Phylogeny and ontogeny of mental time

Humans have mental time in our mind, apart from physical time that is a part of system that governs the physical world, and memory is our key cognitive ability for recognizing the passage of time. Recent studies have suggested that the memory system of several nonhuman animals may have an incidental nature, which is also a feature of episodic memory. In addition, apes, which are phylogenetically close to humans, have an ability to remember a single past event. In the case of humans, preverbal infants under the age of two are able to retain long-term memory of a single event and apply it to predict a future event. Thus, nonhuman animals and preverbal human infants both have their own specific mental time travel abilities, and there is a phylogenetic and ontogenic basis of full-fledged mental time travel that can be found in human adults

Atypical gaze patterns in children and adults with autism spectrum disorders dissociated from developmental changes in gaze behaviour

Eye tracking has been used to investigate gaze behaviours in individuals with autism spectrum disorder (ASD). However, traditional analysis has yet to find behavioural characteristics shared by both children and adults with ASD. To distinguish core ASD gaze behaviours from those that change with development, we examined temporo-spatial gaze patterns in children and adults with and without ASD while they viewed video clips. We summarized the gaze patterns of 104 participants using multidimensional scaling so that participants with similar gaze patterns would cluster together in a two-dimensional plane. Control participants clustered in the centre, reflecting a standard gaze behaviour, whereas participants with ASD were distributed around the periphery. Moreover, children and adults were separated on the plane, thereby showing a clear effect of development on gaze behaviours. Post hoc frame-by-frame analyses revealed the following findings: (i) both ASD groups shifted their gaze away from a speaker earlier than the control groups; (ii) both ASD groups showed a particular preference for letters; and (iii) typical infants preferred to watch the mouth rather than the eyes during speech, a preference that reversed with development. These results highlight the importance of taking the effect of development into account when addressing gaze behaviours characteristic of ASD

Synchronization of spontaneous eyeblinks while viewing video stories

Blinks are generally suppressed during a task that requires visual attention and tend to occur immediately before or after the task when the timing of its onset and offset are explicitly given. During the viewing of video stories, blinks are expected to occur at explicit breaks such as scene changes. However, given that the scene length is unpredictable, there should also be appropriate timing for blinking within a scene to prevent temporal loss of critical visual information. Here, we show that spontaneous blinks were highly synchronized between and within subjects when they viewed the same short video stories, but were not explicitly tied to the scene breaks. Synchronized blinks occurred during scenes that required less attention such as at the conclusion of an action, during the absence of the main character, during a long shot and during repeated presentations of a similar scene. In contrast, blink synchronization was not observed when subjects viewed a background video or when they listened to a story read aloud. The results suggest that humans share a mechanism for controlling the timing of blinks that searches for an implicit timing that is appropriate to minimize the chance of losing critical information while viewing a stream of visual events

Patterns of outgrowth of regenerating axons through spinal cord lesion

We found that bone marrow stromal cells (BMSCs) do not survive for long enough to serve as a scaffold for regenerating axons after transplantation in the injured spinal cord of rats. However, axonal regeneration was facilitated, possibly by trophic factors secreted from transplanted BMSCs. Regenerating axons were not associated with astrocytes, but surrounded by Schwann cells (SCs), and embedded in collagen fibril matrices just as the axons of peripheral nerves. Experiments involving the transplantation of SCs themselves indicated that, besides exogenous SCs, intrinsic SCs infiltrated the lesion and formed myelin sheaths on regenerating axons in the same manner as described with BMSC transplantation. The transplantation of olfactory ensheathing cells (OECs) showed that OECs themselves enclosed regenerating axons in the same manner as SCs. No study has been carried out to address whether such Schwann-like cells were derived from transplanted OECs or intrinsic SCs. However, the possibility cannot be excluded that intrinsic SCs contributed to surround regenerating axons. Neural stem cells (NSCs) derived from iPS cells survived long-term, emanating numerous axons that extended over a long distance through the host spinal cord tissue. However, no myelination occurred on regenerating axons, and no behavioral improvement was observed. It would be difficult to manipulate iPS-derived NSCs to appropriately integrate them into the host spinal cord tissue. In this respect, iPS cells have crucial problems concerning whether they can be integrated appropriately into the host tissue. Muse cells (multilineage-differentiating stress-enduring cells) were separated as SSEA3-positive cells from BMSCs. Transplanted Muse cells survived long-term, but they were not as effective as non-Muse cells or BMSCs for the treatment of infarcted brains, suggesting that trophic factors from non-Muse cells and BMSCs are involved in those effects. These findings indicate that intrinsic SCs and trophic factors released from transplants may play important roles in nerve regeneration of the spinal cord. Differing from the generally believed pattern of regeneration, glial cells are not necessarily needed as the scaffolds for growing axons in the spinal cord

Choroid plexus -with special reference to neuroprotective function-

Choroid plexus (CT) produces the cerebrospinal fluid (CSF) that fills the ventricles and subarachnoidal space, and infiltrates the intercellular spaces of CNS parenchyma. CP transplantation enhances axonal outgrowth in the spinal cord lesion. Cultured choroid plexus epithelial cells (CPECs) secret neurotrophic factors into the medium. CP undergoes cytological changes in diseases such as Alzheimer and Huntingon\u27s disease. The ischemia-injured infraction due to middle cerebral artery occlusion is suppressed by transplantation of CPECs into the CSF in the rat. Allo- or xenotransplantation of encapsulated CP has been studied for the treatment of experimental Huntington\u27s disease. CP can be regarded as the neurotrophic center of the CNS, regulating and maintaining the normal brain function via CSF

Are the long-term survival, proliferation, and differentiation of transplanted cells desirable in clinical application for spinal cord injury?

Cell transplantation studies of spinal cord injury have a premise that the transplants should be integrated in the host spinal cord tissue, differentiate into neural cells, and re-establish neural circuits, leading to the improvement of locomotor functions. However, the long-term survival, extensive proliferation, and/or differentiation of transplanted cells are not necessarily desirable clinically, and may, on the contrary, cause serious problems regarding the safety of transplants. The excessive proliferation, migration, and/or differentiation of transplanted cells may deteriorate the histological as well as functional organization of the host spinal cord. The present communication will discuss the feasibility of using three kinds of cell as transplants, including bone marrow-derived cells (BMDCs), Schwann cells, and neural stem/progenitor cells (NSPCs). BMDCs enhance tissue recovery and locomotor improvements; however, they disappear within 2-3 weeks after transplantation from the host spinal cord. This indicates that BMDCs do not serve as scaffolds for the growth of regenerating axons, but promote "endogenous" regenerating capacities of the host spinal cord, probably by secreting some trophic factors. This short-term survival of transplants, although appearing to be a disadvantage, guarantees the safety of cell transplantation. The transplantation of BMDCs is now at the Phase I/II stage of clinical application. Schwann cells have been studied extensively as a transplant material for spinal cord injury. Schwann cells survive long-term, and moderately proliferate and/or migrate in the spinal cord. It can be said that Schwann cells become well integrated in the host spinal cord. Therefore, they are regarded as a safe transplant. NSPCs proliferate, migrate, and differentiate extensively after transplantation in the host spinal cord. It is impossible at present to manipulate or control the proliferation/migration/differentiation of NPSCs to make them properly integrate in the host spinal cord. NSPCs are not considered safe for clinical application. BMDCs and Schwann cells are clinically relevant, while NS/PCs are clinically irrelevant

Data from: Automatic facial mimicry in response to dynamic emotional stimuli in five-month-old infants

Human adults automatically mimic others' emotional expressions, which is believed to contribute to sharing emotions with others. Although this behaviour appears fundamental to social reciprocity, little is known about its developmental process. Therefore, we examined whether infants show automatic facial mimicry in response to others' emotional expressions. Facial electromyographic activity over the corrugator supercilii (brow) and zygomaticus major (cheek) of four- to five-month-old infants was measured while they viewed dynamic clips presenting audiovisual, visual and auditory emotions. The audiovisual bimodal emotion stimuli were a display of a laughing/crying facial expression with an emotionally congruent vocalization, whereas the visual/auditory unimodal emotion stimuli displayed those emotional faces/vocalizations paired with a neutral vocalization/face, respectively. Increased activation of the corrugator supercilii muscle in response to audiovisual cries and the zygomaticus major in response to audiovisual laughter were observed between 500 and 1000 ms after stimulus onset, which clearly suggests rapid facial mimicry. By contrast, both visual and auditory unimodal emotion stimuli did not activate the infants' corresponding muscles. These results revealed that automatic facial mimicry is present as early as five months of age, when multimodal emotional information is present

Supplementary Material from Automatic facial mimicry in response to dynamic emotional stimuli in five-month-old infants

Human adults automatically mimic others' emotional expressions, which is believed to contribute to sharing emotions with others. Although this behaviour appears fundamental to social reciprocity, little is known about its developmental process. Therefore, we examined whether infants show automatic facial mimicry in response to others' emotional expressions. Facial electromyographic activity over the corrugator supercilii (brow) and zygomaticus major (cheek) of four- to five-month-old infants was measured while they viewed dynamic clips presenting audiovisual, visual and auditory emotions. The audiovisual bimodal emotion stimuli were a display of a laughing/crying facial expression with an emotionally congruent vocalization, whereas the visual/auditory unimodal emotion stimuli displayed those emotional faces/vocalizations paired with a neutral vocalization/face, respectively. Increased activation of the corrugator supercilii muscle in response to audiovisual cries and the zygomaticus major in response to audiovisual laughter were observed between 500 and 1000 ms after stimulus onset, which clearly suggests rapid facial mimicry. By contrast, both visual and auditory unimodal emotion stimuli did not activate the infants' corresponding muscles. These results revealed that automatic facial mimicry is present as early as five months of age, when multimodal emotional information is present