1. Andy Dykstra HST.722 November 1, 2007
The role of gamma oscillations in perceptual binding and scene analysis.
Andy Dykstra
HST.722
November 1, 2007

2. Perceptual Binding? Objects have features
However, we perceive them as whole entities
How does one associate the various features with each other to form the representation of the object?
How does one assign features to objects when multiple objects are present?
How do different neuronal patterns, each representing a feature, “bind” together to bring about unified percepts and meaningful action?
Von der Malsburg (1981), Roskies (1999), Tallon-Baudry and Bertrand (1999)

3. Gamma Oscillations?
30 – 80 Hz fluctuations in neuronal signals measured at varying levels (units, local field potentils, EEG, MEG)
Three types:
Steady-state response
Evoked (synchronized with stimulus)
Induced (brought about by stimulus, but not synchronous with stimulus)
Epiphenomena or fundamental role in perception and cognition?
Gray (1994), Buzsáki (2006), Buzsáki and Draguhn (2004), Tallon-Baudry and Bertrand (1999)

4. Are they related?
Gamma oscillations may provide mechanism of synchronizing neuronal populations representing different features
This, when observed, could bind features

5. Results from the Auditory System.
Joilot et al. (1994)
Evoked ~40Hz track perception of one or two clicks

6. Results from the Auditory System.
Ross et al. (2005)
Stimulus induced reset of 40-Hz ASSR

7. Results from the Auditory System.
Lakatos et al. (2005)
Hierarchy of oscillatory activity in primary auditory cortex
Delta (1-4Hz) modulates theta (4-10Hz), which modulates gamma (30-50Hz)
Suggests that auditory cortex is optimized to process rhythmic inputs and provides possible mechanism for rhythmic expectation

8. Questions?