While much is understood about neural mechanisms that analyze the physical attributes of the visual environment, little is known about the culmination of these analyses: the assignment of categories that give stimuli meaning. Our group has developed a novel paradigm for studying visual categories. A morphing system is used to blend prototypes of """"""""cats"""""""" and """"""""dogs"""""""" into single images, with each image having a certain proportion of cat vs. dog. This allows us to continuously vary shape and precisely define a category boundary. Monkeys are trained to judge whether two successively presented images are from the same category. We recently found a neural correlate of category information in the prefrontal cortex (PFC): single neurons that show a sharp change in neural activity at the boundary between categories but relatively little differences in activity within a category. We now plan to use this paradigm to address fundamental questions about category representations. Using multiple electrode techniques, we will simultaneously record neural activity from the PFC and the inferior temporal cortex (TIC), a visual cortical area thought to be important for visual categories. This will allow us to directly compare and contrast their neural properties and relative timing and thus afford a precise assessment of the respective contributions to category-based behaviors. We will also test for category-coding in the hippocampus, a region that shares a close anatomical and functional relationship with the TIC and PFC. To explore whether categorization and identification have common neural substrates, we will record PFC and ITC activity while monkeys switch back and forth between categorizing stimuli and identifying individual category members. To determine if category-coding neurons are highly specialized (like """"""""face cells""""""""), we will test them with a wide range of real world stimuli. To determine whether multiple category memberships are represented by separate neural ensembles or instead multiplexed onto single neurons, we will record while monkeys switch between categorizing a set of stimuli under two different category schemes. Because categorization is central to cognition, data from this project has the potential to impact on a wide range of behaviors and human disorders. The ability to quickly glean concepts and meaning from experience is disrupted in a variety of neuro psychiatric disorders such as autism and schizophrenia. By identifying brain structures important for these abilities, discerning their relative roles, and uncovering their neural mechanisms, we can open a path to drug and behavioral therapies designed to alleviate their dysfunction.

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Research Project (R01)
Project #
5R01MH065252-05
Application #
7054642
Study Section
Integrative, Functional and Cognitive Neuroscience 8 (IFCN)
Program Officer
Quinn, Kevin J
Project Start
2002-04-01
Project End
2007-01-31
Budget Start
2006-02-01
Budget End
2007-01-31
Support Year
5
Fiscal Year
2006
Total Cost
$357,701
Indirect Cost
Name
Massachusetts Institute of Technology
Department
Miscellaneous
Type
Schools of Arts and Sciences
DUNS #
001425594
City
Cambridge
State
MA
Country
United States
Zip Code
02139
Stanley, David A; Roy, Jefferson E; Aoi, Mikio C et al. (2018) Low-Beta Oscillations Turn Up the Gain During Category Judgments. Cereb Cortex 28:116-130
Villagrasa, Francesc; Baladron, Javier; Vitay, Julien et al. (2018) On the Role of Cortex-Basal Ganglia Interactions for Category Learning: A Neurocomputational Approach. J Neurosci 38:9551-9562
Wutz, Andreas; Loonis, Roman; Roy, Jefferson E et al. (2018) Different Levels of Category Abstraction by Different Dynamics in Different Prefrontal Areas. Neuron 97:716-726.e8
Loonis, Roman F; Brincat, Scott L; Antzoulatos, Evan G et al. (2017) A Meta-Analysis Suggests Different Neural Correlates for Implicit and Explicit Learning. Neuron 96:521-534.e7
Antzoulatos, Evan G; Miller, Earl K (2016) Synchronous beta rhythms of frontoparietal networks support only behaviorally relevant representations. Elife 5:
McKee, Jillian L; Riesenhuber, Maximilian; Miller, Earl K et al. (2014) Task dependence of visual and category representations in prefrontal and inferior temporal cortices. J Neurosci 34:16065-75
Antzoulatos, Evan G; Miller, Earl K (2014) Increases in functional connectivity between prefrontal cortex and striatum during category learning. Neuron 83:216-25
Roy, Jefferson E; Buschman, Timothy J; Miller, Earl K (2014) PFC neurons reflect categorical decisions about ambiguous stimuli. J Cogn Neurosci 26:1283-91
Cromer, Jason A; Roy, Jefferson E; Buschman, Timothy J et al. (2011) Comparison of primate prefrontal and premotor cortex neuronal activity during visual categorization. J Cogn Neurosci 23:3355-65
Antzoulatos, Evan G; Miller, Earl K (2011) Differences between neural activity in prefrontal cortex and striatum during learning of novel abstract categories. Neuron 71:243-9

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