TitleWhite noise analysis of visual selectivity in area MT during fixation and eye movements
NameHartmann, Till Sebastian (author), Tepper, James M (chair), Paré, Denis (internal member), Koos, Tibor (internal member), Krekelberg, Bart (internal member), Goldberg, Michael E (outside member), Rutgers University, Graduate School - Newark,
SubjectBehavioral and Neural Sciences,
Brain—Localization of functions,
Visual evoked response
DescriptionIt is crucial for survival to rapidly and accurately determine the location of objects. As humans, we constantly estimate positions of stationary and moving targets around us, and do so successfully, despite eye movements that induce motion on the retina. One vital brain area has been identified for localization and motion processing: the middle temporal area (MT). We set forth to investigate the responses of single cells and local field potentials (LFP) in area MT of the rhesus macaque in order to study its tuning properties during eye movements. We presented randomly positioned, flickering bars to map neurons’ visual responses. Meanwhile, we superimposed a fixation point to keep the eyes still or a moving random dot pattern, which induced Optokinetic Nystagmus, a specific type of eye movement. During fixation, we found the responses of area MT to be—contrary to the current beliefs in literature—polarity sensitive (project 1). Our findings indicate that the receptive field (RF) position in area MT is yoked to the eye, independent of eye position and eye movement. That is, the cells are coding in an eye-centered reference frame and the cells’ RFs do not shift (project 2). We found that in area MT, eye position modulated not only neurons’ firing rates; the power in the gamma spectrum exhibited gain modulation as well—gain fields (project 3). Finally, we show dramatic changes during fast eye movements of both neuronal firing rates and LFP. The LFP modulation depended highly on the frequency band, i.e. theta power was strongly enhanced while the stimulus frequencies in the gamma range were decreased. We speculate that the LFP modulations allow us to identify layer specific differences. Furthermore, these modulations lead us to suggest a new mechanism for saccadic suppression: de-synchronization (project 4). In conclusion, we advanced the knowledge on motion processing and perceptual stability and proposed a novel role for de-synchronization in the phenomenon of saccadic suppression.
NoteIncludes bibliographical references
Noteby Till Sebastian Hartmann
CollectionGraduate School - Newark Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.