The caudal part of the posterior insula of rats participates in the maintenance but not the acquisition of morphine conditioned place preference.

The heterogeneous insular cortex plays an interoceptive role in drug addiction by signaling the availability of drugs of abuse. Here, we tested whether the caudal part of the multisensory posterior insula (PI) stores somatosensory-associated rewarding memories. Using Sprague Dawley rats as subjects, we first established a morphine-induced conditioned place preference (CPP) paradigm, mainly based on somatic cues. Secondly, an electrolytic lesion of the caudal portion of the PI was carried out before and after the establishment of CPP, respectively. Our data demonstrated that the caudal PI lesions disrupted the maintenance, but not the acquisition of morphine-induced CPP. Lesion or subtle disruption of the PI had no major impact on locomotor activity. These findings indicate that the caudal portion of the PI might be involved in either the storage or the retrieval of morphine CPP memory.

Prolonged secretion of cortisol as a possible mechanism underlying stress and depressive behaviour.

Stress is associated with the onset of depressive episodes, and cortisol hypersecretion is considered a biological risk factor of depression. However, the possible mechanisms underlying stress, cortisol and depressive behaviours are inconsistent in the literature. This study examined the interrelationships among stress, cortisol and observed depressive behaviours in female rhesus macaques for the first time and explored the possible mechanism underlying stress and depressive behaviour. Female monkeys were video-recorded, and the frequencies of life events and the duration of huddling were analysed to measure stress and depressive behaviour. Hair samples were used to measure chronic cortisol levels, and the interactions between stress and cortisol in the development of depressive behaviour were further evaluated. Significant correlations were found between stress and depressive behaviour measures and between cortisol levels and depressive behaviour. Stress was positively correlated with cortisol levels, and these two factors interacted with each other to predict the monkeys' depressive behaviours. This finding extends the current understanding of stress/cortisol interactions in depression, especially pertaining to females.

Neurons Differentiated from Transplanted Stem Cells Respond Functionally to Acoustic Stimuli in the Awake Monkey Brain.

Here, we examine whether neurons differentiated from transplanted stem cells can integrate into the host neural network and function in awake animals, a goal of transplanted stem cell therapy in the brain. We have developed a technique in which a small "hole" is created in the inferior colliculus (IC) of rhesus monkeys, then stem cells are transplanted in situ to allow for investigation of their integration into the auditory neural network. We found that some transplanted cells differentiated into mature neurons and formed synaptic input/output connections with the host neurons. In addition, c-Fos expression increased significantly in the cells after acoustic stimulation, and multichannel recordings indicated IC specific tuning activities in response to auditory stimulation. These results suggest that the transplanted cells have the potential to functionally integrate into the host neural network.

Face recognition increases during saccade preparation.

Face perception is integral to human perception system as it underlies social interactions. Saccadic eye movements are frequently made to bring interesting visual information, such as faces, onto the fovea for detailed processing. Just before eye movement onset, the processing of some basic features, such as the orientation, of an object improves at the saccade landing point. Interestingly, there is also evidence that indicates faces are processed in early visual processing stages similar to basic features. However, it is not known whether this early enhancement of processing includes face recognition. In this study, three experiments were performed to map the timing of face presentation to the beginning of the eye movement in order to evaluate pre-saccadic face recognition. Faces were found to be similarly processed as simple objects immediately prior to saccadic movements. Starting ∼ 120 ms before a saccade to a target face, independent of whether or not the face was surrounded by other faces, the face recognition gradually improved and the critical spacing of the crowding decreased as saccade onset was approaching. These results suggest that an upcoming saccade prepares the visual system for new information about faces at the saccade landing site and may reduce the background in a crowd to target the intended face. This indicates an important role of pre-saccadic eye movement signals in human face recognition.

A natural model of behavioral depression in postpartum adult female cynomolgus monkeys (Macaca fascicularis).

Postpartum depression (PPD) is a modified form of major depressive disorders (MDD) that can exert profound negative effects on both mothers and infants than MDD. Within the postpartum period, both mothers and infants are susceptible; but because PPD typically occurs for short durations and has moderate symptoms, there exists challenges in exploring and addressing the underlying cause of the depression. This fact highlights the need for relevant animal models. In the present study, postpartum adult female cynomolgus monkeys (Macaca fascicularis) living in breeding groups were observed for typical depressive behavior. The huddle posture behavior was utilized as an indicator of behavioral depression postpartum (BDP) as it has been established as the core depressive-like behavior in primates. Monkeys were divided into two groups: A BDP group (n=6), which were found to spend more time huddling over the first two weeks postpartum than other individuals that formed a non-depression control group (n=4). The two groups were then further analyzed for locomotive activity, stressful events, hair cortisol levels and for maternal interactive behaviors. No differences were found between the BDP and control groups in locomotive activity, in the frequencies of stressful events experienced and in hair cortisol levels. These findings suggested that the postpartum depression witnessed in the monkeys was not related to external factors other than puerperium period. Interestingly, the BDP monkeys displayed an abnormal maternal relationship consisting of increased infant grooming. Taken together, these findings suggest that the adult female cynomolgus monkeys provide a natural model of behavioral postpartum depression that holds a number of advantages over commonly used rodent systems in PPD modeling. The cynomolgus monkeys have a highly-organized social hierarchy and reproductive characteristics without seasonal restriction-similar to humans-as well as much greater homology to humans than rodents. As such, this model may provide a greater translational efficiency and research platform for systematically investigating the etiology, treatment, prevention of PPD.

Social rank and cortisol among female rhesus macaques (Macaca mulatta).

In animal societies, some stressful events can lead to higher levels of physiological stress. Such stressors, like social rank, also predict an increased vulnerability to an array of diseases. However, the physiological relationship between social rank and stress varies between different species, as well as within groups of a single species. For example, dominant individuals are more socially stressed at times, while at other times it is the subordinate ones who experience this stress. Together, these variations make it difficult to assess disease vulnerability as connected to social interactions. In order to learn more about how physiological rank relationships vary between groups of a single species, cortisol measurements from hair samples were used to evaluate the effects of dominance rank on long-term stress levels in despotic and less stringent female rhesus macaque hierarchal groups. In despotic groups, cortisol levels were found not to be correlated with social rank, but a negative correlation was found between social rank and cortisol levels in less stringent hierarchies. Low ranking monkeys in less stringent groups secreted elevated levels of cortisol compared to higher ranking animals. These data suggest that variations in the strictness of the dominance hierarchy are determining factors in rank related stress physiology. The further consideration of nonhuman primate social system diversity and the linear degree of their hierarchies may allow for the development of valid rank-related stress models that will help increase our understanding and guide the development of new therapeutics for diseases related to human socioeconomic status.

What interests them in the pictures?--differences in eye-tracking between rhesus monkeys and humans.

Studies estimating eye movements have demonstrated that non-human primates have fixation patterns similar to humans at the first sight of a picture. In the current study, three sets of pictures containing monkeys, humans or both were presented to rhesus monkeys and humans. The eye movements on these pictures by the two species were recorded using a Tobii eye-tracking system. We found that monkeys paid more attention to the head and body in pictures containing monkeys, whereas both monkeys and humans paid more attention to the head in pictures containing humans. The humans always concentrated on the eyes and head in all the pictures, indicating the social role of facial cues in society. Although humans paid more attention to the hands than monkeys, both monkeys and humans were interested in the hands and what was being done with them in the pictures. This may suggest the importance and necessity of hands for survival. Finally, monkeys scored lower in eye-tracking when fixating on the pictures, as if they were less interested in looking at the screen than humans. The locations of fixation in monkeys may provide insight into the role of eye movements in an evolutionary context.

[Glaucoma model for stem cell transplantation research in New Zealand white rabbits].

Glaucoma is a typical irreversible blind neurodegenerative disease for which there is no effective treatment for halting visual deterioration. The recent development of neural stem cells studies sheds light on a potential resolution for this disease. As a result, an appropriate glaucoma modeling method for stem cell transplantation study is needed. In the present study, Dexamethasone was injected unilaterally into the conjunctiva of New Zealand rabbit at the dose of 2.5 mg (5 mg/mL), three times a week. After eight weeks, the eye ground photography showed that the optic nerve head of the treated eye was expanded, and the blood vessel was geniculate compared to the control eye, while the ocular media remained transparent. The hematoxylin-eosin (HE) stain of the retinal nerve fiber layer (RNFL) sections showed optic neuron death in the treated eye. The Heidelberg Retina Tomography (HRT) results showed optic disk morphological changes consistent with the pathophysiology of glaucoma in the treated eye, including a decrease in the rim area (1.10±0.88) mm(2) and mean RNFL thickness (0.44±0.31) mm, and an increase in the cup/disk ratio 0.17±0.13. Then neural stem cells were injected into the vitreous body of the treated eye. After five months, surviving transplanted cells were observed. These results suggest a simple and reproducible chronic glaucoma model, which is appropriate for neural stem cell transplant research, has been successfully developed.

[Effects of propranolol on acquisition and retrieval of morphine- induced conditioned place preference memories in ICR mice].

To interfere with the drug-cue memory processes of addicts such as reconsolidation by the administration of the ß-adrenergic receptor (ß-AR) of norepinephrine (NE) antagonist propranolol (PRO) has become a potential therapy in the future to decrease or inhibit relapse. However, the relationship between PRO and the acquisition or retrieval of morphine-cue memory is not clear. This study examined the effects of PRO on the acquisition and retrieval of memories in morphine-induced conditioned place preference (CPP) mice model. We found that during memory acquisition period, PRO had no effects on the expression and extinction of morphine-CPP, which suggests that the ß-AR was irrelevant to the CPP memory acquisition. However, during memory retrieval period, although PRO did not affect the expression of CPP, but it delayed the occurrence of CPP extinction, which indicates that PRO has an inhibit effect on CPP memory extinction, and ß-AR plays an important role in modulating the extinction of morphine-CPP. Our study further improved the relationship between drug addiction and ß-AR, and proposed a new theory to help developing potential therapy to cure addiction and other neuropsychiatric disorders.

[A traumatic brain injury model for distinguishing between transplanted neural cells and host cells in vivo].

To perform electrophysiological recording and other investigations on transplanted neural cells in vivo, we used mechanical damage to establish a special traumatic brain injury model that could distinguish transplanted cells from host cells. The morphology of the trauma-induced holes in the cortex of the rat brain was regular. The model was stable and repeatable. Neural stem cells were transplanted into the trauma-induced hole, and were able to survive for a long time. Most of the transplanted cells differentiated into neurons, and only a small amount turned into glia cells. There was a clear boundary between the host cells and the transplanted cells. Single cell electrophysiological recording on transplanted neural cells were detected in vivo. This study established a stable and repeatable traumatic brain injury model, which could be used to conduct in vivo electrophysiological recording research on transplanted neural cells.