BRAIN ASYMMETRY FOR EMOTIONAL PROSODY IN KLINEFELTER:
CAUSAL RELATIONS INVESTIGATED WITH TMS

BRAIN ASYMMETRY FOR EMOTIONAL PROSODY IN KLINEFELTER: CAUSAL RELATIONS
INVESTIGATED WITH TMS RELATIONS INVESTIGATED WITH TMS. Laterality of the human
brain forms one of the most interesting asymmetries described in humans.
However, little is known about the origin of these asymmetries (Geschwind,
1998). A genetic disorder that is associated with abnormal brain development
and behavior is Klinefelter Syndrome (KS), characterised by the presence of an
extra X chromosome in males (47, XXY karyotype). The phenotype of KS may
include physical abnormalities such as tall stature, hypogonadism, infertility
and gynecomastia and behavioural and cognitive abnormalities. Men with KS also
have an increased risk of psychosis. However, difficulties in social
interaction form one of the most disabling symptoms in Klinefelter men. It has
been proposed that these problems in social communication can be explained by
disabilities in the language domain (Rovet et al., 1996). Both left and right
hemispheric language functions have been shown to be impaired in KS. Van Rijn
and colleagues also found that men with KS show high levels of schizophrenia
spectrum pathology (van Rijn et al., 2006a). Difficulties in social adaptation
together with the structural brain abnormalities associated with the XXY
karyotype, suggest that a genetic mechanism involving genes on the X chromosome
might lead to disturbances in the development of social cognition in XXY men.
Language and emotion form the corner stones of social cognition. Interestingly,
for both language and emotion, functional asymmetries have been found. Most
aspects of language, like semantics and syntax, are lateralized to the left
hemisphere in healthy subjects, while emotion is hypothesized to be mostly
lateralized to the right hemisphere. Impairments in language processing have
been reported in various studies on KS. Reduced or abnormal lateralization of
language has also been found in Klinefelter syndrome (Geschwind, 1998; van Rijn
et al., 2008). Impairments in emotional prosody perception have been reported
in KS (van Rijn et al., 2007), but no studies have been done on the
lateralization of this function.

The aim of the present experiment is to test whether the normally
right-lateralised response to emotional prosody is reduced in KS.

The hypothesis will be tested by means of transcranial magnetic stimulation
(TMS) and functional magnetic resonance imaging (fMRI). To study the neural
substrate of emotional prosody perception in men with KS, subjects will perform
an emotional prosody task in the scanner. The results will give us information
about the degree of lateralization in KS men. TMS is used to establish causal
relations between processing in localized brain regions and emotional language
processing. An area most consistently found to be crucial for emotional prosody
perception is the superior temporal gyrus (STG) (Adolphs et al, 2002 ;
(Beaucousin et al., 2007). The present study includes rTMS over not only the
right STG but also the left STG, which allows conclusions regarding
lateralization of: i) emotional prosody and emotional semantics, and ii)
withdrawal and approach emotions. Our main question is wether the
lateralizations of emotional prosody (and emotional semantics) are aberrant in
KS as compared to healthy controls.

First we will phone the participants to inform them about the experiment, and
check all in and exclusiecriteria.
We ask the participants to come twice.
Duration of the three sessions together will be around 330 minutes.
There are no risks in participating in our study.
No benefits.