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• Kv3.1 potassium channels regulate cortical fast-spiking behavior postnatally. • Visual cortical receptive field properties develop normally in the absence of Kv3.1. • Sensory plasticity is slowed but critical period timing is normal without Kv3.1. • Rate of plasticity reflects Kv3.1 gene dosage controlling prolonged spiking. • Diazepam effectively rescues Kv3.1 deficiency of relevance to mental disorders. Experience-dependent plasticity within visual cortex is controlled by postnatal maturation of inhibitory circuits, which are both morphologically diverse and precisely connected. Gene-targeted disruption of the voltage-dependent potassium channel K v 3.1 broadens action potentials and reduces net inhibitory function of parvalbumin (PV)-positive GABA subtypes within the neocortex. In mice lacking K v 3.1, the rate of input loss from an eye deprived of vision was slowed two-fold, despite otherwise normal critical period timecourse and receptive field properties. Rapid ocular dominance plasticity was restored by local or systemic enhancement of GABAergic transmission with acute benzodiazepine infusion. Diazepam instead exacerbated a global suppression of slow-wave oscillations during sleep described previously in these mutant mice, which therefore did not account for the rescued plasticity. Rapid ocular dominance shifts closely reflected K v 3.1 gene dosage that prevented prolonged spike discharge of their target pyramidal cells in vivo or the spike amplitude decrement of fast-spiking cells during bouts of high-frequency firing in vitro. Late postnatal expression of this unique channel in fast-spiking interneurons thus subtly regulates the speed of critical period plasticity with implications for mental illnesses. [ABSTRACT FROM AUTHOR]

Fear of doctors is a common source of distress among infants; however, the underlying sources of this distress are unknown. To investigate the doctor-infant relationship, the behaviors of 61 healthy infants (176–617 days old) were observed in a simulated examination room. Their behaviors and electrocardiograms were recorded. Two groups of infants were analyzed: those who cried and those who did not. When an experimenter dressed in the doctor's attire entered the room, all 9 infants who were crying (14.8% of all infants) stopped crying, all infants gazed at the experimenter, and their mean heart rate (HR) decreased. After the auscultation started, 29.5% of all infants cried, and the HRs of infants who cried were higher than those of infants who did not cry. During the auscultation, 80.0% of infants who cried averted from the experimenter, while 34.4% of infants who did not cry. Within 5 s of gazing at the stethoscope, the number of infants who cried increased from 3 to 12, and their mean HR also increased. Our findings suggest that the fear of doctors is not due to the appearance of doctors but rather to specific actions performed by doctors, such as auscultation. Infants may regard a doctor's appearance as a source of interest. Furthermore, a stethoscope is a possible trigger for infants' crying. These behavioral observations suggest the potential for patient-centered care for infants. [ABSTRACT FROM AUTHOR]

‘Infant shyness’, in which infants react shyly to adult strangers, presents during the third quarter of the first year. Researchers claim that shy children over the age of three years are experiencing approach-avoidance conflicts. Counter-intuitively, shy children do not avoid the eyes when scanning faces; rather, they spend more time looking at the eye region than non-shy children do. It is currently unknown whether young infants show this conflicted shyness and its corresponding characteristic pattern of face scanning. Here, using infant behavioral questionnaires and an eye-tracking system, we found that highly shy infants had high scores for both approach and fear temperaments (i.e., approach-avoidance conflict) and that they showed longer dwell times in the eye regions than less shy infants during their initial fixations to facial stimuli. This initial hypersensitivity to the eyes was independent of whether the viewed faces were of their mothers or strangers. Moreover, highly shy infants preferred strangers with an averted gaze and face to strangers with a directed gaze and face. This initial scanning of the eye region and the overall preference for averted gaze faces were not explained solely by the infants’ age or temperament (i.e., approach or fear). We suggest that infant shyness involves a conflict in temperament between the desire to approach and the fear of strangers, and this conflict is the psychological mechanism underlying infants’ characteristic behavior in face scanning. [ABSTRACT FROM AUTHOR]

We investigated whether categorical perception and dimensional perception can co-occur while decoding emotional facial expressions. In Experiment 1, facial continua with endpoints consisting of four basic emotions (i.e., happiness–fear and anger–disgust) were created by a morphing technique. Participants rated each facial stimulus using a categorical strategy and a dimensional strategy. The results show that the happiness–fear continuum was divided into two clusters based on valence, even when using the dimensional strategy. Moreover, the faces were arrayed in order of the physical changes within each cluster. In Experiment 2, we found a category boundary within other continua (i.e., surprise–sadness and excitement–disgust) with regard to the arousal and valence dimensions. These findings indicate that categorical perception and dimensional perception co-occurred when emotional facial expressions were rated using a dimensional strategy, suggesting a hybrid theory of categorical and dimensional accounts. [ABSTRACT FROM AUTHOR]

Abstract: Adults typically address infants in a special speech mode called infant-directed speech (IDS). IDS is characterized by a special prosody (i.e., higher pitched, slower and hyperarticulated) and a special lexicon (“baby talk”). Here we investigated which areas of the adult brain are involved in processing IDS, which aspects of IDS (prosodic or lexical) are processed, to what extent the experience of being a parent affects the way adults process IDS, and the effects of gender and personality on IDS processing. Using functional magnetic resonance imaging, we found that mothers with preverbal infants showed enhanced activation in the auditory dorsal pathway of the language areas, regardless of whether they listened to the prosodic or lexical component of IDS. We also found that extroverted mothers showed higher cortical activation in speech-related motor areas than did mothers with lower extroverted personality scores. Increased cortical activation levels were not found for fathers, non-parents, or mothers with older children. [ABSTRACT FROM AUTHOR]

Although the emotional outcome of a choice generally affects subsequent decisions, humans can inhibit the influence of emotion. Heart rate variability (HRV) has emerged as an objective measure of individual differences in the capacity for inhibitory control. In the present study, we investigated how individual differences in HRV at rest are associated with the emotional effects of the outcome of a choice on subsequent decision making using a decision-making task in which emotional pictures appeared as decision outcomes. We used a reinforcement learning model to characterize the observed behaviors according to several parameters, namely, the learning rate and the motivational value of positive and negative pictures. Consequently, we found that individuals with a lower resting HRV exhibited a greater negative motivational value in response to negative pictures, suggesting that these individuals tend to avoid negative pictures compared with individuals with a higher resting HRV. [ABSTRACT FROM AUTHOR]