Show Reference: "A subcortical pathway to the right amygdala mediating "unseen" fear"

A subcortical pathway to the right amygdala mediating "unseen" fear Proceedings of the National Academy of Sciences of the United States of America, Vol. 96, No. 4. (16 February 1999), pp. 1680-1685 by John S. Morris, Arne Öhman, Raymond J. Dolan
@article{morris-et-al-1999,
    abstract = {Neuroimaging studies have shown differential amygdala responses to masked ("unseen") emotional stimuli. How visual signals related to such unseen stimuli access the amygdala is unknown. A possible pathway, involving the superior colliculus and pulvinar, is suggested by observations of patients with striate cortex lesions who show preserved abilities to localize and discriminate visual stimuli that are not consciously perceived ("blindsight"). We used measures of right amygdala neural activity acquired from volunteer subjects viewing masked fear-conditioned faces to determine whether a colliculo-pulvinar pathway was engaged during processing of these unseen target stimuli. Increased connectivity between right amygdala, pulvinar, and superior colliculus was evident when fear-conditioned faces were unseen rather than seen. Right amygdala connectivity with fusiform and orbitofrontal cortices decreased in the same condition. By contrast, the left amygdala, whose activity did not discriminate seen and unseen fear-conditioned targets, showed no masking-dependent changes in connectivity with superior colliculus or pulvinar. These results suggest that a subcortical pathway to the right amygdala, via midbrain and thalamus, provides a route for processing behaviorally relevant unseen visual events in parallel to a cortical route necessary for conscious identification.},
    address = {Wellcome Department of Cognitive Neurology, Queen Square, London, WC1N 3BG, United Kingdom.},
    author = {Morris, John S. and \"{O}hman, Arne and Dolan, Raymond J.},
    day = {16},
    issn = {0027-8424},
    journal = {Proceedings of the National Academy of Sciences of the United States of America},
    keywords = {amygdala, biology, fear, sc},
    month = feb,
    number = {4},
    pages = {1680--1685},
    pmcid = {PMC15559},
    pmid = {9990084},
    posted-at = {2013-10-30 09:03:56},
    priority = {2},
    title = {A subcortical pathway to the right amygdala mediating "unseen" fear},
    url = {http://www.pnas.org/content/96/4/1680.abstract},
    volume = {96},
    year = {1999}
}

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Patients with lesions in V1 or striate were found to still be able to discriminate gender and expression of faces.

Masking visual face stimuli---ie. presenting faces visually for too short to detect them consciously, then presenting a masking stimulus---can evoke measurable changes in conductance.

Masking visual face stimuli can evoke responses in sc, pulvinar, and amygdala.

The right amygdala responded differently to masked than to unmasked stimuli, while the left did not in Morris et al.'s experiments.

SC has been implicated as part of a subcortical visual pathway which may drive face detection and orienting towards faces in newborns.