Signal Timing Across the Macaque Visual System

Abstract

The onset latencies of single-unit responses evoked by flashing visual stimuli were measured in the parvocellular (P) and magnocellular (M) layers of the dorsal lateral geniculate nucleus (LGNd) and in cortical visual areas V1, V2, V3, V4, middle temporal area (MT), medial superior temporal area (MST), and in the frontal eye field (FEF) in individual anesthetized monkeys. Identical procedures were carried out to assess latencies in each area, often in the same monkey, thereby permitting direct comparisons of timing across areas. This study presents the visual flash-evoked latencies for cells in areas where such data are common (V1 and V2), and are therefore a good standard, and also in areas where such data are sparse (LGNd M and P layers, MT, V4) or entirely lacking (V3, MST, and FEF in anesthetized preparation). Visual-evoked onset latencies were, on average, 17 ms shorter in the LGNd M layers than in the LGNd P layers. Visual responses occurred in V1 before any other cortical area. The next wave of activation occurred concurrently in areas V3, MT, MST, and FEF. Visual response latencies in areas V2 and V4 were progressively later and more broadly distributed. These differences in the time course of activation across the dorsal and ventral streams provide important temporal constraints on theories of visual processing.

Integration of EEG source imaging and fMRI during continuous viewing of natural movies

“…Thirdly, crosscorrelation analysis revealed that the mean response latency in Area 17 was slightly earlier than that observed in Area 18 and significantly earlier than responses in Area 19 (Pb.01). This trend is consistent with a recent study where visual stimuli were presented to subjects (selected for clinical purposes) with subdural electrodes implanted over different regions of the visual cortex [36], as well as with signal arrival times recorded across distinct visual regions in nonhuman primates [37]. Taken together, these EEG source imaging results indicate that the artifact-correction methodology correctly identified and removed unwanted nonneural components of the EEG signal while preserving those containing information which reflected the movie stimulus.…”

From affective blindsight to emotional consciousness

“…For comparison, consider that the average response latency in macaques' V1 ranges from 60 to 80 ms and the response to face stimuli occur around 100-150 ms post stimulus onset (Lamme & Roelfsema, 2000;Schmolesky et al, 1998). According to the authors, superior colliculus neurons filter face-like patterns with short latency to enable rapid processing of coarse facial information, while stimulus categorization develops in later processing phases through feedback from upstream areas.…”

Spikes, synchrony, and attentive learning by laminar thalamocortical circuits

“…Axonal delays were chosen to be consistent with both known transmission delays in cortical and subcortical areas, and with the spatial conformation of the model, and are summarized in Supplementary Table 3 online. In general, inhibitory to excitatory connections have small delays, intra-cortical feedforward connections have longer delays (Dinse and Kruger, 1994), and feedback connections (both corticocortial and corticothalamic) have even longer delays (Schmolesky et al, 1998;Miller, 1996). The model accounts for the driving vs. modulatory nature of synaptic connections by exploiting both the magnitude of the synaptic weight and the passive neuron cable properties.…”