Monkey
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Monkey Human The prefrontal cortex Executive control: The ability to coordinate thought and action by directing them toward goals. 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.
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Executive control : The ability to coordinate thought and action by directing them toward goals. Human. The prefrontal cortex. Monkey. - PowerPoint PPT Presentation
Transcript of Monkey
Monkey
Human
The prefrontal cortex
Executive control:
The ability to coordinate thought and action by directing them toward goals.
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.
Category boundary
Prototypes
100% Cat
80% Cat Morphs
60% Cat Morphs
60% Dog Morphs 80% Dog
Morphs
Prototypes 100% Dog
Model-Building in the Prefrontal Cortex: “Cats” Versus “Dogs”
Learned categories: monkeys had no prior experience with cats and dogs and could learn to categorize the stimuli after their reassignment to arbitrary categories.
“cats”
“dogs”
category boundary
C1
C2
C3
D2
D3D1
Activity to individual stimuli along the 9 morph lines that crossed the category boundary
Single neuron:
0 0.5 1.0
Normalized firing rate
C1C1C1C2C2C2
C3C3
C3
D1D2D3D1D2D3
D2D3
D1
About 1/3 of Randomly-Selected Prefrontal Neurons Respond to Category Membership not Physical Appearance
Freedman, Riesenhuber, Poggio, and Miller (2001) ScienceFreedman, Riesenhuber, Poggio, and Miller (2002) J. NeurophysiologyFreedman, Riesenhuber, Poggio, and Miller (2003) J. Neuroscience
Are Prefrontal Neurons Category Multi-taskers?
We trained monkeys to categorize the same images under two different category schemes
Are Prefrontal Neurons Category Multi-taskers?
Many individual PFC neurons are only reflected one category distinction (and only when it was relevant).
Are Prefrontal Neurons Category Multi-taskers?
Next, we trained monkeys on two independent (non-competing) category distinctions.
Are Prefrontal Neurons Category Multi-taskers?
More individual PFC neurons reflected both category distinctions.
Category Representations in the PFC are Highly Dependent on Task Demands
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.
More overlap in neural representations when they are independent…
…then when they are related and competing.
MTLIP
PFC
ITC
New Project:How Do “Top-Down” Signals Flow Across the Cortex?
MTLIP
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.
