title: Correlated neural activity as the driving force for functional changes in auditory cortex.
abstract: The functional role of neural synchrony is reflected in cortical tonotopic map reorganization and in the emergence of pathological phenomena such as tinnitus. First of all experimenter-centered and subject-centered views of neural activity will be contrasted; this argues against the use of stimulus-correction procedures and favors the use of a correction procedure based on neural activity without reference to stimulus timing. Within a cortical column neurons fired synchronously with on average about 6% of their spikes in a 1 ms bin and occasionally showing 30% or more of such coincident spikes. For electrode separations exceeding 200 microm the average peak correlation strength only occasionally reached 3%. The experimental evidence for coincidence of neural activity, neural correlation and neural synchrony shows that horizontal fibers activity can induce strong neural correlations. Cortico-cortical connections for a large part connect cell groups with characteristic frequencies differing by more than one octave. Such neurons have generally non-overlapping receptive fields but still can have sizeable peak cross-correlations. Correlated neural activity and heterotopic neural interconnections are presented as the substrates for cortical reorganization; increased neural synchrony and tonotopic map reorganization go hand in hand. This links cortical reorganization with hypersynchrony that can be considered as an important driving force underlying tinnitus.
authors.affiliation: Department of Physiology and Biophysics, University of Calgary, Calgary, Alberta, Canada. eggermon@ucalgary.ca
authors.forename: Jos J
authors.initials: JJ
authors.lastname: Eggermont
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D001303:Auditory Cortex / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology; D001931:Brain Mapping; D002415:Cats; D003056:Cochlear Nerve / Q000502:physiology; D004827:Epilepsy / Q000503:physiopathology / Q000523:psychology; D005072:Evoked Potentials, Auditory; D006801:Humans; D008959:Models, Neurological; D014012:Tinnitus / Q000503:physiopathology / Q000523:psychology