Simple fall-off pattern of correlated neural activity in the developing lateral geniculate nucleus.

Activity-dependent models for cortical simple-cell receptive field development predict specific patterns of correlated neural activity within the visual pathway, such as a Mexican hat-shaped pattern of correlated activity in the lateral geniculate nucleus (LGN). However, such activity patterns have yet to be experimentally demonstrated. We performed multielectrode recordings in the LGN of immature awake ferrets and found simple fall-off-shaped, rather than Mexican hat-shaped, patterns of correlated activity. A weak surround in the LGN neuron's receptive field and the statistics of the input contributed to this pattern of correlated activity. Computer simulation of cortical receptive field development incorporating the experimentally observed activity patterns demonstrated that a simple-cell receptive field emerges when a newly devised 'split' constraint on synaptic growth is combined with Hebbian synaptic modification rules. Thus, given certain developmental constraints on synaptic plasticity, patterns of correlated activity within the LGN are compatible with Hebbian models of simple-cell receptive field development.