S&P102

Instructor:
Dr. Ione Fine
858-822-0606
fine@salk.edu
office hours: Tuesday 12-1, Thursday 12-1
                  CHIP annex, RM 3570

TAs:
Edward Hubbard
edhubbard@psy.ucsd.edu
office hours: Tues 1-2, Wednesday 11-12
B-517 (Basement McGill Annex).

Lindsay Shenk
lshenk@ucsd.edu
Office hours: Monday 9:30-10:30
B-545 (Basement McGill Annex)

McGill building has a figure-8 configuration, one part of the figure 8 (the part without elevators) is the annex.

To get to the 3rd floor of the annex. Go to the main McGill building. Go up the elevators to the third floor. On the wall outside the elevator will be an small sign pointing towards the annex.

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Class Paper

The class paper is worth 25% of the final grade. Read one of the original research papers below and summarize it in no more than 1000 words.
paper to be handed in, May 29th (in class)

(1) Ernst, M. O. and M. S. Banks (2000). “Touch can change visual slant perception.” Nature Neuroscience 3(1): 69-73. Paper link
    The visual system uses several signals to deduce the three-dimensional structure of the environment, including binocular disparity, texture gradients, shading and motion parallax. Although each of these sources of information is independently insufficient to yield reliable three-dimensional structure from everyday scenes, the visual system combines them by weighting the available information; altering the weights would therefore change the perceived structure. We report that haptic feedback (active touch) increases the weight of a consistent surface-slant signal relative to inconsistent signals. Thus, appearance of a subsequently viewed surface is changed: the surface appears slanted in the direction specified by the haptically reinforced signal.

(2) Gandhi, S. P., D. J. Heeger, et al. (1999). “Spatial attention affects brain activity in human primary visual cortex.” Proc Natl Acad Sci U S A 96(6): 3314-9. Paper link
    Functional MRI was used to test whether instructing subjects to attend to one or another location in a visual scene would affect neural activity in human primary visual cortex. Stimuli were moving gratings restricted to a pair of peripheral, circular apertures, positioned to the right and to the left of a central fixation point. Subjects were trained to perform a motion discrimination task, attending (without moving their eyes) at any moment to one of the two stimulus apertures. Functional MRI responses were recorded while subjects were cued to alternate their attention between the two apertures. Primary visual cortex responses in each hemisphere modulated with the alternation of the cue; responses were greater when the subject attended to the stimuli in the contralateral hemifield. The attentional modulation of the brain activity was about 25% of that evoked by alternating the stimulus with a uniform field.

(3) Kanwisher, N., J. McDermott, et al. (1997). “The fusiform face area: a module in human extrastriate cortex specialized for face perception.” J Neurosci 17(11): 4302-11.Paper link
    Using functional magnetic resonance imaging (fMRI), we found an area in the fusiform gyrus in 12 of the 15 subjects tested that was significantly more active when the subjects viewed faces than when they viewed assorted common objects. This face activation was used to define a specific region of interest individually for each subject, within which several new tests of face specificity were run. In each of five subjects tested, the predefined candidate "face area" also responded significantly more strongly to passive viewing of (1) intact than scrambled two-tone faces, (2) full front-view face photos than front- view photos of houses, and (in a different set of five subjects) (3) three-quarter-view face photos (with hair concealed) than photos of human hands; it also responded more strongly during (4) a consecutive matching task performed on three-quarter-view faces versus hands. Our technique of running multiple tests applied to the same region defined functionally within individual subjects provides a solution to two common problems in functional imaging: (1) the requirement to correct for multiple statistical comparisons and (2) the inevitable ambiguity in the interpretation of any study in which only two or three conditions are compared. Our data allow us to reject alternative accounts of the function of the fusiform face area (area "FF") that appeal to visual attention, subordinate-level classification, or general processing of any animate or human forms, demonstrating that this region is selectively involved in the perception of faces.

(4) Roorda, A., A. B. Metha, et al. (2001). “Packing arrangement of the three cone classes in primate retina.” Vis Research 41(10-11): 1291-306. Paper link
    We describe a detailed analysis of the spatial arrangement of L, M and S cones in the living eyes of two humans and one monkey. We analyze the cone mosaics near 1 degrees eccentricity using statistical methods that characterize the arrangement of each type of cone in the mosaic of photoreceptors. In all eyes, the M and L cones are arranged randomly. This gives rise to patches containing cones of a single type. In human, but not in monkey, the arrangement of S-cones cannot be distinguished from random.

(5) Shadlen, M. N. and W. T. Newsome (1996). “Motion perception: Seeing and deciding.” Proc Natl Acad Sci U S A 93: 628-633. Paper link
    The primate visual system offers unprecedented opportunities for investigating the neural basis of cognition. Even the simplest visual discrimination task requires processing of sensory signals, formation of a decision, and orchestration of a motor response. With our extensive knowledge of the primate visual and oculomotor systems as a base, it is now possible to investigate the neural basis of simple visual decisions that link sensation to action. Here we describe an initial study of neural responses in the lateral intraparietal area (LIP) of the cerebral cortex while alert monkeys discriminated the direction of motion in a visual display. A subset of LIP neurons carried high-level signals that may comprise a neural correlate of the decision process in our task. These signals are neither sensory nor motor in the strictest sense; rather they appear to ref lect integration of sensory signals toward a decision appropriate for guiding movement. If this ultimately proves to be the case, several fascinating issues in cognitive neuroscience will be brought under rigorous physiological scrutiny.

(6) Watanabe, T., J. E. Nanez, et al. (2001). “Perceptual learning without perception.” Nature 413(6858): 844-8. Paper link
    The brain is able to adapt rapidly and continually to the surrounding environment, becoming increasingly sensitive to important and frequently encountered stimuli. It is often claimed that this adaptive learning is highly task-specific, that is, we become more sensitive to the critical signals in the tasks we attend to. Here, we show a new type of perceptual learning, which occurs without attention, without awareness and without any task relevance. Subjects were repeatedly presented with a background motion signal so weak that its direction was not visible; the invisible motion was an irrelevant background to the central task that engaged the subject's attention. Despite being below the threshold of visibility and being irrelevant to the central task, the repetitive exposure improved performance specifically for the direction of the exposed motion when tested in a subsequent suprathreshold test. These results suggest that a frequently presented feature sensitizes the visual system merely owing to its frequency, not its relevance or salience.

S&P 102