"Gourmand syndrome" in a child with pharmacoresistant epilepsy

We report the case of a 10-year-old boy with pharmacoresistant epilepsy, symptomatic of a right temporoparietal hemorrhagic lesion, who displayed an eating passion as described for the gourmand syndrome (GS) in adults and discuss the role of epilepsy in GS. This patient presented with a significant change in his eating habits (abnormal preoccupation with the preparation and eating of fine-quality food) concordant with the onset of his seizure disorder, without any previous history of eating disorders or psychiatric illness. This observation corroborates the important role of the right cerebral hemisphere in disturbed eating habits, including the relatively benign GS, and, possibly rarely, in less benign eating disorders such as anorexia and obesity.     

Sensory acuity and reasoning in delusional disorder

Systematic research on delusional disorder (DD) is limited. The goal of this study was to assess DD patients in the following areas: sensory capacities, decision-making style, and complex reasoning. Ten DD patients and 10 matched normal controls completed the following (1) smell, taste, and vision testing; (2) a probabilistic inference test in which subjects made probability decisions; and (3) a gambling task assessing complex reasoning. No significant difference was found between DD subjects and normals for taste acuity, olfactory acuity, or olfactory discrimination. No difference in visual acuity was noted, but sample size was limited. In addition, DD subjects required significantly less data to make probability decisions than normal controls. Despite using less data, DD subjects were as certain as controls regarding the accuracy of their decisions. As for complex reasoning, DD subjects performed as well as normal controls, but tended to surmise the purpose of the task sooner than normals, a difference that approached significance. In conclusion, these results suggest no differences between DD and normal subjects regarding olfaction, taste, and vision. The reasoning studies suggest that DD subjects may have a "cognitive set" that predisposes them to make conclusions with significantly less data than normals. Further, the study suggests that this reasoning difference generalizes to events outside the DD subjects' delusional realm and can be evoked in an experimental environment.     

Taste laterality in the split brain

Two patients with corpus callosum resection, one complete and the other sparing the genu and the rostrum, were tested for discrimination of three basic taste stimuli (sour, bitter, salty) applied to the right or left sides of the tongue. Responses were made by pointing with either hand to written words or images of visual objects corresponding to the stimuli, a language-based discrimination. In both patients, response accuracy was significantly above chance for both hemitongues but there was a significant advantage for the left side. Reaction time was shorter for left stimuli than for right stimuli but the difference was not significant. Eight normal controls matched for age with the patients performed equally well with right and left hemitongue stimuli and so did a third callosotomy patient with sparing of the posterior callosum, including the splenium. Tactile and visual tests showed that the left hemisphere was responsible for language-based responses in the first two patients. The results confirm and extend previous findings in another callosotomy patient, indicating that: (i) taste information from either side of the tongue can reach the left hemisphere in the absence of the corpus callosum; (ii) the ipsilateral input from the tongue to the left hemisphere is more potent functionally than the contralateral input and (iii) in the normal brain, the corpus callosum, specifically its posterior part including the splenium, appears to equalize the effects of the ipsilateral and contralateral gustatory inputs on the left hemisphere. Taken together with evidence about lateralized taste deficits following unilateral cortical lesions, the results also suggest that the gustatory pathways from tongue to cortex are bilaterally-distributed with an ipsilateral predominance that may be subject to individual variations.     

Taste function in patients with Parkinson disease

Despite the important role of taste function in nutrition and health, little is known about changes in taste function caused by Parkinson disease (PD). The taste function of 31 PD patients and 29 healthy controls was assessed quantitatively using filter paper taste strip tests (TSTs) impregnated with four basic taste qualities at four different concentrations. The mean TST score was significantly lower in PD patients, as a consequence of taste impairment in the female PD patients (it did not differ significantly in males), which was likely to be attributable to the lower Mini-Mental State Examination score in patients with PD than in controls in women. TST scores in PD patients were not correlated with patient age, duration, or severity of their PD, or olfactory function. The findings of our study suggest that taste dysfunction should be included in the list of nonmotor symptoms of PD.     

Umami: a delicious flavor formed by convergence of taste and olfactory pathways in the human brain

Umami taste is produced by glutamate acting on a fifth taste system. However, glutamate presented alone as a taste stimulus is not highly pleasant, and does not act synergistically with other tastes (sweet, salt, bitter and sour). We show here that when glutamate is given in combination with a consonant, savory, odour (vegetable), the resulting flavor can be much more pleasant. Moreover, we showed using functional brain imaging with fMRI that the glutamate taste and savory odour combination produced much greater activation of the medial orbitofrontal cortex and pregenual cingulate cortex than the sum of the activations by the taste and olfactory components presented separately. Supralinear effects were much less (and significantly less) evident for sodium chloride and vegetable odour. Further, activations in these brain regions were correlated with the pleasantness and fullness of the flavor, and with the consonance of the taste and olfactory components. Supralinear effects of glutamate taste and savory odour were not found in the insular primary taste cortex. We thus propose that glutamate acts by the nonlinear effects it can produce when combined with a consonant odour in multimodal cortical taste-olfactory convergence regions. We propose the concept that umami can be thought of as a rich and delicious flavor that is produced by a combination of glutamate taste and a consonant savory odour. Glutamate is thus a flavor enhancer because of the way that it can combine supralinearly with consonant odours in cortical areas where the taste and olfactory pathways converge far beyond the receptors.     

Regional metabolism in microsmic patients with schizophrenia.

The cerebral glucose metabolism of eight patients with schizophrenia and an olfactory agnosia was compared with that of eight normosmic patients with schizophrenia and eight normal controls. Since all patients were scanned while on their current medication regimen, the duration and dosage of the medication of the two patient groups were compared. Similarly, duration and dosage were correlated with absolute regional metabolic rates. No significant effects were found in these analyses. The patients with schizophrenia had significantly lower rates of frontal metabolism than the normal controls. However, the patients with schizophrenia and an olfactory agnosia had a lower right basal ganglia and thalamic metabolism than the normosmic patients with schizophrenia.     

MEG evaluation of taste by gender difference

Magnetoencephalographic recordings were evaluated in five different states: normal condition, sweet, bitter, sour, and salt taste. Twenty-eight healthy volunteers, 14 male and 14 female, ranging from 12 to 50 years of age, were included in the study. The results showed that, in the normal condition, as well as in the sweet and the bitter taste, the male volunteers exhibited a higher count of low-frequency than high-frequency channels compared to the femal ones; in the case of the sour taste, there was no clear differentiation between the genders; with the salt taste, the female volunteers exhibited a higher count of low-frequency channels whereas there was no clear differentiation in the number of high frequencies between the gender. A discrimination in the spatial distribution of the frequencies provides novel insights into the identification of gender-related taste sensation.     

Taste-olfactory convergence, and the representation of the pleasantness of flavour, in the human brain

The functional architecture of the central taste and olfactory systems in primates provides evidence that the convergence of taste and smell information onto single neurons is realized in the caudal orbitofrontal cortex (and immediately adjacent agranular insula). These higher-order association cortical areas thus support flavour processing. Much less is known, however, about homologous regions in the human cortex, or how taste-odour interactions, and thus flavour perception, are implemented in the human brain. We performed an event-related fMRI study to investigate where in the human brain these interactions between taste and odour stimuli (administered retronasally) may be realized. The brain regions that were activated by both taste and smell included parts of the caudal orbitofrontal cortex, amygdala, insular cortex and adjoining areas, and anterior cingulate cortex. It was shown that a small part of the anterior (putatively agranular) insula responds to unimodal taste and to unimodal olfactory stimuli, and that a part of the anterior frontal operculum is a unimodal taste area (putatively primary taste cortex) not activated by olfactory stimuli. Activations to combined olfactory and taste stimuli where there was little or no activation to either alone (providing positive evidence for interactions between the olfactory and taste inputs) were found in a lateral anterior part of the orbitofrontal cortex. Correlations with consonance ratings for the smell and taste combinations, and for their pleasantness, were found in a medial anterior part of the orbitofrontal cortex. These results provide evidence on the neural substrate for the convergence of taste and olfactory stimuli to produce flavour in humans, and where the pleasantness of flavour is represented in the human brain.     

Olfactory cortex and Olfactory bulb volume alterations in patients with post-infectious Olfactory loss

Upper respiratory tract infection (URI) is one of the most common etiology of olfactory loss. Previous studies demonstrated that both olfactory bulb (OB) volume and sulcus (OS) depth decreased in patients with post-infectious olfactory loss (PIOL) compared to normal controls. The aim of our study was to observe alterations of central olfactory pathways in patients with PIOL. T1 weighted magnetic resonance images were acquired in 19 PIOL patients and 19 age- and sex-matched control subjects on a 3 T scanner. Voxel-based morphometry (VBM) was performed using VBM8 toolbox and SPM8 in a Matlab environment. We also analyzed OB volume in coronal T2-weighted images. Whole-brain analysis revealed a significant gray matter volume loss in the right orbitofrontal cortex (OFC) in patients group. Further analysis with region of interest exhibited a significant negative correlation between gray matter volume in right OFC as well as OB volume and the duration of olfactory loss in these patients (r = -0.566 and r = -0.535 both P?<?0.05, respectively). In conclusion, the morphological alterations in the right OFC and OB might contribute to the pathogenic mechanism of olfactory dysfunction after upper respiratory tract infection.     

A case of ‘sign blindness’ following left occipital damage in a deaf signer

We report on a right-handed, deaf, life long signer who suffered a left posterior cerebral artery (PCA) stroke. The patient presented with right homonymous hemianopia, alexia and a severe sign comprehension deficit. Her production of sign language was, however, virtually normal. We suggest that her syndrome can be characterized as a case of ‘sign blindness’, a disconnection of the intact right hemisphere visual areas from intact left hemisphere language areas. This case provides strong evidence that the neural systems supporting sign language processing are predominantly in the left hemisphere, but also suggests that there are some differences in the neural organization of signed vs spoken language within the left hemisphere.     

Lack of support for the inability to taste phenylthiocarbamide as an endophenotypic marker in patients with schizophrenia and their first-degree relatives

OBJECTIVE: This study sought to replicate recent findings that both patients and relatives are significantly more likely to be phenylthiocarbamide (PTC) nontasters than healthy controls, and that within the patient group, nontasters have more severe positive and/or negative symptoms than tasters. Associations between PTC-tasting status and olfactory identification scores also were examined. METHOD: PTC perception and olfactory identification were assessed in 48 patients with schizophrenia or schizoaffective disorder, 28 first-degree relatives, and 32 healthy volunteers. RESULTS: The three groups did not differ in PTC taste sensitivity. Findings did not change after: a sensitivity analysis that re-categorized participants who "possibly" tasted PTC, excluding Caucasian participants, or restricting the sample of patients to only those with schizophrenia. Among the patients, tasters and nontasters did not differ with regard to positive, negative, or general psychopathology symptoms. In the combined sample and the three groups separately, there were no associations between PTC-tasting status and olfactory identification scores. CONCLUSIONS: This study, conducted specifically as an attempt to replicate previously reported findings, failed to provide support for PTC perception as an endophenotypic marker for schizophrenia. Further research is warranted.     

PET and SPECT in whiplash syndrome: a new approach to a forgotten brain?

Whiplash associated disorders are a medicolegally controversialcondition becoming increasingly worrisome in the western world. Thisstudy was designed to evaluate perfusion and glucose metabolism inwhiplash brain. Using Tc-99m-bicisate (ECD) single photon emission computed tomography (SPECT) and F-18-fluorodeoxyglucose (FDG) PET,six clinically and neuropsychologically controlled patients (patientgroup) with whiplash syndrome and 12 normal controls (control group)were investigated. Standardised elliptical regions of interest (ROIs)were determined in three adjacent transaxial slices in the frontal,parietal, temporal, and parieto-occipital cortex, cerebellum, brainstem, basal ganglia, and thalamus. For PET, the glucose metabolic index(GMI; =ROI uptake/global uptake at the level of the basal ganglia) and,for SPECT, the perfusion index (PI; =ROI/global) were calculated. Inthe patient group there was significant hypometabolism andhypoperfusion in the parieto-occipital regions (on the right (R) andleft (L) side) compared with the control group: PET data: GMIparieto-occipital R: control 1.066 (0.081) (mean (SD)), patient 0.946 (0.065); P=0.0092, Mann Whitney. GMI parieto-occipital L: control 1.034 (0.051), patient 0.922 (0.073); p=0.0067. SPECT data: PIparieto-occipital R: control 1.262 (0.066), patient 1.102 (0.063);P=0.0039. PI parieto-occipital L: control 1.226 (0.095), patient 1.098 (0.075); P=0.0273. In some patients there was hypometabolism (>2 SD of control) in regions other than the parieto-occipital region. It ishypothesised that parieto-occipital hypometabolism may be caused byactivation of nociceptive afferent nerves from the upper cervical spine.

     

Addresses

Abstract

Forty-two patients with senile dementia of the Alzheimer type (SDAT), 38 patients with Huntington's disease (HD) and matched normal controls were administered tests of olfactory, verbal, and visual recognition after being screened for normal olfactory discrimination. Early-affected Huntington's patients (EHD) with minimal chorea or cognitive deficit displayed marked deficits in olfactory recognition despite normal verbal and visual performance, even after correction for task difficulty, suggesting involvement of olfactory brain regions early in the disease process. In the early Alzheimer's group (EAD), marked deficits were seen on all recognition modalities indicating more global impairment. Both overall (early plus late) patient groups were impaired relative to controls on all recognition tasks, with the olfactory paradigm being most affected.     

Trial measurement of brain activity underlying olfactory–gustatory synchrony perception using event-related potentials from five female participants

Temporal synchrony between odor and taste plays an important role in flavor perception. When we investigate temporal synchrony between odor and taste, it is necessary to pay attention not only to physical simultaneity of the presentation of olfactory and gustatory stimuli, but also to the perceptual simultaneity between the two stimuli. In this study, we examined short-latency brain activity underlying synchrony perception for olfactory–gustatory combinations. While five female participants performed a simultaneity judgment (SJ) task using soy sauce odor and salt solution, single-channel event-related potentials (ERPs) were recorded at the position of Cz. In each trial, the participant was asked whether olfactory and gustatory stimuli were perceived simultaneously or successively. Based on the judgment responses acquired from participants (i.e., simultaneous or successive), ERP data were classified into two datasets. The means of ERPs from each participant were calculated for each type of judgment response, considering the onset of olfactory or gustatory stimuli (OERPs or GERPs, respectively) as the starting point. The latencies of the P1 component of GERPs were very similar between simultaneous and successive judgment responses, whereas the P1 amplitudes differed significantly. These results indicated that neural activity affecting SJ for an olfactory–gustatory combination is generated during a period of about 130 ms from the onset of gustatory stimulus. Thus, olfactory and gustatory information processing related to flavor perception (more specially, synchrony perception between odor and taste) might be initiated at a relatively early stage of the central pathway.     

Regional cerebral glucose metabolism in never-medicated patients with schizophrenia.

OBJECTIVE: The purpose of this study was to assess regional cerebral glucose metabolism in patients with schizophrenia who had never received antipsychotic medication and whose olfactory identification ability had been assessed. Two hypotheses were examined. First, the patients were compared with normal controls to determine whether differences in regional cerebral metabolism were apparent. Second, regional rates of metabolism were correlated with olfactory ability and the relation between them determined. METHODS: The patient (n = 26) and control (n = 32) subjects were scanned at rest using positron emission tomography (PET) after administration of 18F-fluorodeoxyglucose (FDG). In addition, the University of Pennsylvania Smell Identification Test was administered to each patient. RESULTS: Patients with schizophrenia had reduced rates of glucose metabolism in the right and left thalamus that reached significance if not corrected for multiple comparisons. However, if a Bonferroni correction was applied over the 27 regions of interest, the differences were not significant. Scores on the Smell Identification Test were negatively correlated with 8 regions of interest. When scores were analyzed using multiple regression, the left frontal cortex and the medial parietal cortex were significant predictors. CONCLUSIONS: The finding of reduced metabolism in the thalami is consistent with some of the previous literature, whereas the negative correlations between specific regions and olfactory function are not consistent with studies using activation paradigms.     

Individuals with Down's syndrome demonstrate abnormal olfactory event-related potentials.

OBJECTIVE: Recent research has demonstrated that individuals with Down's syndrome (DS) develop plaques and tangles in the brain similar to people with Alzheimer's disease. As a result, they show increased dementia and decreased olfactory functioning compared to healthy individuals. The olfactory event-related potential (OERP) has been used as an objective quantitative measure of olfactory functioning in normal and clinical populations. The present study investigated the utility of the latency and amplitude of the OERP components in examining olfactory dysfunction in DS individuals. METHODS: OERPs were recorded monopolarly at the Fz, Cz and Pz electrode sites, using amyl acetate at a 60 s inter-stimulus interval, from individuals with DS (mean age 26.0 years) and age-matched normal controls. Participants were screened for nasal health and odor thresholds were assessed. Dementia was assessed using the dementia rating scale (DRS). RESULTS: Results indicate that DS subjects have significantly longer latencies in the sensory (N1, P2, and N2) and cognitive (P3) components of the OERP than normal controls. Odor threshold was significantly associated with sensory OERP components. In addition, DS subjects with a higher level of dementia showed significantly longer P3 latencies than those with lower dementia levels. CONCLUSIONS: The study suggests that the OERP may be a useful measure of olfactory dysfunction in DS which may precede developing dementia in this population.     

Psychomotor seizures,arterio-venous malformation and the olfactory reference syndrome: A CASE REPORT

A case history is reported of a 44-year-old man with a 6-year history of psychomotor seizures. For the past year he had described persistent olfactory hallucinations of an unpleasant nature which he referred to himself. In many respects these symptoms conform to the pattern observed in the olfactory reference syndrome, a recently described but apparently quite discrete psychiatric disorder; there were, however, certain atypical features. At a later stage unilateral anosmia was noted. Radiological examination then demonstrated an arterio-venous malformation in the right frontal lobe. The relationship between the malformation and the psychomotor seizures, and the implications that each has for the development of an olfactory reference syndrome are fully discussed.     

Chemosensory interaction: acquired olfactory impairment is associated with decreased taste function

Olfaction, taste and trigeminal function are three distinct modalities. However, in daily life they are often activated concomitantly. In health and disease, it has been shown that in two of these senses, the trigeminal and olfactory senses, modification of one sense leads to changes in the other sense and vice versa. The objective of the study was to investigate whether and (if so) how, the third modality, taste, is influenced by olfactory impairment. We tested 210 subjects with normal (n = 107) or impaired (n = 103) olfactory function for their taste identification capacities. Validated tests were used for olfactory and gustatory testing (Sniffin’ Sticks, Taste Strips). In an additional experiment, healthy volunteers underwent reversible olfactory cleft obstruction to investigate short-time changes of gustatory function after olfactory alteration. Mean gustatory identification (taste strip score) for the subjects with impaired olfaction was 19.4 ± 0.6 points and 22.9 ± 0.5 points for those with normal olfactory function (t = 4.6, p < 0.001). The frequencies of both, smell and taste impairments interacted significantly (Chi², F = 16.4, p < 0.001), and olfactory and gustatory function correlated (r ₂₁₀ = 0.30, p < 0.001). Neither age nor olfactory impairment cause effects interfered with this olfactory–gustatory interaction. In contrast, after short-lasting induced olfactory decrease, gustatory function remained unchanged. The present study suggests that longstanding impaired olfactory function is associated with decreased gustatory function. These findings seem to extend previously described mutual chemosensory interactions also to smell and taste. It further raises the question whether chemical senses in general decrease mutually after acquired damage.     

Asymmetrical olfactory acuity and neuroleptic treatment in schizophrenia

Uni-rhinal olfactory acuity in schizophrenia was investigated in two experiments. The first assessed the presence of a predicted atypical asymmetry of nostril laterality and the second assessed the effect of antipsychotic treatment on the asymmetry. Although olfactory identification impairment has been well documented in schizophrenia, olfactory acuity has been neglected. This may be an oversight as cerebral structures of the mesial temporal lobe important to olfactory perception have often been implicated in the pathophysiology of schizophrenia and it is thus reasonable to postulate a primary impairment of olfactory acuity in schizophrenia. In addition, unmedicated patients with schizophrenia have exhibited asymmetrical laterality favouring the right over the left hemisphere in studies of visual, haptic, and auditory perception, and the few published prospective treatment studies have suggested a reversal of this asymmetry with first generation neuroleptic treatments. In experiment 1 a generalization of the perceptual asymmetry to olfactory acuity was examined by measurement of n-butanol olfactory thresholds with the Connecticut Chemosensory Perception Exam (CCPE) in an unmedicated sample of 17 patients with schizophrenia and 17 age, gender, and handedness matched normal controls. The patient sample showed an asymmetrical impairment of the left nostril that was not apparent in the normal control sample. In experiment 2, the CCPE was administered to a new sample of 10 patients with schizophrenia before and after neuroleptic treatment. The asymmetry observed in experiment 1 was replicated, and the relative advantage of the right nostril shifted to a relative advantage of the left nostril over the course of 8weeks of treatment. Results are discussed in relation to cerebral aspects of schizophrenia and potential implications to cognitive change from treatment.