A robust and compact population code for competing sounds in auditory cortex.

Cortical circuits encoding sensory information consist of populations of neurons, yet how information aggregates via pooling individual cells remains poorly understood. Such pooling may be particularly important in noisy settings where single-neuron encoding is degraded. One example is the cocktail party problem, with competing sounds from multiple spatial locations. How populations of neurons in auditory cortex code competing sounds have not been previously investigated. Here, we apply a novel information-theoretic approach to estimate information in populations of neurons in mouse auditory cortex about competing sounds from multiple spatial locations, including both summed population (SP) and labeled line (LL) codes. We find that a small subset of neurons is sufficient to nearly maximize mutual information over different spatial configurations, with the labeled line code outperforming the summed population code and approaching information levels attained in the absence of competing stimuli. Finally, information in the labeled line code increases with spatial separation between target and masker, in correspondence with behavioral results on spatial release from masking in humans and animals. Taken together, our results reveal that a compact population of neurons in auditory cortex provides a robust code for competing sounds from different spatial locations.NEW & NOTEWORTHY Little is known about how populations of neurons within cortical circuits encode sensory stimuli in the presence of competing stimuli at other spatial locations. Here, we investigate this problem in auditory cortex using a recently proposed information-theoretic approach. We find a small subset of neurons nearly maximizes information about target sounds in the presence of competing maskers, approaching information levels for isolated stimuli, and provides a noise-robust code for sounds in a complex auditory scene.

AIM: A network model of attention in auditory cortex.

Attentional modulation of cortical networks is critical for the cognitive flexibility required to process complex scenes. Current theoretical frameworks for attention are based almost exclusively on studies in visual cortex, where attentional effects are typically modest and excitatory. In contrast, attentional effects in auditory cortex can be large and suppressive. A theoretical framework for explaining attentional effects in auditory cortex is lacking, preventing a broader understanding of cortical mechanisms underlying attention. Here, we present a cortical network model of attention in primary auditory cortex (A1). A key mechanism in our network is attentional inhibitory modulation (AIM) of cortical inhibitory neurons. In this mechanism, top-down inhibitory neurons disinhibit bottom-up cortical circuits, a prominent circuit motif observed in sensory cortex. Our results reveal that the same underlying mechanisms in the AIM network can explain diverse attentional effects on both spatial and frequency tuning in A1. We find that a dominant effect of disinhibition on cortical tuning is suppressive, consistent with experimental observations. Functionally, the AIM network may play a key role in solving the cocktail party problem. We demonstrate how attention can guide the AIM network to monitor an acoustic scene, select a specific target, or switch to a different target, providing flexible outputs for solving the cocktail party problem.

Ultrasonography: An Unchartered Modality in the Current Pandemic - A Study among Patients Admitted in the COVID-19 Intensive Care Unit.

BACKGROUND: The objectives were to perform an analysis of lung ultrasonography (LUS) findings in severely ill patients with novel coronavirus disease-2019 (COVID-19) and to compare the accuracy with high-resolution computed tomography (HRCT) of the thorax. METHODS: Sixty-two intensive care unit (ICU) patients with COVID-19 were evaluated during their hospital stay. LUS was performed with convex and linear transducers using a designated ultrasonography machine placed in the COVID-19 ICU. The thorax was scanned in 12 areas. Initial LUS was performed on admission and follow-up LUS was done in 7 (mean) days. At the time of the initial LUS, HRCT was performed in 28/62 patients and a chest radiography in 19/62 patients. RESULTS: On admission, LUS detected pleural line thickening (>6 lung areas) in 49/62, confluent B-lines in 38/62, and separate B-lines in 34/62, consolidation in 12/62, C prime profile in 19/62, and pleural and cardiac effusions in 4/62 and 1/62, respectively. The single beam "torchlight" artifact was seen in 16/62, which may possibly be a variation of the B-line which has not been described earlier. Follow-up LUS detected significantly lower rates (P < 0.05) of abnormalities. CONCLUSION: Ultrasound demonstrated B-lines, variable consolidations, and pleural line irregularities. This study also sheds light on the appearance of the C prime pattern and "torchlight" B-lines which were not described in COVID-19 earlier. LUS findings were significantly reduced by the time of the follow-up scan, insinuating at a rather slow but consistent reduction in some COVID-19 lung lesions. However, the lung ultrasound poorly correlated with HRCT as a diagnostic modality in COVID-19 patients.

A Decline in Response Variability Improves Neural Signal Detection during Auditory Task Performance.

The detection of a sensory stimulus arises from a significant change in neural activity, but a sensory neuron's response is rarely identical to successive presentations of the same stimulus. Large trial-to-trial variability would limit the central nervous system's ability to reliably detect a stimulus, presumably affecting perceptual performance. However, if response variability were to decrease while firing rate remained constant, then neural sensitivity could improve. Here, we asked whether engagement in an auditory detection task can modulate response variability, thereby increasing neural sensitivity. We recorded telemetrically from the core auditory cortex of gerbils, both while they engaged in an amplitude-modulation detection task and while they sat quietly listening to the identical stimuli. Using a signal detection theory framework, we found that neural sensitivity was improved during task performance, and this improvement was closely associated with a decrease in response variability. Moreover, units with the greatest change in response variability had absolute neural thresholds most closely aligned with simultaneously measured perceptual thresholds. Our findings suggest that the limitations imposed by response variability diminish during task performance, thereby improving the sensitivity of neural encoding and potentially leading to better perceptual sensitivity. SIGNIFICANCE STATEMENT: The detection of a sensory stimulus arises from a significant change in neural activity. However, trial-to-trial variability of the neural response may limit perceptual performance. If the neural response to a stimulus is quite variable, then the response on a given trial could be confused with the pattern of neural activity generated when the stimulus is absent. Therefore, a neural mechanism that served to reduce response variability would allow for better stimulus detection. By recording from the cortex of freely moving animals engaged in an auditory detection task, we found that variability of the neural response becomes smaller during task performance, thereby improving neural detection thresholds.

A Novel Triage Tool: Optic Nerve Sheath Diameter in Traumatic Brain Injury and its Correlation to Rotterdam Computed Tomography (CT) Scoring.

BACKGROUND: Optic nerve sheath diameter (ONSD) evaluated in CT imaging as well as Rotterdam CT Score (RCTS) are proven independent predictors of outcome in patients with traumatic brain injury (TBI). To date, no study has correlated ONSD on admission CT scan with RCTS. MATERIAL/METHODS: Retrospective cohort study comprised of consecutive patients undergoing CT imaging for traumatic brain injury recruited between January and October 2015. Bilateral ONSD was measured 3 mm behind the eyeball in axial and sagittal planes and mean value was calculated. RCTS was assessed on the same CT images, bias was eliminated by blinding RCTS to ONSD measurement. RESULTS: 150 patients were included; mean age in the group was 42.94±16.7 years. ONSD in mild TBI, RCTS 2 and 3 were 3.3 mm (SD 0.39 mm) and 4.1 mm (0.047 mm), respectively. Mean ONSD in moderate and severe TBI (RCTS score 4 and above) was 4.83 mm and above, SD 0.4 mm. Mean ONSD correlated with occurrence of diffuse cerebral oedema, presence of subdural and extradural hematoma; however in isolation there was no statistical significance. CONCLUSIONS: Higher ONSD was observed in patients with moderate and severe TBI, correlating with admission RCTS of 4 and above. Subsequent increase in ONSD was also found with increase in RCTS. ONSD could serve as an initial triage tool in the emergency department as well as a method of determining the need for sequential CT in patients with mild TBI.

Seasonal plasticity of precise spike timing in the avian auditory system.

Vertebrate audition is a dynamic process, capable of exhibiting both short- and long-term adaptations to varying listening conditions. Precise spike timing has long been known to play an important role in auditory encoding, but its role in sensory plasticity remains largely unexplored. We addressed this issue in Gambel's white-crowned sparrow (Zonotrichia leucophrys gambelii), a songbird that shows pronounced seasonal fluctuations in circulating levels of sex-steroid hormones, which are known to be potent neuromodulators of auditory function. We recorded extracellular single-unit activity in the auditory forebrain of males and females under different breeding conditions and used a computational approach to explore two potential strategies for the neural discrimination of sound level: one based on spike counts and one based on spike timing reliability. We report that breeding condition has robust sex-specific effects on spike timing. Specifically, in females, breeding condition increases the proportion of cells that rely solely on spike timing information and increases the temporal resolution required for optimal intensity encoding. Furthermore, in a functionally distinct subset of cells that are particularly well suited for amplitude encoding, female breeding condition enhances spike timing-based discrimination accuracy. No effects of breeding condition were observed in males. Our results suggest that high-resolution temporal discharge patterns may provide a plastic neural substrate for sensory coding.

Online stimulus optimization rapidly reveals multidimensional selectivity in auditory cortical neurons.

Neurons in sensory brain regions shape our perception of the surrounding environment through two parallel operations: decomposition and integration. For example, auditory neurons decompose sounds by separately encoding their frequency, temporal modulation, intensity, and spatial location. Neurons also integrate across these various features to support a unified perceptual gestalt of an auditory object. At higher levels of a sensory pathway, neurons may select for a restricted region of feature space defined by the intersection of multiple, independent stimulus dimensions. To further characterize how auditory cortical neurons decompose and integrate multiple facets of an isolated sound, we developed an automated procedure that manipulated five fundamental acoustic properties in real time based on single-unit feedback in awake mice. Within several minutes, the online approach converged on regions of the multidimensional stimulus manifold that reliably drove neurons at significantly higher rates than predefined stimuli. Optimized stimuli were cross-validated against pure tone receptive fields and spectrotemporal receptive field estimates in the inferior colliculus and primary auditory cortex. We observed, from midbrain to cortex, increases in both level invariance and frequency selectivity, which may underlie equivalent sparseness of responses in the two areas. We found that onset and steady-state spike rates increased proportionately as the stimulus was tailored to the multidimensional receptive field. By separately evaluating the amount of leverage each sound feature exerted on the overall firing rate, these findings reveal interdependencies between stimulus features as well as hierarchical shifts in selectivity and invariance that may go unnoticed with traditional approaches.

Competing sound sources reveal spatial effects in cortical processing.

Why is spatial tuning in auditory cortex weak, even though location is important to object recognition in natural settings? This question continues to vex neuroscientists focused on linking physiological results to auditory perception. Here we show that the spatial locations of simultaneous, competing sound sources dramatically influence how well neural spike trains recorded from the zebra finch field L (an analog of mammalian primary auditory cortex) encode source identity. We find that the location of a birdsong played in quiet has little effect on the fidelity of the neural encoding of the song. However, when the song is presented along with a masker, spatial effects are pronounced. For each spatial configuration, a subset of neurons encodes song identity more robustly than others. As a result, competing sources from different locations dominate responses of different neural subpopulations, helping to separate neural responses into independent representations. These results help elucidate how cortical processing exploits spatial information to provide a substrate for selective spatial auditory attention.

Pancreatico-pleural and bronchial fistulae and associated pseudocysts: case series.

CONTEXT: Pancreatico-pleural fistula is rare complication of chronic or acute pancreatitis. Previous studies have reported imaging features and various management options of this condition including conservative/medical management, endoscopic treatments and surgery.This article reviews the myriad of imaging appearances of this condition in multimodality imaging and different strategies for the successful management in a short case series. METHODS: After obtaining the institutional ethics committee approval, retrospective review of the medical records of five patients of pancreatico-pleural fistulae who were diagnosed and successfully managed in our hospital in 2012 and 2013 was done. Follow up with out patient records of these patients was also included.Findings were compared with the current available literature on this entity. RESULTS AND DISCUSSION: Pancreatico-pleural fistulae presents with massive pleural effusion.A high index of suspicion is essential for accurate diagnosis. Demonstration of the fistulous tracts requires cross sectional imaging with contrast enhanced CT being most commonly used and affords accurate diagnosis. MRI demonstrates the tracts and ductal disruptions with greater detail and are helpful in confirming the CT findings. Endoscopic ultrasound and ERCP also offer potential of diagnosis, although being technically demanding and invasive is reserved for interventions. Management of these conditions should be initially conservative with endoscopic stenting being offered in selected cases with favourable anatomy and not responding to conservative management. Surgery is reserved for cases not responding to conservative and endoscopic management. CONCLUSION: In conclusion this case series highlights the clinical and imaging spectrum of pancreatico-pleural fistulae and provides insight into the different management strategies that can be adopted for this condition.

fNIRS Dataset During Complex Scene Analysis.

When analyzing complex scenes, humans often focus their attention on an object at a particular spatial location. The ability to decode the attended spatial location would facilitate brain computer interfaces for complex scene analysis (CSA). Here, we investigated capability of functional near-infrared spectroscopy (fNIRS) to decode audio-visual spatial attention in the presence of competing stimuli from multiple locations. We targeted dorsal frontoparietal network including frontal eye field (FEF) and intra-parietal sulcus (IPS) as well as superior temporal gyrus/planum temporal (STG/PT). They all were shown in previous functional magnetic resonance imaging (fMRI) studies to be activated by auditory, visual, or audio-visual spatial tasks. To date, fNIRS has not been applied to decode auditory and visual-spatial attention during CSA, and thus, no such dataset exists yet. This report provides an open-access fNIRS dataset that can be used to develop, test, and compare machine learning algorithms for classifying attended locations based on the fNIRS signals on a single trial basis.

Overexpression of the schizophrenia risk gene C4 in PV cells drives sex-dependent behavioral deficits and circuit dysfunction.

Fast-spiking parvalbumin (PV)-positive cells are key players in orchestrating pyramidal neuron activity, and their dysfunction is consistently observed in myriad brain diseases. To understand how immune complement pathway dysregulation in PV cells drives disease pathogenesis, we have developed a transgenic line that permits cell-type specific overexpression of the schizophrenia-associated C4 gene. We found that overexpression of mouse C4 (mC4) in PV cells causes sex-specific alterations in anxiety-like behavior and deficits in synaptic connectivity and excitability of PFC PV cells. Using a computational model, we demonstrated that these microcircuit deficits led to hyperactivity and disrupted neural communication. Finally, pan-neuronal overexpression of mC4 failed to evoke the same deficits in behavior as PV-specific mC4 overexpression, suggesting that perturbations of this neuroimmune gene in fast-spiking neurons are especially detrimental to circuits associated with anxiety-like behavior. Together, these results provide a causative link between C4 and the vulnerability of PV cells in brain disease.

Overexpression of the schizophrenia risk gene C4 in PV cells drives sex-dependent behavioral deficits and circuit dysfunction.

Fast-spiking parvalbumin (PV)-positive cells are key players in orchestrating pyramidal neuron activity, and their dysfunction is consistently observed in myriad brain diseases. To understand how immune complement dysregulation - a prevalent locus of brain disease etiology - in PV cells may drive disease pathogenesis, we have developed a transgenic mouse line that permits cell-type specific overexpression of the schizophrenia-associated complement component 4 (C4) gene. We found that overexpression of mouse C4 (mC4) in PV cells causes sex-specific behavioral alterations and concomitant deficits in synaptic connectivity and excitability of PV cells of the prefrontal cortex. Using a computational network, we demonstrated that these microcircuit deficits led to hyperactivity and disrupted neural communication. Finally, pan-neuronal overexpression of mC4 failed to evoke the same deficits in behavior as PV-specific mC4 overexpression, suggesting that C4 perturbations in fast-spiking neurons are more harmful to brain function than pan-neuronal alterations. Together, these results provide a causative link between C4 and the vulnerability of PV cells in brain disease.

An Effect of Gaze Direction in Cocktail Party Listening.

It is well established that gaze direction can influence auditory spatial perception, but the implications of this interaction for performance in complex listening tasks is unclear. In the current study, we investigated whether there is a measurable effect of gaze direction on speech intelligibility in a "cocktail party" listening situation. We presented sequences of digits from five loudspeakers positioned at 0°, ± 15°, and ± 30° azimuth, and asked participants to repeat back the digits presented from a designated target loudspeaker. In different blocks of trials, the participant visually fixated on a cue presented at the target location or at a nontarget location. Eye position was tracked continuously to monitor compliance. Performance was best when fixation was on-target (vs. off-target) and the size of this effect depended on the specific configuration. This result demonstrates an influence of gaze direction in multitalker mixtures, even in the absence of visual speech information.

Parvalbumin neurons enhance temporal coding and reduce cortical noise in complex auditory scenes.

Cortical representations supporting many cognitive abilities emerge from underlying circuits comprised of several different cell types. However, cell type-specific contributions to rate and timing-based cortical coding are not well-understood. Here, we investigated the role of parvalbumin neurons in cortical complex scene analysis. Many complex scenes contain sensory stimuli which are highly dynamic in time and compete with stimuli at other spatial locations. Parvalbumin neurons play a fundamental role in balancing excitation and inhibition in cortex and sculpting cortical temporal dynamics; yet their specific role in encoding complex scenes via timing-based coding, and the robustness of temporal representations to spatial competition, has not been investigated. Here, we address these questions in auditory cortex of mice using a cocktail party-like paradigm, integrating electrophysiology, optogenetic manipulations, and a family of spike-distance metrics, to dissect parvalbumin neurons' contributions towards rate and timing-based coding. We find that suppressing parvalbumin neurons degrades cortical discrimination of dynamic sounds in a cocktail party-like setting via changes in rapid temporal modulations in rate and spike timing, and over a wide range of time-scales. Our findings suggest that parvalbumin neurons play a critical role in enhancing cortical temporal coding and reducing cortical noise, thereby improving representations of dynamic stimuli in complex scenes.

Diagnostic Performance of Ultrasonography Versus Magnetic Resonance Cholangiopancreatography in Biliary Obstruction.

Background In a suspected case of biliary obstruction with clinical and laboratory data suggesting obstructive jaundice, the major goal is to confirm the presence of obstruction, its nature and cause, location, and extent. Ultrasonography (USG) and magnetic resonance cholangiopancreatography (MRCP) are primarily used to diagnose suspected biliary tract illnesses. The aim of the study is to evaluate and compare the accuracy of MRCP and USG with endoscopic retrograde cholangiopancreatography (ERCP)/surgical/histopathological outcomes for finding the cause and level of obstruction in the case of clinically suspected biliary obstruction. Methods This was a prospective observational study conducted at Kalinga Institute of Medical Sciences and Pradyumna Bal Memorial Hospital, Bhubaneswar, India, from September 2020 to September 2022 on 120 patients. It included patients with clinical suspicion of biliary obstruction who underwent both USG and MRCP. Characteristics of the obstruction were evaluated for both benign and malignant lesions through USG and MRCP. The findings were then correlated with ERCP, histopathology, or surgery to calculate the diagnostic performance of the former two modalities. Results Out of 120 patients, USG was correctly able to predict the cause of obstruction in 40 patients. The sensitivity, specificity, and accuracy of detecting the nature of obstruction by USG were 33.3%, 84%, and 48.9%, respectively. The overall diagnostic accuracy of USG in predicting the site of obstruction was 64.3%. MRCP was correctly able to predict the cause of obstruction in 113 patients. The sensitivity, specificity, and accuracy of detecting the nature of obstruction by MRCP were 94.1%, 91.9%, and 94.8% respectively. The overall diagnostic accuracy of MRCP in predicting the site of obstruction was 98.33%. Out of 120 patients, no cause of biliary obstruction could be found in 71 patients by USG, out of which the correct diagnosis was made in 67 patients through MRCP. Conclusion USG should be used as the initial screening modality of choice for predicting the level and nature of obstruction in patients with a clinical suspicion of obstructive jaundice. MRCP should be the radiological investigation of choice in patients with clinical suspicion of obstructive jaundice. MRCP has the potential to become the new "Gold standard" investigation for diagnosis in patients with biliary obstruction owing to its excellent diagnostic performance, and non-invasiveness.

Barotrauma and its complications in COVID-19 patients: a retrospective study at tertiary care hospital of Eastern India.

Background: The development of barotrauma in COVID-19 patients who were ventilated and admitted to the intensive treatment unit seemed to have been a problematic issue in the COVID era. This study aimed to explore the possibility of developing the barotrauma-related issues with mechanical ventilation in the cases of individuals suffering from COVID-19. Results: Out of 48 patients who developed barotrauma, 30 (62.5%) presented with pneumothorax, 22 (45.8%) with pneumomediastinum, 10 (20.8%) with subcutaneous emphysema, and 2 (4.1%) with pneumopericardium. Of those that developed barotrauma, 45 (93.7%) patients were in acute respiratory distress syndrome. In patients with and without barotrauma, significant factors were white blood cell count (p = 0.001), neutrophil percentage (p = 0.012), and lymphocyte percentage (p = 0.014). There were no statistically significant differences in CRP, procalcitonin, d-dimer test, LDH, or ferritin. Conclusions: Patients infected with COVID-19 have a high risk of barotrauma when on mechanical ventilation. As a result, the death rate in this patient group is higher.

Deep Transfer Learning for Automatic Prediction of Hemorrhagic Stroke on CT Images.

Intracerebral hemorrhage (ICH) is the most common type of hemorrhagic stroke which occurs due to ruptures of weakened blood vessel in brain tissue. It is a serious medical emergency issues that needs immediate treatment. Large numbers of noncontrast-computed tomography (NCCT) brain images are analyzed manually by radiologists to diagnose the hemorrhagic stroke, which is a difficult and time-consuming process. In this study, we propose an automated transfer deep learning method that combines ResNet-50 and dense layer for accurate prediction of intracranial hemorrhage on NCCT brain images. A total of 1164 NCCT brain images were collected from 62 patients with hemorrhagic stroke from Kalinga Institute of Medical Science, Bhubaneswar and used for evaluating the model. The proposed model takes individual CT images as input and classifies them as hemorrhagic or normal. This deep transfer learning approach reached 99.6% accuracy, 99.7% specificity, and 99.4% sensitivity which are better results than that of ResNet-50 only. It is evident that the deep transfer learning model has advantages for automatic diagnosis of hemorrhagic stroke and has the potential to be used as a clinical decision support tool to assist radiologists in stroke diagnosis.

Evaluation of Sequential Head Computed Tomography in Traumatic Brain Injuries.

BACKGROUND: The grading of the severity of head trauma plays a vital role in acute patient management and planning a case-appropriate follow-up protocol. Few studies have been published regarding the Rotterdam scoring. In this study, we have established a correlation between the Rotterdam scores, need for sequential CTs, and the cumulative radiation dose. This correlation has helped develop a preliminary protocol that can be followed for patients hence bringing about better planned and efficient patient care. MATERIALS AND METHODS:  From August 2014 to December 2020, 88 cases of traumatic head injury on whom a minimum of one sequential CT was performed, with no surgical intervention, were included and studied. Sequential head CTs of each patient were evaluated by skilled radiologists with a minimum experience of five years, all of whom were blinded to the findings of the initial and previous head CT findings. The serial head CTs were evaluated for the Rotterdam CT score (RCTS).  Results: Among the patients with extradural hemorrhage (EDH), only 28.6% (8) progressed over successive CTs and 75.5% (34) of patients with subdural hemorrhage (SDH) showed significant progression over sequential CTs. Maximum number of serial CTs were obtained for cases presenting with a score of 3 (34 cases) with about three of them requiring up to a total of three CTs. However, no significant change in findings was noted on serial CTs. On the contrary, significant disease progression was noted in patients with baseline scores of 4 (76.9%) and 5 (100%), with statistical significance obtained on further analysis (P = 0.001). CONCLUSIONS: We are of the opinion that there is no additional role of sequential CT for the cases with Rotterdam score of 1 or 2 in the initial CT unless there is clinical evidence of deterioration. Rotterdam score 3 needs sequential CT after 24 hours and Rotterdam scores 4 and 5 need sequential CT after 12 hours if surgical intervention is delayed. The Rotterdam score may help predict any further need for a second CT, hence decreasing the unwanted radiation exposure.

A biologically oriented algorithm for spatial sound segregation.

Listening in an acoustically cluttered scene remains a difficult task for both machines and hearing-impaired listeners. Normal-hearing listeners accomplish this task with relative ease by segregating the scene into its constituent sound sources, then selecting and attending to a target source. An assistive listening device that mimics the biological mechanisms underlying this behavior may provide an effective solution for those with difficulty listening in acoustically cluttered environments (e.g., a cocktail party). Here, we present a binaural sound segregation algorithm based on a hierarchical network model of the auditory system. In the algorithm, binaural sound inputs first drive populations of neurons tuned to specific spatial locations and frequencies. The spiking response of neurons in the output layer are then reconstructed into audible waveforms via a novel reconstruction method. We evaluate the performance of the algorithm with a speech-on-speech intelligibility task in normal-hearing listeners. This two-microphone-input algorithm is shown to provide listeners with perceptual benefit similar to that of a 16-microphone acoustic beamformer. These results demonstrate the promise of this biologically inspired algorithm for enhancing selective listening in challenging multi-talker scenes.

A robust and biologically plausible spike pattern recognition network.

The neural mechanisms that enable recognition of spiking patterns in the brain are currently unknown. This is especially relevant in sensory systems, in which the brain has to detect such patterns and recognize relevant stimuli by processing peripheral inputs; in particular, it is unclear how sensory systems can recognize time-varying stimuli by processing spiking activity. Because auditory stimuli are represented by time-varying fluctuations in frequency content, it is useful to consider how such stimuli can be recognized by neural processing. Previous models for sound recognition have used preprocessed or low-level auditory signals as input, but complex natural sounds such as speech are thought to be processed in auditory cortex, and brain regions involved in object recognition in general must deal with the natural variability present in spike trains. Thus, we used neural recordings to investigate how a spike pattern recognition system could deal with the intrinsic variability and diverse response properties of cortical spike trains. We propose a biologically plausible computational spike pattern recognition model that uses an excitatory chain of neurons to spatially preserve the temporal representation of the spike pattern. Using a single neural recording as input, the model can be trained using a spike-timing-dependent plasticity-based learning rule to recognize neural responses to 20 different bird songs with >98% accuracy and can be stimulated to evoke reverse spike pattern playback. Although we test spike train recognition performance in an auditory task, this model can be applied to recognize sufficiently reliable spike patterns from any neuronal system.