Selim Onat

My main occupation is Neuroscience.

In the past, I have been interested on how the visual system processes natural scenes. To this end, I have recorded naturalistic movies using micro-cameras carried by cats while they were actively exploring a natural environment. I used these movies to train neuronal networks in an unsupervised manner and compared learnt features to the known properties of neurons in visual cortex. I also used these videos as stimuli during physiological recordings to gain insights on the principles of natural signal processing in the visual cortex.

Recently, I started working on how humans make generalizations based on what they have previously learnt. To this end, I am using a variety of methodologies including fMRI (1), autonomous (2), as well as eye-movement recordings (3). This research emanates from the well-established field of "stimulus generalization" following mainly the "lineage" of Hovland, Hull and Roger Shepard (4), and including the more recent computational work of Josua Tenenbaum (5). Furthermore, it integrates work on anxiety disorders, as it is believed that these mechanisms are impaired in people suffering from anxiety problems.

During the Experiment

The participant is being recorded in the scanner while this movie is taken.

The movie starts with a view on the monitor of the Eyelink 2000 stimulus-computer that shows the current stimuli presented to the subject being scanned, together with his eye position depicted as a bluish circle moving from mouth toward between the eyes. At some point later one can see the eye of the participant with the detected pupil and Purkinje images. 

The second view is on the physio-computer that records breathing, pulse-oxymeter, and the skin conductance data. The physio-data is AD converted using CED system, it all runs with Spike2 software. Skin-conductance recordings are carried out with a BioPac system. The TRIO scanner is also connected directly to the CED system to record the start of each volume acquisition.

In the next few seconds, there is a glimpse on the CED rack that is used to A/D convert the data. The Digitimer current generator that is connected to the participant's hand via an electrode for Pavlovian conditioning is unfortunately not seen.

The third view is on the stimulus computer that presents images to the participant. Stimuli are presented using Matlab and Psychophysics Toolbox. The connection between Matlab and the Eyelink system is done via Eyelink Toolbox through an ethernet connection. Matlab is also connected to the CED system to store the onset of the relevant events as sequences of pulses together with the pulses of the scanner.

Last few shots wander around control desk showing some basic brain slices and the volunteer lying in the magnet on a background of noisy people.