Bay Area Vision Research Day
BAVRD 2008
University of California, Berkeley

September 13th, 2008

Jump To: Speaker Abstracts , Poster Abstracts

Schedule:

All talks will be held in Minor Hall Rm. 489

 

Speaker Abstracts:

9-9:30 - Marla Feller - UC Berkeley
The development of functional circuits in the retina
Anishchenko A, Elstrott J, Greschner M, Sher A, 'Litke AM , Feller MB, 'Chichilnisky EJ
The development of functional circuits in the retinaAnishchenko A (1), Elstrott J (1), Greschner M (2), Sher A (3), 'Litke AM (3), Feller MB (4), 'Chichilnisky EJ (2). ''1. Biological Sciences, UC San Diego, CA, USA. 2. Systems Neurobiology, The Salk Institute, La Jolla, CA, USA. 3. Institute for Particle Physics, UC Santa Cruz, CA, USA. 4.Molecular and Cell Biology & Helen Wills Neuroscience Institute, UC Berkeley, CA, USA. A characteristic feature of the adult retina is mosaic organization: a spatial arrangement of cells of each morphological and functional type that ensures uniform sampling over visual space. Here, we test the hypothesis that patterned activity induced by early visual experience is necessary for the formation of receptive field mosaics of RGCs. '''We use a large-scale multielectrode array to record from isolated retinas of mice right after eye opening (postnatal day 14; P14). To exclude the influence of the limited vision that occurs through closed eyelids or the brief visual experience between eye opening and the time of the experiments, we dark reared the mice starting at P7. Based on their intrinsic firing properties and responses to white noise checkerboard stimulation, we characterized 3 types of RGCs -- direction selective and two distinct types of OFF RGCs in P14 dark-reared mice. For the OFF RGC types, their receptive fields formed a spatial mosaic with uniform overlap. We conclude that 1) distinct receptive fields and 2) functional mosaics can be formed in the retina with no visual experience.

9:30-10 - Volodymyr Ivanchenko - Smith Kettlewell Eye Research Inst.
Detecting and Locating Crosswalks using a Camera Phone
Volodymyr Ivanchenko, James Coughlan and Huiying Shen
Urban intersections are the most dangerous parts ofa blind or visually impaired person's travel. To addressthis problem, this paper describes the novel 'Crosswatch'system, which uses computer vision to provide informationabout the location and orientation of crosswalks to ablind or visually impaired pedestrian holding a camera cellphone. A prototype of the system runs on an off-the-shelfNokia N95 camera phone in real time, which automaticallytakes a few images per second, analyzes each image in afraction of a second and sounds an audio tone when it detectsa crosswalk. Real-time performance on the cell phone,whose computational resources are limited compared to thetype of desktop platform usually used in computer vision, ismade possible by coding in Symbian C++. Tests with blindsubjects demonstrate the feasibility of the system.

10-10:30 - Susana Chung - UC Berkeley School of Optometry
Feature Maps for Letters
Susana Chung, Bosco Tjan, Yiji Lin
Object recognition involves the detection and integration of valid features to form a coherent percept. Previous studies hinted that different parts of letters are used for identification in the fovea and the periphery; and that more valid features in the stimulus are required for identifying crowded than for single letters. However, the specific features used for identifying individual letters are unknown. Are these features different between the fovea and periphery, and between crowded and uncrowded conditions? To answer these questions, we used a set of 26 lowercase letters that were constructed of Gaussian patches, with each patch having the chance to be individually turned on or off. We tracked observers' response (letter identity) to each stimulus letter presented singly, or when flanked by two nearby letters, at the fovea and 10' lower field. 'Letter size was twice the acuity-threshold separately determined for each condition. On each trial, a random subset of the patches that constituted the target and and its flanking letters (if present) was shown. The probability of a patch being shown was adjusted such that each observer's overall performance accuracy was close to 52% correct. We performed a reverse-correlation analysis to identify the patch locations that significantly correlated with each observer's response for a given letter, resulting in a 'feature map' for identifying that letter. Contrary to the expectations based on previous studies, the feature maps are very similar between the fovea and 10' lower field, and between the crowded and single-letter conditions. 'For some letters, there are subtle differences across conditions in how much observers rely on a given patch location. Our findings suggest that when letter size is scaled to equate for overall performance, the critical features for letter identification are largely invariant between the fovea and periphery, and between the crowded and uncrowded conditions.

10:30-11 - Bruce Bridgeman - UC Santa Cruz
Hidden Image Substitution: Change Blindness in a Continuous Transformation Paradigm
Bruce Brideman, Chad Sampanes & Philip Tsent
Studies of change blindness suggest that we bring only a few attended features of a scene, plus a gist, from one visual fixation to the next. It remains unclear whether eventual change detection occurs from fortunate attention to the changing element or from a gradually improving internal scene representation. We resolve this question by substituting one image with a different image of the same gist, while suppressing attention. A natural image is masked with an 8x8 checker pattern, and progressively substituted by squares of a new image of the same gist. Jittering the image suppresses details without forcing eye movements. 40% of complete image exchanges went undetected. Detection rate remained constant with repeated substitutions, indicating that observers compared the current image only with the preceding one. Geometrically similar image pairs of different gist were detected more frequently than same-gist pairs. Progressive exchange to an image of different gist was always detected. Subsequent experiments show that the effect is not due to perceptual changes and that gist is responsible for the effect. We conclude that gist is automatically encoded, separately from specific features.

11-11:30 - Jay M. Enoch - UC Berkeley School of Optometry
A Mesolithic Artificial Eye Found In Situ!
Jay M. Enoch
"A Mesolithic Artifical Eye Found in situ! by Jay M. EnochLast year, I presented a paper on an amazing ancient artificial eye found in Iran! That artificial eye is about 5000 years old. A reader in Spain of some of my writings spotted this report, and called my attention to another artificial eye of a similar sort, but 2000 years older (about 7000 years before present during the Middle Stone Age!) which has been unearthed in Spain! Just incredible! This eye was found in the right orbit of a scull of a man who died at age 40-45. He was tall, and apparently he was also wealthy (based upon other goods found in the grave). The eye was composed of ochre. An incised iris can be identified and possibly a pupil. This artificial eye was much more primitive in design than the Iranian one found at "The Burnt City." This man's body (containing the eye) was found at an archaeological site known as Cingle del Mas Nou, Ares del Maestro, Castellon, Spain. This man's body was found at an archaeological site known as *Cingle del Mas Nou, Ares del Maestro, Castellon, Espagne. This is located in the Eastern part of Spain, not far North of Valencia near the coast.

11:30-1pm Lunch and Poster Presentations

1-1:30 - Christopher R. L. Cantor - UC Berkeley Vision Science
A new temporal illusion occurring early in the visual system
Christopher R. L. Cantor & Clifton M. Schor
In a temporal order judgment (TOJ) task, observers view asynchronously presented pairs of short-duration visual objects and report which one occurred first. Typical stimuli are ultra-brief (temporally broadband) rectangular pulses, and thresholds can approach 3 ms when a pair of identical pulses is used (Westheimer & McKee, 1977).A different stimulus configuration results in a striking misperception of temporal order. Our observers view pulses with a narrower temporal bandwidth (e.g. temporal Gabors) and perform TOJ for stimulus pairs with differing temporal frequency content. This manipulation produces bias in the perceived asynchrony between high and low temporal frequency stimuli, with high temporal frequencies appearing delayed up to ~100 ms. We believe these effects occur early in the magnocellular visual pathway, and present a model that shows how the biphasic temporal impulse responses of magnocellular ganglion cells could account for our data. Westheimer, G., & McKee, S. P. (1977). Perception of temporal order in adjacent visual stimuli. Vision Research, 17(8), 887-892.

1:30-2 - Ashutosh Saxena - Stanford University
Learning 3-D Structure from a Single Still Image
Ashutosh Saxena, Prof. Andrew Y. Ng, et al.
We present an algorithm to convert standard digital pictures into 3-d models.This is a challenging problem, since an image is formed by a projection of the 3-d scene onto two dimensions, thus losing the depth information. We take a supervised learning approach to this problem, and use a Markov Random Field (MRF) to model the image depth cues as well as the relationships between different parts of the image. We show that even on unstructured scenes (of indoorand outdoor environments, including forests, trees, buildings, etc.), our algorithm is frequently able to recover fairly accurate 3-d models.We use our method to create visually pleasing 3-d flythroughs from the image. We also present a few extensions of these ideas, such as additionally incorporating triangulation (stereo) cues, using multiple images to produce large scale 3-d models, and improving the performance of object detection and image segmentation. We also apply our methods to two robotics applications: (a) high speed off-road obstacle avoidance on an autonomously driven remote-controlled car, and (b) having a robot unload items from a dishwasher and open new doors.To convert your own image of an outdoor scene, landscape, etc. to a 3-d model, please visit: http://make3d.stanford.edu

2-2:30 - Dennis Levi - UC Berkeley
Letter recognition, crowding and reading in amblyopia.
Dennis M. Levi, Denis G. Pelli & Shuang Song
Crowding, not letter recognition acuity, limits reading in the amblyopic visual system.

2:30-3 - Brandon Lujan - UC Berkeley
Spectral Domain OCT Imaging of Dry AMD
Brandon Lujan, MD; Giovanni Gregori, PhD; Philip Rosenfeld, MD, PhD
Dry AMD can be characterized and quantitated using Spectral Domaing Optical Coherence Tomography

3-3:30 - Alex Bronstein - Novafora Inc
A metric approach to nonrigid shape analysis
Alex Bronstein, Michael Bronstein, Ron Kimmel
Non-rigid shapes are ubiquitous in the world surrounding us, at all levels from micro to macro. The need to study such shapes and model their behavior arises in a wide spectrum of applications. In recent years, non-rigid shapes have attracted a growing interest, which has led to rapid development of the field, where state-of-the-art results from very different sciences - theoretical and numerical geometry, optimization, linear algebra, graph theory, machine learning and computer graphics, to mention a few - are applied to find solutions. In this talk, we will approach the non-rigid world from the perspective of metric geometry. The discussion will focus on two archetype problems in non-rigid shape analysis: similarity and correspondence. We will start with the construction of similarity criteria for deformation-invariant shape comparison, based on intrinsic geometric properties of the shapes, and show that such criteria are related to the Gromov-Hausdorff distance. Next, we will extend the problem of similarity to partially similar shapes, and present a construction of set-valued distances, based on the notion of Pareto optimality. Next, we will consider a particular setting of self-similarity of shapes, which will allow us to determine intrinsic symmetries of the shapes. Finally, we will show that the correspondence between non-rigid shapes can be obtained as a byproduct of the non-rigid similarity problem. Part of the talk will be dedicated to the numerical core of our method, the generalized multidimensional scaling (GMDS). As examples of applications, we will use problems from the fields of computer vision and computer graphics.(Joint work with Ron Kimmel, Alfred Bruckstein, and Dan Raviv, Technion, Israel)

3:30-4 -- Reception

Poster Abstracts:

Austin Roorda UC Berkeley
Cone Identification and Tracking Using High-Resolution in vivo Imaging
Austin Roorda, Sanna Sundquist, Yuhua Zhang, Chiaki Nakanishi, Anna Solovyev, Jarel Gandhi, Jacque L. Duncan
Purpose: Adaptive optics facilitates the unprecedented ability to identify and track single cells, such as photoreceptors, over time in a living human eye. Our purpose is to establish methods to track cones of healthy retinas in adaptive optics scanning laser ophthalmoscope (AOSLO) images with the intent to apply these methods to eyes with retinal degenerations. Methods: AOSLO was used to image the macular region in one eye of 6 healthy subjects. All subjects were imaged on more than 1 occasion, separated by no more than one year, an interval during which little to no change was likely to occur. High signal-to-noise images of the macula were generated. In regions where unambiguous cones were seen on more than one occasion, individual cones were identified and compared between sessions. We counted cones that were observed in both sessions (common - C), and those that were seen in one session but not in the other (noncommon - NC). Repeatability was quantified as (C-NC)/(C+NC) spanning a possible range from -1 to 1. To quantify changes in cone reflectance we measured the correlation in individual cone intensities between sessions. Results: Repeatability of 18 locations in 6 healthy eyes was >0.99. Cone reflectivity, however, changed significantly between sessions, with essentially no correlation in reflectivity between sessions. (avg R-squared value = 0.052) Conclusions: Virtually all cones in healthy eyes can be tracked between imaging sessions. The only errors were due to extreme changes in the reflectivity of some cones rendering them invisible in one of the sessions. Cone reflectivity changes have been observed by others using a flood-illuminated AO system(1). In patients with cone abnormalities, for whom repeatability will be more useful and important, greater variability in cone appearance suggests that repeatability in eyes with retinal degenerations will be lower. 1. Pallikaris A, Williams DR, Hofer H. IOVS. 2003;44:4580-4592.


Justin Elstrott Feller lab, UC Berkeley
Development of on-off direction selective cells in the mouse retina.
J. Elstrott, A. Anishchenko, M. Greschner, A. Sher, A. M. Litke, E. J. Chichilnisky, M. B. Feller.
On-off direction selective ganglion cells (DSGCs) respond to stimuli moving in one of four cardinal directions: nasal, dorsal, temporal, and ventral. The directional responses are believed to arise primarily from asymmetric inhibitory inputs onto DSGCs. Here we test the hypothesis that early retinal activity is necessary for the establishment of normal DSGCs. We used a multielectrode array to measure a tuning curve for each cell indicating the strength of response to sinusoidal gratings moving in one of 16 directions. We identified on-off DSGCs based on two criteria: 1) non-uniform direction tuning curves 2) frequency doubling in the power spectra of the response. In the adult retina, tuning widths varied between 70-150 degrees, with the more broadly tuned cells exhibiting an increased firing in response to stimulation in the null direction. In P14 retinas, the distribution of tuning widths was similar to the adult, with a small (5 degrees) but significant (p < 0.05) shift towards broader tuning. To assay the role of early visual activity and early spontaneous activity in the development of DSGCs, we examined the tuning widths of DSGCs in dark-reared P14 animals and in b2-nAChR -/- P14 animals, which exhibit uncorrelated spontaneous activity during the first post-natal week. The P14 dark reared mice had slightly (7 degrees) but significantly (p < 0.05) broader tuning than P14, whereas the b2 -/- showed no significant difference. These results suggest that the asymmetric inhibition underlying retinal direction selectivity is established early in development before the onset of light responses. We have begun studying DSGCs before eye-opening to further characterize the development of the directional circuit.


Cary Feria San Jose State University
Spatial probabilities and a center bias affect the distribution of attention within untracked objects during multiple object tracking
Cary Feria
When several moving objects are tracked, the distribution of attention within each tracked object is biased toward the center of the object (Alvarez & Scholl, 2005) and is also prioritized to high probability locations on the object (Feria & Doyle, 2006). However, previous research has not investigated whether spatial probabilities affect the distribution of attention within untracked distractor objects. In this experiment's multiple object tracking task, observers tracked several long moving lines among identical distractors. Small circular probes appeared briefly on target and distractor lines, and observers' performance at detecting the probes was used to measure the distribution of attention. The probability of a probe occurring at different locations on the lines was manipulated. Results demonstrated both an attentional bias toward centers of objects, and attentional prioritization based on spatial probability, for distractor objects as well as target objects. These findings suggest that attentional prioritizations based on spatial probabilities can move along with continuously moving tracked and untracked objects. Supported by KY NSF EPSCoR Grant 4-69018-05-496


Leigh A. Needleman UC Davis
Localization of MHC class I molecules during development of the visual cortex
Leigh A. Needleman, Xiao-Bo Liu, A. Kimberley McAllister
Recent research has demonstrated that major histocompatibility complex class I (MHCI) genes are expressed in the brain where they regulate the synaptic refinement of retinogeniculate connections in the visual system and synaptic plasticity in the hippocampus (Corriveau et al., 1998; Huh et al., 2000). Recently, our laboratory has shown that the surface expression of MHCI molecules regulates the initial formation of both excitatory and inhibitory connections between early postnatal visual cortical neurons in dissociated cultures. To begin dissecting the mechanism whereby MHCI molecules negatively regulates visual cortical connectivity, we have characterized the expression patterns of MHCI molecules in the intact rat brain at several stages of cortical development: during the peak of synaptogenesis (P7), during the critical period of synaptic refinement (P23), and in adulthood. To that end, we used confocal microscopy to characterize the localization of MHCI protein in neurons and glia, and preembedding immunogold labeling combined with electron microscopy to investigate the ultrastructural localization of MHCI protein at synapses. MHCI molecules are expressed in both inhibitory and excitatory neurons of the rat visual cortex throughout development, with expression increasing in GABAergic cells with age. In addition, MHCI protein is found in dendrites and dendritic spines and was unexpectedly abundant in presynaptic terminals at all ages. These results suggest that MHCI molecules may function on both sides of the synapse to negatively regulate the initial estabilishment of connections in the visual cortex.


Zhi-Lei Zhang UC Berkeley
Luminance And Saccadic Supression On Perisaccadic Spatial Distortions
Zhi-Lei Zhang ,Christopher Cantor & Clifton M. Schor
Visual direction of foveal targets flashed just prior to the onset of a saccade is misperceived as shifted in the direction of the eye movement. We examined the effects of luminance level and temporal interactions on the amplitude of these PSDs (Perisaccadic Spatial Distortions). PSDs for single pre-saccadic flash were larger with low than high luminance levels, and there was a reduction of PSDs for low luminance targets flashed immediately before the saccade. Paradoxically, when two pre-saccadic flashes (ISI = 50ms) were presented near the saccade onset, the earlier flash was distorted more than the later flash, even though the later flash occurred closer in time to the saccade.To explain these effects, we propose that stimulus-dependent nonlinearities (contrast gain control and saccadic suppression) influence the duration of the temporal impulse response of both single- and double-flashed stimuli.


Katharine Campi UC Davis
Connections of Visual Cortex in the Prairie Vole (Microtus ochrogaster)
K.L. Campi and L.A. Krubitzer
Behavioral specializations are often reflected in the organization of sensory areas of the cortex, and examination of diverse species allows us to elucidate which features of cortical organization are specialized and which are common to all mammals. The prairie vole (Microtus ochrogaster) is an interesting model to study behavioral specialization and associated cortical specialization because of its exceptional lifestyle. It is one of the 3% of mammals classified as socially monogamous (Kleiman, 1977). Previously, we examined the functional and myeloarchitectonic organization of the sensory neocortex in the prairie vole and found that although the primary sensory areas were dominated by responses to the expected modality, 13% of responses were to other than the expected modality (i.e., an auditory response in the primary visual area) here termed multimodal responses (Campi et al., 2007). Specifically in the primary visual area (V1), 86% of recording sites contained neurons that were responsive to auditory and visual stimulation, 7% of sites contained neurons that were responsive to auditory and somatosensory stimulation, and 7% of sites contained neurons that were responsive to all three modalities. In order to further investigate these multimodal responses we used neuroanatomical tracer injections in cortex to examine the connections of the primary sensory areas. Two injections were placed in the rostrolateral half of area 17 and one in the caudal half of area 17. Cortical connections were observed with area 18, multimodal cortex, auditory cortex, and pyriform cortex. Thalamic connections were observed with the lateral geniculate, lateral dorsal, lateral posterior, anteroventral, and posterior nuclei. Thus both visual and non visual areas and thalamic nuclei provide input to the primary visual area in prairie voles. These data are compared with findings from other rodents that have different social systems and lifestyles.


Jason Fischer UC Davis
Attention narrows position tuning of population responses in V1
Jason Fischer, David Whitney
The mechanisms underlying spatial attention have been extensively studied, but are still not well-understood. Single-unit and functional imaging studies have found boosted neuronal responses to attended stimuli, and one view holds that multiplicative gain alone effectuates the improved visual resolution that attention affords. However, a much more efficient way to achieve fine spatial resolution would additionally involve increasing position selectivity (ie, narrowing position tuning) at the neural population level. Despite the theoretical appeal of such a mechanism, it remains unclear whether attention produces any position tuning narrowing independently of signal gain. Here, using a multivariate pattern analysis to track how attention changes retinotopic mapping in the cortex, we show that attention produces both gain and narrowed position tuning in early visual areas including V1. Our results reveal an important mechanism of visual attention that operates at the earliest cortical stages of visual analysis and has the power to dramatically improve the resolution of position coding and spatial vision.


Paul F. Bulakowski UC Davis
The hand doesn't grasp our perception of cluttered scenes
Paul F. Bulakowski, Robert B. Post, & David Whitney
The characteristics of visual crowding are well documented, however its effect on action is largely unknown. It is possible that the mechanisms that limit perceptual resolution in cluttered, or crowded, scenes may similarly affect movement planning. This study sought to directly compare orientation discrimination between perceptual and visuomotor tasks across eccentricities and visual fields. Subjects discriminated the tilt of a crowded target bar using a standard perceptual 3AFC key-press, or by reaching and grasping the target. An Optotrak tracking system recorded the angle of subjects' pincer grasp on the target bar. The results demonstrated that the accuracy of perceptual and visuomotor judgments of crowded targets were similar, with the lowest performance in the upper visual field, consistent with previous findings (He et al., Nature, 1996). Interestingly, while perceptual responses were attracted to the mean or ensemble orientation of the target and flankers (Parkes et al, Nature Neuro, 2001), the visuomotor responses displayed a relative discounting of the mean tilt. Further, while perceptual results revealed the trademark radial asymmetry of crowding, this effect was not present in the reaching data. These results suggest that while crowding may be an absolute bottleneck for both perceptual and visuomotor tilt discrimination, the spatial extent and/or weighting of visual space for perception and action are dissociable.


Elizabeth Osborne UC Davis
Novel Small-molecule and Nanoparticle Based Probes for Imaging Redox Activity
Elizabeth Osborne, Chuqiao Tu, Benjamin Jarrett, Angelique Y. Louie
Research in the Louie lab on photo- and electrochromic materials has led to the development of a redox active MR and optical imaging agent that tethers a spirooxazine molecule to a Gd-DO3A moiety. The agent responds to NADH by modulation of signal intensity in both MR and optical imaging. Elevated NADH levels have been found in hypoxic retinal tissue and are implicated in increased superoxide production; therefore, we believe our probe will offer insight as to the role of NADH-related biochemical processes in disease progression. Studies are in progress to develop a series of contrast agents, based on small molecule Gd chelates and nanoparticles functionalized with 'molecular switches', that are capable of reporting on various biological redox indicators such as superoxide radical anion, peroxides, glutathione, etc. The success of these probes would open up a novel opportunity for MR functional imaging of the eye and offer an important tool for understanding how redox environment contributes to the deleterious cascade of molecular events that result in vision loss for those afflicted with retinal degenerative diseases.


Linh Dang Smith-Kettlewell Eye Research Institute
Predicting Visual Functions from Microperimetry Data
Linh Dang, Laura Walker Renninger,;& Donald Fletcher
Most low-vision clinics and rehabilitation centers do not have access to a Scanning Laser Ophthalmoscope (SLO), thus must rely on less dependable methods. The lack of available measurements often limit a clinician's measurements to be more subjective and coarse in evaluation. We seek to understand how field loss affects reading performance in patients with age-related macular degeneration (AMD) and other retinal diseases. Visibility maps produced from visual loss estimation of microperimetry data using weighted nearest neighbor classification, where neighboring data points vote on the visibility of the selected location. The weight of each vote depends on the eccentricity of the selected location and proximity of data points. Our estimates of the dense scotoma size correlate well with the clinical evaluation when thresholds are conservative (t= 0.1). We also compared the two methods in predicting reading performance using the MN Read chart. Both clinical and quantitative methods produced similar correlations between reading performance and field loss from microperimetry data. Our approach with the small sample size was statistically better for maximum reading rates (p= 0.10). Future work will include a larger sample size and will explore alternatives to microperimetry for measuring field loss. This quantitative method provides a more flexible representation of field loss and a stronger foundation for examing certain scotoma characteristics (i.e. ring scotoma and multiple scotomas) that may be problematic to evaluate consistently. Quantitative analysis of microperimetry data may provide a stronger foundation for understanding the relationship between field loss and functional outcome.


Adele M H Seelke UC Davis
Establishing a Quantitative Method of Receptive Field Determination in Developing Mammals
Adele M H Seelke and Leah A Krubitzer
While the organization of sensory cortical areas in adult mammals is well understood, very little is known about how this organization develops. This is in large part because working with infant animals is difficult under the best of circumstances. In order to examine the development of sensory cortical organization we developed a protocol for mapping the receptive fields for all body parts of very young (i.e., postnatal day [P]5-15) rats and quantifying the changes that occur in receptive fields over the first two postnatal weeks, which is a critical time in the development of sensory systems. Pilot recordings were performed within the primary somatosensory cortex (S1) of P7 and P13 subjects. These data reveal several developmental changes in cortical organization, including a developmental decrease in receptive field size as well as an age-related increase in the number of body parts represented in the cortex. These data provide a novel view of the developing cortex and allow us to witness the developmental changes in receptive field size and organization as they occur. While our pilot trials have been performed in S1, the techniques established in these pilot tests will also be used to examine the development of receptive fields within primary visual cortex (V1) and compare V1 organization across a variety of developmental timepoints. Finally, future work will benefit from the addition of data acquisition and analysis software that allows us to quantify neuronal activity evoked through sensory stimulation of the subject.