Inside a synesthete's head: a functional connectivity analysis with grapheme-color synesthetes

Grapheme-color synesthesia is a condition in which letters are perceived with an additional color dimension. To identify brain regions involved in this type of synesthesia and to analyze functional connectivity of these areas, 18 grapheme-color synesthetes and 18 matched controls were stimulated with letters and pseudo-letters presented in black and color in an event-related fMRI experiment. Based on the activation-differences between synesthetes and non-synesthetic controls regions of interest were defined. In a second analysis step functional connectivity was calculated using beta series correlation analysis for these seed regions. First we identified one seed region in the left inferior parietal (IPL) cortex (BA7) showing activation differences between grapheme-color synesthetes and controls. Furthermore, we found activation differences in brain areas involved in processing of letters and pseudo-letters, in particular the right IPL cortex (BA7), but also two more clusters in the right hemispheric BA 18 and BA 40. Functional connectivity analysis revealed an increased connectivity between the left IPL seed region and primary/secondary visual areas (BA 18) in synesthetes. Also the right BA 7 showed a stronger connectivity with primary/secondary visual areas (BA 18) in grapheme-color synesthetes. The results of this study support the idea that the parietal lobe plays an important role in synesthetic experience. The data suggest furthermore that the information flow in grapheme-color synesthetes was already modulated at the level of the primary visual cortex which is different than previously thought. Therefore, the current models of grapheme-color synesthesia have to be refined as the unusual communication flow in synesthetes is not restricted to V4, fusiform cortex and the parietal lobe but rather involves a more extended network.

Effects of amitriptyline, fluoxetine, tranylcypromine and venlafaxine on rat vascular smooth muscle in vitro--the role of the endothelium

Hypotension is a frequent side effect of the antidepressant treatment. It is controversial whether this effect is attributable to interactions within the central nervous or the cardiovascular system. We examined often used antidepressants for their vasoactive properties in vitro in rat aortal rings with and without endothelium. The influence of pre-incubation with the antidepressants (0.5 μM) on adrenergic elicited smooth muscle contraction and the effects of cumulative concentrations (0.05 μM-500 μM) of the antidepressants on isometric tension were measured. In addition, conceivable modulation of the NO-cGMP, adrenergic and potassium channel pathways were examined. Amitriptyline and fluoxetine inhibited, whereas tranylcypromine enhanced adrenergic elicited responses of smooth muscle contraction. The antidepressants amitriptyline, fluoxetine and tranylcypromine showed, to a different extent, vasorelaxing properties in the preparations pre-contracted with phenylephrine 0.1 μM; the pEC50, (means and S.E.M.) in descending order of potency: amitriptyline 6.98 (0.13), fluoxetine 6.11 (0.05), tranylcypromine 5.33 (0.05) (n=8 each, preparations with endothelium); or after pre-contraction with KCl 20 mM: fluoxetine 6.00 (0.06), tranylcypromine 4.99 (0.30), amitriptyline, 4.89 (0.11), (n=7 each, preparations with endothelium). Venlafaxine did not relax the aortal rings and even lead to further contraction of the endothelium intact preparations. The observed effects were partially endothelium dependent via activation of the NO-cGMP pathway and some probably mediated through K+ channel activation. Amitriptyline, fluoxetine and tranylcypromine relax rat aorta in vitro. They partially delay vascular smooth muscle reactions to adrenergic agonists and can lead to sustained hypotension episodes despite administration of sympathomimetic drugs.

The neural correlates of coloured music: a functional MRI investigation of auditory-visual synaesthesia

In auditory-visual synaesthesia, all kinds of sound can induce additional visual experiences. To identify the brain regions mainly involved in this form of synaesthesia, functional magnetic resonance imaging (fMRI) has been used during non-linguistic sound perception (chords and pure tones) in synaesthetes and non-synaesthetes. Synaesthetes showed increased activation in the left inferior parietal cortex (IPC), an area involved in multimodal integration, feature binding and attention guidance. No significant group-differences could be detected in area V4, which is known to be related to colour vision and form processing. The results support the idea of the parietal cortex acting as sensory nexus area in auditory-visual synaesthesia, and as a common neural correlate for different types of synaesthesia.

Impact of disease concepts on attitudes towards alcohol dependent patients

Introduction

Stigmatizing attitudes regarding mentally ill people are common (Rusch et al., 2010). Study result suggest that the degree of stigmatization may depend on concepts of psychiatric diseases (Crisafulli et al., 2008).

Aims

We aimed to investigate the impact of a sole neurobiological vs. a sole sociodynamic disease concept on the attitudes of students towards the alcohol dependent patients (Crisafulli et al., 2008).

Methods

200 students were randomly assigned to read information explaining alcohol dependence sole neurobiologically/sociodynamically. Subsequently, the students completed a series of questionnaires (adapted from Crisafulli et al. (2008)) regarding their attitudes towards the alcohol dependent patients. Attitudes were compared to attitudes of students not exposed to any disease concept.

Results

Consistent with former study results we found increased blaming and decreased willingness to finance therapy in those students exposed to the sociodynamic explanation. Attitudes regarding blaming and harmfulness of the alcohol dependent patients were increased in the neurobiological and sociodynamic group compared to the un-exposed control group.

Conclusions

Information regarding possible causalities regarding the development of alcohol dependence is associated with more negative attitudes towards alcohol dependent patients in the questioned students compared to unexposed controls. This may be reasoned by the recognition of alcohol dependence as a manifestation of mental illness and the subsequent inclusion of the alcohol dependent patients in the prejudices and acts of discrimination commonly leveled against the mentally ill. Therefore, multimodal interventions rather than medicinal information seem to be necessary in order to decrease stigmatization of the alcohol dependent patients.

Maladaptive connectivity of broca’s area in schizophrenia during audiovisual speech perception: an FMRI study

Introduction

Natural speech perception relies on both, auditory and visual information. Both sensory channels provide redundant and complementary information, such that speech perception is enhanced in healthy subjects, when both information channels are present.

Objectives

Patients with schizophrenia have been reported to have problems regarding this audiovisual integration process, but little is known about which neural processes are altered.

Aims

In this study we investigated functional connectivity of Broca’s area in patients with schizophrenia.

Methods

Functional magnetic resonance imaging (fMRI) was performed in 15 schizophrenia patients and 15 healthy controls to study functional connectivity of Broca’s area during perception of videos of bisyllabic German nouns, in which audio and video either matched (congruent condition) or die not match (incongruent; e.g. video = hotel, audio = island).

Results

There were differences in connectivity between experimental groups and between conditions. Broca’s area of the patient group showed connections to more brain areas than the control group. This difference was more prominent in the incongruent condition, for which only one connection between Broca's area and the supplementary motor area was found in control participants, whereas patients showed connections to 8 widely distributed brain areas.

Conclusions

The findings imply that audiovisual integration problems in schizophrenia result from maladaptive connectivity of Broca's area in particular when confronted with incongruent stimuli and are discussed in light of recent audio visual speech models.

Homocysteine and cognitive function in geriatric depression

BACKGROUND/OBJECTIVES

Cognitive dysfunction is a common aspect of the spectrum of symptoms of geriatric depression. High homocysteine levels have been linked to cognitive decline in neuropsychiatric disorders. The present study investigated possible associations between cognitive impairment observed in geriatric depression and homocysteine levels.

METHODS

The performance of 25 mentally healthy individuals and 40 patients with geriatric depression in terms of language processing, processing speed, concentration and attention was assessed with the Stroop Test and the d2 Test of Attention. Serum homocysteine was determined with an enzyme immunoassay.

RESULTS

The performance of depressed patients was significantly worse in language processing (p = 0.001) and processing speed (p < 0.0001). Depressed patients with high levels of homocysteine performed better than patients with homocysteine concentrations <or=11.7 micromol/l in both cognitive domains (p = 0.006 and 0.009, respectively). Moreover, homocysteine level was positively associated with language processing (p = 0.002) and processing speed (p = 0.002).

CONCLUSIONS

These findings indicate that under the special circumstances of geriatric depression (perturbation of glutamatergic transmission and glutamate metabolism), homocysteine is positively associated with the performance in language processing and processing speed.

Short-term influence of elevation of plasma homocysteine levels on cognitive function in young healthy adults

BACKGROUND

Acute homocysteine elevation has been shown to have a significant impact on cognitive function in animal models.

OBJECTIVES

Investigation of the short-term impact of elevation of plasma homocysteine levels through a dietary intervention on cognitive abilities of young healthy adults.

PARTICIPANTS

100 healthy medical students of both genders were enrolled in the study.

DESIGN AND MEASUREMENTS

Homocysteine levels and cognitive abilities were measured at 08:30 (before breakfast) and at 15:00 (two hours after lunch and six hours after breakfast). Food intake was restricted to specified comestibles. The cognitive assessment comprised a version of the Short Test for General Intelligence, three subtests of the Syndrome Short Test and the Stroop test.

RESULTS

At 15:00 plasma homocysteine was significantly elevated in 56 participants (P < 0.00001), whilst in 44 it was decreased (P < 0.00001) in comparison to baseline (08:30). The decrease was however of limited clinical significance. The differences in the changes in cognitive performance between the two groups did not attain statistical significance (P > 0.05) and the direction of the changes did not differ between them. Accordingly, the multiple linear regression analysis did not reveal an important influence of homocysteine elevation on cognitive performance variations.

CONCLUSIONS

Significant increase of plasma homocysteine is not associated with a straightforward inhibitory or facilitatory short-term effect on physiological cognitive parameters in young healthy adults.