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Disentangling the web of fear: amygdala reactivity and functional connectivity in spider and snake phobia
Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Psychiatry, Ulleråker, University Hospital.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
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2009 (English)In: Psychiatry Research: Neuroimaging, ISSN 0925-4927, Vol. 172, no 2, 103-108 p.Article in journal (Refereed) Published
Abstract [en]

The objective was to study effects of fear on brain activity, functional connectivity and brain-behavior relationships during symptom provocation in subjects with specific phobia. Positron emission tomography (PET) and (15)O water was used to measure regional cerebral blood flow (rCBF) in 16 women phobic of either snakes or spiders but not both. Subjects watched pictures of snakes and spiders serving either as phobic or fear-relevant, but non-phobic, control stimuli depending on phobia type. Presentation of phobic as compared with non-phobic cues was associated with increased activation of the right amygdala and cerebellum as well as the left visual cortex and circumscribed frontal areas. Activity decreased in the prefrontal, orbitofrontal and ventromedial cortices as well as in the primary somatosensory cortex and auditory cortices. Furthermore, amygdala activation correlated positively with the subjective experience of distress. Connectivity analyses of activity in the phobic state revealed increased functional couplings between voxels in the right amygdala and the periamygdaloid area, fusiform gyrus and motor cortex. During non-phobic stimulation, prefrontal activity correlated negatively with amygdala rCBF, suggesting a phobia-related functional decoupling. These results suggest that visually elicited phobic reactions activate object recognition areas and deactivate prefrontal areas involved in cognitive control over emotion-triggering areas like the amygdala, resulting in motor readiness to support fight or flight.

Place, publisher, year, edition, pages
2009. Vol. 172, no 2, 103-108 p.
Keyword [en]
Specific phobia, anxiety, fear-circuit, PET, subjective experience
National Category
Medical and Health Sciences
URN: urn:nbn:se:uu:diva-98987DOI: 10.1016/j.pscychresns.2008.11.004ISI: 000265779800003PubMedID: 19321315OAI: oai:DiVA.org:uu-98987DiVA: diva2:201843
Available from: 2009-03-05 Created: 2009-03-05 Last updated: 2012-03-12Bibliographically approved
In thesis
1. The Amygdala, Arousal and Memory: From Lesions to Neuroimaging
Open this publication in new window or tab >>The Amygdala, Arousal and Memory: From Lesions to Neuroimaging
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Emotional events are better remembered than neutral events. But what are the mechanisms behind this memory enhancing effect? It seems that they depend on the arousal level at the moment we experience the event to be remembered.

The first study of the present thesis mapped the brain areas that changed their activity in a highly arousing situation in subjects with snake or spider phobia. Looking at pictures of their feared object engaged the amygdala, situated in the medial temporal lobe. This area has previously been demonstrated to be necessary for fear reactions. Here, the novel question was what other brain areas the amygdala engages when the brain is in a state of high arousal. Results suggest that the amygdala recruits other limbic and cortical areas known to be involved in motor behavior and object recognition. In contrast, when subjects watched fear-relevant but non-phobic pictures, amygdala activity was negatively correlated to the anterior cingulate cortex suggesting cortical inhibition.

The final two studies aimed at explaining the physiological brain mechanisms behind arousal enhancement of memory. In the first one, epileptic patients with medial temporal lobe resections including the amygdala were compared to healthy controls on a recognition memory task where the pictures to be remembered varied in arousal intensities. Results suggested that the anterior medial temporal lobe including the amygdala is necessary for arousal enhancement of memory because the enhancement effect was abolished in resectioned patients.

The last study related inter-individual differences in bodily arousal to amygdala-parahippocampal interaction. Results suggest that the beneficial effects of emotion on memory depend on arousal regulating mechanisms of the amygdala that in turn affects parahippocampal activity.

Collectively, results suggest that the amygdala is regulating changes in arousal states of the brain and body during distressful situations. Further, arousal in turn determines memory strength through gating amygdala influences on the parahippocampal cortex. Thus, the amygdala is a node both in a fear and a memory network and arousal influences the amygdala to prepare for action and to enhance memory. This seems evolutionary sound.


Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2009. 53 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Social Sciences, ISSN 1652-9030 ; 48
National Category
Research subject
urn:nbn:se:uu:diva-98978 (URN)978-91-554-7447-8 (ISBN)
Public defence
2009-04-17, Sal X, Universitetshuset, Uppsala, 10:15 (English)
Available from: 2009-03-27 Created: 2009-03-05 Last updated: 2010-12-09Bibliographically approved

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Frans, ÖrjanFurmark, TomasAppel, LieuweFredrikson, Mats
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Department of PsychologyPsychiatry, Ulleråker, University HospitalDepartment of NeuroscienceSection of Nuclear Medicine and PET
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Psychiatry Research: Neuroimaging
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