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You searched for +publisher:"Harvard University" +contributor:("Lee, Daeyeol"). Showing records 1 – 2 of 2 total matches.

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Harvard University

1. Luo, Zhihao. Dissociating Components of Visuo-Spatial Attention.

Degree: 2016, Harvard University

Neuronal signals related to visuo-spatial attention are found in widespread brain regions, and these signals are generally assumed to participate in a common mechanism of attention. However, the effects of visuo-spatial attention on the behavioral performance of human and animal observers can be separated into two distinct components. When a subject directs its attention to a visual location, the subject can change either its criterion or its sensitivity between the attended and unattended locations. I first found that when monkeys are trained to do a variant of the Posner attention paradigm, a task used in many single-neuron studies of visuo-spatial attention, enhanced performance is typically associated with both changes in the subject’s criterion and changes in its sensitivity. This finding indicates that the neuronal modulations attributed to visuo-spatial attention in previous studies could be associated with a behavioral change in sensitivity, a change in criterion, or a combination of both. To measure how neuronal signals across the brain are associated with the two components of attention, I designed a task to isolate attentional changes in either the criterion or the sensitivity of the subject. While monkeys were performing this task, I recorded from area V4 of their visual cortex and found that attention-related neuronal modulations in V4 corresponded to behavioral changes in sensitivity, but not changes in criterion. Subsequently, I recorded from prefrontal cortex (areas 45 and 46) and found that unlike V4, visual responses in prefrontal cortex were modulated when either the animal’s sensitivity or its criterion was changed between visual locations. Either an enhancement in sensitivity or a liberal change in criterion was associated with an increase in the firing rates of visual neurons in prefrontal cortex. These findings show that attention-related neuronal signals across the brain are not equivalent in their contribution to the mechanisms of visuo-spatial attention. Neuronal modulations in prefrontal cortex contribute to behavioral changes in both criterion and sensitivity, while modulations in visual cortex contribute to only changes in sensitivity. The results indicate that visuo-spatial attention is not a single neurobiological process but instead consists of at least two separable mechanisms mediated by overlapping groups of brain structures.

Medical Sciences

attention; neurophysiology; V4; prefrontal cortex; signal detection theory

Advisors/Committee Members: Born, Richard T., Maunsell, John H., Assad, John, Lee, Daeyeol, Livingstone, Margaret.

Subjects/Keywords: Biology; Neuroscience

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Luo, Z. (2016). Dissociating Components of Visuo-Spatial Attention. (Thesis). Harvard University. Retrieved from http://nrs.harvard.edu/urn-3:HUL.InstRepos:37944942

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Luo, Zhihao. “Dissociating Components of Visuo-Spatial Attention.” 2016. Thesis, Harvard University. Accessed October 24, 2020. http://nrs.harvard.edu/urn-3:HUL.InstRepos:37944942.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Luo, Zhihao. “Dissociating Components of Visuo-Spatial Attention.” 2016. Web. 24 Oct 2020.

Vancouver:

Luo Z. Dissociating Components of Visuo-Spatial Attention. [Internet] [Thesis]. Harvard University; 2016. [cited 2020 Oct 24]. Available from: http://nrs.harvard.edu/urn-3:HUL.InstRepos:37944942.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Luo Z. Dissociating Components of Visuo-Spatial Attention. [Thesis]. Harvard University; 2016. Available from: http://nrs.harvard.edu/urn-3:HUL.InstRepos:37944942

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


Harvard University

2. Wang, Alice. Neural Substrates of Choosing Actions and Motivational Drive, a Role for the Striatum.

Degree: PhD, Neurobiology, 2012, Harvard University

Optimal decision making requires one to determine the best action among available alternatives as well as the most appropriate level of engagement for performance. While current research and models of decision making have largely focused on the former problem, or action selection, less is known about the latter problem of the selection of motivational drive. Thus, I designed a self-paced decision-making paradigm that aimed to dissociate both facets of selection in rats. First, I showed that the expected net value of potential options influenced rats' general motivation to perform: rats globally exhibited shorter latency to initiate trials in states of high net return than in states of low net return. In contrast, the relative value of options biased choice direction. To study the neural substrates underlying either process, I examined the role of the striatum, which is closely connected with cortex and dopamine neurons, acting as a major hub for reward-related information. In chapter 1, I show that selective lesions of the dorsomedial (DMS) but not ventral striatum (VS) impaired net value-dependent motivational drive but largely spared choice biases. Specifically, DMS lesions rendered animals' latency to initiate trials dependent on the absolute value of immediately preceding trial outcomes rather than on the net value of options. Accordingly, tetrode recordings in Chapter 2 showed that the DMS rather than VS predominantly encodes net value. In fact, net value representation in the DMS was stronger than either absolute or relative value representations during early trial epochs. Thus, the DMS flexibly encodes net expected return, which can guide the selection of motivational drive. Advisors/Committee Members: Uchida, Naoshige (advisor), Hikosaka, Okihide (committee member), Lee, Daeyeol (committee member), Born, Richard (committee member).

Subjects/Keywords: basal ganglia; decision making; motivation; neurosciences

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Wang, A. (2012). Neural Substrates of Choosing Actions and Motivational Drive, a Role for the Striatum. (Doctoral Dissertation). Harvard University. Retrieved from http://nrs.harvard.edu/urn-3:HUL.InstRepos:9830345

Chicago Manual of Style (16th Edition):

Wang, Alice. “Neural Substrates of Choosing Actions and Motivational Drive, a Role for the Striatum.” 2012. Doctoral Dissertation, Harvard University. Accessed October 24, 2020. http://nrs.harvard.edu/urn-3:HUL.InstRepos:9830345.

MLA Handbook (7th Edition):

Wang, Alice. “Neural Substrates of Choosing Actions and Motivational Drive, a Role for the Striatum.” 2012. Web. 24 Oct 2020.

Vancouver:

Wang A. Neural Substrates of Choosing Actions and Motivational Drive, a Role for the Striatum. [Internet] [Doctoral dissertation]. Harvard University; 2012. [cited 2020 Oct 24]. Available from: http://nrs.harvard.edu/urn-3:HUL.InstRepos:9830345.

Council of Science Editors:

Wang A. Neural Substrates of Choosing Actions and Motivational Drive, a Role for the Striatum. [Doctoral Dissertation]. Harvard University; 2012. Available from: http://nrs.harvard.edu/urn-3:HUL.InstRepos:9830345

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