Symmetric patterns with different luminance polarity (anti‐symmetry) generate an automatic response in extrastriate cortex

Neuroimaging studies have indicated involvement of left prefrontal cortex and temporal areas in verbal memory processes. The current study used event-related functional neuroimaging to compare encoding of subsequently recalled and not recalled words in high and low memory performers. Fifteen healthy volunteers were given lists of words to learn with immediate recall and to read as a control condition. High performers reported to have visualized the words whereas low performers used a rehearsal strategy. Compared to reading, unsuccessful encoding was associated with thalamic and left premotor area (BA 6) activity. Comparing successful with unsuccessful learning yielded widespread activity of the left prefrontal and posterior temporal gyrus as well as the left superior parietal lobe in the whole group. Low performers showed activation of the left premotor area throughout learning and additionally of the left middle temporal and parahippocampal gyrus during successful encoding. High performers showed increased activation in the extrastriate cortex throughout learning and additionally in the left parietal post- and paracentral areas as well as in the right precuneus during successful encoding. The results suggest that high verbal memory performance is the result of spatiovisual activation concomitant to imagery and low performance of hippocampal and motor activation, the latter being associated with rehearsal, with a common memory circuit subserving both groups.

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Automatic Response to Intrusion

10.21236/ada408394 ◽

2002 ◽

Author(s):

Dan Schnackenberg ◽

Harley Holliday ◽

Travis Reid ◽

Kelly Bunn ◽

Dan Sterne

Keyword(s):

Automatic Response

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Differentiating Real-World Autobiographical Experiences without Recourse to Behaviour

Brain Sciences ◽

10.3390/brainsci11040521 ◽

2021 ◽

Vol 11 (4) ◽

pp. 521

Author(s):

Jonathan Erez ◽

Marie-Eve Gagnon ◽

Adrian M. Owen

Keyword(s):

Medial Temporal Lobe ◽

Brain Injuries ◽

Brain Activity ◽

Extrastriate Cortex ◽

First Person ◽

Autobiographical Memories ◽

True Nature ◽

Person Perspective ◽

Machine Learning Model ◽

First Person Perspective

Investigating human consciousness based on brain activity alone is a key challenge in cognitive neuroscience. One of its central facets, the ability to form autobiographical memories, has been investigated through several fMRI studies that have revealed a pattern of activity across a network of frontal, parietal, and medial temporal lobe regions when participants view personal photographs, as opposed to when they view photographs from someone else’s life. Here, our goal was to attempt to decode when participants were re-experiencing an entire event, captured on video from a first-person perspective, relative to a very similar event experienced by someone else. Participants were asked to sit passively in a wheelchair while a researcher pushed them around a local mall. A small wearable camera was mounted on each participant, in order to capture autobiographical videos of the visit from a first-person perspective. One week later, participants were scanned while they passively viewed different categories of videos; some were autobiographical, while others were not. A machine-learning model was able to successfully classify the video categories above chance, both within and across participants, suggesting that there is a shared mechanism differentiating autobiographical experiences from non-autobiographical ones. Moreover, the classifier brain maps revealed that the fronto-parietal network, mid-temporal regions and extrastriate cortex were critical for differentiating between autobiographical and non-autobiographical memories. We argue that this novel paradigm captures the true nature of autobiographical memories, and is well suited to patients (e.g., with brain injuries) who may be unable to respond reliably to traditional experimental stimuli.

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How complete is physiological compensation in extrastriate cortex after visual cortex damage in kittens?

Experimental Brain Research ◽

10.1007/bf00227841 ◽

1992 ◽

Vol 91 (3) ◽

Cited By ~ 22

Author(s):

William Guido ◽

PeterD. Spear ◽

Lillian Tong

Keyword(s):

Visual Cortex ◽

Extrastriate Cortex

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Event-Related Functional Magnetic Resonance Imaging Study of the Extrastriate Cortex Response to a Categorically Ambiguous Stimulus Primed by Letters and Familiar Geometric Figures

Journal of Cerebral Blood Flow & Metabolism ◽

10.1097/00004647-200111000-00009 ◽

2001 ◽

Vol 21 (11) ◽

pp. 1330-1341 ◽

Cited By ~ 22

Author(s):

Hélène Gros ◽

Kader Boulanouar ◽

Gérard Viallard ◽

Emmanuelle Cassol ◽

Pierre Celsis

Keyword(s):

Magnetic Resonance Imaging ◽

Magnetic Resonance ◽

Functional Magnetic Resonance Imaging ◽

Right Hemisphere ◽

Extrastriate Cortex ◽

Functional Magnetic Resonance ◽

Resonance Imaging ◽

Ambiguous Stimulus ◽

Form Processing ◽

Geometric Figures

Functional neuroimaging studies have suggested a specific role of the extrastriate cortex in letter string and visual word form processing. However, this region has been shown to be involved in object recognition and its specificity for the processing of linguistic stimuli may be questioned. The authors used an event-related functional magnetic resonance imaging design with category priming to record the response elicited by the passive viewing of single letters, geometric figures, and of the categorically ambiguous stimulus “O” that pertains to both sets of familiar symbols. Bilateral activations in the extrastriate cortex were found, with a left predominance particularly pronounced for the ambiguous stimulus. Individual analysis of spatial extent and signal intensity showed a priming × stimulus × hemisphere interaction. When primed by the congruous categoric set, a bilateral decrease in activation was observed for letters and geometric figures. The ambiguous stimulus behaved as a letter for the left hemisphere, with decreased activation when primed by letters, whereas in the right hemisphere, an adaptation effect occurred when primed by geometric figures. These priming effects suggest that, for the ambiguous stimulus, letter processing was systematically involved in the left extrastriate cortex. The current results support the existence of a neural substrate for the abstract category of letters.

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