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Behavior in oblivion: the neurobiology of subliminal priming.

Jacobs C, Sack AT - Brain Sci (2012)

Bottom Line: Evidence favoring the necessity of recurrent connectivity for visual awareness is accumulating, although some questions, such as the need for global versus local recurrent processing, are not clarified yet.However, this is not to say that recurrent processing is sufficient for consciousness, as a neural definition of consciousness in terms of recurrent connectivity would imply.We argue that the limited interest cognitive neuroscience currently has for the NCSP is undeserved, because the discovery of the NCSP can give insight into why people do (and do not) express certain behavior.

View Article: PubMed Central - PubMed

Affiliation: Department of Cognitive Neuroscience, FPN, Maastricht University, Maastricht, 6200 MD, The Netherlands. christianne.jacobs@maastrichtuniversity.nl.

ABSTRACT
Subliminal priming refers to behavioral modulation by an unconscious stimulus, and can thus be regarded as a form of unconscious visual processing. Theories on recurrent processing have suggested that the neural correlate of consciousness (NCC) comprises of the non-hierarchical transfer of stimulus-related information. According to these models, the neural correlate of subliminal priming (NCSP) corresponds to the visual processing within the feedforward sweep. Research from cognitive neuroscience on these two concepts and the relationship between them is discussed here. Evidence favoring the necessity of recurrent connectivity for visual awareness is accumulating, although some questions, such as the need for global versus local recurrent processing, are not clarified yet. However, this is not to say that recurrent processing is sufficient for consciousness, as a neural definition of consciousness in terms of recurrent connectivity would imply. We argue that the limited interest cognitive neuroscience currently has for the NCSP is undeserved, because the discovery of the NCSP can give insight into why people do (and do not) express certain behavior.

No MeSH data available.


Related in: MedlinePlus

(A) Possible pathways of subliminal prime information. Two possible routes for unconscious visual prime processing have been suggested. In the top one (gray) the prime information travels from the eye via subcortical routes to extrastriate cortex, circumventing early visual cortex (EVC) altogether. In the lower route, prime information passes by EVC before further processing in extrastriate areas. The finding that transcranial magnetic stimulation (TMS; thunderbolt) applied to EVC 90 ms post-prime leads to decreased priming [53] renders support to the lower model; (B) Possible routes of supraliminal (conscious) visual stimulus. Two recurrent pathways for conscious visual stimulus processing have been suggested. Both pathways would predict that early visual cortex (EVC) is relevant for visual awareness at two time periods, the first reflecting feedforward processing and the second reflecting feedback. However, dependent on whether the origin of the feedback activity is placed in higher level areas within visual cortex (local recurrent processing) or outside visual cortex (global recurrent processing), the timing of this second period differs. Because there is empirical evidence in favor of each pathway, and because they are not mutually exclusive, we leave the possibility open that visual information can take both pathways.
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brainsci-02-00225-f002: (A) Possible pathways of subliminal prime information. Two possible routes for unconscious visual prime processing have been suggested. In the top one (gray) the prime information travels from the eye via subcortical routes to extrastriate cortex, circumventing early visual cortex (EVC) altogether. In the lower route, prime information passes by EVC before further processing in extrastriate areas. The finding that transcranial magnetic stimulation (TMS; thunderbolt) applied to EVC 90 ms post-prime leads to decreased priming [53] renders support to the lower model; (B) Possible routes of supraliminal (conscious) visual stimulus. Two recurrent pathways for conscious visual stimulus processing have been suggested. Both pathways would predict that early visual cortex (EVC) is relevant for visual awareness at two time periods, the first reflecting feedforward processing and the second reflecting feedback. However, dependent on whether the origin of the feedback activity is placed in higher level areas within visual cortex (local recurrent processing) or outside visual cortex (global recurrent processing), the timing of this second period differs. Because there is empirical evidence in favor of each pathway, and because they are not mutually exclusive, we leave the possibility open that visual information can take both pathways.

Mentions: Recently, a version of recurrent processing theory has been put forward that proposes local recurrent processing within EVC as opposed to global recurrent processing across more distant brain regions to be the process underlying visual awareness (see Figure 2B, [2,19]). Because of the emphasis on the local nature of the awareness-related neural modulation, the model predicts that it should only occur (tenths of) milliseconds after the feedforward sweep. Based on the observation that people report awareness of incorrectly bound features [19], they assume that the later global feedback activity is responsible for feature binding. The suggested time line of recurrent processing is supported by neurophysiological research [16,17]. MEG measures the magnetic field distributions, induced by the electrical activity of neuronal populations close to the scalp, over time. The magnetic physical properties allow accurate localization of the neural source with high temporal resolution. Boehler et al. [17] employed MEG in a study on visual awareness and discovered event-related modulations in V1 centered around 110 and 220 ms post-stimulus. Event-related activity in the first time window was found to correlate with visual awareness, and occurred only 11 ms after the first observations of feedforward responses in extrastriate areas. The much later modulation of neural responses in the striate cortex around 220 ms reflected attention-related recurrent processing. Evidently, the finding that early recurrent activity prior to the occurrence of attentional modulation correlated with visual awareness speaks in favor of local instead of global models of recurrent processing as NCC.


Behavior in oblivion: the neurobiology of subliminal priming.

Jacobs C, Sack AT - Brain Sci (2012)

(A) Possible pathways of subliminal prime information. Two possible routes for unconscious visual prime processing have been suggested. In the top one (gray) the prime information travels from the eye via subcortical routes to extrastriate cortex, circumventing early visual cortex (EVC) altogether. In the lower route, prime information passes by EVC before further processing in extrastriate areas. The finding that transcranial magnetic stimulation (TMS; thunderbolt) applied to EVC 90 ms post-prime leads to decreased priming [53] renders support to the lower model; (B) Possible routes of supraliminal (conscious) visual stimulus. Two recurrent pathways for conscious visual stimulus processing have been suggested. Both pathways would predict that early visual cortex (EVC) is relevant for visual awareness at two time periods, the first reflecting feedforward processing and the second reflecting feedback. However, dependent on whether the origin of the feedback activity is placed in higher level areas within visual cortex (local recurrent processing) or outside visual cortex (global recurrent processing), the timing of this second period differs. Because there is empirical evidence in favor of each pathway, and because they are not mutually exclusive, we leave the possibility open that visual information can take both pathways.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4061795&req=5

brainsci-02-00225-f002: (A) Possible pathways of subliminal prime information. Two possible routes for unconscious visual prime processing have been suggested. In the top one (gray) the prime information travels from the eye via subcortical routes to extrastriate cortex, circumventing early visual cortex (EVC) altogether. In the lower route, prime information passes by EVC before further processing in extrastriate areas. The finding that transcranial magnetic stimulation (TMS; thunderbolt) applied to EVC 90 ms post-prime leads to decreased priming [53] renders support to the lower model; (B) Possible routes of supraliminal (conscious) visual stimulus. Two recurrent pathways for conscious visual stimulus processing have been suggested. Both pathways would predict that early visual cortex (EVC) is relevant for visual awareness at two time periods, the first reflecting feedforward processing and the second reflecting feedback. However, dependent on whether the origin of the feedback activity is placed in higher level areas within visual cortex (local recurrent processing) or outside visual cortex (global recurrent processing), the timing of this second period differs. Because there is empirical evidence in favor of each pathway, and because they are not mutually exclusive, we leave the possibility open that visual information can take both pathways.
Mentions: Recently, a version of recurrent processing theory has been put forward that proposes local recurrent processing within EVC as opposed to global recurrent processing across more distant brain regions to be the process underlying visual awareness (see Figure 2B, [2,19]). Because of the emphasis on the local nature of the awareness-related neural modulation, the model predicts that it should only occur (tenths of) milliseconds after the feedforward sweep. Based on the observation that people report awareness of incorrectly bound features [19], they assume that the later global feedback activity is responsible for feature binding. The suggested time line of recurrent processing is supported by neurophysiological research [16,17]. MEG measures the magnetic field distributions, induced by the electrical activity of neuronal populations close to the scalp, over time. The magnetic physical properties allow accurate localization of the neural source with high temporal resolution. Boehler et al. [17] employed MEG in a study on visual awareness and discovered event-related modulations in V1 centered around 110 and 220 ms post-stimulus. Event-related activity in the first time window was found to correlate with visual awareness, and occurred only 11 ms after the first observations of feedforward responses in extrastriate areas. The much later modulation of neural responses in the striate cortex around 220 ms reflected attention-related recurrent processing. Evidently, the finding that early recurrent activity prior to the occurrence of attentional modulation correlated with visual awareness speaks in favor of local instead of global models of recurrent processing as NCC.

Bottom Line: Evidence favoring the necessity of recurrent connectivity for visual awareness is accumulating, although some questions, such as the need for global versus local recurrent processing, are not clarified yet.However, this is not to say that recurrent processing is sufficient for consciousness, as a neural definition of consciousness in terms of recurrent connectivity would imply.We argue that the limited interest cognitive neuroscience currently has for the NCSP is undeserved, because the discovery of the NCSP can give insight into why people do (and do not) express certain behavior.

View Article: PubMed Central - PubMed

Affiliation: Department of Cognitive Neuroscience, FPN, Maastricht University, Maastricht, 6200 MD, The Netherlands. christianne.jacobs@maastrichtuniversity.nl.

ABSTRACT
Subliminal priming refers to behavioral modulation by an unconscious stimulus, and can thus be regarded as a form of unconscious visual processing. Theories on recurrent processing have suggested that the neural correlate of consciousness (NCC) comprises of the non-hierarchical transfer of stimulus-related information. According to these models, the neural correlate of subliminal priming (NCSP) corresponds to the visual processing within the feedforward sweep. Research from cognitive neuroscience on these two concepts and the relationship between them is discussed here. Evidence favoring the necessity of recurrent connectivity for visual awareness is accumulating, although some questions, such as the need for global versus local recurrent processing, are not clarified yet. However, this is not to say that recurrent processing is sufficient for consciousness, as a neural definition of consciousness in terms of recurrent connectivity would imply. We argue that the limited interest cognitive neuroscience currently has for the NCSP is undeserved, because the discovery of the NCSP can give insight into why people do (and do not) express certain behavior.

No MeSH data available.


Related in: MedlinePlus