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Laboratory of Neuropsychology Laboratory of Neuropsychology (LN)

Research

Our research is focused on bridging the causal gap between visual perception and neuronal activity along the ventral stream of visual processing. Specifically, we like to parametrically characterize the perceptual effects of direct brain stimulation in various levels of cortical visual processing. We aim to use this knowledge to develop effective visual prosthetics for patients with severe vision loss.

The following is a summary of some of the ongoing projects in the lab:

Behavioral detectability of optogenetic stimulation of the inferior temporal cortex.

More information:

In this project, we transduce subregions of the inferior temporal (IT) cortex with optogenetic viral constructs. Then we implant an array of LEDs on the transduced photosensitive parts of the cortex. Next, we train animals to behavioral detect and report a short stimulation impulse delivered randomly to the cortex. We have found that behavioral detection of cortical stimulation in the IT cortex highly depends on the visual input to the eyes at the stimulation time. We use this visual stimulus dependence to infer and describe the perceptual effects of direct brain stimulation in the IT cortex.

Selected publications:

https://www.nature.com/articles/s41592-021-01238-9 

https://www.researchsquare.com/article/rs-1331186/v4 

Behavioral detectability of optogenetic stimulation of V4 cortex.

More information:

In this study, we transduce subregions of the V4 cortex with optogenetic viral constructs. Then and similar to our IT projects, we implant an array of LEDs on the transduced photosensitive parts of the cortex. Next, we train animals to behavioral detect and report a short stimulation impulse delivered randomly to the cortex. We then vary the visual input to the eyes at the time of stimulation and measure the interaction of the visual input with the stimulation detection task in order to infer and describe the perceptual effects of direct brain stimulation in the IT cortex.

Perceptography

More information:

The Optogenetics procedures of this project are similar to the previous two projects. ,Also similar to the other projects, we train the animals to behaviorally detect and report delivery of a short optogenetic stimulation impulse to their IT cortex. Based on the results of the above mentioned projects, we know that the animals use stimulation induced transient visual hallucinations in order to perform such a task. Now, we use machine learning in order to perturb the visual input (images on the screen) in a way that would make the animal think his cortex is stimulated (without actual cortical stimulation). In this process we develop images, called “perceptograms”, looking at which is not discriminable for the animal from the state of being locally stimulated in each subregion of the IT cortex. Using this technique, we take pictures of the perceptual events induced by direct brain stimulation in high level visual cortical areas.

Selected publications:

https://www.abstractsonline.com/pp8/#!/10485/presentation/16778  (SfN 2021 Abstract)

Behavioral detectability of local electrical stimulation in the primary visual cortex.

More information:

In this project we implant the primary visual cortex (area V1) and train animals to behavioral detect and report a short stimulation impulse delivered randomly to the cortex. The animals perform this task while fixating on dynamic white noise patterns. We then use the behavioral mistakes, in combination with the exact noise patterns presented at the time of the behavioral mistake in order to reconstruct the perceptual effects of brain stimulation in the primary visual cortex.

Selected publications:

https://www.abstractsonline.com/pp8/#!/10485/presentation/16776  (SfN 2021 Abstract)

Behavioral detectability of local electrical stimulation in inferior temporal cortex.

More information:

This project is very similar in essence and design to “Behavioral detectability of optogenetic stimulation of inferior temporal cortex.” mentioned earlier. The difference here is that we use electrical stimulation instead of optogenetics. While optogenetic stimulation is more precise, in this study we appeal to the older technique, electrical stimulation, because we can use the same electrodes in order to record the neuronal activity at the stimulation site.

Behavioral detectability of local electrical stimulation in V4 cortex.

More information:

This project is very similar in essence and design to “Behavioral detectability of optogenetic stimulation of V4 cortex.” mentioned earlier. The difference here is that we use electrical stimulation instead of optogenetics. While optogenetic stimulation is more precise, in this study we appeal to the older technique, electrical stimulation, because we can use the same electrodes in order to record the neuronal activity at the stimulation site.

The causal role of inferior temporal cortex on eye movements.

More information:

Perturbing the neural activity in inferior temporal cortex perturbs visual perception and as a result, affects the patterns of eye movements. This study aims at understanding how IT neurons causally contribute to eye movements. We use fMRI in order to target specific neurons within IT cortex (e.g. face selective neurons), then we reversibly inactivate various subregions of the cortex using microinjection of muscimol (a potent neural silencer) and measure the effects on free viewing of various visual stimuli (e.g. faces).