Neuroscience 2004 Abstract
| Presentation Number: | 774.7 |
|---|---|
| Abstract Title: | Neural correlates of perceptual learning in visual hyperacuity: A functional MRI study. |
| Authors: |
Schultheiss, N. W.*1
; Stilla, R.1
; Sathian, K.1
1Dept. of Neurol., Emory Univ. Sch. of Med., Atlanta, GA |
| Primary Theme and Topics |
Cognition and Behavior - Human and Animal Cognition and Behavior -- Learning & memory: Physiology and imaging |
| Secondary Theme and Topics | Sensory Systems<br />- Vision<br />-- Visual cortex: Functional organization and circuitry |
| Session: |
774. Learning: Functional Imaging Poster |
| Presentation Time: | Tuesday, October 26, 2004 3:00 PM-4:00 PM |
| Location: | San Diego Convention Center - Hall A-H, Board # LL4 |
| Keywords: | CORTICAL PLASTICITY, BRAIN IMAGING, VISUAL CORTEX, VISUAL PERCEPTION |
Visual perceptual learning is often specific for the region of the visual field where training is carried out, suggesting that learning-related plasticity occurs at a level of the visual cortical hierarchy where receptive fields are small. In an ongoing fMRI study, we are investigating the neural correlates of perceptual learning in a visual hyperacuity task. Subjects reported the direction of lateral offset of the center dot of a linear, vertically oriented, 3-dot array, presented at 5 degrees of eccentricity in the lower left quadrant of the visual field. Psychophysical thresholds were expressed in terms of the magnitude of offset required for 75% correct discrimination. This threshold declined over a number of training sessions (~10). fMRI data and high-resolution anatomic scans were acquired during pre-training and post-training sessions using a Siemens 3T scanner, and analyzed using BrainVoyager QX. A block design was used for fMRI data acquisition, with alternating active and fixation blocks, each of 20s duration. During active blocks, subjects performed one of two tasks: the hyperacuity (spatial) task and a temporal control task where subjects judged the duration of stimulus presentations. A new trial began every 2s during task blocks. Each task was repeated four times within a run, in a pseudorandom sequence. There were four such runs in each scanning session. Contrasts between the spatial task and the temporal control revealed a number of right hemisphere activations in lateral occipital, superior parietal, parieto-occipital, and frontal cortex. Training increased activation of primary visual cortex. Psychophysically, learning effects were specific to the trained visual quadrant. These preliminary results, consistent with reverse hierarchy theory (Ahissar & Hochstein, Nature 387:401-6, 1997), suggest a shift in visual cortical activity from lateral to medial occipital areas as a function of learning.
Supported by NEI and NINDS
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2004 Neuroscience Meeting Planner. San Diego, CA: Society for Neuroscience, 2004. Online.
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