TRANSPLANT OF POLYMER-ENCAPSULATED CELLS GENETICALLY-ENGINEERED TO RELEASE NERVE GROWTH-FACTOR ALLOWS A NORMAL FUNCTIONAL-DEVELOPMENT OF THE VISUAL-CORTEX IN DARK-REARED RATS

Visual experience is necessary for the normal development of the visua l system. Dark-reared mammals show abnormal vision when reintroduced i nto a normal environment.(20,25) The absence of visual experience duri ng the critical period results in reduced and/or inappropriate neural responses in visual cortical neurons.(4,13) The change in electrical a ctivity induced by dark rearing is probably reflected by the modulatio n of specific unknown molecules. Neurotrophins are present in the deve loping visual cortex and their production depends on visually driven e lectrical activity.(7,9) Recent findings support the possibility that an important link between electrical activity in the visual pathway an d correct development of visual properties is represented by neurotrop hins.(5,8,10,11,15,16,18,23) We advance the hypothesis that the visual abnormalities present in dark-reared animals could be due to a decrea sed production of a neurotrophin secondary to the lack of visual stimu lation. We report that some properties of,visual cortical response suc h as receptive field size, orientation selectivity, adaptation to repe ated stimulation, response latency and visual acuity are virtually nor mal in dark-reared rats transplanted with polymer-encapsulated baby ha mster kidney cells genetically engineered to release nerve growth fact or. (C) 1997 IBRO. Published by Elsevier Science Ltd.