Demystifying wine expertise: olfactory threshold,perceptual skill and semantic memory in expert and novice wine judges

We investigated recognition and identification of wine-relevant odours as a function of domain-specific expertise. Eleven wine experts and 11 wine novices participated in tasks measuring olfactory threshold, odour recognition, odour identification, and consistency of odour naming. Twenty-four wine-relevant odorants were sampled orthonasally by each participant in the semantic (identification; consistency of naming) and episodic (recognition) memory tasks. Results showed superior olfactory recognition by expert wine judges, despite their olfactory sensitivity and bias measures being similar to those of novices. Contrary to predictions based on reports of an association between odour memory and semantic processing, wine experts did not perform better than novices on the verbal memory tasks. Further, ability to recognize odours and ability to name odours were not positively correlated, although the novices' data showed a trend in this direction. The results imply that the source of superior odour recognition in wine experts was not enhanced semantic memory and linguistic capabilities for wine-relevant odours. One interpretation of the data is that wine experts were less susceptible than wine novices to verbal overshadowing. When forced to identify the odorants, experts' superior perceptual skills protected them from verbal interference, whereas novices' generated verbal representations of the odours were emphasized at the expense of the odorant itself. This has implications for training in wine-evaluation skills.     

Odor identification, consistency of label use, olfactory threshold and their relationships to odor memory over the human lifespan.

The purpose of this study was to investigate olfactory threshold, odor identification, consistency of label use and their relationships to odor memory in the context of semantic/episodic memory across the human lifespan. A total of 137 subjects aged 4-90 years were tested with several olfactory test procedures. We found that olfactory sensitivity was well developed in children despite the finding that their odor naming and odor memory were inferior to that of adults. In the elderly population, olfactory functions gradually declined, with odor memory and odor identification demonstrating the most significant decline. Semantic encoding was differentially related to odor memory over the human age span. Whereas consistency of label use was the main predictor for odor memory in children and young adults, olfactory identification ability was the main predictor in the elderly study group. We also calculated response bias for the separate age groups and found no differences between children, young adults and elderly. However, with age false alarm rates increased. We conclude that children possess equal olfactory sensitivity compared with adults; however, due to limitations in linguistic capabilities and familiarity to odorants, odor memory and odor identification performance was limited. Additionally, our data indicate major alterations of olfactory processing in advanced age with substantial losses in odor memory and odor identification performance.     

蜜蜂对复合气味中特征因素的选择性记忆巩固的研究

目的 蜜蜂天生具有丰富的嗅觉辨识能力,觅食、交配、导航以及社交活动均依赖其嗅觉系统,是研究嗅觉感知和学习记忆的行为及神经机制的理想模型。蜜蜂既能够将某个复合气味作为一个整体也可以将复合气味的各组成成分进行辨别和区分,但是在特征依赖的联合记忆中依据何种原则进行加工并存储到长期记忆还不清楚。方法 本文利用特征阳性（feature positive：AB+,B-）和特征阴性（feature negative：AB-,B+）的奖赏性嗅觉条件化,训练蜜蜂对复合气味和成分气味的辨别,并检测蜜蜂对复合气味（AB）、成分气味（B）以及特征气味（A）的中长时记忆（3 h）和长时记忆（24 h）。结果 在特征阳性的奖赏性嗅觉条件化中,蜜蜂对训练过的气味可以形成稳定的中长时和长时记忆,并且对复合气味中的特征气味的记忆与复合气味的记忆呈现高度相似。但在特征阴性的奖赏性嗅觉条件化中,蜜蜂虽能够在3 h和24 h对训练过的两种气味具有显著的伸喙反应差异,且对特征阴性的气味无显著反应,但对复合气味的反应随时间的推移而增加。结论 实验结果表明,蜜蜂选择性地将与奖赏信息联合出现的气味巩固到长时记忆中,但并未依据特征成分加工储存到长时记忆中。奖赏信息预示着食物源,与生存息息相关,表明对环境信息进行选择性的记忆巩固加工并储存可能是低等动物高效地编码生存相关信息的重要策略。     

Olfactory deficits in patients affected by minimal hepatic encephalopathy: a pilot study

Minimal hepatic encephalopathy (MHE) is the earliest stage of hepatic encephalopathy and is associated with changes in cognitive functions, in electrophysiological parameters, and in cerebral neurochemical/neurotransmitter homeostasis. MHE can be observed in patients with cirrhosis who have no clinical evidence of hepatic encephalopathy (HE). At present, no data are available on a possible olfactory dysfunction in such a syndrome, although the pathophysiology of HE may alter olfactory functions since some of the neurotransmitters impaired in the syndrome are involved in the transmission of olfactory information. In the present paper, we performed a preliminary study aimed at detecting whether identification and recognition odor memory is altered in patients with MHE. Twelve patients diagnosed as MHE on the basis of their scores at the portosystemic encephalopathy (PSE)-syndrome test battery, and 12 age-matched controls were studied. Consistent with the hypothesis, patients performed significantly worse than controls for both odor identification and recognition tasks. In addition, a significant correlation between the two olfactory tests and the PSE-syndrome test score was found. This pattern supports the notion that olfactory alterations related to cognitive dysfunction in patients with MHE may be linked to the pathophysiology of HE.     

Episodic memory: insights from semantic dementia

Semantic dementia, also known as the temporal lobe variant of fronto-temporal dementia, results in a progressive yet relatively pure loss of semantic knowledge about words, objects and people, and is associated with asymmetric, focal atrophy of the antero-lateral temporal lobes. Semantic dementia provides a unique opportunity to study the organization of long-term memory particularly since initial observations suggested sparing of episodic memory. Recent studies reveal, however, a more complex but theoretically revealing pattern. On tests of autobiographical memory, patients with semantic dementia show a 'reverse step function' with sparing of recall of events from the most recent 2 to 5 years but impairment on more distant life periods. Anterograde recognition memory for visual materials is extremely well preserved, except in the most deteriorated cases, although performance is heavily reliant upon perceptual information about the studied stimuli, particularly for items that are no longer known by the subjects. On tests of verbal anterograde memory such as word learning, performance is typically poor even for words which are 'known' to the patients. A source discrimination experiment, designed to evaluate familiarity and recollection-based anterograde memory processes, found that patients with semantic dementia showed good item detection, although recollection of source was sometimes impaired. Semantic knowledge about studied items and measures of item detection and source discrimination were largely independent. The implications of these findings for models of long-term memory are discussed. The results support the concept that episodic memory, or at least the recall of temporally specific autobiographical experiences, draws upon a number of separable memory processes, some of which can function independently of semantic knowledge.     

Verbal cues modulate hedonic perception of odors in 5-year-old children as well as in adults

The judgment of pleasantness/unpleasantness is the prominent reaction to the olfactory world. In human adults, the hedonic valence of odor perception is affected by various factors, among which is an individual's lexical knowledge about smells. The present study examined whether such top-down effects of lexical knowledge on hedonic judgment of olfactory input are similar in children (5-6 years) and adults (20-25 years). In both groups, the lexical knowledge was found to influence the perception of the least emotional (or most neutral) odors: the pleasantness of the smells of banana and mint was enhanced when participants were given the corresponding odor label before olfactory sensation. These results lend support to the notion that, during childhood, smells are not only encoded perceptually but that verbal encoding also steers contextual effects that may be prominent factors in the early memorization and categorization of odors.     

Odor recognition memory as a function of odor-naming performance

A series of experiments sought to clarify the relationship between odor naming and memory by manipulating odor label availability during a dual naming-memory task. Experiment 1 demonstrated that recognition memory and odor naming were both better when the naming task provided participants with odor label alternatives. Consistent and correct odor naming was associated with nearly perfect memory, whereas inconsistent or incorrect naming was associated with very weak memory if any at all. Experiment 2 showed that the availability of odor labels was effective at improving memory only if labels were available at both memory encoding and retrieval, suggesting that the labels were aiding memory by improving the identification of the odors. Odor naming was manipulated in Experiment 3 by varying the number of available labels from 4 to 16 during each odor-naming trial. As found in the previous experiments, naming and memory were strongly related in each of the labeling conditions. Experiment 4 showed that corrective naming feedback produced better memory performance but only when the feedback led to correct odor naming. It was concluded that perceptual processes related to matching olfactory input to acquired, multidimensional representations of odors play a critical role in both odor naming and episodic memory.     

Remembrance of odors past: human olfactory cortex in cross-modal recognition memory

Episodic memory is often imbued with multisensory richness, such that the recall of an event can be endowed with the sights, sounds, and smells of its prior occurrence. While hippocampus and related medial temporal structures are implicated in episodic memory retrieval, the participation of sensory-specific cortex in representing the qualities of an episode is less well established. We combined functional magnetic resonance imaging (fMRI) with a cross-modal paradigm, where objects were presented with odors during memory encoding. We then examined the effect of odor context on neural responses at retrieval when these same objects were presented alone. Primary olfactory (piriform) cortex, as well as anterior hippocampus, was activated during the successful retrieval of old (compared to new) objects. Our findings indicate that sensory features of the original engram are preserved in unimodal olfactory cortex. We suggest that reactivation of memory traces distributed across modality-specific brain areas underpins the sensory qualities of episodic memories.     

Olfactory bulb proteins linked to olfactory memory in C57BL/6J mice

Information on systematic analysis of olfactory memory-related proteins is poor. In this study, the odor discrimination task to investigate olfactory recognition memory of adult male C57BL/6J mice was used. Subsequently, olfactory bulbs (OBs) were taken, proteins extracted, and run on two-dimensional gel electrophoresis with in-gel-protein digestion, followed by mass spectrometry and quantification of differentially expressed proteins. Dual specificity mitogen-activated protein kinase kinase 1 (MEK1), dihydropyrimidinase-related protein 1 (DRP1), and fascin are related with Lemon odor memory. Microtubule-associated protein RP/EB family member 3 is related to Rose odor memory. Hypoxanthine-guanine phosphoribosyltransferase is related with both Lemon and Rose odors memory. MEK1 and DRP1 levels were increased, while microtubule-associated protein RP/EB family member 3, fascin and hypoxanthine-guanine phosphoribosyltransferase levels were decreased during olfactory memory. In summary, neurogenesis, signal transduction, cytoskeleton, and nucleotide metabolism are involved in olfactory memory formation and storage of C57BL/6J mice.     

Semantic memory and the human hippocampus

It has been unclear whether the hippocampus is uniquely important for episodic memory (memory for events that are specific to time and place) or whether the hippocampus is also important for learning and remembering facts (semantic memory). In two studies, we assessed the capacity for semantic memory in patients with bilateral damage thought to be restricted primarily to the hippocampal region who developed memory impairment at a known time. Since the onset of their memory impairment, the patients have acquired less factual knowledge than controls. The patients also exhibit temporally limited retrograde amnesia for factual information from the several years preceding the onset of memory impairment. Remote memory for factual knowledge (from 11-30 years before amnesia) is intact. The results show that the hippocampal region supports semantic memory as well as episodic memory and that its role in the acquisition and storage of semantic knowledge is time limited.     

A Lateralized Odor Learning Model in Neonatal Rats for Dissecting Neural Circuitry Underpinning Memory Formation

Rat pups during a critical postnatal period (≤ 10 days) readily form a preference for an odor that is associated with stimuli mimicking maternal care. Such a preference memory can last from hours, to days, even life-long, depending on training parameters. Early odor preference learning provides us with a model in which the critical changes for a natural form of learning occur in the olfactory circuitry. An additional feature that makes it a powerful tool for the analysis of memory processes is that early odor preference learning can be lateralized via single naris occlusion within the critical period. This is due to the lack of mature anterior commissural connections of the olfactory hemispheres at this early age. This work outlines behavioral protocols for lateralized odor learning using nose plugs. Acute, reversible naris occlusion minimizes tissue and neuronal damages associated with long-term occlusion and more aggressive methods such as cauterization. The lateralized odor learning model permits within-animal comparison, therefore greatly reducing variance compared to between-animal designs. This method has been used successfully to probe the circuit changes in the olfactory system produced by training. Future directions include exploring molecular underpinnings of odor memory using this lateralized learning model; and correlating physiological change with memory strength and durations.     

Reversing Stimulus Timing in Visual Conditioning Leads to Memories with Opposite Valence in Drosophila

Animals need to associate different environmental stimuli with each other regardless of whether they temporally overlap or not. Drosophila melanogaster displays olfactory trace conditioning, where an odor is followed by electric shock reinforcement after a temporal gap, leading to conditioned odor avoidance. Reversing the stimulus timing in olfactory conditioning results in the reversal of memory valence such that an odor that follows shock is later on approached (i.e. relief conditioning). Here, we explored the effects of stimulus timing on memory in another sensory modality, using a visual conditioning paradigm. We found that flies form visual memories of opposite valence depending on stimulus timing and can associate a visual stimulus with reinforcement despite being presented with a temporal gap. These results suggest that associative memories with non-overlapping stimuli and the effect of stimulus timing on memory valence are shared across sensory modalities.     

Episodic memory and common sense: how far apart?

Research has revealed facts about human memory in general and episodic memory in particular that deviate from both common sense and previously accepted ideas. This paper discusses some of these deviations in light of the proceedings of The Royal Society's Discussion Meeting on episodic memory. Retrieval processes play a more critical role in memory than commonly assumed; people can remember events that never happened; and conscious thoughts about one's personal past can take two distinct forms-'autonoetic' remembering and 'noetic' knowing. The serial-dependent-independent (SPI) model of the relations among episodic, semantic and perceptual memory systems accounts for a number of puzzling phenomena, such as some amnesic patients' preserved recognition memory and their ability to learn new semantic facts, and holds that episodic remembering of perceptual information can occur only by virtue of its mediation through semantic memory. Although common sense endows many animals with the ability to remember their past experiences, as yet there is no evidence that humanlike episodic memory-defined in terms of subjective time, self, and autonoetic awareness-is present in any other species.     

Higher Olfactory Threshold and Decreased Odor Identification Ability in HIV-infected Persons

In order to evaluate whether the olfactory system is involvedin HIV infection, two patient groups defined along a decreasein cellular immunity and a healthy control group were testedfor olfactory threshold, odor identification and odor memory.Chem. Senses 20: 325–328, 1995.     

Memory for events and their spatial context: models and experiments

The computational role of the hippocampus in memory has been characterized as: (i) an index to disparate neocortical storage sites; (ii) a time-limited store supporting neocortical long-term memory; and (iii) a content-addressable associative memory. These ideas are reviewed and related to several general aspects of episodic memory, including the differences between episodic, recognition and semantic memory, and whether hippocampal lesions differentially affect recent or remote memories. Some outstanding questions remain, such as: what characterizes episodic retrieval as opposed to other forms of read-out from memory; what triggers the storage of an event memory; and what are the neural mechanisms involved? To address these questions a neural-level model of the medial temporal and parietal roles in retrieval of the spatial context of an event is presented. This model combines the idea that retrieval of the rich context of real-life events is a central characteristic of episodic memory, and the idea that medial temporal allocentric representations are used in long-term storage while parietal egocentric representations are used to imagine, manipulate and re-experience the products of retrieval. The model is consistent with the known neural representation of spatial information in the brain, and provides an explanation for the involvement of Papez''s circuit in both the representation of heading direction and in the recollection of episodic information. Two experiments relating to the model are briefly described. A functional neuroimaging study of memory for the spatial context of life-like events in virtual reality provides support for the model''s functional localization. A neuropsychological experiment suggests that the hippocampus does store an allocentric representation of spatial locations.     

A Preliminary Investigation of Parent–Progeny Olfactory Recognition and Parental Investment

The role of olfaction in kin recognition and parental investment is documented in many mammalian/vertebrate species. Research on humans, however, has only focused on whether parents are able to recognize their children by smell, not whether humans use these cues for investment decisions. Here we show that fathers exhibit more affection and attachment and fewer ignoring behaviors toward children whose smell they can identify than toward those whose smell they cannot recognize. Thus, olfaction might serve as a means for males to determine their genetic relatedness to purported offspring. We also demonstrate that mothers’ olfactory recognition and hedonistic ratings are linked with the use of physical punishment. Mothers report using more punishment with children whose odor they cannot recognize and less with children whose odor they rated as more pleasant. These results provide the first preliminary evidence in humans that olfactory cues may guide parents in the allocation of care.     

Which format for odor images?

Olfactory mental images are defined as short-term memory representationsof olfactory events that give rise to the experience of "smellingwith the mind's nose." The present paper reviewed convergingevidences that support the view that as visual mental images,odor mental images preserve some aspects of olfactory percepts.The role of olfactomotor mechanisms in recalling olfactory mentalimages from long-term memory to short-term memory is also discussed.     

Priming picture naming with a semantic task: an fMRI investigation

Prior semantic processing can enhance subsequent picture naming performance, yet the neurocognitive mechanisms underlying this effect and its longevity are unknown. This functional magnetic resonance imaging study examined whether different neurological mechanisms underlie short-term (within minutes) and long-term (within days) facilitation effects from a semantic task in healthy older adults. Both short- and long-term facilitated items were named significantly faster than unfacilitated items, with short-term items significantly faster than long-term items. Region of interest results identified decreased activity for long-term facilitated items compared to unfacilitated and short-term facilitated items in the mid-portion of the middle temporal gyrus, indicating lexical-semantic priming. Additionally, in the whole brain results, increased activity for short-term facilitated items was identified in regions previously linked to episodic memory and object recognition, including the right lingual gyrus (extending to the precuneus region) and the left inferior occipital gyrus (extending to the left fusiform region). These findings suggest that distinct neurocognitive mechanisms underlie short- and long-term facilitation of picture naming by a semantic task, with long-term effects driven by lexical-semantic priming and short-term effects by episodic memory and visual object recognition mechanisms.     

The Hippocampus Remains Activated over the Long Term for the Retrieval of Truly Episodic Memories

The role of the hippocampus in declarative memory consolidation is a matter of intense debate. We investigated the neural substrates of memory retrieval for recent and remote information using functional magnetic resonance imaging (fMRI). 18 young, healthy participants learned a series of pictures. Then, during two fMRI recognition sessions, 3 days and 3 months later, they had to determine whether they recognized or not each picture using the "Remember/Know" procedure. Presentation of the same learned images at both delays allowed us to track the evolution of memories and distinguish consistently episodic memories from those that were initially episodic and then became familiar or semantic over time and were retrieved without any contextual detail. Hippocampal activation decreased over time for initially episodic, later semantic memories, but remained stable for consistently episodic ones, at least in its posterior part. For both types of memories, neocortical activations were observed at both delays, notably in the ventromedial prefrontal and anterior cingulate cortices. These activations may reflect a gradual reorganization of memory traces within neural networks. Our data indicate maintenance and strengthening of hippocampal and cortico-cortical connections in the consolidation and retrieval of episodic memories over time, in line with the Multiple Trace theory (Nadel and Moscovitch, 1997). At variance, memories becoming semantic over time consolidate through strengthening of cortico-cortical connections and progressive disengagement of the hippocampus.