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Uncovering Camouflage: The Neural Basis of Long-Term Memory for One-Shot Perceptual Exposure. Nava Rubin Center for Neural Science New York University. Yadin Dudai & Kelly Ludmer Neurobiology Dept. Weizman Institute of Science. Abrupt transitions in perceptual organization. 4.

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Presentation Transcript
slide1

Uncovering Camouflage:

The Neural Basis of Long-Term Memory

for One-Shot Perceptual Exposure

Nava Rubin

Center for Neural Science

New York University

Yadin Dudai & Kelly Ludmer

Neurobiology Dept.

Weizman Institute of Science

slide3

Abrupt transitions in perceptual organization

(Rubin, Nakayama and Shapley, 1997, 2004)

4

slide4

Hebb (1949):

“is insight or hypothesis -- or, in the broadest terms, intelligence -- something distinct from the mechanism of association?”

[In order to induce insight, one needs]

“tasks ... of just the right degree of difficulty ... [they] must neither be so easy so that the animal solves the problem at once, thus not

allowing to analyze the solution; nor so hard that the animal fails to solve it except by rote learning in a long series of trials.”

6

slide5

1 -

0.5 -

0 -

Fraction responses “thin”

Inducers’ rotation (deg)

Illusory Shape Discrimination Task

“thin”

or

“fat”?

(Ringach & Shapley, 1996)

8

slide6

100 ms

Abrupt improvement in performance

10

slide8

Abrupt improvement in performance

- specific to retinal size!

14

slide10

Perceptual Learning:

Prevailing Paradigms and Findings

Incremental,

Watanabe

et al

2002

Stimulus-specific

Ahissar

And

Hochstein

2000

common conclusion: (neurally) early learning site(s)

18

slide11

Hebb (1949):

“insight ... continually affects the learning of the adult animal … it is not wholly separate from rote learning.”

Hebb proposed a unitary mechanism, based on the associations of co-occurring internal states, within which to understand all learning phenomena.

However, he emphasized that the sequence of internal states is not merely determined by external events, but is rather an active process in which the animal is continually attempting to discover structure and meaning in the incoming information.

20

slide13

Making camouflage images:

Original  Gaussian blur (1 free parameter: s) B/W threshold (2nd free param, q)

However, not all images lend themselves to becoming good camouflages.

Many images are “too easy” even after blur+thresholding:

… whereas others are not “perceptually compelling” even after seeing the solution:

(“two-tone”)

24

slide14

Camouflage images vary in how perceptually compelling the are. Also, observers vary in how compelling they judge a particular image to be.

Conjecture: the degree to which a camouflage is perceptually compelling (after being shown the solution) will have an effect on how likely it is to be remembered in the future.

26

slide15

Ingredients of the camouflage paradigm

Perceptual (re-)organization

Bottom-up/top-down interactions

Perceptual learning

Spontaneous insight (“Aha!”)

or

Induced insight

Encoding

Consolidation

Short- and long-term recognition

~Episodic memory

 A rich yet relatively controlled paradigm to study

perceptual learning, short- and long-term memory formation.

}

Perception

(Previously studied, e.g. Dolan et al 1997)

}

Memory

28

slide16

Induced Insight Protocol: the ‘study’ phase

(30 images per observer, out of a pool of 40 images total)

If you think you identified the object, press “Yes”

spontaneous recognition: 30%

30

slide17

Induced Insight Protocol: the ‘test’ phase

Performed on 30 images from ‘study’ +10 novel images

Administered to three different groups:

10 min, 1 day, 7 or 21 days after study

Up to 10 sec Up to 10 sec

Up to 10 sec

32

the memory curve each time point a is from a different group of 10 12 observers
The memory curve (each time point a is from a different group of 10-12 observers)

‘study’

34

brain imaging of induced insight
Brain Imaging of Induced Insight
  • 17 subjects (3 eliminated; 9/14 men)
  • fMRI scanning during the ‘study’ phase
  • ‘Test’ phase a week later (outside the magnet).
  • 3T Siemens Allegra scanner
  • Quadra coil, 36 slices, 4mm, ac-pc
  • 3x3 mm voxels
  • TR=2 sec

36

slide20

….

“Rem “NotRem” “Rem” “Spont” .…

Subsequent Memory Analysis

‘Study’ phase events are classified according to the behavioral performance during ‘Test’:

(Note: ‘spont’ determined already at ‘study’ time)

38

slide21

….

….

“Rem “NotRem” “Rem” “Spont” .…

Terminology, within-trial sub-events:

CAM1 SOL CAM2

(10 sec) (4 sec) (2 sec)

Terminology, trial type classification:

40

analysis
Analysis
  • Generate cortical “regions of interests” (ROIs) from contiguous voxels that showed higher activation during the SOL (all event types) than during blank control trials.
  • Compare the event-triggered average time-courses* of each ROI for the different event types (Rem, NotRem, Spont)

* - or alternatively deconvolved time-courses

42

slide23

ROI Results: Visual Cortex

SPONT

NoRec

Rem

NoRem

early vis cortex

(V1/V2)

% signal change

0 2 4 6 8 10 12 [sec]

0 2 4 6 8 10 12 [sec]

LOC

Mid-level visual areas predict subsequent

SOL memory

0 2 4 6 8 10 12 [sec]

0 2 4 6 8 10 12 [sec]

pFs

(aka

VOT)

…and hi-level

vis areas (VOT/pFs)

do not!

0 2 4 6 8 10 12 [sec]

0 2 4 6 8 10 12 [sec]

44

slide24

ROI Results: Amygdala

SPONT

NoRec

Rem

NoRem

% signal change

0 2 4 6 8 10 12 [sec]

0 2 4 6 8 10 12 [sec]

Activity in the amygdala during SOL viewing is the strongest predictor for subsequent SOL memory

46

slide26

Conclusions

The degree to which a camouflage image is perceptually compelling, as manifested by LOC activity, will have an effect on how likely it is to be remembered in the future.

There is an involvement of an emotional component: camouflage images that survive in long term memory are associated with greater activity in the amygdala.

50