Background: We investigated the connection between long term infarct evolution and functional consequences of subcortical lesions after transient middle cerebral artery occlusion (MCAO) in rats. Methods: MCAO was induced in Wistar rats for 60min. Lesion volumes and absolute T2 times on MRI were assessed 1 and 14 days and up to 10 weeks after MCAO using a 4.7 T animal scanner, and combined with functional testing (adhesive tape removal, cylinder test, ledged beam walking).Tissue damage was analyzed histologically (HE, Luxol, and Nissl staining). Results: Functional test scores were not distinguishable between sham operated (n=5) animals and those with exclusive subcortical infarct involvement (n=8, group A) at any time point, but were significantly worse in animals with cortico-subcortical infarctions (n=10, group B). Group A showed lower absolute T2 times and a more pronounced reduction in T2 infarct volume than the subcortical lesion component in group B. Ten weeks after MCAO, initial signal increments on...

Whereas zebra finch males produce song in a more sexual context, females rather use long calls for acoustic recognition of conspecific and affinitive birds. Recognition of biologically relevant information in acoustic signals is thought to be accomplished (partly) by NCM (caudomedial neostriatum or nidopallium), a telencephalic brain region with a maximum size of 3 mm3. In order to prepare in-vivo studies of NCM activation in response to acoustic stimuli, the hypercapnic response of NCM was explored with both optical imaging (non-invasive in-vivo broadband time-resolved spectroscopy) and functional MRI (Blood Oxygenation Level Dependent, BOLD). Subsequently, local variations in CBV and hemoglobin saturation levels obtained from optical data in songbird brain can be correlated with local BOLD signal variations which provide overall information on CBF, CBV and alterations in hemoglobin oxygenation. Female zebra finches were anesthetized with 2% isoflurane under spontaneously breathing, while they underwent t...

Humans can judge grating orientation by touch. Previous studies indicate that the extrastriate cortex is involved in tactile orientation judgments, suggesting that this area is related to visual imagery. However, it has been unclear which neural mechanisms are crucial for the tactile processing of orientation, because visual imagery is not always required for tactile spatial tasks. We expect that such neural mechanisms involve multisensory areas, because our perception of space is highly integrated across modalities. The current study uses functional magnetic resonance imaging during the classification of grating orientations to evaluate the neural substrates responsible for the multisensory spatial processing of orientation. We hypothesized that a region within the intraparietal sulcus (IPS) would be engaged in orientation processing, regardless of the sensory modality. Sixteen human subjects classified the orientations of passively touched gratings and performed two control tasks with both the right and ...

[Aim] Recent studies using functional magnetic resonance imaging (fMRI) have demonstrated the capability of mapping submillimeter-scale functional structures. However, the functional maps have not been evaluated by other conventional techniques. The purpose of this study was to compare iso-orientation maps obtained from fMRI to those with optical intrinsic signal (OIS) imaging in the same recording area. [Methods] Orientation specific activation was measured with cerebral blood volume (CBV)-weighted fMRI and OIS imaging sequentially from the same anesthetized cat. An identical periodic visual stimulation (continuous full-field moving gratings of 8 orientations (10 s each) / period) was used in both measurements. CBV-weighted fMRI was performed at 9.4 Tesla with monocrystalline iron oxide nanoparticle (10 mg/kg MION) on a 2 x 2-cm area parallel to the marginal gyrus of one hemisphere. An imaging slice (128 x 128 pixels, 1 mm thickness) was positioned ~500 µm below the pial mater. The position of the imaging...

Subjects were trained on a pursuit task in which the target trajectory was predictable only on the horizontal axis. Half of them were sleep deprived on the first post-training night ( n = 13). Three days later, functional magnetic resonance imaging revealed task-related increases in brain responses to the learned trajectory, as compared with a new trajectory. In the sleeping group ( n = 12) as compared with the sleep-deprived group, subjects' performance was improved, and their brain activity was greater in the superior temporal sulcus (STS). Increased functional connectivity was observed between the STS and the cerebellum and between the supplementary eye field and the frontal eye field. These differences indicate sleep-related plastic changes during motor skill learning in areas involved in smooth pursuit eye movements.

This study utilized functional MRI to evaluate the early stages of a kainic acid induced seizure in a fully conscious rat. Seizure activity was confirmed by EEG, and blood oxygen level dependant (BOLD) signal was temporally consistent with this activity. Male SD rats where anesthetized using medetomidine (Pfizer) and ketamine and EEG electrodes were implanted. The animal was then placed into a special animal restraint/Rf coil system (Insight Neuroimaging systems). This system was put into a 4.7T MRI (Bruker) and the animal was awoken with atipamizole (Pfizer). Physiologic parameters were recorded for the entire duration of the experiment. Anatomical images were acquired before and after the seizure. A 45 repetition functional sequence was acquired with 14 baseline repetitions (3 minutes) followed by an IP injection of kainic acid (10mg/kg). Seizure activity was noted via EEG within a minute. The anatomical images were subtracted to confirm that the awake animal remained immobile during the experiment. All ...

Functional magnetic resonance imaging (fMRI) was used in rats to study CNS effects of the dopamine D2/3 receptor agonist quinelorane in vivo. Male Sprague-Dawley rats (250-300g, n=5 per group) were anaesthetised (α-chloralose, 60mg/kg i.v. bolus, then 30mg/kg/hr) and scanned using multi-echo gradient echo imaging (TE=5,10 and 15ms, TR =460ms, 120 volumes in 2 hours). Quinelorane (30µg/kg, s.c.) or saline vehicle were randomly administered 30-60 minutes after scan initiation. Mean echo images were realigned, normalised to a rat-brain template and analysed using a general linear model[1]. Statistically significant signal intensity increases over controls (T>4.3, p<0.05) were detected within the nucleus accumbens, ventromedial striatum and olfactory nuclei. These results are consistent with previous microdialysis experiments where quinelorane, a potent D3 receptor agonist with high D3/D2 selectivity[2], reduced dopamine release in the nucleus accumbens and ventral striatum[3], areas rich in D3 receptors[2]. O...

Manganese chloride (MnCl2) can selectively enter the ventricles within a few minutes after systemic administration and enhanced MR signals of hippocampal formation in one day. Therefore, manganese enhancement could be a good indicator to detect ischemic cells in the hippocampus. The aim of this study was to determine whether manganese-enhanced MRI (MEMRI) can be used to visualize neuronal death in the hippocampus after transient global ischemia. Nine male Wistar rats were divided into two groups; a sham-operated control group (n = 5) and a group subjected to ischemia (n = 4). An ischemia was induced using the four-vessel occlusion method described by Pulsinelli et al. The vertebral arteries were permanently occluded at the first cervical vertebra. On the following day, the animals subjected to ischemia were induced to a 10-minute transient global ischemia by clamping the carotid arteries. At 14 days after ischemia, the animals were infused with a 50 mM MnCl2 solution. Two days after the MnCl2 infusion, the...

Diffusion tensor imaging (DTI) of brain development in fetal alcohol spectrum disorders (FASD) has revealed structural abnormalities, but studies have been limited by the use of cross-sectional designs. Longitudinal scans can provide key insights into trajectories of neurodevelopment within individuals with this common developmental disorder. Here we evaluate serial DTI and T1-weighted volumetric MRI in a human sample of 17 participants with FASD and 27 controls aged 5–15 years who underwent 2–3 scans each, ∼2–4 years apart (92 scans total). Increases of fractional anisotropy and decreases of mean diffusivity (MD) were observed between scans for both groups, in keeping with changes expected of typical development, but mixed-models analysis revealed significant age-by-group interactions for three major white matter tracts: superior longitudinal fasciculus and superior and inferior fronto-occipital fasciculus. These findings indicate altered developmental progression in these frontal-association tracts, with...

Human hand dexterity depends on the ability to move digits independently and to combine these movements in various coordinative patterns. It is well established that the primary motor cortex (M1) is important for skillful digit actions but less is known about the role played by the nonprimary motor centers. Here we use functional magnetic resonance imaging to examine the hypothesis that nonprimary motor areas and the posterior parietal cortex are strongly activated when healthy humans move the right digits in a skillful coordination pattern involving relatively independent digit movements. A task in which flexion of the thumb is accompanied by extension of the fingers and vice versa, i.e., a learned “nonsynergistic” coordination pattern, is contrasted with a task in which all digits flex and extend simultaneously in an innate synergistic coordination pattern (opening and closing the fist). The motor output is the same in the two conditions. Thus, the difference when contrasting the nonsynergistic and syner...