The inferior temporal (IT) cortex is associated with a primary function;visual object recognition. However, the main body of evidence for the role of IT neural activity in object recognition is only correlational. The potential causal role of the IT neurons in behavior and perception has remained largely unexplored. In the proposed research, I will systematically study the causal role of IT neural representations in visual object recognition.
In Aim 1, I will study the causal role of anatomically defined sub-regions of IT corte in object recognition behavior. Specifically, by local muscimol injection, in each experimental session I will inactivate a small sub- region of IT cortex and measure the effect of its inactivatin on psychophysical performance for a set of object recognition tasks. This will be done systematically for the entire anatomical span of IT cortex to map the causal role of different parts of the cortex in a set of object recognition tasks. I will also measure the neural stimulus selectivity in the targeted areas to investigate to relationship between neural selectivity (a correlational measure) and the behavioral impact of the causal intervention.
In Aim 2, I will investigate the causal role of different temporal segments of the IT neural response profile in object recognition behavior. Through correlational studies, it has been shown that early and late segments of the temporal response profile of IT neurons carry different information about visual objects. However, we don't know yet if the brain mechanisms that create behavior actually discriminate between these temporal segments and use their information in object recognition behavior. To address this question, using rapid optogenetic silencing, I will inactivate various time segments of the IT neural response profile to measure the causal role of each segment in a set of object recognition tasks. In sum, this endeavor aims at establishing a systematic causal link between IT neural representation of information (in spatial and temporal domains) and object recognition behavior. The proposed work will be started in the laboratory of Jim DiCarlo at MIT with close collaboration with the laboratory of Ed Boyden at MIT. Dr. DiCarlo is a committed mentor who leads a highly collaborative, interdisciplinary research group that studies object recognition. Dr Boyden is an enthusiastic scientist and one of the leaders of optogenetic research who will help me in development of the technical skills required for a part of this proposal. During the mentored phase of the project (K99:
Aim 1 and the pilot phase of Aim 2), I will acquire training in techniques for high precision X-ray localization and mapping of IT cortex, pharmacological inactivation and optogenetics providing an experimental platform for transition to an independent position in the second phase (R00:
Aim 2) of the research.
Object recognition is one of the core functions of human vision and impairment of object recognition (e.g. in agnosia) is a debilitating condition. Understanding the causal role of IT cortex in object recognition may directly help with development of treatments for severe object recognition impairment, also it is a necessary precondition for design and development of neural prosthetics. In addition, technical achievements of the proposed research may lead to invention of a new treatment for Temporal Lobe Epilepsy, the most common cause of epilepsy in human adults (see Innovation).
|Afraz, Arash; Boyden, Edward S; DiCarlo, James J (2015) Optogenetic and pharmacological suppression of spatial clusters of face neurons reveal their causal role in face gender discrimination. Proc Natl Acad Sci U S A 112:6730-5|