title: Sensitivity to timing and order in human visual cortex.
abstract: Visual recognition takes a small fraction of a second and relies on the cascade of signals along the ventral visual stream. Given the rapid path through multiple processing steps between photoreceptors and higher visual areas, information must progress from stage to stage very quickly. This rapid progression of information suggests that fine temporal details of the neural response may be important to the brain's encoding of visual signals. We investigated how changes in the relative timing of incoming visual stimulation affect the representation of object information by recording intracranial field potentials along the human ventral visual stream while subjects recognized objects whose parts were presented with varying asynchrony. Visual responses along the ventral stream were sensitive to timing differences as small as 17 ms between parts. In particular, there was a strong dependency on the temporal order of stimulus presentation, even at short asynchronies. From these observations we infer that the neural representation of complex information in visual cortex can be modulated by rapid dynamics on scales of tens of milliseconds.
authors.affiliation: Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts;
authors.forename: Jedediah M
authors.initials: JM
authors.lastname: Singer
authors.affiliation: Department of Neurosurgery, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts;
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Madsen
authors.affiliation: Department of Neurosurgery, Johns Hopkins Hospital, Johns Hopkins University School of Medicine, Baltimore, Maryland;
authors.forename: William S
authors.initials: WS
authors.lastname: Anderson
authors.affiliation: Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts; Center for Brain Science, Harvard University, Cambridge, Massachusetts; and Swartz Center for Theoretical Neuroscience, Harvard University, Cambridge, Massachusetts gabriel.kreiman@tch.harvard.edu.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Kreiman
mesh_terms: D005074:Evoked Potentials, Visual; D005260:Female; D006801:Humans; D008297:Male; D010364:Pattern Recognition, Visual; D011930:Reaction Time; D014793:Visual Cortex / Q000502:physiology*
keywords: computational models; electrocorticography; human neurophysiology; intracranial field potentials; temporal coding; ventral visual cortex; visual object recognition