Transcript Electrophysiological correlates of biased memory

A conditioning experiment
Marianne Littel
FADO 2010
Classical conditioning has been suggested to
play an important role in the development,
maintenance, and relapse of drug use
(e.g., Davis and Gould, 2008; Hyman, 2005; Killen and Fortmann, 1997; O'Brien et al., 1975; Poulos et al., 1981).
UCS
SUBJECTIVE
CRAVING
UCR
CR
SMOKING
CS-2
CS
DRUG SEEKING
BEHAVIORS
CHANGES IN
PHYSIOLOGICAL
MEASURES

Smokers show increased physiological reactions and report
higher levels of craving following the presentation of smokingrelated stimuli than following the presentation of non-smoking
stimuli (e.g., Bevins et al., 2004; Carter & Tiffany, 1999; Chiamulara, 2005)
• It can only be assumed that these responses reflect prior classical conditioning!

Few studies demonstrate conditioning in smoking addiction
(Dols et al., 2002; Dols et al., 2000; Lazev et al., 1999; Thewissen et al., 2007; Thewissen et al., 2005)


No studies demonstrate higher-order conditioning in smoking
addiction
No studies reveal electrophysiological correlates of (higherorder) conditioning in smoking addiction
(time course, intensity, location)
1
2
No studies demonstrate higher-order conditioning in smoking
addiction
No studies reveal electrophysiological correlates of (higherorder) conditioning in smoking addiction
(time course, intensity, location)
Event Related Potentials
(ERP)
P3 component:
-Motivational engagement
-Allocation of attentional resources
-Motivated attention
Smokers
[µV]
-8
[µV]
-8
-4
-4
0
0
4
4
Neutral
Smoking
8
8
1 sec
1 sec
Littel M. & Franken, I.H.A. (2007). J Psychopharmacology.

30 smokers
◦ Min. 10 cig/day, M=15.6, SD=4.2
◦ FTND score 4.4 (low - medium levels of dependence)

31 non-smokers
◦ Max. 5 cig lifetime, M=1.1, SD=1.5
ERP
+
ERP
+
Smoking
trial
+
Fixation cross
1000 ms
+
Neutral
trial
CS2
400 ms
CS2 + CS1
400 ms
Design based on Franken et al. (in press).

160 trials: 80 CSsmoke, 80 CSneutral

Counterbalancing

Focus on P3 component
◦ Associated with motivational relevance & preference of
cues
◦ Previous studies show that P3 is enhanced in smokers
in response to smoking pictures that are suggested to
have acquired motivational significance through prior
first-order classical conditioning

2 blocks (first 40 vs. last 40)
Smokers display sign.
enhanced P3
amplitudes in response
to CS-1smoke
(compared to non-smokers
and CS-1neutral)
Non-smokers show no difference in P3
amplitudes to CS-2smoke and CS-2neutral
during block 1
SMOKERS
No P3 differences to CS-2smoke
and CS-2neutral during block 2
Smokers display a sign. enhanced P3 in
response to CS-2smoke during block 1
(compared to CS-2neutral )
SMOKE
Smokers display a
sign. enhanced P3 in
response to CS-2smoke
during block 1
(compared to non-smokers)
Smokers display a sign.
enhanced P3 in
response to CS-2neutral
during block 2
NEU
(compared to non-smokers)
P3
Block 1
P3
Block 2
Smokers
CS2smoke > CS2neutral
CS2smoke = CS2neutral
Non-smokers
CS2smoke = CS2neutral
CS2smoke = CS2neutral
P3
Block 1
P3
Block 2
CS2smoke
Smokers > Non-smokers Smokers = Non-smokers
CS2neutral
Smokers = Non-smokers Smokers > Non-smokers
The
Neutral
Smokers
conditioning
cues
display
that some
effect
are paired
sort
disappears...
of
with
delayed
motivationally
conditioning
relevant
for the
smokingrelated
neutralstimuli
cues..??are learned better and faster and gain more
motivational significance, at least for a short period of time, even
though they were never paired directly with an UCS.



Second-order conditioning is intrinsically
weaker than first-order conditioning and
appears typically to be transient
(Gewirtz & Davis, 2000).
Conditioned inhibition: the CS2 becomes a
signal for the nonoccurrence of reinforcement
and therefore inhibits the elicitation of
conditioned responses
Contingency awareness is necessary for
learned motivation in humans
(Hogarth and Duka, 2006).
Inhibition
After some time smokers loose their interest in
the stimuli paired with smoking cues, since they
predict no real smoking and subsequent
reinforcement (i.e., they become conditioned
inhibitors) and start focusing on the stimuli
paired with neutral cues instead.
Inhibition


Craving before the task - QSU
Valence, arousal & craving ratings of the
geometrical figures (cube, pyramid) - VAS
VAS scores
10
9
8
7
6
5
4
3
2
1
0
*
*
Smokers
*
Arousal Arousal Valence Valence Craving Craving
Smoke Neutral Smoke Neutral Smoke Neutral
Non-smokers
Enhanced P3 to CS-2smoke
Block 1; smokers
Enhanced P3 to CS-2neutral
Block 2; smokers
Craving
Valence rating
Craving
Valence rating
The observed shift in conditioning from smoking cues to neutral cues,
occurs slower or to a lesser extent in smokers that rate smoking
pictures as more positive AND in smokers that experience higher
craving levels.
Smokers show biased memory..
..as reflected by pathological learning patterns in which neutral cues
that are paired with motivationally relevant smoking-related stimuli
are learned better and faster and gain more motivational significance,
at least for a short period of time, even though they were never paired
directly with an UCS (smoking).
Results may help in understanding the etiology of smoking
addiction and its persistence.
Craving and relapse might not be triggered by concrete cues
and contexts only, but also, or predominantly, by more
complex and divergent cues and contexts that do not
necessarily have intrinsic motivational value, but have
motivational value that is acquired through the relatively
quick and easy processes of higher-order conditioning.



Smokers found the CS2smoke more arousing and more
pleasurable than non-smokers.
Smokers rated the CS2neutral as less pleasurable than nonsmokers.
Smokers reported more cue-elicited craving for the CS2smoke
compared to the CS2neutral.
VAS scores
10
9
8
7
6
5
4
3
2
1
0
Smokers
Non-smokers
Arousal Arousal Valence Valence Craving Craving
Smoke Neutral Smoke Neutral Smoke Neutral
CS1
P3 (300-450 ms): Fz, Cz, Pz
LPP (450-600 ms): Fz, Cz
CS2
P3 (330-430 ms): Fz, Pz