Selim Onat

I am a neuroscientist working currently on how humans make generalizations based on what they have previously learnt. To do so, 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.

In the past, I have been working on how the nervous system processes natural scenes both at the electrophysiological and sensory-motor level. Since the times of Hubel and Wiesel, visual processing had been
overwhelmingly studied with artificial stimuli such as moving edges. However this type of stimuli suffer from an ecological validity problem, as they only rarely occur in real-life. We therefore investigated cortical processing during viewing of natural movies. This previous work focused on visual processing using mostly the technique of voltage-sensitive dye imaging and eye-tracking.

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.