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Conditional associative learning examined in a paralyzed patient with amyotrophic lateral sclerosis using brain-computer interface technology.

Iversen I, Ghanayim N, Kübler A, Neumann N, Birbaumer N, Kaiser J - Behav Brain Funct (2008)

Bottom Line: A smiley was presented as a reward when he hit the correct target.In contrast, the patient showed clear evidence that A-B and B-C training had resulted in formation of equivalence classes.The brain-computer interface technology combined with the matching to sample method is a useful way to assess various cognitive abilities of severely paralyzed patients, who are without reliable motor control.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Medical Psychology, Goethe-University, Frankfurt am Main, Germany. j.kaiser@med.uni-frankfurt.de.

ABSTRACT

Background: Brain-computer interface methodology based on self-regulation of slow-cortical potentials (SCPs) of the EEG (electroencephalogram) was used to assess conditional associative learning in one severely paralyzed, late-stage ALS patient. After having been taught arbitrary stimulus relations, he was evaluated for formation of equivalence classes among the trained stimuli.

Methods: A monitor presented visual information in two targets. The method of teaching was matching to sample. Three types of stimuli were presented: signs (A), colored disks (B), and geometrical shapes (C). The sample was one type, and the choice was between two stimuli from another type. The patient used his SCP to steer a cursor to one of the targets. A smiley was presented as a reward when he hit the correct target. The patient was taught A-B and B-C (sample - comparison) matching with three stimuli of each type. Tests for stimulus equivalence involved the untaught B-A, C-B, A-C, and C-A relations. An additional test was discrimination between all three stimuli of one equivalence class presented together versus three unrelated stimuli. The patient also had sessions with identity matching using the same stimuli.

Results: The patient showed high accuracy, close to 100%, on identity matching and could therefore discriminate the stimuli and control the cursor correctly. Acquisition of A-B matching took 11 sessions (of 70 trials each) and had to be broken into simpler units before he could learn it. Acquisition of B-C matching took two sessions. The patient passed all equivalence class tests at 90% or higher.

Conclusion: The patient may have had a deficit in acquisition of the first conditional association of signs and colored disks. In contrast, the patient showed clear evidence that A-B and B-C training had resulted in formation of equivalence classes. The brain-computer interface technology combined with the matching to sample method is a useful way to assess various cognitive abilities of severely paralyzed patients, who are without reliable motor control.

No MeSH data available.


Top: Schematic of the three types of stimuli used: signs, colored disks, and geometrical forms. The objective of training was to form three classes of stimuli, with each class consisting of one sign, one color, and one geometrical form. Middle: Training related a stimulus from type A to a stimulus from type B, the A → B relations, and a stimulus from type B to a stimulus from type C, the B → C relations (solid arrows). All other relations among the stimuli were not trained (punctuated arrows). Instead, they were tested. Bottom: Sequence of relations trained and tested. Numbers refer to the arrows in the middle display.
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Figure 1: Top: Schematic of the three types of stimuli used: signs, colored disks, and geometrical forms. The objective of training was to form three classes of stimuli, with each class consisting of one sign, one color, and one geometrical form. Middle: Training related a stimulus from type A to a stimulus from type B, the A → B relations, and a stimulus from type B to a stimulus from type C, the B → C relations (solid arrows). All other relations among the stimuli were not trained (punctuated arrows). Instead, they were tested. Bottom: Sequence of relations trained and tested. Numbers refer to the arrows in the middle display.

Mentions: The present research is a further development to study conditional relational learning in ALS patients. The experiment was designed to determine whether the patient could learn arbitrary conditional relations and whether the training formed classes of equivalent stimuli (e.g., [1,2]). Fig. 1 illustrates the logic of the experiment. The stimuli are of three types: signs, colored disks, and geometrical shapes. These stimuli are to be associated arbitrarily to form three classes with each class consisting of one sign, one colored disk, and one geometrical shape. Fig. 1, top, shows the stimulus types and the classes to be formed; for example, class 1 will consist of the three stimuli: a $ sign, a blue disk, and a white triangle. The training method is to show one stimulus from one type as a sample in the matching to sample method and have two stimuli as comparison or choice stimuli, the correct comparison is a stimulus from the same class as the sample, while the incorrect stimulus is from another class. Thus, for class 1, to teach the relation between type A and type B stimuli, or the A → B relation (sample → comparison), the sample on a given trial may be the $ sign and the two comparisons a blue disk and a red disk, with the blue disk being correct. On another trial, the sample may be the & sign with the two comparisons being one red and one blue disk, with the red disk being correct. Thus, whether red or blue is the correct choice is conditional on the sample being $ or &. Customarily with healthy human subjects, teaching the A → B and B → C relations makes the stimuli form classes of equivalent stimuli. Once the equivalence classes form, the subject can also correctly match all the untaught relations among the stimuli, and the stimuli show symmetrical, transitive, and equivalence relations [2]. The solid arrows in the middle part of Fig. 1 show the trained relations A → B and B → C. The punctuated arrows show the relations that the participant was not explicitly taught but should also have learned if the stimuli in each class became equivalent during training. Thus, to determine whether our patient had formed equivalence classes after training to do A → B and B → C relations, we tested the two symmetry relations B → A and C → B, the transitivity relation A → C, and the equivalence or reversed transitivity relation C → A. The specific aim of the study was to determine whether the ALS patient could use conditional association learning to form classes of arbitrarily related visual items and whether the class items had become equivalent.


Conditional associative learning examined in a paralyzed patient with amyotrophic lateral sclerosis using brain-computer interface technology.

Iversen I, Ghanayim N, Kübler A, Neumann N, Birbaumer N, Kaiser J - Behav Brain Funct (2008)

Top: Schematic of the three types of stimuli used: signs, colored disks, and geometrical forms. The objective of training was to form three classes of stimuli, with each class consisting of one sign, one color, and one geometrical form. Middle: Training related a stimulus from type A to a stimulus from type B, the A → B relations, and a stimulus from type B to a stimulus from type C, the B → C relations (solid arrows). All other relations among the stimuli were not trained (punctuated arrows). Instead, they were tested. Bottom: Sequence of relations trained and tested. Numbers refer to the arrows in the middle display.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC2599893&req=5

Figure 1: Top: Schematic of the three types of stimuli used: signs, colored disks, and geometrical forms. The objective of training was to form three classes of stimuli, with each class consisting of one sign, one color, and one geometrical form. Middle: Training related a stimulus from type A to a stimulus from type B, the A → B relations, and a stimulus from type B to a stimulus from type C, the B → C relations (solid arrows). All other relations among the stimuli were not trained (punctuated arrows). Instead, they were tested. Bottom: Sequence of relations trained and tested. Numbers refer to the arrows in the middle display.
Mentions: The present research is a further development to study conditional relational learning in ALS patients. The experiment was designed to determine whether the patient could learn arbitrary conditional relations and whether the training formed classes of equivalent stimuli (e.g., [1,2]). Fig. 1 illustrates the logic of the experiment. The stimuli are of three types: signs, colored disks, and geometrical shapes. These stimuli are to be associated arbitrarily to form three classes with each class consisting of one sign, one colored disk, and one geometrical shape. Fig. 1, top, shows the stimulus types and the classes to be formed; for example, class 1 will consist of the three stimuli: a $ sign, a blue disk, and a white triangle. The training method is to show one stimulus from one type as a sample in the matching to sample method and have two stimuli as comparison or choice stimuli, the correct comparison is a stimulus from the same class as the sample, while the incorrect stimulus is from another class. Thus, for class 1, to teach the relation between type A and type B stimuli, or the A → B relation (sample → comparison), the sample on a given trial may be the $ sign and the two comparisons a blue disk and a red disk, with the blue disk being correct. On another trial, the sample may be the & sign with the two comparisons being one red and one blue disk, with the red disk being correct. Thus, whether red or blue is the correct choice is conditional on the sample being $ or &. Customarily with healthy human subjects, teaching the A → B and B → C relations makes the stimuli form classes of equivalent stimuli. Once the equivalence classes form, the subject can also correctly match all the untaught relations among the stimuli, and the stimuli show symmetrical, transitive, and equivalence relations [2]. The solid arrows in the middle part of Fig. 1 show the trained relations A → B and B → C. The punctuated arrows show the relations that the participant was not explicitly taught but should also have learned if the stimuli in each class became equivalent during training. Thus, to determine whether our patient had formed equivalence classes after training to do A → B and B → C relations, we tested the two symmetry relations B → A and C → B, the transitivity relation A → C, and the equivalence or reversed transitivity relation C → A. The specific aim of the study was to determine whether the ALS patient could use conditional association learning to form classes of arbitrarily related visual items and whether the class items had become equivalent.

Bottom Line: A smiley was presented as a reward when he hit the correct target.In contrast, the patient showed clear evidence that A-B and B-C training had resulted in formation of equivalence classes.The brain-computer interface technology combined with the matching to sample method is a useful way to assess various cognitive abilities of severely paralyzed patients, who are without reliable motor control.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Medical Psychology, Goethe-University, Frankfurt am Main, Germany. j.kaiser@med.uni-frankfurt.de.

ABSTRACT

Background: Brain-computer interface methodology based on self-regulation of slow-cortical potentials (SCPs) of the EEG (electroencephalogram) was used to assess conditional associative learning in one severely paralyzed, late-stage ALS patient. After having been taught arbitrary stimulus relations, he was evaluated for formation of equivalence classes among the trained stimuli.

Methods: A monitor presented visual information in two targets. The method of teaching was matching to sample. Three types of stimuli were presented: signs (A), colored disks (B), and geometrical shapes (C). The sample was one type, and the choice was between two stimuli from another type. The patient used his SCP to steer a cursor to one of the targets. A smiley was presented as a reward when he hit the correct target. The patient was taught A-B and B-C (sample - comparison) matching with three stimuli of each type. Tests for stimulus equivalence involved the untaught B-A, C-B, A-C, and C-A relations. An additional test was discrimination between all three stimuli of one equivalence class presented together versus three unrelated stimuli. The patient also had sessions with identity matching using the same stimuli.

Results: The patient showed high accuracy, close to 100%, on identity matching and could therefore discriminate the stimuli and control the cursor correctly. Acquisition of A-B matching took 11 sessions (of 70 trials each) and had to be broken into simpler units before he could learn it. Acquisition of B-C matching took two sessions. The patient passed all equivalence class tests at 90% or higher.

Conclusion: The patient may have had a deficit in acquisition of the first conditional association of signs and colored disks. In contrast, the patient showed clear evidence that A-B and B-C training had resulted in formation of equivalence classes. The brain-computer interface technology combined with the matching to sample method is a useful way to assess various cognitive abilities of severely paralyzed patients, who are without reliable motor control.

No MeSH data available.