Neuroscience 2003 Abstract
| Presentation Number: | 194.22 |
|---|---|
| Abstract Title: | Further explorations of the dissociative effect. |
| Authors: |
Sheth, B. R.*1
1Biol. / CNS, California Inst. Technol, Pasadena, CA |
| Primary Theme and Topics |
Cognition and Behavior - Human Cognition and Behavior -- Learning and memory |
| Session: |
194. Human Cognition and Behavior: Memory II Poster |
| Presentation Time: | Sunday, November 9, 2003 9:00 AM-10:00 AM |
| Location: | Morial Convention Center - Hall F-I, Board # R5 |
| Keywords: | CLASSICAL CONDITIONING, ASSOCIATIVE LEARNING, ORIENTATION, LEARNING AND MEMORY |
We reported a novel finding termed the dissociative effect (SFN, 2002). After induction to two static full-field patterns--red horizontal (h) stripes and achromatic (achr.) h stripes--, alternating with a 10s-10s induction cycle (ind. cyc.) for 20 min. total, test h stripes appeared redder and test vertical (v) stripes greener than before, contrary to past reports (McCollough, 1965). Here, we explore four possible mechanisms. There may be a high but transient neural response to the red h, but a weak but sustained response to the immediate greenish h (reddish v) aftereffect (AE). It is claimed that the longer the response, the longer its AE will last, which explains the AE of the AE or after-aftereffect (AAE, or dissociative AE: reddish h, greenish v). Thus, a shorter 2s-2s ind. cyc. should reduce or even reverse the dissociative AE. However, it remained unabated. A second model claims that, as the presented color activates the brain more than does its weaker AE, it should be inhibited more, which would favor the AAE over the AE in the long term. If the h stripes were not red but weakly reddish, the signal would be too weak to be inhibited, and the final AE would be associative (greenish h). However, no AE was seen; also, longer (40 min.) induction still elicited a dissociative AE. A third model claims that, as the achr. inducer succeeds the chromatic one, it selectively blocks the chromatic AE (greenish h); if the achr. inducer were to last longer, it should also block the AAE. However, a strong dissociative AE was seen with a 2 s red h, 18 s achr. h ind. cyc. Interestingly, a classical associative AE was seen with an 18 s red h, 2 s achr. h cycle. We are presently exploring a model in which adaptation affects multiple levels of the neural hierarchy. Induction on red h stripes fatigues red h neurons, disinhibiting green h and red v neurons. The achr. inducer stimulus causes the disinhibition to be neurally expressed (not stored) as a weak AE, which then creates its own AAE downstream. The AAE, being at a higher brain level, overrides the AE.
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2003 Neuroscience Meeting Planner. New Orleans, LA: Society for Neuroscience, 2003. Online.
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