Affective neuroscience: Fear and pain

Chair:  P. Pauli,

Department of Psychology, University of Wuerzburg, Germany


Abstract:

This symposium deals with basic and applied research questions in the field of affective
neuroscience focusing on fear and pain. The first talk (Pauli) will elaborate basic context
conditioning mechanisms which might plan an important role for the development and
maintenance of anxiety disorders, and will present first results on reinstatement of fear
related to context conditioning as reflected in startle response modulation. The second
talk (Miltner) mainly deals with phobia and associated biases in information processing.
fMRI studies revealing how treatment affects theses biases will be presented. The third
talk (Angrilli) will present data on the emotion pain interaction with a focus on gender
differences using ERPs as dependent measure. The fourth talk (Montoya) will present brain
response data of chronic pain patients triggered by the processing of facial simuli,
expressing pain or other emotions. The final talk (Esteves) will present new results on the
emotional effects of the putative pheromone androstadienone on human participants, i.e.,
an enhanced startle reflex modulation related to pleasant and unpleasant pictures in the
absence of an effect in ratings.

Talk 1:

Context fear conditioning in humans

P. Pauli, E. Glotzbach, M. Andreatta, & A. Mühlberger
University of Würzburg, Germany

During extinction a fear eliciting stimulus is experienced without aversive consequences
and consequently conditioned fear responses decrease. Previous studies on cue
conditioning revealed reinstatement of fear, meaning that extinguished fear responses
can return after the presentation of the unconditioned stimulus (US) indicating fear
memory is not erased but inhibited. In contextual conditioning an aversive event is linked
to a complex context. Until now it is unsettled which effects extinction and reinstatement
have on contextual fear memories. To study contextual conditioning in humans we created
two immersive virtual environments (office rooms). On day one participants (N=24)
received electric stimuli (US) in one context (CXT+) but never in a second context (CXT-).
On day two participants underwent extinction. On day three, one unsignaled US was
presented and afterwards participants were again exposed to the two contexts. We found
successful fear acquisition on day one as reflected in startle potentiation and higher
arousal in CXT+ compared to CXT-. Furthermore, physiological and explicit fear responses
were extinguished at the end of day 2. After US presentation on day 3, fear responses
returned as indicated by increased startle and arousal ratings for CXT+ compared to CXT-.
In sum, we found reinstatement of contextual fear on physiological and explicit levels in
analogy to cue conditioning studies. This return of contextual fear may account for relapse
in anxiety disorders mainly characterized by sustained anxiety states like generalized
anxiety disorder or agoraphobia.

Talk 2:

Neural Basis of Biased Information Processing in Phobics and its Modulation by Exposure Therapy

Wolfgang H. R. Miltner
Department of Psychology, University of Jena, Gemany

Many studies have demonstrated biased processing of threat information in phobics and
patients with other anxiety disorders. Functional MRI data and data from other imaging
methods like ERPs and source analysis of neural activities indicate that several neural
networks in the brain of these subjects are critical for this processing peculiarities
including the amygdala, the anterior insula, the subgenual anterior cingulate cortex and
several networks of the frontal brain including Brodmann area 9 and 10, and the
ventromedial part of the orbitofrontal cortex. Several fMRI and ERP-studies will be
presented that show increased activities of these structures in phobics as compared to
non-phobic subjects when subjects were exposed to threatening stimuli of personal
concern as compared to general threatening or neutral stimuli. In the second section of
the presentation results of three studies will be presented that show that the
hyperactivities of these brain structures might become significantly modified in
accordance with subjects fear behaviors and subjective experiences in response to threat
following brief periods of exposure therapy.

Talk 3:

Gender differences in pain responses under emotional stimulation: an ERP study

Alessandro Angrilli & Francesca Fardo,
Department of Psychology, University of Padova, Italy

Research on pain and emotions has shown clear gender differences in psychophysiological
responses of these domains, however less investigation has been carried out on the
interaction between the two variables. In the present experiment, emotions were elicited
through five categories of pictures with different content, valence and arousal: pleasant
(erotic and sport), neutral (household objects) and unpleasant (threat and mutilation).
During the 4s picture presentation, electrical painful stimuli were delivered to the left
forearm with a fixed intensity of 40% above subjective pain thresholds. 17 female and 17
male participants were required to watch each picture and then to rate the perceived pain
intensity and the picture pleasantness on two 10 point visuo-analogue scales. Results
showed for erotic pictures compared with the other four categories, decreased self-
perceived pain intensity (F4= 15.11, p<0.001) and dampened N150 and P260 (F4 >5.69,
p<0.001) amplitudes independently from gender. Also Sport pictures were able, although
to a less extent, to evoke dampened pain perception compared with mutilation slides, and
no clear self-perceived pain differentiation was found among neutral, threat and mutilation
pictures. In addition, a significant Gender by Eelectrode by Category interaction (F8,256=
2.08, p< 0.05) for the N150 component was found. Women showed N150 amplitude
significantly varying across all categories while males had smaller N150 to erotic
compared with all other categories. Men and women showed clear differences in emotion
modulation of pain responses with women exhibiting a stronger and more complex
modulation.

Talk 4:

Brain responses to others’ expressions of pain in chronic pain patients

P. Montoya, A.M. González-Roldán, M.A. Muñoz, I. Cifre, & C. Sitges
Research Institute on Health Sciences (IUNCS), University of the Balearic Islands, Spain

It is well-known that facial expression is one of the most relevant components of pain and
that viewing others’ emotional faces may influence our own affective mood. Nevertheless,
little is known about physiological responses to pain and other emotional faces in chronic
pain patients. Event-related potentials (ERPs) and brain oscillations, corrugator activity,
and heart rate were recorded in 20 patients with fibromyalgia and 20 pain-free controls,
while they were passively viewing pain, anger, happy and neutral faces. In addition,
ratings of valence and arousal elicited by the faces were obtained. Pain and anger faces
elicited greater unpleasantness, arousal and corrugator activity than happy and neutral
faces in all participants. Results also indicated that brain and heart rate responses to pain,
anger and happy faces were different in fibromyalgia patients and pain-free controls. Thus,
fibromyalgia patients displayed more enhanced ERP amplitudes, larger theta power and
more reduced alpha power to pain and anger faces, as well as more prominent cardiac
deceleration to anger faces than to either happy or neutral faces. Pain-free controls
showed larger ERP amplitudes to happy faces than to negative faces. These findings
indicate that information processing in fibromyalgia patients was characterized by
enhanced defensive reactions and increased mobilization of attention resources to pain
and anger faces, as well as by reduced allocation of attention to happy faces.
Furthermore, our results suggest that pain symptoms in fibromyalgia would be worsened
by a greater vulnerability to negative mood and an inappropriate response to positive
emotions.

Talk 5:

Emotional effects of the putative pheromone androstadienone on human participants

F. Esteves & Patrícia Arriaga
University Institute of Lisbon/ISCTE, Portugal

The existence of human pheromones is widely accepted among layman. However, the
scientific evidence for possible effects on humans is scarce and still under scrutiny. The
goal of this experiment was to test possible effects of androstadienone on mood changes
(verbal evaluation) and peripherical psychophysiological measures (skin conductance,
heart rate and modulation of the startle reflex). Sixty female participants were randomly
assigned by two double-blind male experimenters to the experimental group (exposed to
androstadienone) or to a control condition. They had to rate their mood before and after
the experiment, and look to a series of emotional pictures (pleasant, unpleasant and
neutral) while their skin conductance, heart rate, and startle reflex were monitored. In
general, no differences between groups were obtained in the subjective ratings of the
pictures and in the mood ratings before and after the exposure. However, the analysis of
the eyeblink response comparing positive versus negative pictures showed a significant
interaction between Group and Valence, revealing a better differentiation between
positive and negative images in the experimental group. Although the general pattern of
results is unclear, the fact that exposure to androstadienone seems to enhance the
emotional differentiation between positive and negative stimuli, could be interpreted as a
higher sensitivity to emotional material after exposure to androstadienone.