Spatial and temporal visual properties of single neurons in the feline anterior ectosylvian visual area

Abstract

The spatial and temporal visual sensitivity to drifting sinusoidal gratings was studied in 75 neurons of the feline anterior ectosylvian visual area (AEV). Extracellular single-unit recordings were performed in halothane-anesthetized (0.6%), immobilized, artificially ventilated cats. Most cells were strongly sensitive to the direction of drifting gratings. The mean value of the direction tuning widths was approximately 90 deg. Most of the cells (69 of the 75 cases) displayed rather narrowly tuned band-pass characteristics in the low spatial frequency range, with a mean optimal spatial frequency of 0.2 cycles/degree (c/deg). The mean spatial bandwidth was 1.4 octaves. The remainder of the units was low-pass tuned. A majority of the units responded optimally to high temporal frequencies (mean 6.3 Hz), although some cells did exhibit preferences for every examined temporal frequency between 0.6 Hz and 10.8 Hz. The temporal frequency-tuning functions mostly revealed a band-pass character with a mean temporal bandwidth of 1.1 octaves. Our results demonstrate that the neurons along the anterior ectosylvian sulcus display particular spatial and temporal characteristics. The AEV neurons, with their preference for low spatial frequencies and with their fine spatial and temporal tuning properties, seem to be candidates for special tasks in motion perception.

Spatio-temporal visual properties in the ascending tectofugal system

“…Anatomical, physiological and functional differences between SCs and SCi the spatio-temporal properties of the SCs and SCi also show significant differences. Our results, together with earlier studies (see Introduction), suggest a functional relationship of the SCs to the geniculo-striate visual system, while the SCi is a part of the ascending tectofugal system [44,45] that also provides the visual information to the associative cortical areas along the AES [19] (Figure 3).…”

“…shape, size, 3 dimensional extent, color) whereas the ascending tectofugal visual system isinvolved in the detection of dynamic visual information [17][18][19]. The classical visual receptive field properties and the neuronal coding of spatial visual information of the geniculo-striate and the ascending tectofugal systems are different.…”

“…The neurons of different structures of the ascending tectofugal system (i.e. in the SC, the Sg of the posterior thalamus, the visual associative cortex along the anterior ectosylvian cortex (AES cortex) and the caudate nucleus (CN) neurons) prefer low spatial and high temporal frequencies and display narrow spatial and temporal frequency tuning [19,[28][29][30][31].…”

The Development of Cortical Multisensory Integration

“…Although there is some evidence suggesting that AES may be important for the perception of visual stimulus motion (Scannell et al, 1996;Nagy et al, 2003) and sound source localization (Middlebrooks et al, 1998;Furukawa et al, 2000), more work is needed to determine its behavioral and/or perceptual roles.…”

Spatial Heterogeneity of Cortical Receptive Fields and Its Impact on Multisensory Interactions

“…Such an integrated output demonstrates that these neurons are actively transforming this input information, likely in a way that facilitates the behavioral and/or perceptual role of the AES. Although this functional role has remained enigmatic, the selectivities of the neuronal populations within AES and its anatomical input/output organization point toward its playing a role in eye movements (Kimura and Tamai 1992;Tamai et al 1989), spatial localization (Lomber and Payne 2004;Malhotra et al 2004Malhotra et al , 2007, motion perception (Nagy et al 2003b;Scannell et al 1996), and coordinate transformations between the different sensory systems (Wallace et al 1992(Wallace et al , 2006.…”