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Monkey

Executive control : The ability to coordinate thought and action by directing them toward goals. Human. The prefrontal cortex. Monkey.

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Monkey

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  1. Executive control: The ability to coordinate thought and action by directing them toward goals. Human The prefrontal cortex Monkey Our approach: Multiple-electrode recording in trained monkeys. This allows detailed comparisons between neuron populations that are not confounded by extraneous factors (e.g., behavioral performance, training, level of experience, etc.), especially the timing of neural activity.

  2. Model-Building in the Prefrontal Cortex: “Cats” Versus “Dogs” 60% Dog Morphs 60% Cat Morphs 80% Cat Morphs 80% Dog Morphs Prototypes 100% Dog Prototypes 100% Cat Category boundary Learned categories: monkeys had no prior experience with cats and dogs and could learn to categorize the stimuli after their reassignment to arbitrary categories.

  3. C1 D1 C1 D2 C2 C1 D3 C2 D1 C3 C1 C2 D2 “cats” C2 D3 C3 D1 C3 D2 category boundary C3 D3 1.0 0.5 0 “dogs” Normalized firing rate D1 D3 D2 About 1/3 of Randomly-Selected Prefrontal Neurons Respond to Category Membership not Physical Appearance Activity to individual stimuli along the 9 morph lines that crossed the category boundary Single neuron: Freedman, Riesenhuber, Poggio, and Miller (2001) ScienceFreedman, Riesenhuber, Poggio, and Miller(2002) J. NeurophysiologyFreedman, Riesenhuber, Poggio, and Miller(2003) J. Neuroscience

  4. Are Prefrontal Neurons Category Multi-taskers? We trained monkeys to categorize the same images under two different category schemes

  5. Are Prefrontal Neurons Category Multi-taskers? Many individual PFC neurons are only reflected one category distinction (and only when it was relevant).

  6. Are Prefrontal Neurons Category Multi-taskers? Next, we trained monkeys on two independent (non-competing) category distinctions.

  7. Are Prefrontal Neurons Category Multi-taskers? More individual PFC neurons reflected both category distinctions.

  8. Category Representations in the PFC are Highly Dependent on Task Demands More overlap in neural representations when they are independent… …then when they are related and competing. Note: If PFC representations depended more on bottom-up (sensory) information, there should be more overlap for the related category sets because they use the same stimuli.

  9. LIP MT PFC ITC New Project: How Do “Top-Down” Signals Flow Across the Cortex?

  10. LIP MT PFC ITC Tracing the Flow of Signals Using Neural Synchrony The directed information flow was quantified as the baseline-corrected asymmetry of the generalized partial directed coherence (GPDC) derived from a sliding window multivariate autoregression.

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