Persistent elevations of cerebrospinal fluid concentrations of corticotropin-releasing factor in adult nonhuman primates exposed to early-life stressors: implications for the pathophysiology of mood and anxiety disorders.

There is increasing evidence for an important role of adverse early experience on the development of major psychiatric disorders in adulthood. Corticotropin-releasing factor (CRF), an endogenous neuropeptide, is the primary physiological regulator of the mammalian stress response. Grown nonhuman primates who were exposed as infants to adverse early rearing conditions were studied to determine if long-term alterations of CRF neuronal systems had occurred following the early stressor. In comparison to monkeys reared by mothers foraging under predictable conditions, infant monkeys raised by mothers foraging under unpredictable conditions exhibited persistently elevated cerebrospinal fluid (CSF) concentrations of CRF. Because hyperactivity of CRF-releasing neurons has been implicated in the pathophysiology of certain human affective and anxiety disorders, the present finding provides a potential neurobiological mechanism by which early-life stressors may contribute to adult psychopathology.

Cerebral organization for language in deaf and hearing subjects: Biological constraints and effects of experience

Cerebral organization during sentence processing in English and in American Sign Language (ASL) was characterized by employing functional magnetic resonance imaging (fMRI) at 4 T. Effects of deafness, age of language acquisition, and bilingualism were assessed by comparing results from (i) normally hearing, monolingual, native speakers of English, (ii) congenitally, genetically deaf, native signers of ASL who learned English late and through the visual modality, and (iii) normally hearing bilinguals who were native signers of ASL and speakers of English. All groups, hearing and deaf, processing their native language, English or ASL, displayed strong and repeated activation within classical language areas of the left hemisphere. Deaf subjects reading English did not display activation in these regions. These results suggest that the early acquisition of a natural language is important in the expression of the strong bias for these areas to mediate language, independently of the form of the language. In addition, native signers, hearing and deaf, displayed extensive activation of homologous areas within the right hemisphere, indicating that the specific processing requirements of the language also in part determine the organization of the language systems of the brain.