{"id":1038,"date":"2018-06-12T09:52:00","date_gmt":"2018-06-12T13:52:00","guid":{"rendered":"https:\/\/sites.bu.edu\/vision\/?p=1038"},"modified":"2018-07-23T16:34:40","modified_gmt":"2018-07-23T20:34:40","slug":"visuocortical-changes-during-a-freezing-like-state-in-humans","status":"publish","type":"post","link":"https:\/\/sites.bu.edu\/vision\/2018\/06\/12\/visuocortical-changes-during-a-freezing-like-state-in-humans\/","title":{"rendered":"Visuocortical changes during a freezing-like state in humans"},"content":{"rendered":"

Neuroimage\u00a0(2018)<\/em>
\nMaria Lojowska, Sam Ling, Karin Roelofs, Erno Hermans<\/h4>\n
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\"ScreenAn adaptive response to threat requires optimized detection of critical sensory cues. This optimization is thought to be aided by freezing – an evolutionarily preserved defensive state of immobility characterized by parasympathetically mediated fear bradycardia and regulated by the amygdala-periaqueductal grey (PAG) circuit. Behavioral observations in humans and animals have suggested that freezing is also a state of enhanced visual sensitivity, particularly for coarse visual information, but the underlying neural mechanisms remain unclear. We induced a freezing-like state in healthy volunteers using threat of electrical shock and measured threat-related changes in both stimulus-independent (baseline) and stimulus-evoked visuocortical activity to low- vs. high-spatial frequency gratings, using functional MRI. As measuring immobility is not feasible in MRI environments, we used fear bradycardia and amygdala- PAG coupling in inferring a freezing-like state. An independent functional localizer and retinotopic mapping were used to assess the retinotopic specificity of visuocortical modulations. We found a threat- induced increase in baseline (stimulus-independent) visuocortical activity that was retinotopically nonspecific, which was accompanied by increased connectivity with the amygdala. A positive correlation between visuocortical activity and fear bradycardia (while controlling for sympathetic activation), and a concomitant increase in amygdala-PAG connectivity, suggest the specificity of these findings for the parasympathetically dominated freezing-like state. Visuocortical responses to gratings were retinotopically specific but did not differ between threat and safe conditions across participants. However, individuals who exhibited better discrimination of low-spatial frequency stimuli showed reduced stimulus-evoked V1 responses under threat. Our findings suggest that a defensive state of freezing involves an integration of preparatory defensive and perceptual changes that is regulated by a common mechanism involving the amygdala.<\/p>\n<\/div>\n<\/div>\n<\/div>\n

<\/a><\/a>\u00a0Download it here\u00a0<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

Neuroimage\u00a0(2018) Maria Lojowska, Sam Ling, Karin Roelofs, Erno Hermans An adaptive response to threat requires optimized detection of critical sensory cues. This optimization is thought to be aided by freezing – an evolutionarily preserved defensive state of immobility characterized by parasympathetically mediated fear bradycardia and regulated by the amygdala-periaqueductal grey (PAG) circuit. Behavioral observations in […]<\/p>\n","protected":false},"author":8254,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[],"_links":{"self":[{"href":"https:\/\/sites.bu.edu\/vision\/wp-json\/wp\/v2\/posts\/1038"}],"collection":[{"href":"https:\/\/sites.bu.edu\/vision\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/sites.bu.edu\/vision\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/sites.bu.edu\/vision\/wp-json\/wp\/v2\/users\/8254"}],"replies":[{"embeddable":true,"href":"https:\/\/sites.bu.edu\/vision\/wp-json\/wp\/v2\/comments?post=1038"}],"version-history":[{"count":5,"href":"https:\/\/sites.bu.edu\/vision\/wp-json\/wp\/v2\/posts\/1038\/revisions"}],"predecessor-version":[{"id":1049,"href":"https:\/\/sites.bu.edu\/vision\/wp-json\/wp\/v2\/posts\/1038\/revisions\/1049"}],"wp:attachment":[{"href":"https:\/\/sites.bu.edu\/vision\/wp-json\/wp\/v2\/media?parent=1038"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/sites.bu.edu\/vision\/wp-json\/wp\/v2\/categories?post=1038"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/sites.bu.edu\/vision\/wp-json\/wp\/v2\/tags?post=1038"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}