594 THE CEREBRAL CORTEX AND LIMBIC STRUCTURES - - - Cortical Neurons Are Coincidence Detectors Many cortical neurons react primarily when information about two events reaches them simultaneously, like cells in the visual cortex that respond poorly to signals from one eye only but vigorously to simultaneous signals from both eyes (binocular cells). Like a good detective who has a special eye for coincidences (events occurring simultaneously) and disregards numerous trivial bits of information, the cortical neurons respond preferentially to certain coincidences of stimuli that have a survival value. This characteristic property of cortical cells is probably built into the inborn wiring pattern ("hardware") of the brain,but it also needs proper use to be further developed and maintained (see The Parietal Lobe and the Development of the Ability to Integrate Somatosensory and Visual Information, later in this chapter). Glutamatergic thalamocortical fibers appear to act via AMP A receptors on cortical neurons but not via NMDA receptors (the latter being related to induction of LTP). The recurrent pyramidal cell collaterals, however, act also on NMDA receptors. There is experimental evidence that simultaneous activation of a cortical neuron from the thalamus (AMP A) and from other cortical neurons (NMDA) can induce LTP. In the monkey motor cortex LTP has been established during the learning of new motor skills. Thus, not only are the cortical neurons especially sensitive to coincident inputs, this may also be the cellular basis of associative learning in the cortex. - - -