Biomedical subjects

Yonatan Goshen-Gottstein

Publications and source records attributed to Yonatan Goshen-Gottstein.

10 recordsLinked to original sources

PubMed2006

Sleep-anticipating effects of melatonin in the human brain.

Melatonin, the hormone produced nocturnally by the pineal gland, is an endogenous regulator of the sleep-wake cycle. The effects of melatonin on brain activities and their relation to induction of sleepiness were studied in a randomized, double-blind, placebo controlled functional magnetic resonance imaging (fMRI) study. Melatonin, but not placebo, reduced task-related activity in the rostro-medial aspect of the occipital cortex during a visual-search task and in the auditory cortex during a music task. These effects correlated with subjective measurements of fatigue. In addition, melatonin enhanced the activation in the left parahippocampus in an autobiographic memory task. Results demonstrate that melatonin modulates brain activity in a manner resembling actual sleep although subjects are fully awake. Furthermore, the fatigue inducing effect of melatonin on brain activity is essentially different from that of sleep deprivation thus revealing differences between fatigues related to the circadian sleep regulation as opposed to increased homeostatic sleep need. Our findings highlight the role of melatonin in priming sleep-associated brain activation patterns in anticipation of sleep.

Adult↗

PubMed2006

The long-term recency effect in recognition memory.

Three classes of theories explain the recency effect: the modal model, single-store models, and the composite view, which integrates the two positions. None could explain the absence of a long-term recency effect in recognition memory in previous studies. We suggest that prior work did not obtain a recency effect because testing used a multiple-probe rather than a single-probe recognition procedure. Here we tested memory using a single-probe recognition procedure. Experimental conditions included an immediate test, a delayed test after a filled interval, and a continuous-distractor paradigm in which the same filled delay preceded the first word and followed every study word. The long-term recency effect in continuous-distractor recognition was equivalent to the recency effect in immediate recognition. Its absence in the delayed recognition condition demonstrated that it was not attributed to the use of a putative short-term memory store. Single-store models and the composite view can account for this novel finding.

Adult↗

PubMed2006

Semantic similarity dissociates short- from long-term recency effects: testing a neurocomputational model of list memory.

The finding that recency effects can occur not only in immediate free recall (i.e., short-term recency) but also in the continuous-distractor task (ie., long-term recency) has led many theorists to reject the distinction between short- and long-term memory stores. Recently, we have argued that long-term recency effects do not undermine the concept of a short-term store, and we have presented a neurocomputational model that accounts for both short- and long-term recency and for a series of dissociations between these two effects. Here, we present a new dissociation between short- and long-term recency based on semantic similarity, which is predicted by our model. This dissociation is due to the mutual support between associated items in the short-term store, which takes place in immediate free recall and delayed free recall but not in continuous-distractor free recall.

Arousal↗

PubMed2005

The involvement of the "fusiform face area" in processing facial expression.

We conducted an fMRI investigation to test the widely accepted notion that the fusiform face area (FFA) mediates the processing of facial identity but not expression. Participants attended either to the identity or to the expression of the same set of faces. If the processing of identity is neuroanatomically dissociable from that of expression, then one might expect the FFA to show higher activation when processing identity as opposed to expression. Contrary to this prediction, the FFA showed higher activation for judgments of expression. Furthermore, the FFA was sensitive to variations in expression even when attention was directed to identity. Finally, an independent observation showed higher activation in the FFA for passive viewing of faces when expression was varied as compared to when it remained constant. These findings suggest an interactive network for the processing of expression and identity, in which information about expression is computed from the unique structure of individual faces.

Analysis of Variance↗

PubMed2005

The demise of short-term memory revisited: empirical and computational investigations of recency effects.

In the single-store model of memory, the enhanced recall for the last items in a free-recall task (i.e., the recency effect) is understood to reflect a general property of memory rather than a separate short-term store. This interpretation is supported by the finding of a long-term recency effect under conditions that eliminate the contribution from the short-term store. In this article, evidence is reviewed showing that recency effects in the short and long terms have different properties, and it is suggested that 2 memory components are needed to account for the recency effects: an episodic contextual system with changing context and an activation-based short-term memory buffer that drives the encoding of item-context associations. A neurocomputational model based on these 2 components is shown to account for previously observed dissociations and to make novel predictions, which are confirmed in a set of experiments.

Adult↗

PubMed2005

Neuroimaging the serial position curve. A test of single-store versus dual-store models.

Neuroimaging data could help clarify the long-standing dispute between dual-store and single-store models of the serial position curve. Dual-store models assume that retrieval from late positions is dependent on short-term memory (STM), whereas retrieval from early positions is dependent on long-term memory (LTM). Single-store models, however, assume that retrieval processes for early and late items are similar, but that early items are more difficult to discriminate than late items. The present study used functional magnetic resonance imaging to examine this question. Ten young adults were scanned while they recognized items from early or late serial positions. Recognition of early items uniquely activated brain areas traditionally associated with LTM, namely, regions within the hippocampal memory system. None of these areas was activated for retrieval of late items. These results indicate differential use of LTM retrieval processes, and therefore support dual-store models over single-store models.

Adult↗

PubMed2004

Interactions between the processing of gaze direction and facial expression.

In this article, we explored the relationship between the processing of facial expression and the processing of gaze direction. In Experiment 1, participants were unable to ignore gaze while classifying expression-or to ignore expression while classifying gaze. This suggests that the processing of expression and the processing of gaze are interdependent. In Experiment 2, the faces were inverted to isolate configural from part-based contributions to this interdependence. Inversion had a striking effect on expression judgments, which could now be processed independently of gaze, but not on gaze judgments, which were still influenced by expression, even when photos that contained only the eye region of faces were presented (Experiment 4). In Experiment 3 the processing of expression was found to be sensitive to even small variations in the direction of gaze. These results suggest that the processing underlying judgments of expression is configural and entails an obligatory computation of gaze direction. Judgments of gaze direction, however, are carried out in a part-based manner using local features around the eyes and are insensitive to the configural aspects of facial processing.

Adult↗

PubMed2004

Effects of familiarity on the perceptual integrality of the identity and expression of faces: the parallel-route hypothesis revisited.

The effects of familiarity on selective attention for the identity and expression of faces were tested using Garner's speeded-classification task. In 2 experiments, participants classified expression (or identity) of familiar and unfamiliar faces while the irrelevant dimension of identity (or expression) was either held constant (baseline condition) or varied randomly (filtering condition). Selective attention was measured by the difference in performance between these 2 conditions. Failure of selective attention was larger for familiar than for unfamiliar faces. In addition, failure of selective attention was found both for identity and for expression judgments. These findings show that familiarity increases (he perceptual integrality between identity and expression, and they question previous studies arguing that identity judgments are always resistant to irrelevant variations in expression. The authors suggest that the systems processing identity and expression are interconnected in that facial identity serves as a reference from which expressions can be more easily derived.

Adult↗

PubMed2002

The origins of levels-of-processing effects in a conceptual test: evidence for automatic influences of memory from the process-dissociation procedure.

In three experiments, we explored automatic influences of memory in a conceptual memory task, as affected by a levels-of-processing (LoP) manipulation. We also explored the origins of the LoP effect by examining whether the effect emerged only when participants in the shallow condition truncated the perceptual processing (the lexical-processing hypothesis) or even when the entire word was encoded in this condition (the conceptual-processing hypothesis). Using the process-dissociation procedure and an implicit association-generation task, we found that the deep encoding condition yielded higher estimates of automatic influences than the shallow condition. In support of the conceptual processing hypothesis, the LoP effect was found even when the shallow task did not lead to truncated processing of the lexical units. We suggest that encoding for meaning is a prerequisite for automatic processing on conceptual tests of memory.

Automatism↗

PubMed2002

Perceptual integrality of sex and identity of faces: further evidence for the single-route hypothesis.

According to current face-recognition models, sex (gender) and identity of faces are processed in independent routes. Using Garner's speeded-classification task, the authors provide evidence that sex and identity are processed within a single route. In 4 experiments, participants judged the sex or the familiarity of faces while the other dimension remained constant or varied randomly. The results of Experiments 1, 2, and 4 showed that participants could not selectively attend to either sex or familiarity without being influenced by the other, irrelevant dimension. Thus, identity and sex are integral dimensions. Experiment 3 provided evidence that when sex judgments are based on hairstyle heuristics, false separability can emerge. The findings support the claim that identity and sex are processed within a single route.

Adult↗