Multisensory Logic of Infant-Directed Aggression by Males.

Newborn mice emit signals that promote parenting from mothers and fathers but trigger aggressive responses from virgin males. Although pup-directed attacks by males require vomeronasal function, the specific infant cues that elicit this behavior are unknown. We developed a behavioral paradigm based on reconstituted pup cues and showed that discrete infant morphological features combined with salivary chemosignals elicit robust male aggression. Seven vomeronasal receptors were identified based on infant-mediated activity, and the involvement of two receptors, Vmn2r65 and Vmn2r88, in infant-directed aggression was demonstrated by genetic deletion. Using the activation of these receptors as readouts for biochemical fractionation, we isolated two pheromonal compounds, the submandibular gland protein C and hemoglobins. Unexpectedly, none of the identified vomeronasal receptors and associated cues were specific to pups. Thus, infant-mediated aggression by virgin males relies on the recognition of pup's physical traits in addition to parental and infant chemical cues.

Dorsolateral Striatum is a Bottleneck for Responding to Task-Relevant Stimuli in a Learned Whisker Detection Task in Mice.

A learned sensory-motor behavior engages multiple brain regions, including the neocortex and the basal ganglia. How a target stimulus is detected by these regions and converted to a motor response remains poorly understood. Here, we performed electrophysiological recordings and pharmacological inactivations of whisker motor cortex and dorsolateral striatum to determine the representations within, and functions of, each region during performance in a selective whisker detection task in male and female mice. From the recording experiments, we observed robust, lateralized sensory responses in both structures. We also observed bilateral choice probability and preresponse activity in both structures, with these features emerging earlier in whisker motor cortex than dorsolateral striatum. These findings establish both whisker motor cortex and dorsolateral striatum as potential contributors to the sensory-to-motor (sensorimotor) transformation. We performed pharmacological inactivation studies to determine the necessity of these brain regions for this task. We found that suppressing the dorsolateral striatum severely disrupts responding to task-relevant stimuli, without disrupting the ability to respond, whereas suppressing whisker motor cortex resulted in more subtle changes in sensory detection and response criterion. Together these data support the dorsolateral striatum as an essential node in the sensorimotor transformation of this whisker detection task.SIGNIFICANCE STATEMENT Selecting an item in a grocery store, hailing a cab - these daily practices require us to transform sensory stimuli into motor responses. Many decades of previous research have studied goal-directed sensory-to-motor transformations within various brain structures, including the neocortex and the basal ganglia. Yet, our understanding of how these regions coordinate to perform sensory-to-motor transformations is limited because these brain structures are often studied by different researchers and through different behavioral tasks. Here, we record and perturb specific regions of the neocortex and the basal ganglia and compare their contributions during performance of a goal-directed somatosensory detection task. We find notable differences in the activities and functions of these regions, which suggests specific contributions to the sensory-to-motor transformation process.

Global, Low-Amplitude Cortical State Predicts Response Outcomes in a Selective Detection Task in Mice.

Spontaneous neuronal activity strongly impacts stimulus encoding and behavioral responses. We sought to determine the effects of neocortical prestimulus activity on stimulus detection. We trained mice in a selective whisker detection task, in which they learned to respond (lick) to target stimuli in one whisker field and ignore distractor stimuli in the contralateral whisker field. During expert task performance, we used widefield Ca2+ imaging to assess prestimulus and post-stimulus neuronal activity broadly across frontal and parietal cortices. We found that lower prestimulus activity correlated with enhanced stimulus detection: lower prestimulus activity predicted response versus no response outcomes and faster reaction times. The activity predictive of trial outcome was distributed through dorsal neocortex, rather than being restricted to whisker or licking regions. Using principal component analysis, we demonstrate that response trials are associated with a distinct and less variable prestimulus neuronal subspace. For single units, prestimulus choice probability was weak yet distributed broadly, with lower than chance choice probability correlating with stronger sensory and motor encoding. These findings support low amplitude and low variability as an optimal prestimulus cortical state for stimulus detection that presents globally and predicts response outcomes for both target and distractor stimuli.

Neural Basis of Somatosensory Spatial and Temporal Discrimination in Humans: The Role of Sensory Detection.

While detecting somatic stimuli from the external environment, an accurate determination of their spatial and temporal properties is essential for human behavior. Whether and how detection relates to human capacity for somatosensory spatial discrimination (SD) and temporal discrimination (TD) remains unclear. Here, participants underwent functional magnetic resonance imaging scanning when simply detecting vibrotactile stimuli of the leg, judging their location (SD), or deciding their number in time (TD). By conceptualizing tactile discrimination as consisting of detection and determination processes, we found that tactile detection elicited activation specifically involved in SD within the right inferior and superior parietal lobules, 2 regions previously implicated in the control of spatial attention. These 2 regions remained activated in the determination process, during which functional connectivity between these 2 regions predicted individual SD ability. In contrast, tactile detection produced little activation specifically related to TD. Participants' TD ability was implemented in brain regions implicated in coding temporal structures of somatic stimuli (primary somatosensory cortex) and time estimation (anterior cingulate, pre-supplementary motor area, and putamen). Together, our findings indicate a close link between somatosensory detection and SD (but not TD) at the neural level, which aids in explaining why we can promptly respond toward detected somatic stimuli.

Single-Cell Stimulation in Barrel Cortex Influences Psychophysical Detection Performance.

A single whisker stimulus elicits action potentials in a sparse subset of neurons in somatosensory cortex. The precise contribution of these neurons to the animal's perception of a whisker stimulus is unknown. Here we show that single-cell stimulation in rat barrel cortex of both sexes influences the psychophysical detection of a near-threshold whisker stimulus in a cell type-dependent manner, without affecting false alarm rate. Counterintuitively, stimulation of single fast-spiking putative inhibitory neurons increased detection performance. Single-cell stimulation of putative excitatory neurons failed to change detection performance, except for a small subset of deep-layer neurons that were highly sensitive to whisker stimulation and that had an unexpectedly strong impact on detection performance. These findings indicate that the perceptual impact of excitatory barrel cortical neurons relates to their firing response to whisker stimulation and that strong activity in a single highly sensitive neuron in barrel cortex can already enhance sensory detection. Our data suggest that sensory detection is based on a decoding mechanism that lends a disproportionally large weight to interneurons and to deep-layer neurons showing a strong response to sensory stimulation.SIGNIFICANCE STATEMENT Rat whisker somatosensory cortex contains a variety of neuronal cell types with distinct anatomical and physiological characteristics. How each of these different cell types contribute to the animal's perception of whisker stimuli is unknown. We explored this question by using a powerful electrophysiological stimulation technique that allowed us to target and stimulate single neurons with different sensory response types in whisker cortex. In awake, behaving animals, trained to detect whisker stimulation, only costimulation of single fast-spiking inhibitory neurons or single deep-layer excitatory neurons with strong responses to whisker stimulation enhanced detection performance. Our data demonstrate that single cortical neurons can have measurable impact on the detection of sensory stimuli and suggest a decoding mechanism based on select cell types.

Genital Sensory Detection Thresholds and Patient Satisfaction With Vaginoplasty in Male-to-Female Transgender Women.

INTRODUCTION: Gender-affirming surgery is common for the treatment of gender dysphoria, but its effect on genital sensitivity is not well known. AIMS: To investigate genital sensory detection thresholds in male-to-female transgender women postoperatively and their relation to psychological well-being and variables of satisfaction. METHODS: Prospective study on 28 transgender women at least 18 years old operated on at least 3 months before the study by a single surgeon (N.M.J.). MAIN OUTCOME MEASURES: Medical complications; sensory detection thresholds for light touch, pressure, and vibration; and questionnaires on general and sexual satisfaction, sexual function, depression, and psychological well-being. RESULTS: Sensory detection thresholds ranged from 0.07 to 2.82 g for light touch, with the neck being most sensitive; from 20.23 to 34.64 g for pressure, with similar results for the neck and clitoris; and from 0.0052 to 0.0111 V for vibration, with similar findings for all stimulation points. Satisfaction with the appearance of the labia, vulva, clitoris, and sexual function was good to very good. Frequency of sexual activities increased significantly postoperatively for orogenital stimulation and decreased significantly for frequency of fantasies (t = -4.81; P < .0001). Orgasmic function was reported by 80% of participants. Psychological adjustment was good to very good, with low depression scores. Sexual satisfaction was statistically and positively correlated with vaginal function and depth, clitoral sensation, appearance of the vulva and labia minora, and natural lubrication and negatively correlated with depression scores. CONCLUSION: Gender-affirming surgery yields good results for satisfaction with appearance and function. Genital sensitivity showed the best results with pressure and vibration.

The assessment of sensory detection thresholds on the perineum and breast compared with control body sites.

INTRODUCTION: Few studies explored multiple sensory detection thresholds on the perineum and breast, but these normative data may provide standards for clinical conditions such as aging, genital and breast surgeries, pathological conditions affecting the genitals, and sexual function. AIMS: The aim of this study was to provide normative data on sensory detection thresholds of three sensory modalities on the perineum and breast. METHODS: Thirty healthy women aged between 18 and 35 years were assessed on the perineum (clitoris, labia minora, vaginal, and anal margin), breast (lateral, areola, nipple), and control body locations (neck, forearm, abdomen) for three sensory modalities (light touch, pressure, vibration). MAIN OUTCOME MEASURES: Average detection thresholds for each body location and sensory modality and statistical comparisons between the primary genital, secondary sexual, and neutral zones were the main outcome measures. RESULTS: Average detection thresholds for light touch suggest that the neck, forearm, and vaginal margin are most sensitive, and areola least sensitive. No statistical difference is found between the primary and secondary sexual zones, but the secondary sexual zone is significantly more sensitive than the neutral zone. Average detection thresholds for pressure suggest that the clitoris and nipple are most sensitive, and the lateral breast and abdomen least sensitive. No statistical difference is found between the primary and secondary sexual zone, but they are both significantly more sensitive than the neutral zone. Average detection thresholds for vibration suggest that the clitoris and nipple are most sensitive. The secondary sexual zone is significantly more sensitive than the primary and neutral zone, but the latter two show no difference. CONCLUSION: The current normative data from sensory detection threshold are discussed in terms of providing standard values for research and clinical conditions. Additional analysis from breast volume, body mass index, hormonal contraception, menstrual cycle, and sexual orientation do not seem to influence the results. Sexual abstinence and body piercing may have some impact.

Differential roles of auditory and visual cortex for sensory detection in mice.

Sensory cortex encompasses the regions of the cerebral cortex that receive primary sensory inputs and is crucial for conscious sensory perception in humans. Yet, some forms of perception are possible without sensory cortex. For example in animal models, the association of a sound detection to a simple behavior resists to the inactivation of auditory cortex. In contrast, post-training inactivation experiments conducted in visual or somatosensory cortex led to much stronger effects. Here we show that muscimol inactivation of visual or auditory cortex in the same detection protocol transiently abolishes visual but not auditory detection. We also observe that cortex-dependency correlates with longer reaction times. This suggests that auditory cortex is more easily bypassed by other circuits for stimulus detection than other primary sensory areas, which may be due to timing differences between auditory and visual associations.

Le cortex sensoriel englobe les régions du cortex cérébral qui reçoivent les entrées sensorielles primaires et il est crucial pour la perception sensorielle consciente chez les humains. Pourtant, certaines formes de perception sont possibles sans cortex sensoriel. Par exemple, chez des modèles animaux, l'association d'une détection sonore à un comportement simple résiste à l'inactivation du cortex auditif. En revanche, des expériences d'inactivation post-entraînement menées dans le cortex visuel ou somatosensoriel ont conduit à des effets beaucoup plus forts. Nous montrons ici que l'inactivation par le muscimol du cortex visuel ou auditif dans le même protocole de détection abolit transitoirement la détection visuelle mais pas la détection auditive. Nous observons également que la dépendance au cortex est corrélée à des temps de réaction plus longs. Cela suggère que le cortex auditif est plus facilement contourné par d'autres circuits pour la détection des stimuli que d'autres zones sensorielles primaires, ce qui peut être dû à des différences de timing entre les associations auditives et visuelles.

Cortical Localization of the Sensory-Motor Transformation in a Whisker Detection Task in Mice.

Responding to a stimulus requires transforming an internal sensory representation into an internal motor representation. Where and how this sensory-motor transformation occurs is a matter of vigorous debate. Here, we trained male and female mice in a whisker detection go/no-go task in which they learned to respond (lick) following a transient whisker deflection. Using single unit recordings, we quantified sensory-related, motor-related, and choice-related activities in whisker primary somatosensory cortex (S1), whisker region of primary motor cortex (wMC), and anterior lateral motor cortex (ALM), three regions that have been proposed to be critical for the sensory-motor transformation in whisker detection. We observed strong sensory encoding in S1 and wMC, with enhanced encoding in wMC, and a lack of sensory encoding in ALM. We observed strong motor encoding in all three regions, yet largest in wMC and ALM. We observed the earliest choice probability in wMC, despite earliest sensory responses in S1. Based on the criteria of having both strong sensory and motor representations and early choice probability, we identify whisker motor cortex as the cortical region most directly related to the sensory-motor transformation. Our data support a model of sensory encoding originating in S1, sensory amplification and sensory-motor transformation occurring within wMC, and motor signals emerging in ALM after the sensory-motor transformation.

Factors Contributing to Interindividual Variation in Retronasal Odor Perception from Aroma Glycosides: The Role of Odorant Sensory Detection Threshold, Oral Microbiota, and Hydrolysis in Saliva.

Glycosides are sugar conjugates of aroma compounds that are found in many fruits and vegetables, and while glycosides are non-volatile, they can release flavor during eating, through enzyme hydrolysis from oral microbiota. Recently, a range of sensory phenotypes for glucoside perception have been observed, reflecting interindividual variation in response to precursors of floral and smoky flavors, geranyl glucoside and guaiacyl glucoside. To understand this variation and investigate the role of oral microbiota on in vitro hydrolysis of glucosides in saliva, metagenomic screening was conducted using individuals representing the range of sensory phenotypes for geranyl and guaiacyl glucosides. In parallel, sensory retronasal detection thresholds for geranyl glucoside, guaiacyl glucoside, and the volatile odorants geraniol and guaiacol were determined. Oral microbial communities correlated with hydrolysis of glucosides in saliva, but the relationship did not extend to sensory phenotypes. Overall, the retronasal detection threshold of the volatile odorants studied was the main factor determining sensory phenotype.

A Neural Basis for Categorizing Sensory Stimuli to Enhance Decision Accuracy.

Sensory stimuli with graded intensities often lead to yes-or-no decisions on whether to respond to the stimuli. How this graded-to-binary conversion is implemented in the central nervous system (CNS) remains poorly understood. Here, we show that graded encodings of noxious stimuli are categorized in a decision-associated CNS region in Drosophila larvae, and then decoded by a group of peptidergic neurons for executing binary escape decisions. GABAergic inhibition gates weak nociceptive encodings from being decoded, whereas escalated amplification through the recruitment of second-order neurons boosts nociceptive encodings at intermediate intensities. These two modulations increase the detection accuracy by reducing responses to negligible stimuli whereas enhancing responses to intense stimuli. Our findings thus unravel a circuit mechanism that underlies accurate detection of harmful stimuli.

Dissociation in decision bias mechanism between probabilistic information and previous decision.

Target detection performance is known to be influenced by events in the previous trials. It has not been clear, however, whether this bias effect is due to the previous sensory stimulus, motor response, or decision. Also it remains open whether or not the previous trial effect emerges via the same mechanism as the effect of knowledge about the target probability. In the present study, we asked normal human subjects to make a decision about the presence or absence of a visual target. We presented a pre-cue indicating the target probability before the stimulus, and also a decision-response mapping cue after the stimulus so as to tease apart the effect of decision from that of motor response. We found that the target detection performance was significantly affected by the probability cue in the current trial and also by the decision in the previous trial. While the information about the target probability modulated the decision criteria, the previous decision modulated the sensitivity to target-relevant sensory signals (d-prime). Using functional magnetic resonance imaging (fMRI), we also found that activation in the left intraparietal sulcus (IPS) was decreased when the probability cue indicated a high probability of the target. By contrast, activation in the right inferior frontal gyrus (IFG) was increased when the subjects made a target-present decision in the previous trial, but this change was observed specifically when the target was present in the current trial. Activation in these regions was associated with individual-difference in the decision computation parameters. We argue that the previous decision biases the target detection performance by modulating the processing of target-selective information, and this mechanism is distinct from modulation of decision criteria due to expectation of a target.