In most species, the sense of taste is key in the distinction of potentially nutritious and harmful food constituents and thereby in the acceptance (or rejection) of food. Taste quality is encoded by ...specialized receptors on the tongue, which detect chemicals corresponding to each of the basic tastes (sweet, salty, sour, bitter, and savory 1), before taste quality information is transmitted via segregated neuronal fibers 2, distributed coding across neuronal fibers 3, or dynamic firing patterns 4 to the gustatory cortex in the insula. In rodents, both hardwired coding by labeled lines 2 and flexible, learning-dependent representations 5 and broadly tuned neurons 6 seem to coexist. It is currently unknown how, when, and where taste quality representations are established in the cortex and whether these representations are used for perceptual decisions. Here, we show that neuronal response patterns allow to decode which of four tastants (salty, sweet, sour, and bitter) participants tasted in a given trial by using time-resolved multivariate pattern analyses of large-scale electrophysiological brain responses. The onset of this prediction coincided with the earliest taste-evoked responses originating from the insula and opercular cortices, indicating that quality is among the first attributes of a taste represented in the central gustatory system. These response patterns correlated with perceptual decisions of taste quality: tastes that participants discriminated less accurately also evoked less discriminated brain response patterns. The results therefore provide the first evidence for a link between taste-related decision-making and the predictive value of these brain response patterns.
•Large-scale electrophysiological response patterns code for taste quality in humans•Taste quality is represented early in the central gustatory system•Neural response patterns correlate with subjective perceptual experience
Taste allows discriminating nutritious and harmful food constituents. Crouzet et al. show that the earliest taste-evoked neural responses in the human cortex code for taste quality (e.g., salty or sweet). These neural response patterns were correlated with perceptual decisions, indicating that they form the basis of subjective taste experience.
Whether multiparametric MRI improves the detection of clinically significant prostate cancer and avoids the need for systematic biopsy in biopsy-naive patients remains controversial. We aimed to ...investigate whether using this approach before biopsy would improve detection of clinically significant prostate cancer in biopsy-naive patients.
In this prospective, multicentre, paired diagnostic study, done at 16 centres in France, we enrolled patients aged 18–75 years with prostate-specific antigen concentrations of 20 ng/mL or less, and with stage T2c or lower prostate cancer. Eligible patients had been referred for prostate multiparametric MRI before a first set of prostate biopsies, with a planned interval of less than 3 months between MRI and biopsies. An operator masked to multiparametric MRI results did a systematic biopsy by obtaining 12 systematic cores and up to two cores targeting hypoechoic lesions. In the same patient, another operator targeted up to two lesions seen on MRI with a Likert score of 3 or higher (three cores per lesion) using targeted biopsy based on multiparametric MRI findings. Patients with negative multiparametric MRI (Likert score ≤2) had systematic biopsy only. The primary outcome was the detection of clinically significant prostate cancer of International Society of Urological Pathology grade group 2 or higher (csPCa-A), analysed in all patients who received both systematic and targeted biopsies and whose results from both were available for pathological central review, including patients who had protocol deviations. This study is registered with ClinicalTrials.gov, number NCT02485379, and is closed to new participants.
Between July 15, 2015, and Aug 11, 2016, we enrolled 275 patients. 24 (9%) were excluded from the analysis. 53 (21%) of 251 analysed patients had negative (Likert ≤2) multiparametric MRI. csPCa-A was detected in 94 (37%) of 251 patients. 13 (14%) of these 94 patients were diagnosed by systematic biopsy only, 19 (20%) by targeted biopsy only, and 62 (66%) by both techniques. Detection of csPCa-A by systematic biopsy (29·9%, 95% CI 24·3–36·0) and targeted biopsy (32·3%, 26·5–38·4) did not differ significantly (p=0·38). csPCa-A would have been missed in 5·2% (95% CI 2·8–8·7) of patients had systematic biopsy not been done, and in 7·6% (4·6–11·6) of patients had targeted biopsy not been done. Four grade 3 post-biopsy adverse events were reported (3 cases of prostatitis, and 1 case of urinary retention with haematuria).
There was no difference between systematic biopsy and targeted biopsy in the detection of ISUP grade group 2 or higher prostate cancer; however, this detection was improved by combining both techniques and both techniques showed substantial added value. Thus, obtaining a multiparametric MRI before biopsy in biopsy-naive patients can improve the detection of clinically significant prostate cancer but does not seem to avoid the need for systematic biopsy.
French National Cancer Institute.
Previous work has demonstrated that the human visual system can detect animals in complex natural scenes very efficiently and rapidly. In particular, using a saccadic choice task, H. Kirchner and S. ...J. Thorpe (2006) found that when two images are simultaneously flashed in the left and right visual fields, saccades toward the side with an animal can be initiated in as little as 120-130 ms. Here we show that saccades toward human faces are even faster, with the earliest reliable saccades occurring in just 100-110 ms, and mean reaction times of roughly 140 ms. Intriguingly, it appears that these very fast saccades are not completely under instructional control, because when faces were paired with photographs of vehicles, fast saccades were still biased toward faces even when the subject was targeting vehicles. Finally, we tested whether these very fast saccades might only occur in the simple case where the images are presented left and right of fixation by showing they also occur when the images are presented above and below fixation. Such results impose very serious constraints on the sorts of processing model that can be invoked and demonstrate that face-selective behavioral responses can be generated extremely rapidly.
The processes underlying object recognition are fundamental for the understanding of visual perception. Humans can recognize many objects rapidly even in complex scenes, a task that still presents ...major challenges for computer vision systems. A common experimental demonstration of this ability is the rapid animal detection protocol, where human participants earliest responses to report the presence/absence of animals in natural scenes are observed at 250-270 ms latencies. One of the hypotheses to account for such speed is that people would not actually recognize an animal per se, but rather base their decision on global scene statistics. These global statistics (also referred to as spatial envelope or gist) have been shown to be computationally easy to process and could thus be used as a proxy for coarse object recognition. Here, using a saccadic choice task, which allows us to investigate a previously inaccessible temporal window of visual processing, we showed that animal - but not vehicle - detection clearly precedes scene categorization. This asynchrony is in addition validated by a late contextual modulation of animal detection, starting simultaneously with the availability of scene category. Interestingly, the advantage for animal over scene categorization is in opposition to the results of simulations using standard computational models. Taken together, these results challenge the idea that rapid animal detection might be based on early access of global scene statistics, and rather suggests a process based on the extraction of specific local complex features that might be hardwired in the visual system.
Primates can recognize objects embedded in complex natural scenes in a glimpse. Rapid categorization paradigms have been extensively used to study our core perceptual abilities when the visual system ...is forced to operate under strong time constraints. However, the neural underpinning of rapid categorization remains to be understood, and the incredible speed of sight has yet to be reconciled with modern ventral stream cortical theories of object recognition.
Here we recorded multichannel subdural electrocorticogram (ECoG) signals from intermediate areas (V4/PIT) of the ventral stream of the visual cortex while monkeys were actively engaged in a rapid animal/non-animal categorization task. A traditional event-related potential (ERP) analysis revealed short visual latencies (<50–70ms) followed by a rapidly developing visual selectivity (within ~20–30ms) for most electrodes. A multi-variate pattern analysis (MVPA) technique further confirmed that reliable animal/non-animal category information was possible from this initial ventral stream neural activity (within ~90–100ms). Furthermore, this early category-selective neural activity was (a) unaffected by the presentation of a backward (pattern) mask, (b) generalized to novel (unfamiliar) stimuli and (c) co-varied with behavioral responses (both accuracy and reaction times). Despite the strong prevalence of task-related information on the neural signal, task-irrelevant visual information could still be decoded independently of monkey behavior. Monkey behavioral responses were also found to correlate significantly with human behavioral responses for the same set of stimuli.
Together, the present study establishes that rapid ventral stream neural activity induces a visually selective signal subsequently used to drive rapid visual categorization and that this visual strategy may be shared between human and non-human primates.
•Abstract category information available from intermediate areas of the ventral stream•Backward masking dissociates early feedforward vs. late recurrent neural activity.•Feedforward sweep enables rapid behavior.•Feedforward sweep supports monkey generalization to novel natural scenes.
Earlier studies suggested that the visual system processes information at the basic level (e.g., dog) faster than at the subordinate (e.g., Dalmatian) or superordinate (e.g., animals) levels. ...However, the advantage of the basic category over the superordinate category in object recognition has been challenged recently, and the hierarchical nature of visual categorization is now a matter of debate. To address this issue, we used a forced-choice saccadic task in which a target and a distractor image were displayed simultaneously on each trial and participants had to saccade as fast as possible toward the image containing animal targets based on different categorization levels. This protocol enables us to investigate the first 100–120 msec, a previously unexplored temporal window, of visual object categorization. The first result is a surprising stability of the saccade latency (median RT ∼155 msec) regardless of the animal target category and the dissimilarity of target and distractor image sets. Accuracy was high (around 80% correct) for categorization tasks that can be solved at the superordinate level but dropped to almost chance levels for basic level categorization. At the basic level, the highest accuracy (62%) was obtained when distractors were restricted to another dissimilar basic category. Computational simulations based on the saliency map model showed that the results could not be predicted by pure bottom–up saliency differences between images. Our results support a model of visual recognition in which the visual system can rapidly access relatively coarse visual representations that provide information at the superordinate level of an object, but where additional visual analysis is required to allow more detailed categorization at the basic level.
Recent experimental work has demonstrated the existence of extremely rapid saccades toward faces in natural scenes that can be initiated only 100 ms after image onset (Crouzet et al., 2010). These ...ultra-rapid saccades constitute a major challenge to current models of processing in the visual system because they do not seem to leave enough time for even a single feed-forward pass through the ventral stream. Here we explore the possibility that the information required to trigger these very fast saccades could be extracted very early on in visual processing using relatively low-level amplitude spectrum (AS) information in the Fourier domain. Experiment 1 showed that AS normalization can significantly alter face-detection performance. However, a decrease of performance following AS normalization does not alone prove that AS-based information is used (Gaspar and Rousselet, 2009). In Experiment 2, following the Gaspar and Rousselet paper, we used a swapping procedure to clarify the role of AS information in fast object detection. Our experiment is composed of three conditions: (i) original images, (ii) category swapped, in which the face image has the AS of a vehicle, and the vehicle has the AS of a face, and (iii) identity swapped, where the face has the AS of another face image, and the vehicle has the AS of another vehicle image. The results showed very similar levels of performance in the original and identity swapped conditions, and a clear drop in the category swapped condition. This result demonstrates that, in the early temporal window offered by the saccadic choice task, the visual saccadic system does indeed rely on low-level AS information in order to rapidly detect faces. This sort of crude diagnostic information could potentially be derived very early on in the visual system, possibly as early as V1 and V2.
Abstract Background Up to a third of patients with localized prostate cancer have unilateral disease that may be suitable for partial treatment with hemiablation. Objective To evaluate the ability of ...high intensity focused ultrasound (HIFU) to achieve local control of the tumor in patients with unilateral localized prostate cancer. Design, setting, and participants The French Urological Association initiated a prospective IDEAL multi-institutional study (2009–2015), to evaluate HIFU-hemiablation as a primary treatment. Intervention Multiparametric magnetic resonance imaging and biopsy were used for unilateral cancer diagnosis and control, and HIFU-hemiablation. Outcome measurements and statistical analysis Primary: absence of clinically significant cancer (CSC) on control biopsy at 1 yr (CSC: Gleason score ≥ 7 or cancer core length > 3 mm regardless of grade or > 2 positive cores). Secondary: presence of any cancer on biopsy, biochemical response, radical treatment free survival, adverse events, continence (no pad), erectile function (International Index of Erectile Function-5 ≥ 16), and quality of life (European Organization for Research and Treatment of Cancer QLQ-C28) questionnaires. Results and limitations One hundred and eleven patients were treated (mean age: 64.8 yr standard deviation 6.2; mean prostate-specific antigen: 6.2 ng/ml standard deviation 2.6; 68% low risk, 32% intermediate risk). Of the 101 patients with control biopsy, 96 (95%) and 94 (93%) had no CSC in the treated and contralateral lobes, respectively. Mean prostate-specific antigen at 2 yr was 2.3 ng/ml (standard deviation 1.7). The radical treatment-free survival rate at 2 years was 89% (radical treatments: six radical prostatectomies, three radiotherapies, and two HIFU). Adverse events were Grade 3 in 13%. At 12 mo continence and erectile functions were preserved in 97% and 78%. No significant decrease in quality of life score was observed at 12 mo. One limitation is the number of low-risk patients included in this study. Conclusions At 1 yr, HIFU-hemiablation was efficient with 95% absence of clinically significant cancer associated with low morbidity and preservation of quality of life. Radical treatment-free survival rate was 89% at 2 yr. Patient summary This report shows that high intensity focused ultrasound half-gland treatment of unilateral prostate cancer provides promising results with high cancer control and low morbidity.
Object-substitution masking (OSM) occurs when a briefly presented target in a search array is surrounded by small dots that remain visible after the target disappears. The reduction of target ...visibility occurring after OSM has been suggested to result from a specific interference with reentrant visual processing while the initial feedforward processing is thought to be left intact. We tested a prediction derived from this hypothesis: the fastest responses, being triggered before the beginning of reentrant processing, should escape the OSM interference. In a saccadic choice reaction time task, which gives access to very early stages of visual processing, target visibility was reduced either by OSM, conventional backward masking, or low stimulus contrast. A general reduction of performance was observed in all three conditions. However, the fastest saccades did not show any sign of interference under either OSM or backward masking, as they did under the low-contrast condition. This finding supports the hypothesis that masking interferes mostly with reentrant processing at later stages, while leaving early feedforward processing largely intact.
Objectives
To measure benign and malignant prostate tissue stiffness using shear-wave elastography (SWE).
Methods
Thirty consecutive patients underwent transrectal SWE in the axial and sagittal ...planes before prostatectomy. After reviewing prostatectomy specimens, two radiologists measured stiffness in regions corresponding to cancers, lateral and median benign peripheral zone (PZ) and benign transition zone (TZ).
Results
Cancers were stiffer than benign PZ and TZ. All tissue classes were stiffer on sagittal than on axial imaging, in TZ than in PZ, and in median PZ than in lateral PZ. At multivariate analysis, the nature of tissue (benign or malignant;
P
< 0.00001), the imaging plane (axial or sagittal;
P
< 0.00001) and the location within the prostate (TZ, median PZ or lateral PZ;
P
= 0.0065) significantly and independently influenced tissue stiffness. On axial images, the thresholds maximising the Youden index in TZ, lateral PZ and median PZ were respectively 62 kPa, 33 kPa and 49 kPa. On sagittal images, the thresholds were 76 kPa, 50 kPa and 72 kPa, respectively.
Conclusions
SWE can distinguish prostate malignant and benign tissues. Tissue stiffness is influenced by the imaging plane and the location within the gland.
Key Points
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Prostate cancers were stiffer than the benign peripheral zone
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All tissue classes were stiffer on sagittal than on axial imaging
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All tissue classes were stiffer in the transition zone than in the peripheral zone
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All tissue classes were stiffer in the median than in the lateral peripheral zone
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Taking into account imaging plane and zonal anatomy can improve cancer detection
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