Biomedical subjects

Hans Supèr

Publications and source records attributed to Hans Supèr.

4 recordsLinked to original sources

PubMed2004

Correspondence of presaccadic activity in the monkey primary visual cortex with saccadic eye movements.

We continuously scan the visual world via rapid or saccadic eye movements. Such eye movements are guided by visual information, and thus the oculomotor structures that determine when and where to look need visual information to control the eye movements. To know whether visual areas contain activity that may contribute to the control of eye movements, we recorded neural responses in the visual cortex of monkeys engaged in a delayed figure-ground detection task and analyzed the activity during the period of oculomotor preparation. We show that approximately 100 ms before the onset of visually and memory-guided saccades neural activity in V1 becomes stronger where the strongest presaccadic responses are found at the location of the saccade target. In addition, in memory-guided saccades the strength of presaccadic activity shows a correlation with the onset of the saccade. These findings indicate that the primary visual cortex contains saccade-related responses and participates in visually guided oculomotor behavior.

Animals↗

PubMed2003

Figure-ground activity in primary visual cortex (V1) of the monkey matches the speed of behavioral response.

To look at an object its position in the visual scene has to be localized and subsequently appropriate oculo-motor behavior needs to be initiated. This kind of behavior is largely controlled by the cortical executive system, such as the frontal eye field. In this report, we analyzed neural activity in the visual cortex in relation to oculo-motor behavior. We show that in a figure-ground detection task, the strength of late modulated activity in the primary visual cortex correlates with the saccade latency. We propose that this may indicate that the variability of reaction times in the detection of a visual stimulus is reflected in low-level visual areas as well as in high-level areas.

Animals↗

PubMed2003

Internal state of monkey primary visual cortex (V1) predicts figure-ground perception.

When stimulus information enters the visual cortex, it is rapidly processed for identification. However, sometimes the processing of the stimulus is inadequate and the subject fails to notice the stimulus. Human psychophysical studies show that this occurs during states of inattention or absent-mindedness. At a neurophysiological level, it remains unclear what these states are. To study the role of cortical state in perception, we analyzed neural activity in the monkey primary visual cortex before the appearance of a stimulus. We show that, before the appearance of a reported stimulus, neural activity was stronger and more correlated than for a not-reported stimulus. This indicates that the strength of neural activity and the functional connectivity between neurons in the primary visual cortex participate in the perceptual processing of stimulus information. Thus, to detect a stimulus, the visual cortex needs to be in an appropriate state.

Animals↗

PubMed2002

Cognitive processing in the primary visual cortex: from perception to memory.

The primary visual cortex is the first cortical area of the visual system that receives information from the external visual world. Based on the receptive field characteristics of the neurons in this area, it has been assumed that the primary visual cortex is a pure sensory area extracting basic elements of the visual scene. This information is then subsequently further processed upstream in the higher-order visual areas and provides us with perception and storage of the visual environment. However, recent findings show that such neural implementations are observed in the primary visual cortex. These neural correlates are expressed by the modulated activity of the late response of a neuron to a stimulus, and most likely depend on recurrent interactions between several areas of the visual system. This favors the concept of a distributed nature of visual processing in perceptual organization.

Animals↗