Timing and laminar profile of eye-position effects on auditory responses in primate auditory cortex.
We examined effects of eye position on auditory cortical responses in macaques. Laminar current-source density (CSD) and multiunit activity (MUA) profiles were sampled with linear array multielectrodes. Eye position significantly modulated auditory-evoked CSD amplitude in 24/29 penetrations (83%), across A1 and belt regions; 4/24 cases also showed significant MUA AM. Eye-position effects occurred mainly in the supragranular laminae and lagged the co-located auditory response by, on average, 38 ms. Effects in A1 and belt regions were indistinguishable in amplitude, laminar profile, and latency. The timing and laminar profile of the eye-position effects suggest that they are not combined with auditory signals at a subcortical stage of the lemniscal auditory pathways and simply "fed-forward" into cortex. Rather, these effects may be conveyed to auditory cortex by feedback projections from parietal or frontal cortices, or alternatively, they may be conveyed by nonclassical feedforward projections through auditory koniocellular (calbindin positive) neurons.
Cognitive Neuroscience and Schizophrenia Program, Nathan Kline Institute for Psychiatric Research, Orangeburg, New York 10962, USA.
Kai-Ming G
KM
Fu
Ankoor S
AS
Shah
Monica N
MN
O'Connell
Tammy
T
McGinnis
Haftan
H
Eckholdt
Peter
P
Lakatos
John
J
Smiley
Charles E
CE
Schroeder
D000161:Acoustic Stimulation; D000818:Animals; D001303:Auditory Cortex / Q000502:physiology*; D004567:Electrodes, Implanted; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005403:Fixation, Ocular / Q000502:physiology*; D008253:Macaca mulatta; D008297:Male; D011930:Reaction Time / Q000502:physiology; D013017:Sound Localization / Q000502:physiology*; D013028:Space Perception / Q000502:physiology