Abstract

After reviewing the concept of the specific and non specific thalamo-cortical systems, the connectivity of the relay and intralaminar nuclei is analyzed as well as the recent data concerning the chemical identity of thalamic neurones, the concept and distribution of "matrix" and "core" neurones and its functional role. The intrinsic electrical properties of thalamic neurones, its mode of discharge--depending of the membrane potential level--and its functional significance in the context of the brain's global activity are discussed. Of special interest are the studies on the effects of lesion of the relay and intralaminar nuclei as well as its repercussion in the interpretation of the sensory perception. After intralaminar nuclei lesion the individual is not aware of the nformation conveyed through the specific channels. It follows a discussion on the importance of the temporal and spatial mapping in the elaboration of perception and cognition. Due to the intrinsic electrical properties and the connectivity of thalamic neurones two groups of corticothalamic loops are generated, which resonate at a frequency of 40 Hz. The specific thalamo-cortical loops give the content of cognition and the no specific loop, the temporal binding required for the unity of the cognitive experience. Consciousness is then, a product of the resonant thalamo-cortical activity, and the dialogue between the thalamus and cortex, the process that generates subjectivity, the unique experience we all recognized as the existence of the "self".