Sex Differences in the Neuromagnetic Cortical Response to Biological Motion

Abstract

Body motion is a rich source of information for social interaction, and visual biological motion processing may be considered
as a hallmark of social cognition. It is unclear, however, whether the social brain is sex specific. Here we assess sex impact
on the magnetoencephalographic (MEG) cortical response to point-light human locomotion. Sex differences in the cortical MEG
response to biological motion occur mostly over the right brain hemisphere. At early latencies, females exhibit a greater
activation than males over the right parietal, left temporal, and right temporal cortex, a core of the social brain. At later
latencies, the boosts of activation are greater in males over the right frontal and occipital cortices. The findings deliver
the first evidence for gender-dependent modes in the time course and topography of the neural circuitry underpinning visual
processing of biological motion. The outcome represents a framework for studying sex differences in the social brain in psychiatric
and neurodevelopmental disorders.

Full text

Sex Differences in the Neuromagnetic Cortical Response to Biological Motion
Marina A. Pavlova1, Alexander N. Sokolov2,3 and Christel Bidet-Ildei4,5
1
Department of Biomedical Magnetic Resonance, Medical School, Eberhard Karls University of Tübingen, Tübingen, Germany,
2
Center for Pediatric Clinical Studies (CPCS), Children’s Hospital, Medical School, Eberhard Karls University of Tübingen,
Tübingen, Germany,
3
Centre for Women’s Health, Medical School, Eberhard Karls University of Tübingen, Tübingen, Germany,
4
Center de Recherches sur la Cognition et l’Apprentissage (CeRCA), CNRS-UMR 7295, University of Poitiers, Poitiers, France and
5
Department of Sport Sciences, University of Poitiers, Poitiers, France
Address correspondence to Prof. Marina Pavlova, Department of Biomedical Magnetic Resonance, Medical School, Eberhard Karls University of
Tübingen, Hoppe-Seyler-Straße 3, 72076 Tübingen, Germany. Email: marina.pavlova@uni-tuebingen.de
Body motion is a rich source of information for social interaction,
and visual biological motion processing may be considered as a hall-
mark of social cognition. It is unclear, however, whether the social
brain is sex specific. Here we assess sex impact on the magnetoen-
cephalographic (MEG) cortical response to point-light human loco-
motion. Sex differences in the cortical MEG response to biological
motion occur mostly over the right brain hemisphere. At early laten-
cies, females exhibit a greater activation than males over the right
parietal, left temporal, and right temporal cortex, a core of the social
brain. At later latencies, the boosts of activation are greater in males
over the right frontal and occipital cortices. The findings deliver the
first evidence for gender-dependent modes in the time course and
topography of the neural circuitry underpinning visual processing of
biological motion. The outcome represents a framework for studying
sex differences in the social brain in psychiatric and neurodevelop-
mental disorders.
Keywords: biological motion, dynamic topography, gender, MEG, neural
circuitry, point-light displays, sex differences, social brain, time course
Introduction
Visual sensitivity to human body motion may serve as a hall-
mark of daily-life social cognition, and a basis for nonverbal
communication and social competence (Pavlova 2012). In ex-
perimental research, body motion is often represented by a
point-light technique as a set of dots on the joints of an other-
wise invisible body. This helps to isolate information revealed
by body motion from other cues. Visual sensitivity to point-
light body motion emerges early in life: already 2–3-day-old
human newborns are tuned to displays depicting point-light
walkers (Bidet-Ildei et al. 2014) and other vertebrates (Simion
et al. 2008). A wealth of brain imaging and neuropsychological
work in typically developing adults and children, lesional pa-
tients, and individuals with neurodevelopmental disorders
suggest that visual processing of point-light biological motion
involves the parieto-temporal junction and fusiform gyrus, por-
tions of the parietal and frontal cortices, primarily in the right
hemisphere, and subcortical structures such as the cerebellum
and amygdala (e.g., Grossman et al. 2000;Vaina et al. 2001;
Pavlova, Marconato, Sokolov, Braun, Birbaumer, Krägeloh-
Mann 2006;Pavlova et al. 2007;Saygin 2007;Sokolov et al.
2010, 2012,2014;Krakowski et al. 2011;Buzzell et al. 2013;
Han et al. 2013;Kröger et al. 2013;White et al. 2014; for
review, see Puce and Perrett 2003;Pavlova 2012). Recent
voxel-based morphometry analysis indicates that gray matter
volumes of the left posterior superior temporal sulcus (pSTS)
and ventral premotor cortex (PMC) may be considered as
predictors of individual differences in detection of camou-
flaged point-light biological motion (Gilaie-Dotan et al. 2013).
Transcranial magnetic stimulation over the pSTS and PMC
affects visual sensitivity to biological motion (Grossman et al.
2005;van Kamenade et al. 2012). It appears that processing of
biological motion engages a specialized neural network with a
hub in the right temporal cortex (e.g., Grossman and Blake
2002;Beauchamp et al. 2003;Gobbini et al. 2007;Pavlova
et al. 2004;Kaiser et al. 2010;Herrington et al. 2011), where
this network topographically overlaps and likely communi-
cates with the social brain, namely, with the neural circuits
underlying our ability for perception and understanding of
emotions, intentions, drives, desires, dispositions of others,
and body language reading.
It is unclear, however, whether the social brain is sex-
specific, although growing evidence points to sexual dimorph-
ism of the brain (e.g., Cahill 2006). There is a paucity of
research examining sex differences at a neurobiological level.
Yet behavioral data are also controversial. According to
popular beliefs about female superiority on visual social cogni-
tion tasks there are some indications for gender influence on
visual biological motion processing in common marmosets
(Callithrix jacchus): females but not males exhibit curiosity
to point-light biological motion (Brown et al. 2010). Newly
hatched female chicks demonstrate a stronger preference for
point-light biological motion of a walking hen (even over a
walking cat) than their male peers (Miura and Matsushima
2012). Yet, alterations in point-light biological motion process-
ing with age appears to be unaffected by observers’gender
(Billino et al. 2009). Gender congruency between perceivers
and actors enhances visual priming of camouflaged point-light
human locomotion (Bidet-Ildei et al. 2010). Female and male
observers respond differently when judging whether a point-
light walker shown in a frontal view is facing toward
(approaching) or backward (retreating): for females, the facing
bias for male walkers is weaker (Schouten et al. 2010,2013).
Gender of observers affects body language reading in point-
light biological motion movies depicting knocking at a door,
but effects are modulated by emotional content of actions:
males surpass in recognition accuracy of happy actions,
whereas females tend to excel in recognition of angry knock-
ing (Sokolov et al. 2011). A similar pattern of results was found
for subtle emotions expressed by point-light human locomo-
tion: males surpass females in recognition accuracy and readi-
ness to respond to subtle happy walking portrayed by female
actors, whereas females tend to be better in recognition of
angry locomotion expressed by male actors (Krüger et al.
2013). Females are more accurate in recognition of point-light
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Cerebral Cortex
doi:10.1093/cercor/bhu175
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activities (such as walking, jumping on the spot, kicking a ball,
and drinking from a bottle), and excel in some aspects of body
language reading: they are faster in discrimination of emotion-
al from neutral body motion (Alaerts et al. 2011). Most import-
ant, in agreement with the assumption that biological motion
processing and social cognition are intimately linked (Pavlova
2012), in typically developing adults and individuals with aut-
istic disorders, the ability to reveal emotions from point-light
body motion is related to more basic capability for discrimin-
ation between canonical and scrambled biological motion
(Alaerts et al. 2011;Nackaerts et al. 2012). In healthy adults,
some aspects of social cognition (such as empathy) and per-
formance on Reading the Mind in the Eyes Test are related to
point-light biological motion processing (Miller and Saygin
2013).
In adult females, increased functional magnetic resonance
imaging (fMRI) activation is found during passive viewing of
point-light biological motion displays (waving, pat-a-cake, and
peek-a-boo) compared with scrambled versions over the
regions known to be involved in social cognition, in particular,
the temporal pole, medial temporal gyrus, cerebellum, and
amygdala (Anderson et al. 2013). Yet sex differences in brain
activation are less pronounced in children and adolescents
aged 4–16 years (Anderson et al. 2013).
The motivation of the present work was to uncover sex-
specific alterations in the time course and dynamic topography
of the entire cortical network underpinning visual processing
of biological motion. To this end, we focused on analyses of
the whole-head magnetoencephalographic (MEG) response to
biological motion during performance of a one-back repetition
task with canonical and spatially scrambled point-light displays
(Fig. 1).
Materials and Methods
Participants
Fourteen paid right-handed young adults (7 females and 7 males) with
normal or corrected-to-normal vision were enrolled in the study. Age
of females was 25 ± 2.75 years (median ± 95% confidence interval) and
age of males was 25 ± 2.43 years. No age-related differences were
found between females and males (Mann–Whitney test; U= 18, n.s.).
None had a history of neurological or psychiatric disorders, head
injuries, or medication at a period of examination. They were naïve as
to the purpose of the study. Informed written consent was obtained in
accordance with the requirements of the local Ethical Committee at the
University of Tübingen Medical School. Analysis of MEG oscillatory re-
sponse to biological motion in these participants was reported earlier
(Pavlova et al. 2004). Here, we examined sex-related differences in cor-
tical activation to biological motion displays by uncovering alterations
in the evoked root mean square (RMS) activity.
Stimuli, Task, and Experimental Design
The point-light stimuli and task are described in detail elsewhere (e.g.,
Pavlova et al. 2004). In brief, participants were presented with 2 types
of displays: a canonical point-light walker consisting of 11 dots on the
head and main joints of an invisible figure and a spatially scrambled
configuration, for which the spatial positions of dots were randomly
rearranged on the screen (Fig. 1) so that the display lacked an implicit
coherent structure. All other display characteristics remained the same.
The walking figure, facing right, was seen moving as if on a treadmill.
A gait cycle was completed in 40 frames with frame duration of 31 ms
that produced a walking speed of ∼48 cycles per minute. The config-
urations were generated by Cutting’s algorithm (Cutting 1978), and
subtended a visual angle of 9° in height and 6° in width. Participants
were presented with a randomized set of 200 stimuli of both types. The
stimuli appeared for 650 ms on a blank screen with an inter-stimulus
interval that varied randomly between 2.5 and 3.0 s. Participants
fixated a gray cross in the middle of the screen that was seen during
the whole run. They performed a one-back repetition task lifting a fore-
finger placed in a nonmagnetic light-beam response box following the
offset of the second of 2 consecutive identical stimuli of each type.
One-back repetition task obligates attention to all types of stimuli and,
therefore, reduces possible attention effects on recorded MEG traces.
MEG Recording and Analysis
For recording cortical activity, the whole-head MEG system (CTF
Systems, Inc.; Vancouver, Canada) was used. This system consisted of
151 hardware first-order magnetic gradiometers distributed with an
average distance of 3 cm between sensors. A participant was seated in
an electromagnetically shielded chamber (Vakuum-Schmelze, Hanau,
Germany). The signals were sampled at a rate of 312.5 Hz. A baseline
was recorded during 300 ms prestimulus. Participants were instructed to
blink only during inter-trial intervals. Vertical eye movements were mon-
itored by electroencephalography/electrooculography recording from
the left eye (impedance was kept below 5 kΩm). Both at the beginning
and at the end of each recording session, the participant’sheadposition
was determined with 3 localization coils fixed at the nasion and the peri-
auricular sites. Sessions with head movements exceeding 0.5 cm were
discarded. Each MEG recording session (during presentation of a set of
200 stimuli in a run) lasted 10–12 min. All epochs of MEG activity were
first automatically and then manually inspected for artifacts. Epochs con-
taining blinks or eye movements (greater than ±100 μV) were rejected.
The only trials analyzed were those for which a motor response was not
required. If a participant failed to respond to the second identical stimu-
lus, all trials were discarded beginning from the last correct response.
Per participant, a total of ∼70 correct artifact-free trials were processed
for each type of stimulus. For each participant, we computed difference
in RMS amplitude in response to the canonical against control scrambled
configuration. RMS analysis was performed in equivalent temporal
windows of 50 ms from 0 to 500 ms separately for all sensors over the
occipital, parietal, temporal, and frontal areas of each brain hemisphere.
The sensors over the different cortical areas were defined in accord with
the standard MEG sensor layout.
Results
Behavioral Data
Participants (both females and males) performed the task with
great accuracy reaching ceiling level of performance (Pavlova
et al. 2004). There were just a few errors. For each participant,
Figure 1. Static sample stimuli. Participants were presented with a randomized set of
either (A) a canonical point-light human figure walking as if on a treadmill, or (B) its
spatially scrambled version. Vectors illustrate motion of each dot. The displays are
shown in reverse contrast: they were seen as a set of bright dots against a dark
background. From Pavlova et al. (2004), copyright © 2004 Oxford University Press.
2Sex Differences in the Neuromagnetic Cortical Response to Biological Motion •Pavlova et al.
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the miss rate was calculated as a ratio of the number of failures
to respond to the second identical stimulus of each type to the
total number of the required responses. For analysis of false
alarm rate, the number of false alarms for each type of stimulus
was divided by the total number of trials in which this type of
error might occur. Analysis of gender impact on behavioral re-
sponse indicates that in females the miss rate to the canonical
point-light walker was 0.028 ± 0.041 (mean ± standard devi-
ation) and to the scrambled display it was 0.016 ± 0.022. In
males, the miss rate to the canonical walker was 0.008 ± 0.014,
and to the scrambled walker it was 0.005 ± 0.013. No gender
differences in the miss rate were found either in response to
the canonical or to the scrambled walker (Mann–Whitney test;
U= 19 and U= 17, n.s., respectively). Whereas in females, the
false alarm rate to the canonical point-light walker was very
low 0.004 ± 0.007, male participants did not make any false
alarms. In response to the scrambled display, false alarm rate in
females was 0.004 ± 0.011, and in males it was 0.009 ± 0.017.
No difference between females and males in false alarm rate in
response either to the canonical or scrambled walker was found
(U=17.5andU= 28, n.s., respectively).
Following each run, participants briefly indicated any stimu-
lus interpretations they might have had. All female and male
participants spontaneously reported seeing the canonical
walker, and their impression was vivid resulting in high ratings
of the display’s vividness on a 5-point unipolar scale. No
gender differences in the ratings were found (U= 25.5, n.s.;
mean, 4.29 ± 0.49 and 4.29 ± 0.76, for females and males, re-
spectively). For the scrambled walker, the ratings were low in
the absence of any gender differences (U= 26, n.s.; 1.43 ± 0.54
and 1.71 ± 1.11, for females and males, respectively).
Sex Differences in MEG Activity
Individual data were submitted to a 4-way (2 × 10 × 4 × 2)
repeated-measures analysis of variance, ANOVA, with a
between-subject factor Gender of observers (female and male)
and within-subject factors Time window, Cortical region
Figure 2. Sex effects in early MEG response to biological motion. The RMS neuromagnetic response to a point-light canonical walker as compared with a scrambled display over
(A) the right parietal, (B) left temporal, and (C) right temporal cortices. At a latency of 200–250 ms from the stimulus onset, the RMS response is significantly greater in females.
(D) The cortical RMS responses are plotted separately for females and males. R_Parietal, L_Temporal, and R_Temporal stand for the right parietal, left temporal, and right temporal
cortex, respectively. Vertical bars represent ±SEM.
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(occipital, parietal, temporal, and frontal), and Hemisphere
(right and left). The outcome reveals a main effect of Cortical
region (F
3,36
= 3.4, P< 0.029), Cortical region by Time window
interaction (F
27,324
= 1.84, P< 0.008), and Time window by
Gender of observers interaction (F
9,108
= 2.67, P< 0.008). Post
hoc analysis of gender-related simple effects shows that irre-
spective of a cortical region and hemisphere, females exhibit
greater RMS amplitude in the early time window of 200–250
ms (P< 0.004), whereas males tend to exhibit a greater re-
sponse at later latencies (P< 0.07). At early latencies (200–250
ms, Fig. 2), the RMS response is greater in females as compared
with males over the right parietal cortex (mean ± standard
error, 8.02 ± 8.3 fT [femtotesla] in females and −46.5 ± 13.698
fT in males; t
(12)
= 3.4, P< 0.005), left temporal cortex
(10.87 ± 6.58 fT in females and −23.36 ± 11.04 fT in males,
t
(12)
= 2.66, P< 0.02), and over the right temporal cortex
(13.4 ± 6.23 fT in females and −15.64 ± 12.69 fT in males;
t
(12)
=2.44,P< 0.03). At later latencies (Fig. 3), the RMS response
is greater in males as compared with females over the right
frontal lobe at a latency of 250–300 ms (4.89 ± 4.77 fT in males
and −12.6 ± 4.6 fT in females; t
(12)
=2.64, P<0.02), and at a
latency of 350–400 ms (10.46 ± 5.56 fT in males and −9.36 ± 6.11
fT in females, t
(12)
=2.4,P< 0.03). Over the right occipital cortex,
males exhibit the greater RMS response at a latency of 400–450
ms (39.74 ± 5.13 fT in males and −1.99 ± 10.2 fT in females;
t
(12)
=3.65, P< 0.003). Overall, sex differences occur primarily
over the right brain hemisphere.
Discussion
The present work was aimed at uncovering sex-specific altera-
tions in the time course and dynamic topography of the entire
cortical network underpinning visual processing of biological
motion. For this purpose, we analyzed the whole-head MEG
response to biological motion during performance of a one-
back repetition task with unmasked canonical and spatially
scrambled point-light displays. The outcome indicates that in
the absence of behavioral differences, gender of observers
affects the cortical evoked neuromagnetic RMS activation in re-
sponse to human locomotion: (1) Sex differences in the cortical
MEG response to biological motion occur mostly over the right
brain hemisphere; (2) In females, early cortical response to bio-
logical motion is greater over the right parietal, left temporal
and right temporal cortex; and (3) In males, later cortical re-
sponse is greater over the right frontal and occipital cortices.
In the present study, sex differences in the cortical neuro-
magnetic response to biological motion were found over the
regions that are known to be profoundly engaged in visual pro-
cessing of social signals, in particular, in the right brain hemi-
sphere (e.g., Grossman et al. 2004,2005;Gobbini et al. 2007;
Pavlova et al. 2010;Kaiser et al. 2010;Herrington et al. 2011;
Han et al. 2013). Already in 8-month-old infants, the averaged
negative amplitude of the event-related potentials (ERPs) in
the right hemisphere is greater in response to canonical than
to scrambled point-light biological motion (Hirai and Hiraki
2005). While viewing upright as compared with inverted point-
Figure 3. Sex effects in later MEG response to biological motion. The RMS neuromagnetic response to a point-light canonical walker as compared with a scrambled display. In
males, the RMS response is significantly greater (A) over the right frontal lobe at latencies of 250–300 ms and 350–400 ms, and (B) over the right occipital cortex at a latency of
400–450 ms from the stimulus onset. (C) The cortical RMS responses are plotted separately for females and males. R_Frontal_1, R_Frontal_2, and R_Occipital stand for the first
and second time window over the right frontal, and for the right occipital cortex, respectively. Vertical bars represent±SEM.
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light biological motion displays of the whole body, infants of
this age exhibit larger positive ERP amplitude over the right
parietal cortex at a latency of 200–300 ms (Reid et al. 2006). In
healthy adults, electroencephalographic findings on biological
motion processing identify early and late ERP components
with peaks varying in different studies from 120 to 300 ms for
the first and from 190 to 500 ms for the second component
(Hirai et al. 2003,2005;Hirai and Hiraki 2005;Krakowski
et al. 2011;Jokisch et al. 2005;White et al. 2014). It appears
that, in particular, early stages in visual processing of biologic-
al motion are associated with the right hemisphere (Hirai et al.
2003;Krakowski et al. 2011;Kröger et al. 2013). Some studies
also report a late (beyond 300 ms) medial posterior positivity/
ventral lateral negativity (MPP/VAN) ERP component (Hirai
and Hiraki 2005;Krakowski et al. 2011;White et al. 2014),
which likely reflects involvement of higher-order top-down
and task-relevant cognitive processes.
Our MEG findings show that earlier stages in visual process-
ing of biological motion are associated with greater cortical ac-
tivation in females. Keeping in mind that from the evolutionary
and socio-cultural points of view, female roles are often asso-
ciated with offspring care providing and detecting a potential
danger, it appears that the female brain may be more visually
tuned to human locomotion. In accordance with this, recent
behavioral data suggest that in contrast to men, body motion
stimuli automatically capture women’s attention even if these
displays are irrelevant for the task and serve as distractors
(Bidet-Ildei and Bouquet 2014). In males, late boosts of cor-
tical activation over the right frontal and occipital cortices may
point to a stronger higher-order cognitive involvement in bio-
logical motion processing. The greater activation over the right
frontal cortex likely reflects engagement of decision processes,
whereas late boosts over the right occipital cortex may be
driven by feedback from the cortical regions involved in
higher-order cognitive processing. However, this assumption
requires further experimental proof.
Most remarkable outcome of this work is that females exhibit
greater activity over the right temporal cortex, a hub of the
social brain, where the network specialized for biological
motion processing topographically overlaps and communicates
with the neural circuitry underpinning visual social cognition
(perception and understanding of social properties of others
such as intentions, emotions, and expectations). Brain activation
during visual processing of point-light biological motion over-
laps topographically, especially, in the right temporal cortex,
with the network engaged in visual perception of agency and
social attribution in Heider-and-Simmel-like movies represent-
ing motion of geometric shapes (e.g., Gobbini et al. 2007;
Pavlova et al. 2010). Yet sex differences are not evident in the
neural circuitry underpinning visual processing of social inter-
action in Heider-and-Simmel-like animations. Instead, sex differ-
ences are observed only in the regions engaged in perceptual
decision making: in males, the MEG oscillatory induced gamma
response boosts later over the left prefrontal cortex (Pavlova
et al. 2010). It appears that females anticipate social interaction
predicting others’actions ahead of their occurrence, whereas
males require accumulation of more sensory evidence for
proper decisions.
More generally, gender-related brain differences do not always
parallelbehavior. Instead,severaltypesofinterrelations between
behavior and brain mechanisms in respect to sex differences
potentially occur: (1) gender-related differences both in overt
behavioral and brain responses to visual social stimuli; (2)
gender-related differences detectable either at the behavioral
level or (3) solely in brain activation; and (4) a lack of gender-
related differences both at the overt behavioral level and brain
activation. The present findings deliver the first evidence for
gender-dependent modes in the time course and topography
of the neural circuitry underpinning visual processing of
biological motion. In light of the absence of differences in be-
havioral responses, it is conceivable that gender-related di-
morphism in the cortical response may prevent behavioral
differences if they are maladaptive, and in such a way promote
adaptive behavioral response.
Further investigation of sex differences in visual processing
of biological motion and body language reading would en-
courage clarification of the nature of neurodevelopmental and
psychiatric disorders characterized by impairments in social
cognition. Many of these disorders are gender specific: females
and males are differently affected in terms of clinical picture,
prevalence, and severity. Females are more often affected by
anxiety disorders with a ratio of 2:1 or even 3:1, and gender
differences increase with age (Craske 2003;Beesdo-Baum and
Knappe 2012). Depression is approximately twice as common
in females as in males (Diflorio and Jones 2010). By contrast,
males have a higher risk for developing autistic spectrum dis-
orders than females, with a sex ratio of ∼4:1 (Newschaffer et al.
2007) or even higher, but females are more severily affected.
Neuroanatomy of autism differs between females and males
(Lai et al. 2013). Schizophrenia occurs 1.4 times more frequent-
ly in males than females, and the onset of disease is earlier in
men (Picchioni and Murray 2007). Males are at a 14–20%
higher risk for premature birth and of its complications in the
brain development and cognition (Pavlova and Krägeloh-Mann
2013). Males are more often affected by attention deficit hyper-
activity disorder, ADHD (Bloom et al. 2012). Some aspects of
biological motion processing are reported to be impaired in
these and other gender-specific diseases: in schizophrenia
(Kim et al. 2005,2011,2013;Hastings et al. 2013;Spencer
et al. 2013), in autism (e.g., Klin et al. 2009;Kröger et al. 2013;
Nackaerts et al. 2012), in obsessive compulsive disorders
(OCD; Kim et al. 2008), in ADHD (Kröger et al. 2014), and in
individuals who were born preterm (e.g., Pavlova, Marconato,
Sokolov, Braun, Birbaumer, Krägeloh-Mann 2006;Pavlova,
Sokolov, Birbaumer, Krägeloh-Mann 2006;Taylor et al. 2009;
see Pavlova 2012). Yet gender impact on impairments in bio-
logical motion processing and body language reading is
poorly understood. Clarification of sex impact on neural cir-
cuits underpinning biological motion processing would
provide novel insights into understanding of gender vulner-
ability to psychiatric and neurodevelopmental deficits in social
cognition (Pavlova 2012).
Conclusions
By analysis of cortical neuromagnetic activity, the present
work delivers the first evidence for gender dependent modes
in time course and topography of the neural circuitry under-
pinning visual processing of biological motion. The findings
show that in the absence of behavioral differences, gender of
observers affects the cortical evoked RMS response to human
locomotion: (a) sex differences in the cortical MEG response to
biological motion occur mostly over the right brain hemi-
sphere; and (b) females exhibit greater early cortical response
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over the right parietal and bilateral temporal cortex, whereas
males exhibit greater later cortical response to biological
motion over the right frontal and occipital cortex. Gender-
related differences in the time course and topography of cor-
tical neuromagnetic response found in this study may prevent
behavioral differences if they are maladaptive. The outcome re-
presents a framework for studying sex differences in the social
brain in psychiatric and neurodevelopmental disorders.
Funding
This work was supported by the Else Kröner Fresenius Foun-
dation (grant 2013_A127), the Reinhold Beitlich Foundation,
and the Heidehof Foundation (grant 59073.01.1/3.13) to M.A.P.
C.B.-I. was supported by the grant of the National Center for
Scientific Research (CNRS), France.
Notes
We greatly appreciate Krunoslav Stingl and Christoph Braun at the
MEG-Center of the University of Tübingen Medical School for assist-
ance with MEG data analysis, and Jürgen Dax and Gabriele Walker-
Dietrich for technical assistance with MEG recording.
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