Can auditory cues improve visuo-spatial neglect? Results of two pilot studies.

Although neglect is known to be a multimodal deficit, current interventions often address the visual modality only. Experimental studies, however, found that neglect patients can partially overcome their spatial inattention temporarily when being exposed to auditory cues that move towards the neglected side of space. Two pilot studies investigated the impact of dynamic auditory cueing on egocentric neglect severity in a clinical-therapeutic setting. In both studies, the patient groups received 15 sessions of intervention. Study 1, designed as double-blinded trial with a historical control group, targeted severely impaired early-acute patients who listened to music or audio books which were presented as moving dynamically from right to left. Results showed a reduction in egocentric neglect severity that persisted after therapy termination in the intervention but not in the historical control group. In study 2, based on the comparison with reported effect sizes of previous studies, dynamic meaningful auditory cues and optokinetic stimulation were combined in a computer-based training. Both studies found a significant reduction of neglect severity. Results provide evidence for the reduction of egocentric neglect severity after repetitive auditory cueing therapy in both severely and moderately impaired patients. Our promising findings should be verified thoroughly in randomized-controlled trials.

Is there a correlation between hippocampus and amygdala volume and olfactory function in healthy subjects?

Both amygdala (AG) and hippocampus (HC) are integral parts of the olfactory system. The present study, including a large number of healthy subjects, was performed to compare HC and AG volumes, measured by manual tracing, in relation to specific olfactory functions, including odor threshold, discrimination, identification, and odor memory tasks. It also aimed to provide age-related normative data about the volume of the HC and AG. A total of 117 healthy volunteers participated (age range 19-77 years, mean age 37 years; 62 women, 55 men). Using the "Sniffin' Sticks", subjects received lateralized tests for odor threshold, and odor discrimination. In addition, an odor memory and an odor identification task were performed bilaterally. A Mini-Mental-State test excluded dementia. MR scans were performed using a 1.5 T scanner for later manual volumetric measurements. Volumetric measurements exhibited a good reproducibility. The average volume for the right HC was 3.29 cm(3) (SD 0.47), for the left HC it was 3.15 cm(3) (SD 0.47). The average right AG had a volume of 1.60 cm(3) (SD 0.31), left 1.59 cm(3) (SD 0.3). Increasing age was accompanied by a decrease of HC and AG volumes, which were much more pronounced for the right compared to the left side. Only the volume of the right HC showed a small but significant correlation with odor threshold (r(117)=0.21; p=0.02). Importantly, this correlation was not mediated by age as indicated by the significant partial correlation when controlling for age (r(114)=0.18; p=0.049). In conclusion, the present data obtained in a relatively large group of subjects demonstrates a small correlation between the volume of the HC, as an integral part of the olfactory system, and smell function. In addition, these data can be used as the basis for normative values of HC and AG volumes, separately for men, women and different age groups. This is of potential interest in diseases with acute or chronic impairment of olfactory function, in metabolic or neurodegenerative diseases or in disorders with damage of areas involved in adult neurogenesis.

Correlation between olfactory bulb volume and olfactory function in children and adolescents.

The olfactory bulb (OB) is considered to be the most important relay station in odor processing. The present study aimed to investigate the volumetric development of the human bulb and the olfactory function during childhood and youth. Furthermore, the present study aimed to investigate a possible correlation between OB volume and specific olfactory functions including odor threshold, odor discrimination and odor identification. A total of 87 subjects (46 boys, 41 girls), aged 1-17 years (mean age 8 years), participated in this study. None of them reported olfactory dysfunction or had signs of a dysfunctional sense of smell. Whenever possible, participants received a volumetric scan of the brain and lateralized olfactory tests. Volumetric measurements of the right and left OB were taken by manual segmentation of the coronal slices through the OB. Significant correlations between OB volumes and olfactory function were observed. Both, OB volumes and olfactory function increased with age, although the correlation between structure and function was not mediated by the subjects' age. In conclusion, for the first time, the present study showed a correlation between OB volume and olfactory functions in children.

Reduced olfactory bulb volume and olfactory sensitivity in patients with acute major depression.

The purpose of this study was to assess olfactory function and olfactory bulb volume in patients with acute major depression in comparison to a normal population. Twenty-one patients diagnosed with acute major depressive disorder and 21 healthy controls matched by age, sex and smoking behavior participated in this study. Olfactory function was assessed in a lateralized fashion using measures of odor threshold, discrimination and identification. Olfactory bulb volumes were calculated by manual segmentation of acquired T2-weighted coronal slices according to a standardized protocol. Patients with acute major depressive disorder showed significantly lower olfactory sensitivity and smaller olfactory bulb volumes. Additionally, a significant negative correlation between olfactory bulb volume and depression scores was detected. Their results provide the first evidence, to our knowledge, of decreased olfactory bulb volume in patients with acute major depression. These results might be related to reduced neurogenesis in major depression that could be reflected also at the level of the olfactory bulb.

Olfactory bulb ventricles as a frequent finding in magnetic resonance imaging studies of the olfactory system.

UNLABELLED: Background. In some species an embryologic cavity inside the olfactory bulb (OB) persists and is called olfactory bulb ventricle (OBV). It is generally assumed that OBVs in humans are solitary findings representing remnants of embryologic structures that were not fully regressed, although the incidence of OBVs was never examined. Using magnetic resonance imaging (MRI), the present study aimed to study the incidence of OBVs in healthy human subjects. Material and methods. A total of 122 individuals participated. Volumes of the right and left OB were determined using MRI scans and a standardized protocol for OB analysis. For comparison, OBs of 42 cadavers were collected and sectioned. Results. The main finding of this study was the high incidence of OBV-like structures in our study group. Seventy-two out of 122 (59%) participants yielded signs for an OBV whereas three out of 42 postmortem OBs contained histologically detectable OBV. DISCUSSION: This stands in disagreement with the previous assumption of complete obliteration at the time of birth. This discrepancy may be explained by the fact that our present findings are based on modern MRI techniques with much higher resolution than 10 or 20 years ago. Another possible explanation for the discrepancy between studies based on MRI and histopathology might relate to postmortem resorption of cerebrospinal fluid from OBVs. Especially with a long postmortem interval OBVs may collapse and may no longer appear as an open cavity.

Correlation between olfactory bulb volume and olfactory function.

The olfactory bulb (OB) is considered to be the most important relay station in odor processing. Involving 125 randomly selected subjects (58 men, 67 women; age range: 19 to 79 years), the present study aimed to investigate a possible correlation between OB volume and specific olfactory functions including odor threshold, odor discrimination, and odor identification. The history of all participants was taken in great detail to exclude possible causes of smell dysfunction. All participants received an otolaryngological investigation including a volumetric scan of the brain (MRI), lateralized olfactory tests and a screen for cognitive impairment. Volumetric measurements of the right and left OB were performed by manual segmentation of the coronal slices through the OB. Significant correlations between OB volumes in relation to olfactory function were observed, independent of the subjects' age. Additionally, OB volumes decreased with age. In agreement with previous research the present study confirmed the correlation between OB volume and specific olfactory functions. Furthermore, the correlation between OB volume and olfactory function was not mediated by the subjects' age. In conclusion, the present data obtained from a relatively large group of subjects forms the basis for age-related normative values of OB volumes.

Myocardial protection by collateral vessels during experimental coronary ligation: a prospective study in a canine two-infarction model.

Previous work of this laboratory has shown that collateral flow can be increased over six weeks by a subcritical external constriction of the circumflex artery causing a 50 +/- 10% reduction of postocclusive reactive hyperemia. To investigate collateral function in acute myocardial infarction, the model was used to ligate two distant coronary branches on the ventricle simultaneously in order to compare in 8 dogs infarct size and perfusion area of the ligated vessels in control and collateralized sections. The acute collateral flow measured 7.2 +/- 2.5 ml/100 g/min-1 and increased to 17.3 +/- 6.7 (p less than 0.001) over 6 weeks. Separate analysis revealed a predominant increase of collateral flow in the epicardial layers 23.1 +/- 7.5 (p less than 0.01) versus 6.9 +/- 2.8 (p less than 0.01) in the subendocardium. Infarct size in the control area was 52.0 +/- 14.7% of the perfusion area, in the collateralized zone 19.0 +/- 14.2% (p less than 0.001). Infarct size expressed as per cent of perfusion area and collateral flow in the area at risk expressed as per cent of flow of normal sections correlated: (r = 0.76; p less than 0.05). Therefore, infarct size after a 6 hour coronary occlusion can be considered a function of the collateral flow over normal perfusion ratio. Localized induction of collaterals in this model caused a significant reduction of infarct size in relation to the perfusion area at risk.

Development of collaterals. Application of external subcritical fixed constrictors in a canine model.

A canine model for a standardized induction of collaterals is presented with a fixed external constrictor that is not designed to induce an occlusion of the coronary artery and at least over the timespan of 6 weeks does not impair perfusion under resting conditions in the myocardium-at-risk. The coronary constriction was standardized by a reduction of the postocclusive reactive hyperemia of 50%. Flow measurements were performed by flowmeter and by radioactive microspheres acutely and after an interval of 6 weeks of constriction. The results showed an increase of the collateral flow from 21.2 +/- 11.8 ml/100 g/min-1 to 42.8 +/- 16.2 ml/100 g/min-1 (p less than 0.05). The regional perfusion exhibited a transmyocardial gradient in favour of the subepicardial layers with 49.3 +/- 25 ml/100 g/min-1 as compared to 33.1 +/- 17.3 ml/100 g/min-1 (p less than 0.05) of the endocardial layers. Reactive hyperemia, as determined by flowmeter, was decreased by 21% after 6 weeks on account of slow progression of the coronary constriction due to intimal reactions, whereas reactive hyperemia, as determined by the microsphere method, increased by 9% due to additional collateral channels.

Loss of canine myocardial nicotinamide adenine dinucleotides determines the transition from reversible to irreversible ischemic damage of myocardial cells.

We investigated if the loss of nicotinamide coenzymes in ischemic-infarcted myocardium may be responsible for the transition from reversibly ischemic to irreversibly infarcted cell damage. The LAD was occluded in 6 dogs for 4 h. Transmural needle biopsies were taken from he ischemic-infarcted region after 1/2, 1, 11/2, 2, and 4 h of ischemia and further divided into subepicardial and subendocardial halves. At each time interval the concentration of the nicotinamide coenzymes NAD, NADH, and NADPH were measured, and the degree of cellular injury was evaluated by electron microscopy. The glycohydrolase activity (EC 3.2.2.5), the enzyme which splits NAD, was determined in brain, myocardium, kidney, and skeletal muscle of 4 rats. Total NAD, the sum of NAD and NADH, started to decrease significantly in the ischemic subendocardium 1 h after onset of ischemia. Degradation of NADPH occurred later. Loss ot total NAD was about 60-70% when electron microscopy diagnosed irreversible cell injury. The glycohydrolase activity was the highest in brain followed by myocardium, kidney, and skeletal muscle, reflecting the different tolerances of these tissues towards ischemia. The key mechanism for ischemic injury seems to be the tissue acidosis which activates the glycohydrolase leading to a loss of the vital coenzymes.

Anterior and posterior hypothalamus: effects of independent temperature displacements on heat production in conscious goats.

Three goats were chronically implanted with thermodes to alter the temperatures of the anterior and posterior hypothalamus independently of each other. At an air temperature of +14 degrees C the anterior hypothalamus was cooled with different intensities, while the posterior hypothalamus was simultaneously either warmed (39 degrees C) or cooled (29 degrees C). In both conditions cooling anterior hypothalamus increased heat production. However, the increase was smaller, when the posterior hypothalamus was cooled. The inhibiting effect was most pronounced during the first parts of the periods and diminished with time. Nevertheless, in a separate series of experiments, the effects of posterior hypothalamic cooling were found to persist over periods of 3 h. At an air temperature of +3 degrees C the posterior hypothalamus temperature was altered between 28 and 42 degrees C, while anterior hypothalamus temperature was kept close to its control level. Shivering and heat production decreased with cooling and increased with warming of the posterior hypothalamus. The results suggest that those neurons which reside in the posterior hypothalamus and mediate shivering, are sensitive to temperature. Thermosensitivity of these allegedly integrative neurons affects shivering and heat production in a way inverse to the thermosensitivity of the temperature sensing neurons in the anterior hypothalamus.

Intravascular heat exchanger for conscious goats.

Polyethylene tubings were chronically implanted into the vascular system of goats and served as heat exchangers to remove heat directly from the body core at a rate equalling several times resting heat production.

[The effect of (8r)-3alpha-hydroxy-8-isopropyl-1alphaH,5alphaH-tropaniumbromide-(+/-)-tropate ((ipratropiumbromide) on tracheobronchial spasm, bronchial and salivary secretions, ECG and heart rate (author's transl)]. / Wirkung von (8r)-3alpha-Hydroxy-8-isopropyl-1alphaH,5alphaH-tropaniumbromid-(+/-)-tropat (Ipratropiumbromid) auf Spasmen des Tracheobronchialbaumes und die Bronchialsekretion, die Speichelsekretion, EKG und Herzfrequenz

At very low doses (8r)-3alpha-hydroxy-8-isopropyl-1alphaH,5alphaH-tropaniumbromide-(+/-)-tropate (ipratropiumbromide, Sch 1000, Atrovent) and atropine inhibit acetylcholine-induced bronchospasms in guinea-pigs and dogs. The dose ratio main effect vs. most sensitive side effect (inhibition of saliva secretion) is 1:10 for i.v. injection and 1:100 for aerosol application. When both compounds are administered in a nebulized form bronchodilatation occurs immediately. The maximum effect of Sch 1000 occurs somewhat later than that of atropine but the duration of action is much longer. Bronchial secretion in guinea-pigs is increased by small doses of Sch 1000 and atropine. These doses correspond to bronchodilating doses.