Nursing has reciprocal benefits for both mother and infant, helping to promote maternal behavior and bonding. To test the “rewarding” nature of nursing, functional magnetic resonance imaging was used to map brain activity in lactating dams exposed to their suckling pups versus cocaine. Suckling stimulation in lactating dams and cocaine exposure in virgin females activated the dopamine reward system. In contrast, lactating dams exposed to cocaine instead of pups showed a suppression of brain activity in the reward system. These data support the notion that pup stimulation is more reinforcing than cocaine, underscoring the importance of pup seeking over other rewarding stimuli during lactation.

The ability to identify embryonic neural stem cells after therapeutic transplantation is crucial. In particular, there is a need for a non-invasive, longitudinal method of in vivo tracking of such cellular therapies. Embryonic neural stem cells derived from E14 rat spinal cord tissue were co-incubated with encapsulated microspheres (Bangs Laboratories). Each microsphere is 0.96 µm and consists of iron oxide crystals and a fluorescein analogue entrapped in a polymer matrix. Electron microscopy confirmed the intracytoplasmic location of these microspheres after co-culture. Fluorescence and light microscopy confirmed a highly efficient labeling process and the healthy appearance of cells. Magnetic resonance imaging (MRI) was performed at 7.0 Tesla using a Bruker Biospin system. In vitro MRI of labeled, cultured cells demonstrated the ability to resolve individual embryonic neural stem cells. In vivo studies used a spinal cord overhemisection lesion at C4. Labeled embryonic neural stem cells were transplanted ...

Functional MRI (fMRI) has become the most commonly used non-invasive brain imaging technique. With the growing interest in neuroscience applications using fMRI, it became crucial to understand the specificity of its signal with respect to the actual neuronal response. We recently reported a comparison of point spread functions (PSF) of GE BOLD and CBF based fMRI in cat visual cortex (area 18), which provided a quantitative relationship between spatial specificities of both fMRI modalities. In this study we addressed the PSFs of GE BOLD and SE BOLD fMRI at an ultra-high magnetic field, 9.4 T and compared them to the previous results. The PSF was obtained by delivering stimuli that alternately evoked responses from the upper and the lower visual fields. Thus it generated a “retinotopic border” between two adjacent areas in the primary visual cortex. By examining the statistical maps in the region of the retinotopic border and in particular the profiles of the activation maps perpendicular to the border, we e...

Previous work has shown that Mn2+ enters neurons through voltage-gated Ca2+ channels and is transported along axons (anterograde transport) and across synapses during neuronal activation. Paramagnetic Mn2+ shortens the T1 relaxation time of water molecules in its immediate environment enabling visualization of neuronal tracts as hyper-intense regions in T1-weighted MR images. Results from our examination of visual pathways in use-allowed and use-deprived eyes in the rabbit, employing manganese-enhanced MRI to trace functioning neuronal connections, are presented. For our experiments, 1-5 μL of aqueous 1.0 M MnCl2 solution was injected into the vitreous body of one eye of Dutch-belted rabbits. T1-weighted, multi-slice, spin-echo MR images (TR=424 ms, TE=14.6 ms) were acquired on a Bruker Biospin 4.7 Tesla imager immediately following injection with subsequent imaging performed every 48 hours for up to 10 days. Consecutive, 1mm thick slices were acquired in the coronal, axial, and sagittal planes. Deprivatio...

Previously we reported alterations in transverse relaxation times in whole cerebellar vermis of adults with a history of childhood sexual abuse, and children with ADHD following stimulant administration. Preclinical studies, however, indicate functional heterogeneity within the vermis, which extends to individual lobules or lamellae. To study lobular changes in T2, we employed the enhanced S/N afforded by high-field MRI. Using a Siemens 3T Trio scanner with an 8-channel phased-array head coil, segmented EPI (TE/TR = 15, 31…127/6, matrix =256, seg = 8) pixel-wise T2 maps were collected over 7 minutes and calculated for lobule ROIs using least-squares-fit to log-linear data with a single exponential decay model. ROIs of the 10 lobules were drawn using Larsell (1972). Two subjects (M, 33; F, 21) are imaged to date. The male vermis contained 1445 total voxels, with the following for each lobule (#, T2 in msec): I (18, 80.38); II (57, 66.86); III (101, 64.33); IV (68, 70.93); V (271, 64.40); VI (95, 70.88); VII...

Magnetic resonance imaging (MRI) is the most practicable means to assess structural changes in the injured central nervous system (CNS) in vivo over time non-invasively. Thus far, in vivo MRI studies in rodent models of spinal cord injury suffer from low spatial resolution and motion artifacts. The aim of the present study was to assess the capacity of a 17.6 Tesla MRI to detect pathological changes occurring in a rat spinal cord contusion injury model over time. Adult female Fischer 344 rats weighing 150-160g received a contusion injury at thoracic level T10 using the IH Impactor (200 kdyn applied force), which causes severe degeneration of the injured spinal cord parenchyma leading to irreversible impairment of locomotor function. Starting at 1 week up to 4 weeks post-injury, high-resolution images were obtained from anesthetized rats using a Bruker Avance 750WB MRI system at 17.6 Tesla. A multi-slice 2D gradient echo was used as imaging sequence with an echo time of 4.1 ms and a repetition time around 2...

The state of unconsciousness during anaesthesia is not characterized by a global disruption of CNS activity. Instead consciousness is mediated by a specific subset of brain states or processes selectively affected by anaesthetics. Our aim is to study the action sites of different types of anaesthetics in the monkey brain (M. mulatta). Here we report on the neural effects of Ketamine, a dissociative anaesthetic acting primarily on the NMDA receptor, and Midazolam, a benzodiazepine affecting GABA(A)-receptors. Ketamine exhibits both inhibitory and excitatory effects at different brain sites. Midazolam, however, is known to increase the GABA(A)-receptor function, and therefore to inhibit cortical activity. To study the primary sites-of-action of these agents in the monkey brain, high-resolution functional magnetic resonance imaging (fMRI) was used to measure stimulus induced activity changes in the alert and anaesthetized monkey. The activity of neurons in visual cortex was recorded during scanning, as well a...

Region-specific cerebral blood flow (CBF) and apparent diffusion coefficient (ADC) of water in the rat brain were quantified by high-field MRI (9.4 T) for 6-7 hours and up to 5 days after middle cerebral artery occlusion (MCAO), either in the permanent occlusion mode or during reperfusion after 85 min of MCAO. Upon occlusion, average CBF fell from ~1.5-2 ml/g/min to <0.5 ml/g/min in cortical areas and to <0.2 ml/g/min in the caudoputamen (CP). CBF in the homologous contralateral areas also decreased by 25-30%. Corresponding ADC decreases were most profound in the CP and parietal cortex (from ~8 × 10−4 to 5 × 10−4 mm2/s), lesser in the frontal cortex, and negligible in the piriform cortex, suggesting that the perfusion threshold for ADC decrease may be different for different brain regions in the same animal. On average, CBF recovered only to ~30% of the baseline in the first 24 h of reperfusion. After 3-4 days of reperfusion, however, CBF and ADC changes were reversed: a strong hyperperfusion in the ipsila...

Technique for interleaved recording of electroencephalogram(EEG) and functional magnetic resonance imaging(fMRI) was developed and used to investigate neurocognitive processes in a visual oddball task. One of the most serious artifacts during interleaved recording is ballistocardiogram. Sources of this artifact are related to the micro-movements of EEG cables on the head of the subject that oscillate in synchronization with heart pulsations. The conventional method to avoid the artifact, such as twisting EEG cables with bipolar montage gives rise to the reduction of the EEG signal and unequable reference. It was considered that preventing the head micro-movements was, therefore, a shortcut to realize multi-channel recording with monopolar montage, and so a vacuum head supporting system usually used for radiological oncology was employed. The quality of EEG during fMRI was validated by inspection, FFT ,and visual evoked potentials. Using interleaved EEG/fMRI, P300s of healthy subjects were recorded during a...

The scintillating grid illusion consists of dark illusory spots flashing on small white disks superimposed on the intersections of a grey-on-black Hermann grid. Numerous such spots are seen transiently within the white disks during saccadic eye movements or brief exposures. To see whether the pronounced flashing illusion activates brain regions known to process flickering or flashing stimuli (e.g. hMT+) we used fMRI (Siemens Magnetom Vision, 1.5 T, EPI, 16 slices, voxel size 3x3x3 mm) on 7 normal subjects. We compared the pattern of activation from presenting the scintillating grid with that from presenting an identical control grid with the disks shifted horizontally from the intersections which abolishes the scintillation. For identification of hMT+ a flowfield stimulus was included in the stimulation protocol. Results show that hMT+ was activated only during the perception of the illusion. In addition, activation was enhanced in a parietal sulcus bilaterally, a region presumed to be involved when subjec...