Pervasive developmental disorders (PDDs) are defined as neurodevelopmental disorders with impairments in social interaction and communication, as well as restricted repertory of activities and interests. PDDs have various subcategories, but they are all placed on the same spectrum of the disorder. The diagnosis is now applied to less severe forms of PDDs, and especially in these cases, the validity of PDD diagnosis has come to be questioned. In this article, the main focus is on the diagnostic concept of impairment in joint attention. Experimental data suggests that a functional deficit of amygdala-limbic network is involved in the process of joint attention, and the deficit is also strongly related to the severity of PDD symptoms.

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Pervasive Developmental Disorders (PDD) including autism spectrum disorders (ASD) are neurodevelopemntal disorders characterized by delays in the development of multiple basic functions including socialization, communication and repetitive behaviors. Twin and family studies have demonstrated that ASD is highly heritable neurodevelopmental disorders. There are several genetic methods to find the genes for ASD, such as ASD-related genetic syndrome, linkage study, association study, chromosomal abnormality, copy number variation, gene expression study and intermediate phenotype study. Recent advances in the genetics of ASD emphasize its etiological heterogeneity, with each genetic susceptibility locus accounting for only a small fraction of cases or having a small effect. More recently, several causal genes for ASD such as NLGN3/4, SHANK3, NRXN1, etc., has been identified by the application of achievement of recent scientific technology in genetics to ASD genetics. NRXN-NLGN-SHANK pathway is associated with synaptogenesis and imbalance between excitatory and inhibitory currents. Therefore, abnormal synaptic homeostasis is strongly suggested as a risk factor to ASD.

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Many reports suggest the existence of biological background to developmental disabilities. We reported the physiological research, especially electroencephalogram, auditory brainstem response, event-related potentials. But we must consider the influence of mental retardation about the results of past research findings. And we have to think hard about these subjects according to characteristics of developmental disabilities in the research of event-related potentials.

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The brain imaging technology has been advancing at the astonishing rate. With these imaging technologies, region of dysfunction in various psychiatric disorders are the subject of current research, and the Autism spectrum disorder (ASD) is one of them. The morphological brain study and the functional brain study of ASD have been discussed. The morphology of Cerebellum and Cerebral hemisphere of ASD has been studied extensively over the last decade. We discussed the regional volumetric anomaly, the developmental brain hyperplasia, and the decreased regional white matter connectivity. We also discussed the functional brain studies using the tasks such as “theory of mind” “face expression recognized task” “emotion processing task”. We then discussed the possible explanation of how these brain functional impairments are related to the certain autistic symptoms.

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Neurocognitive and psychophysiological studies on pervasive developmental disorder(PDD), which includes autistic disorder and Asperger’s disorder, were reviewed and summarized. Studies using ERP and autonomic measures generally reported abnormalities of vigilance and attention in PDD. Behavioral studies on joint attention indicated impaired social attention. Results of neuroimaging studies on social processing suggested hypofunction of amygdala and face-related areas such as superior temporal sulcus and fusiform face area. There are some studies that reported hypoactivation of mirror neuron in the frontal lobe and orbitofrontal cortex in response to social stimuli. Thus results of these studies seem to suggest hypo- or atypical functioning of brainstem and limbic subcortical areas and neocortices related to social processing.

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Recent new technologies for human molecular genetics such as the genome-wide human SNP array, array-compar-ative genomic hybridization, and high-throughput sequencing, revealed that neural cell adhesion molecules widely implicate the pathophysiology of various neuropsychiatric disorders. Neurexins/Neuroligins were especially discov-ered as one of the susceptibility genes for autism, schizophrenia, and addiction. NrCAM was also explored involving in the pathophysiology of addiction. In this review, recent advances in the genetics of neuropsychiatric disorders and our achievement related to the neural cell adhesion molecules were outlined.

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We have been running the Mental Disease Postmortem Brain Bank for Psychiatric Research since its inception in 1997. In this paper, we introduce the systems employed at Fukushima Brain Bank and our results and report several issues that we have faced while managing the Brain Bank, including financial issues, insufficient staff, the need for more cooperation among clinicians and basic researchers, and the desire to establish a nationwide Brain Bank Network.

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About 150years ago, Dr. Griesinger has proposed that mental illness is a brain disease(“Geisteskrankheiten sind Gehirnkrankheiten”). This famous thesis would lead that the pathogenesis of psychiatric disease had been investigated eagerly as “brain pathology” from point of neuropsychiatry coordinating the neurology and the psychiatry centered in Germany. It has been confronted with the difficulty to clarify the etiology of so called endogenous psychosis from the clinico-neuropathological approach. In this decade, the technique progression of neuroimaging has revealed the changing of brain morphology or molecular biological approach has discovered some candidate gene in these endogenous psychoses. Nowadays, the convergence from many approaches of investigating the pathogenesis of mental illness might be interpretable of the clinical phenomena based on the observation of brain organ or/and tissue.

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The most practical solution to ethical and legal challenges for achieving brain banking is to make independent guidelines among the scientific community. It is not only the best way to get effective guidelines but also to improve public trust. To provide the basis for the development of guidelines, I explore the issues on the samples taken from cadavers and their research use from the legal point of view.

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First, clinical characteristics of pervasive developmental disorder (PDD) were summarized, with a focus on impairment in social interaction, obsessive traits, and a liability to fall into a panic. Differences between subtypes of PDD as well as comorbidity were also explained. Then the conventional idea of criminal liability and how psychiatric factors are related to the idea were reviewed, which indicates that the core impairments of PDD were not regarded as factors that affect the judgment on the criminal liability. Detailed analyses on the behaviors of criminals with PDD, however, seem to provide evidence that they were not completely criminally liable. Possible relationships between the criminal liability and the neural background of PDD were discussed.

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The concept of criminal responsibility was almost established one hundred years ago in Japan. But it was mainly conceived as the legal concept not as the medical one. Recently a lot of information about the frontal lobe function has been utilized in accordance with the development of the brain functional image or the neuropsychological assessment. Although these methods are still under developing, they give us a lot of useful information about the human behaviors including the criminal conducts. In this current situation of psychiatry, the criminal responsibility should be judged by these methods. This paper presents two cases of psychiatric testimonies.

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