that this mechanism distorts the V1 orientation representation space, leading stimuli flanking the task stimuli orientations to be generalized as the task stimuli themselves.

Functional patterns of neural activation during vocal emotion recognition in youth with and without refractory epilepsy

Epilepsy has been associated with deficits in the social cognitive ability to decode others’ nonverbal cues to infer their emotional intent (emotion recognition). Studies have begun to identify potential neural correlates of these deficits, but have focused primarily on one type of nonverbal cue (facial expressions) to the detriment of other crucial social signals that inform the tenor of social interactions (e.g., tone of voice). Less is known about how individuals with epilepsy process these forms of social stimuli, with a particular gap in knowledge about representation of vocal cues in the developing brain. The current study compared vocal emotion recognition skills and functional patterns of neural activation to emotional voices in youth with and without refractory focal epilepsy. We made novel use of inter-subject pattern analysis to determine brain areas in which activation to emotional voices was predictive of epilepsy status. Results indicated that youth with epilepsy were comparatively less able to infer emotional intent in vocal expressions than their typically developing peers. Activation to vocal emotional expressions in regions of the mentalizing and/or default mode network (e.g., right temporo-parietal junction, right hippocampus, right medial prefrontal cortex, among others) differentiated youth with and without epilepsy. These results are consistent with emerging evidence that pediatric epilepsy is associated with altered function in neural networks subserving social cognitive abilities. Our results contribute to ongoing efforts to understand the neural markers of social cognitive deficits in pediatric epilepsy, in order to better tailor and funnel interventions to this group of youth at risk for poor social outcomes.