Decision-making deficit of a patient with axonal damage after traumatic brain injury

Patients with traumatic brain injury (TBI) were reported to have difficulty making advantageous decisions, but the underlying deficits of the network of brain areas involved in this process were not directly examined. We report a patient with TBI who demonstrated problematic behavior in situations of risk and complexity after cerebral injury from a traffic accident. The Iowa gambling task (IGT) was used to reveal his deficits in the decision-making process. To examine underlying deficits of the network of brain areas, we examined T1-weighted structural MRI, diffusion tensor imaging (DTI) and Tc-ECD SPECT in this patient. The patient showed abnormality in IGT. DTI-MRI results showed a significant decrease in fractional anisotropy (FA) in the fasciculus between the brain stem and cortical regions via the thalamus. He showed significant decrease in gray matter volumes in the bilateral insular cortex, hypothalamus, and posterior cingulate cortex, possibly reflecting Wallerian degeneration secondary to the fasciculus abnormalities. SPECT showed significant blood flow decrease in the broad cortical areas including the ventromedial prefrontal cortex (VM). Our study showed that the patient had dysfunctional decision-making process. Microstructural abnormality in the fasciculus, likely from the traffic accident, caused reduced afferent feedback to the brain, resulting in less efficient decision-making. Our findings support the somatic-marker hypothesis (SMH), where somatic feedback to the brain influences the decision-making process.     

How can reward contribute to efficient self-control? Reinforcement of task-defined responses diminishes ego-depletion

We examined whether reinforcement learning of habitual actions diminishes ego depletion after a cognitive control task. Participants performed the Stroop task after a card selection task, in which one group was reinforced to respond to colors in the Stroop task (Stroop-color group) while another group was reinforced to respond to colors not in the Stroop task (non-Stroop-color group). We measured ego depletion in terms of decrement in endurance on an isometric handgrip task after the Stroop task. The Stroop-color group exhibited less decrease in their isometric handgrip endurance compared to the non-Stroop-color group. These results suggest that the former needed less effort for cognitive control during conflict processing, as reinforcement learning make task-defined response habitual. This finding provides a new perspective on the role of reward in cognitive control.     

Reexamination of mood-mediation hypothesis of background-music-dependent effects in free recall

The present study reexamined the mood-mediation hypothesis for explaining background-music-dependent effects in free recall. Experiments 1 and 2 respectively examined tempo- and tonality-dependent effects in free recall, which had been used as evidence for the mood-mediation hypothesis. In Experiments 1 and 2, undergraduates (n?=?75 per experiment) incidentally learned a list of 20 unrelated words presented one by one at a rate of 5 s per word and then received a 30-s delayed oral free-recall test. Throughout the study and test sessions, a piece of music was played. At the time of test, one third of the participants received the same piece of music with the same tempo or tonality as at study, one third heard a different piece with the same tempo or tonality, and one third heard a different piece with a different tempo or tonality. Note that the condition of the same piece with a different tempo or tonality was excluded. Furthermore, the number of sampled pieces of background music was increased compared with previous studies. The results showed neither tempo- nor tonality-dependent effects, but only a background-music-dependent effect. Experiment 3 (n?=?40) compared the effects of background music with a verbal association task and focal music (only listening to musical selections) on the participants’ moods. The results showed that both the music tempo and tonality influenced the corresponding mood dimensions (arousal and pleasantness). These results are taken as evidence against the mood-mediation hypothesis. Theoretical implications are discussed.     

Discrete cortical regions associated with the musical beauty of major and minor chords

Previous research has demonstrated that the degree of aesthetic pleasure a person experiences correlates with the activation of reward functions in the brain. However, it is unclear whether different affective qualities and the perceptions of beauty that they evoke correspond to specific areas of brain activation. Major and minor musical keys induce two types of affective qualities--bright/happy and dark/sad--that both evoke aesthetic pleasure. In the present study, we used positron emission tomography to demonstrate that the two musical keys (major and minor) activate distinct brain areas. Minor consonant chords perceived as beautiful strongly activated the right striatum, which has been assumed to play an important role in reward and emotion processing, whereas major consonant chords perceived as beautiful induced significant activity in the left middle temporal gyrus, which is believed to be related to coherent and orderly information processing. These results suggest that major and minor keys, both of which are perceived as beautiful, are processed differently in the brain.     

Time-shrinking: A discontinuity in the perception of auditory temporal patterns

Recent research at our laboratories in the field of human auditory time perception revealed that the duration of short empty time intervals (<～200 msec) is considerably underestimated if they are immediately preceded by shorter time intervals. Within a certain range, the amount of subjective time shrinking is a monotonous function of the preceding time interval: the shorter it is, the more it shrinks its successor. In the present study, the preceding interval was kept constant at 50 msec, and the following interval for which the duration had to be judged, varied from 40 to 280 msec. The results showed that at up to 100 msec, the perceived duration increased to a much lesser extent than did the objective duration. Beyond 120 msec, the perceived duration quickly increased and reached a veridical value at 160 msec. Such a sudden change of perceived duration in a temporal pattern in which the objective duration varies gradually indicates a typical example of categorical perception. We suggest that such a categorization of the time dimension might be a clue for processes of speech and music perception.     

Effects of Feeding on Conditioned Avoidance Responses in Rats

Possible effects of feeding on learning were studied by comparing learned avoidance rates among three groups of Wistar rats that were given a diet at 1 h (1-h pretest group) and 5 h (5-h pretest group) before and immediately after (post-test group) the conditioned avoidance test. Learned avoidance rates during eight test sessions were higher in the order of the 1-h pretest, post-test, and 5-h pretest groups. This suggests that both pre- and post-test (training) feeding facilitates acquisition of conditioned avoidance learning presumably based on neurohumoral processes influenced by available plasma glucose concentrations.     

Effects of Cerebroventricle Administration of Acidic Fibroblast Growth Factor on Conditioned Taste Aversion Learning in Rats

Wistar strain rats were given acidic fibroblast growth factor (aFGF) or denatured aFGF into their cerebroventricle before taste aversion conditioning for saccharin solution. Animals administrated with aFGF showed significantly lower aversion threshold for saccharin at the 1st day and preference ratios for saccharin vs distilled water at the 4th, 6th, and 7th day after the conditioning than those administered with denatured aFGF. These results suggests that aFGF in the cerebrospinal fluid facilitates acquisition of the conditioned taste aversion learning.     

"Robovie, you'll have to go into the closet now": children's social and moral relationships with a humanoid robot

Children will increasingly come of age with personified robots and potentially form social and even moral relationships with them. What will such relationships look like? To address this question, 90 children (9-, 12-, and 15-year-olds) initially interacted with a humanoid robot, Robovie, in 15-min sessions. Each session ended when an experimenter interrupted Robovie's turn at a game and, against Robovie's stated objections, put Robovie into a closet. Each child was then engaged in a 50-min structural-developmental interview. Results showed that during the interaction sessions, all of the children engaged in physical and verbal social behaviors with Robovie. The interview data showed that the majority of children believed that Robovie had mental states (e.g., was intelligent and had feelings) and was a social being (e.g., could be a friend, offer comfort, and be trusted with secrets). In terms of Robovie's moral standing, children believed that Robovie deserved fair treatment and should not be harmed psychologically but did not believe that Robovie was entitled to its own liberty (Robovie could be bought and sold) or civil rights (in terms of voting rights and deserving compensation for work performed). Developmentally, while more than half the 15-year-olds conceptualized Robovie as a mental, social, and partly moral other, they did so to a lesser degree than the 9- and 12-year-olds. Discussion focuses on how (a) children's social and moral relationships with future personified robots may well be substantial and meaningful and (b) personified robots of the future may emerge as a unique ontological category.