Emotion-Cognition Interaction in Psychotic Disorders

Selective attention
A robust finding in patients suffering from schizophrenia is a disturbance in
selective attention. One paradigm to examine selective attention is the Stroop
test. Mostly three types of stimuli are used: colour-words written in the same
(congruent) or a different (incongruent) colour and neutral stimuli, for
example a certain number of *X*, or non-colour words. Subjects are asked to
react to the colour of the letters words are written in and to ignore the
content of the word. Two phenomena are described, interference, e.g. an
increase in reaction time (RT) for incongruent compared to neutral stimuli, and
facilitation, e.g. a decrease of RT for congruent compared to neutral stimuli.
The same holds true for words with an emotional compared to neutral content in
several patient groups. Compared to healthy controls for schizophrenic patients
the results are divergent regarding the Stroop effect. In a pilot study
performed at Erasmus MC patients suffering from schizophrenia showed a reduced
Stroop effect to colour words, and no influence of emotional words (negative,
neutral, and positive) compared to healthy control subjects.

Working memory
Working memory (WM) is a modular system that enables subjects to maintain and
manipulate information over short periods of time (e.g., a few seconds) in the
service of other cognitive tasks (e.g., problem solving; guidance of response
behaviour etc.). Working memory is limited by capacity (number of items to be
recognized) and a time span of only several seconds wherein information can be
maintained. Furthermore, working memory is very sensitive to interference.
Since the investigation of Park and Holzman (1992) numerous studies
demonstrated spatial working memory deficits in schizophrenic patients (for an
overview see Barch (2006)). While verbal WM seems not to be impaired in
schizophrenic patients, it is well established for visuo-spatial tasks. Some
authors (Cohen 1999) attribute the demonstrated impairments to a basic deficit
in context processing. To investigate the emotional component in the working
memory, we want to adapt the response-inhibition (go/no-go) task described by
Servan-Schreiber (1996) and Cohen (1999).

Long-term memory
Long-term memory is the ability to acquire and store information over a period
of time. Due to the time span it is divided in long- (e.g. 24 hours), secondary
memory (less than one hour) and short-term (seconds to minutes) memory (Green
2000). If the amount of data to be remembered exceeds working memory capacity,
and can*t be hold online, content has to be stored in long-term memory. Remote
memory is typically tested after a delay period of 24 hours. It has been shown
in several studies that emotional content of visual (Kensinger 2003) and verbal
stimuli (Goschke 1996) influences long-term memory performance. Emotional
stimuli will be better recognized than neutral. In healthy subjects, emotional
words are recalled significantly better than neutral words. Recognition of
emotional words is relatively stable, in contrast to memory for neutral words,
which decays over time. Memory for neutral words is enhanced when words are
presented in an emotional context. This suggests that there is emotional
enhancement of memory at short and long delays and that emotional context may
be encoded independently of word meaning (Brierley 2007). In a recent study
schizophrenic patients demonstrate a lack of memory enhancement for positive
pictures (Herbener 2007). In order to a better control for this influence the
long term memory task will be presented in two modalities, a verbal and a
visual long-term memory task.

The main goal of our proposal is to study the interaction between cognitive and
emotional capacities in schizophrenia.
In numerous studies patients with schizophrenia show impairments in all major
cognitive domains (6) as well as impairments in the recognition of facial
expression (7). Most neuropsychological research, focusing on emotion, examines
the ability of patients with schizophrenia to detect and interpret facial
emotional expressions. Less knowledge exists on the way behaviour in patients
with schizophrenia is guided and influenced by the emotional context in which
cognitive demands occur (8). The way the cognitive and emotional domain may
interact in experimental and more naturalistic environments received only
little attention. Furthermore, it remains unclear, in which way deficits in
this domain may predict the further course of the disease(9). Treatment
compliance and limited attention span are well known problems in young
schizophrenic patients. By studying the influence of emotion on cognitive
functions, it is possible to identify a factor that can increase the
effectiveness of standard treatment programs.

Selective attention (Stroop)
A modified version of the Stroop test:
A computer-based single-trial design will be presented with button response on
the keyboard. Six categories of stimuli will be presented: congruent
colour-words; incongruent colour-words; non-words (XXXX); negative-, neutral-
and positive-valenced words. Each session comprises 40 congruent and 40
incongruent colour words, 40 non-words and 20 emotional words from each
category, summing up in total 180 stimuli. Words will be presented for 2000 ms
with an interstimulus interval of 1000 ms. Stimuli will be presented in a
randomised order, no feedback will be provided. Four keys of the
computer-keyboard are labelled in the same colour wherein the words are
displayed (blue, green, red and yellow). Two sessions with different emotional
words have to be performed. Prior to the runs subjects get accustomed to the
task with a practice session comprising 160 trials with non-words, congruent,
incongruent and neutral words (40 each). In order to learn the task during the
practice session at the end a summary of errors will be provided. A speed
instruction will be given, asking subjects to respond as fast as possible to
the presented item.

Working memory task (WM)
A modified version of the Response-Inhibition task:
In our version a stream of faces is presented instead of letters. A
computer-based design will be presented with one button assigned to *YES* on
the keyboard. The participants* task is to respond to one specific neutral face
(target face = X) when preceded by a certain female (male) face (= A).
Participants have to refrain from responding when the target face is preceded
by any other female (male) face (= B) or the female face is followed by another
face than the target face (= Y) (inhibition). Time to respond will be limited
to 1000 ms. A feedback signal will be provided in form of different sounds for
correct hits, correct rejection and misses or false alarms. Subjects will
receive an accuracy and speed instruction, asking subjects to answer as precise
as possible.

Visual long term memory
To test the interference of emotion on remote and secondary visual memory,
pictures from the
International Affective Pictures System (IAPS)(63), a standardized database of
photographs which has been validated by means of valence and arousal will be
used. Recently a set of pictures from the IAPS has been validated for
schizophrenic patients demonstrating no differences to healthy control subjects
(25).
Task
Testing will be computer-based and will take place on two successive days. On
the first day of testing, participants will be shown a total of 60 pictures.
These will consist of 20 pictures with a positive content, 20 pictures with a
neutral content and 20 with a negative content in a randomized order. Pictures
with negative and positive emotional content will be matched for arousal
values, because arousal has a significant effect on recognition memory (28).
For neutral pictures arousal level is usually lower, so we expect, that neutral
stimuli will statistically differ from emotional stimuli by means of arousal.
Pictures with explicitly sexual content or mutilation will not be used.
Pictures will be displayed for 2000 ms on a computer screen with a black
background and participants are instructed to encode the pictures due to a
recognition task the day after. Directly after the presentation subjects will
have five minutes to give a free recall of the pictures they have seen. After
each picture presentation subjects are asked to assign whether they recognize
the picture and after that to On the consecutive day, participants will be
presented a series of 120 pictures from the IAPS in a randomized order with a
duration of 2000ms, comprising the 60 pictures previously seen (list 1) and 20
new pictures each with a positive, neutral and negative content (list 2).
Participants are instructed to indicate if they recognize the picture from the
first day to test remote visual memory by pressing a designated button on the
computer keyboard for *YES* or *NO*. For the recognition test an accuracy
instruction will be given. Further subjects will be asked to rate the pictures
for valence and arousal scale using the self-assessment manikin (SAM)(64),
which will be displayed separately from the IAPS-picture. After scoring the
following picture will be displayed on the screen of the computer. To avoid
systematic influences half of the group will see list 1 on day 1 and the other
half list 2. Time necessary to succeed the task will be recorded.

Verbal long term memory
To test the interference of emotion on remote and secondary verbal memory the
same procedure as for visual memory will be used. In total 120 words of list of
Dutch words (65), rated for their affective valence and familiarity will be
used.
Task
Testing will be computer-based and will find place on two successive days. On
the first day of testing, participants will be shown a total of 60 words. These
will comprise of 20 words with a positive content, 20 words with a neutral
content and 20 words with a negative content. Words with negative and positive
emotional content will be matched for arousal values, because arousal has a
significant effect on recognition memory (28). For neutral words arousal level
is usually lower, so we expect that neutral stimuli will statistically differ
from emotional stimuli by means of arousal. Words will be displayed for 1000 ms
on a computer screen with a black background and participants are instructed to
encode the pictures due to a recognition task the consecutive day. Directly
after the presentation subjects will have five minutes to give a free recall of
the words they have seen. On the consecutive day, participants will be
presented a series of 120 words in a randomized order with a duration of
1000ms, comprising the 60 words previously seen (list 1) and 20 new words each
with a positive, neutral and negative content (list 2). Participants are
instructed to indicate if they recognize the words from the first day to test
remote verbal memory by pressing a designated button on the computer keyboard
for *YES* or *NO*. For the recognition test an accuracy instruction will be
given. Further subjects will be asked to rate the words for valence and arousal
scale using the self-assessment manikin (SAM)(64), which will be displayed
separately from the words. To avoid systematic influences half of the group
will see list 1 on day 1 and the other half list 2. Time necessary to succeed
the task will be recorded.

All examinations are computer-based neuropsychological examinations. For none
of them any risk is known. The burden for all subjects is two hours spend in
front of a computer next to complete some questionnaires.
There is no immediate benefit for any of the participants.