Biomedical subjects

Jennifer Mangels

Publications and source records attributed to Jennifer Mangels.

4 recordsLinked to original sources

PubMed2006

Predictive codes for forthcoming perception in the frontal cortex.

Incoming sensory information is often ambiguous, and the brain has to make decisions during perception. "Predictive coding" proposes that the brain resolves perceptual ambiguity by anticipating the forthcoming sensory environment, generating a template against which to match observed sensory evidence. We observed a neural representation of predicted perception in the medial frontal cortex, while human subjects decided whether visual objects were faces or not. Moreover, perceptual decisions about faces were associated with an increase in top-down connectivity from the frontal cortex to face-sensitive visual areas, consistent with the matching of predicted and observed evidence for the presence of faces.

Amygdala↗

PubMed2006

Neocortical connectivity during episodic memory formation.

During the formation of new episodic memories, a rich array of perceptual information is bound together for long-term storage. However, the brain mechanisms by which sensory representations (such as colors, objects, or individuals) are selected for episodic encoding are currently unknown. We describe a functional magnetic resonance imaging experiment in which participants encoded the association between two classes of visual stimuli that elicit selective responses in the extrastriate visual cortex (faces and houses). Using connectivity analyses, we show that correlation in the hemodynamic signal between face- and place-sensitive voxels and the left dorsolateral prefrontal cortex is a reliable predictor of successful face-house binding. These data support the view that during episodic encoding, "top-down" control signals originating in the prefrontal cortex help determine which perceptual information is fated to be bound into the new episodic memory trace.

Adult↗

PubMed2005

Mistaking a house for a face: neural correlates of misperception in healthy humans.

Individuals with normal vision can sometimes momentarily mistake one object for another. In this functional magnetic resonance imaging study, we investigated how extrastriate visual regions respond during these erroneous perceptual judgements. Subjects were asked to discriminate images of houses and faces that were degraded such that they were close to an individually defined threshold for perception. On correct trials, voxels localized on the inferior occipital (OFA), fusiform (FFA) and parahippocampal (PPA) gyri exhibited selectivity for face and house images as expected. On incorrect trials, no face- or place-selectivity was observed for OFA or PPA. However, consistent with 'predictive coding' accounts of perception, we observed that the FFA also responded robustly on trials where a house was misperceived as a face, and concurrent activation was observed in medio-frontal and right parietal regions previously implicated in decision making under uncertainty. We suggest that FFA responses during misperception may be driven by a predictive top-down signal from these regions.

Adult↗

PubMed2003

Typical and atypical antipsychotic medications differentially affect two nondeclarative memory tasks in schizophrenic patients: a double dissociation.

Nondeclarative memory (NDM) has subtypes associated with different brain regions; learning of a probabilistic classification task is impaired by striatal damage and learning of a gambling task is impaired by ventromedial prefrontocortical damage. Typical and atypical antipsychotic medications differentially affect immediate early gene expression in the striatum and frontal cortex in normal rats. This suggested the hypothesis that schizophrenic patients treated with typical antipsychotics will have impaired probabilistic classification learning (PCL) and that similar patients treated with atypical antipsychotics will have impaired learning of the gambling task. Groups of schizophrenia patients treated with typical or atypical antipsychotics did not differ from each other on the Brief Psychiatric Rating Scale (BPRS), Mini Mental State Exam (MMSE) or a number of indexes of the Wisconsin Card Sorting Task (WCST) but performed worse than normal controls on these instruments. In the first study, patients treated with typicals (n=20) but not atypicals (n=20) or normal controls (n=32) were impaired in probabilistic classification. In the second study, those treated with atypicals (n=18) but not typicals (n=18) or normal controls (n=18) were impaired in the gambling task. Results suggest that typical and atypical antipsychotics differentially affect nondeclarative memory mediated by different brain regions.

Adult↗