Critical roles of mecamylamine-sensitive mushroom body neurons in insect olfactory learning

In insects, cholinergic neurons are thought to transmit olfactory conditioned stimulus (CS) to the sites for associating the CS with unconditioned stimulus (US), but the types of acetylcholine (ACh) receptor used by neurons participating in the association have not been determined. In cockroaches, a type of nicotinic ACh receptor specifically antagonized by mecamylamine (MEC) has been characterized. Here we investigated the roles of neurons possessing MEC-sensitive ACh receptors (MEC-sensitive neurons) in olfactory conditioning of salivation, monitored by changes in activities of salivary neurons, in cockroaches. Local and bilateral microinjection of MEC into each of the three olfactory centers, antennal lobes, calyces of the mushroom bodies and lateral protocerebra, impaired olfactory responses of salivary neurons, indicating that MEC-sensitive neurons in all olfactory centers participate in pathways mediating olfactory responses of salivary neurons. Conditioning of olfactory CS with sucrose US was impaired by injection of MEC into the antennal lobes or calyces, i.e., conditioned responses were absent even after recovery from MEC injection, suggesting that the CS-US association occurs in MEC-sensitive neurons in calyces (most probably Kenyon cells) or in neurons in downstream pathways. In contrast, conditioned responses appeared after recovery from MEC injection into the lateral protocerebra, suggesting that MEC-sensitive neurons in the lateral protocerebra are downstream of the association sites. Since lateral protocerebra are major termination areas of mushroom body efferent neurons, we suggest that input synapses of MEC-sensitive Kenyon cells, or their output synapses upon mushroom body efferent neurons, are the sites for CS-US association for conditioning of salivation.     

Selective bias in retrospective self-reports of negative mood states

Retrospective self-report questionnaires of negative mood states experienced in the past (e.g., the most recent two weeks) tend to be exaggerated in a negative direction relative to the average ratings given to the moods contemporaneously. The present study used three measures that decomposed mood states into their constituent elements to examine whether certain components selectively contributed to this negative bias or all components contributed to this bias equally. Fifty-three participants responded to the questionnaires via the Internet every evening for two weeks. On the final day, participants recalled and retrospectively evaluated their mood state over the previous two weeks as a whole. The results revealed that memory bias occurred selectively for negative mood states. Anxiety, depression, and helplessness were exaggerated in the global compared with the daily ratings. None of the positive mood components showed any bias in the retrospective global ratings. A regression analysis indicated that the difference in daily and global ratings for negative mood was partly explained by peak and final scores. Higher peak scores led to greater overestimation whereas final scores had smaller effects; the higher the final score was, the less participants overestimated their negative mood in the global ratings.     

Hemodynamic and electrophysiological connectivity in the language system: Simultaneous near-infrared spectroscopy and electrocorticography recordings during cortical stimulation

We applied near-infrared spectroscopy (NIRS) and electrocorticography (ECoG) recordings during cortical stimulation to a temporal lobe epilepsy patient who underwent subdural electrode implantation. Using NIRS, changes in blood concentrations of oxyhemoglobin (HbO(2)) and deoxyhemoglobin (HbR) during cortical stimulation of the left language areas were measured in each hemisphere. NIRS revealed that 2Hz stimulation with 5mA produced no significant hemodynamic changes in either hemisphere. By contrast, 50Hz stimulation elicited significant increases in both HbO(2) and HbR at the stimulation site. Furthermore, with 50Hz stimulation of the left superior temporal gyrus, the increases in HbO(2) and HbR were observed not only at the stimulation site but also concurrently at the left inferior frontal gyrus. This suggests the existence of functional connectivity in the language system. The present study demonstrates that simultaneous NIRS and ECoG studies during cortical stimulation allow a novel analysis of cerebral connectivity.     

The effects of acute stress and perceptual load on distractor interference

Selective attention can be improved under conditions in which a high perceptual load is assumed to exhaust cognitive resources, leaving scarce resources for distractor processing. The present study examined whether perceptual load and acute stress share common attentional resources by manipulating perceptual and stress loads. Participants identified a target within an array of nontargets that were flanked by compatible or incompatible distractors. Attentional selectivity was measured by longer reaction times in response to the incompatible than to the compatible distractors. Participants in the stress group participated in a speech test that increased anxiety and threatened self-esteem. The effect of perceptual load interacted with the stress manipulation in that participants in the control group demonstrated an interference effect under the low perceptual load condition, whereas such interference disappeared under the high perceptual load condition. Importantly, the stress group showed virtually no interference under the low perceptual load condition, whereas substantial interference occurred under the high perceptual load condition. These results suggest that perceptual and stress related demands consume the same attentional resources.     

Effects of temporal shapes of sound markers on the perception of interonset time intervals

This study investigated how the temporal characteristics, particularly durations, of sounds affect the perceived duration of very short interonset time intervals (120-360?ms), which is important for rhythm perception in speech and music. In four experiments, the subjective duration of single time intervals marked by two sounds was measured utilizing the method of adjustment, while the markers' durations, amplitude difference (which accompanied the duration change), and sound energy distribution in time were varied. Lengthening the duration of the second marker in the range of 20-100?ms increased the subjective duration of the time interval in a stable manner. Lengthening the first marker tended to increase the subjective duration, but unstably; an opposite effect sometimes appeared for the shortest time interval of 120?ms. The effects of varying the amplitude and the sound energy distribution in time of either marker were very small in the present experimental conditions, thus proving the effects of marker durations per se.     

BRIEF REPORT The dynamic aspects of emotional facial expressions

In this study, we presented computer‐morphing animations of the facial expressions of six emotions to 43 subjects and asked them to evaluate the naturalness of the rate of change of each expression. The results showed that the naturalness of the expressions depended on the velocity of change, and the patterns for the four velocities differed with the emotions. Principal component analysis of the data extracted the structures that underlie the evaluation of dynamic facial expressions, which differed from previously reported structures for static expressions in some aspects. These results suggest that the representations of facial expressions include not only static but also dynamic properties.     

Reduction of contextual control of conditioned responses by extended Pavlovian training in an insect

The effect of repetitive training on learned behavior has been an important subject in neuroscience. In instrumental conditioning in mammals, learned action early in training is often goal-driven and controlled by outcome expectancy, but as training progresses, it becomes more habitual and insensitive to outcome devaluation. Similarly, we recently showed in Pavlovian conditioning in crickets (Gryllus bimaculatus) that a conditioned response (CR) is initially sensitive to devaluation of the unconditioned stimulus but becomes insensitive to it after extended training. It is known that habitual responses after extended instrumental training are characterized by a higher context specificity than are initial goal-directed actions in mammals. In this study, we investigated whether this is applicable to Pavlovian conditioning in crickets. In crickets that received a standard amount of training to associate an odor with water reward under illumination, CR under illumination was stronger than that in the dark. In crickets that received extended training under illumination, on the other hand, the level of CR did not differ in different light conditions. Further experiments confirmed that context specificity decreases with the development of behavioral automaticity by extended training, as opposed to findings in instrumental training in mammals. We conclude that the nature of habitual behaviors after extended training differs in different learning systems of animals.

In humans, habitual behavior often underlies dysfunctional behaviors such as drug addiction (Everitt et al. 2001) and obsessive-compulsive disorder (Gillan et al. 2011). It is for this reason that much research conducted on behavioral neuroscience and psychology has aimed to understand the effects of repetitive training on the performance of learned actions or, in other words, the development of habits (Gardner 2015; Wood and Rünger 2016). One of the most common findings in instrumental conditioning in mammals is that actions in an early stage of training are more goal-driven; i.e., they are controlled by the specific outcome (reinforcer) of their actions. However, as training proceeds, behaviors often become more automatic and independent of the actual value of the outcome, although both the goal-driven and habitual behavioral components often coexist in both early and later stages of training (Dickinson 1985; Yin and Knowlton 2006; Kosaki and Dickenson 2010; Smith and Graybiel 2014). Goal-directed actions and habitual behavior can be distinguished by using an outcome devaluation procedure in which the value of the outcome (reward) is reduced by aversive conditioning (Adams 1982; Dickinson 1985) or by outcome-specific satiation (Balleine and Dickinson 1998).We have investigated associative processes underlying Pavlovian conditioning and its possible neural substrates in the cricket Gryllus bimaculatus (Unoki et al. 2005; Mizunami et al. 2009; Mizunami and Matsumoto 2017; Mizunami et al. 2018), and we recently found that the conditioned response (CR) to an odor (conditioned stimulus, CS) diminishes when the value of water reward (unconditioned stimulus [US]) is reduced after satiation early in training but that it becomes insensitive to US devaluation after extended training in crickets (Mizunami et al. 2019). To our knowledge, these results provide the first evidence of increased automaticity of learned behavior by extended Pavlovian training in any animals. Crickets that received four-trial training to associate an odor CS with water US, which we refer to as standard training, exhibited no CR after water had been given until satiation before the test. On the other hand, crickets that received extended training (i.e., four conditioning trials per day on three consecutive days) exhibited the same level of CR regardless of whether they had been provided with water until satiation or not before the test.Notably, in instrumental conditioning in mammals, it has been documented that habitual behavior that is insensitive to outcome devaluation has features that are distinct from those of goal-directed behavior typically seen after limited training. The most notable one is its higher context specificity: Habitual responses are more likely to occur in the context in which training occurred than outside that context (in rats) (Thrailkill and Bouton 2015). Similarly, in humans, such context specificity is considered a hallmark of the habitual behavior formed by repetition of the same learned responses and it is considered a critical feature to which special attention must be paid in the therapy of mal-adaptive habits (Tricomi et al. 2009; Gardner 2015; Wood and Rünger 2016).The aim of this study was to determine whether the same context specificity that is observed in the habitual response after extended training in mammals is applicable to Pavlovian conditioning in insects. To do so, we performed standard or extended training for crickets under illumination, and their CRs were tested under illumination or in the dark. We used light and darkness as contexts since we observed that a change of background light level between training and testing influences the level of CRs in one paradigm of Pavlovian conditioning in crickets (Matsumoto and Mizunami 2004).     

Is Segmental Trunk Control Related to Gross Motor Performance in Healthy Preterm and Full-Term Infants?

Abstract

The authors’ aim was to verify the correlation between segmental trunk control and gross motor performance in healthy preterm (PT) and full-term (FT) infants aged 6 and 7?months and to verify if there are differences between groups. All infants were assessed at 6 and 7?months by means of Segmental Assessment of Trunk Control (SATCo) to identify the exact level of segmental trunk control and Alberta Infant Motor Scale (AIMS) to measure gross motor performance. A significant correlation between segmental trunk control and gross motor performance was found in healthy PT infants at 7?months and FT infants at 6?months. PT infants showed a delay on segmental trunk control at 6 and 7?months and in supported standing posture at 6?months compared with FT infants. Segmental trunk control and gross motor performance showed an important relationship in healthy PT and FT infants, mainly in sitting posture.