Despite the existence of a core set of features and affected biological networks, autism spectrum disorders (ASDs) are genetically heterogeneous. While variants in hundreds of genes have been implicated as causal or risk-conferring for ASD, a large percentage of the heritability of ASDs remains unaccounted for. This suggests that a number of inherited causal or risk mutations linked to autism have gone undiagnosed.

Many of the social and cognitive behavioral impairments associated with autism spectrum disorders (ASDs) are likely caused by changes in early brain development that alter the formation of neural circuits, and in particular, the neural circuitry of the cerebral cortex. Because early brain development is completed long before the onset of any identifiable behavioral changes, most studies of the developmental origins of autism have focused on animal models of genetic syndromes or rare single-gene mutations that lead to ASD-like behaviors. It is not clear how these different syndromes may be related to one another, or how these distinct genetic changes can each lead to similar behavioral outcomes.

Atypical sensory processing is a proposed etiological factor underlying the development of behavioral deficits in autism spectrum disorder (ASD). In particular, hypo-responsiveness to sensory social stimuli reduces social orienting, thus limiting the number of opportunities in which social learning can occur. Indeed, poorer social communication skills in individuals with ASD are associated with hypo-responsiveness to multiple sensory modalities.

One of the most critical challenges in the identification of new medications to treat autism spectrum disorders (ASDs) is our limited understanding of the biological mechanisms underlying these disorders. In recent years, there have been considerable advances in the genetics of ASD, with a resulting rapidly accumulating pool of reliable ASD risk genes. Currently, we need systems that will allow us to progress from gene discovery to the illumination of relevant biological pathways and novel therapeutics.

Autism spectrum disorders (ASDs) are genetically heterogeneous, but whether they share a common neural-circuit-processing defect is unclear. One hypothesis is that the ratio of excitation to inhibition (the E/I ratio) in the brain's cerebral cortex is elevated in ASDs. Elevations in this ratio could cause hyperexcitability of neural circuits, leading to impaired information processing and hypersensitivity to sensory stimuli, features commonly seen in individuals with ASD.

Animal models play pivotal roles in understanding the relationship between behaviors and underlying brain circuits. One of the key features of autism is a deficit in social communication, including vocal communication. The primary animal models for autism research have been rodents because of the advantage of genetic manipulations. However, rodents lack certain social communication behaviors exhibited by primates, such as eye contact and high-level vocal communication. There is therefore a great need to develop new animal models, preferably nonhuman primate models, for autism research.

A core feature of autism is the expression of repetitive and ritualized behaviors characterized by profound invariability and inflexibility. Autism is also frequently comorbid with anxiety disorders. Despite intensive study, the mechanisms underlying the repetitive and ritualized behavior in autism and the high prevalence of comorbidity between autism and anxiety disorders remain largely unknown.

Dysregulation of the normal immune response appears to underlie the development of a wide variety of neurodegenerative diseases, including autism spectrum disorders (ASDs). Animal models of ASD have demonstrated that maternal infection or abnormal immune signaling contribute to the development of autism-like disorders. Together, these findings suggest that immune response genes play an important role in the generation of ASDs.

All cells, including neurons, possess mechanisms to coordinate protein synthesis with protein degradation to maintain amino acid and protein levels within the appropriate range. Even a subtle imbalance between these processes can disrupt normal neuronal morphology and functions.

The sense of touch allows us to navigate our physical world. The first step in tactile processing involves the activation of low-threshold mechanoreceptor neurons (LTMRs) with highly specialized endings in the skin. Social (affective) touch may be mediated by a unique class of slowly conducting C-fibers, the C-LTMRs.