2. Reverberating activity in the brain Single neuron stimulus selective sustained activity 1s Sample stimulus Test stimulus Delay Delayed matching to sample task: Yakovlev, Fusi, Berman, Zohary, Nature Neuroscience 1998

3. Sustained reverberations as an expression of the collective attractor’s dynamics The landscape metaphor: Each point corresponds to a collective state of a population of neurons The dynamical process goes downhill fbfb fafa Energy 30Hz 20Hz

4. STIMULUS ‘A’ PRESENTATION (before learning) fafa fbfb

5. STIMULUS ‘B’ PRESENTATION (before learning) fafa fbfb

6. Shaping landscapes: synaptic plasticity Neurons activated by A Neurons activated by B

7. STIMULUS ‘A’ PRESENTATION (after learning) fafa fbfb

9. STIMULUS CLASSIFICATION Presentation of a degraded version of A fafa fbfb

10. Amit, Fusi, Yakovlev, 1997 Stimulus rate (Hz)