We describe the first systematic functional magnetic resonance imaging (fMRI) measurements of visual field maps in macaque visual cortex. The boundaries of visual areas V1, V2, V3, V3A, V4, MT/V5, and TEO/V4A were identified using stimuli that create traveling waves of activity in retinotopically organized areas of the visual cortex. Furthermore, these stimuli were used to measure the dimensions of the representations of the central 11° in V1–V3, quantitative visual field eccentricity functions for V1–V3 and MT, and the distribution of foveal and peripheral signals within the occipital lobe. Within areas V1, V2, MT, and portions of V4, the fMRI signals were 5–10 times the noise level (3 mm3 volumes of interest). Signals were weaker but still significant in other cortical regions, including V3, V3A, and TEO. There is good agreement between the fMRI maps and the visual area maps discovered using local anatomical and physiological measurements. The fMRI measurements allow one to obtain a broad view of the dis...

We report a modulation of cortical sensorimotor activity by the acupuncture of GB34 acupoint (located behind the knee, often used for the treatment of hemiplagia). Using a 3T MR scanner, functional MRI(fMRI) was performed across seven normal volunteers (F:M=1:6, Mean Age=27) on two stimulation paradigms; (1) acupuncture manipulation and (2) stimulation of a sham point near the designated acupoint. Gradient-echo EPI sequence (TR/TE=2500/35msec; 24cm field-of-view, 64x64 matrix; 6mm thick) was used to image the whole brain. Each functional session was initiated without the needle insertion. At the 11th scan, the needle was inserted and twisted for 25 seconds at a rate of ~2Hz, followed by a pause for the duration of 25 seconds as a control state. This process was repeated four times. All subjects underwent the acupuncture fMRI session without pain sensation. From the random effect group analysis (p<0.01) using SPM99, bilateral sensorimotor areas (Brodmann's Areas (BA) 3,4,6 and 7) showed acupuncture-related ...

Spontaneous recovery after spinal cord injury is limited. After an incomplete spinal cord injury, however, significant functional recovery occurs, probably due to synaptic plasticity and formation of new circuits. Compared to the motor systems, little is known about regeneration and/or plasticity in the sensory system after spinal cord injury. Therefore we designed methods to explore functional and structural plasticity of sensory pathways following contusion injury of the spinal cord by means of functional MRI and behavioral tests. Rats received a weight drop injury (12.5 or 6.25 mm) and were tested after 1, 4 or 16 weeks. Functional MRI using the BOLD technique in response to electric stimulation of the hindlimbs, gave rise to signals in sensorimotor cortex. The monitored BOLD signals were compared to different behavioral tests, such as BBB, gridway and hotplate. The results suggest a discrepancy between motor and sensory recovery. Thus animals with complete loss of sensation could show a high degree of ...

A new real-time multi-echo fMRI technique with gradient compensation of susceptibility related signal losses was used to measure activation in amygdala and hippocampus during 60 s trials of self-induced sadness. 9 healthy adults (3 males, 6 females, 22-45 years) performed a validated mood induction paradigm with sad and neutral faces in repeated scans (10 trials each, total trials: 235). This technique enabled online comparison with self-rating of sadness in single trials and immediate feedback of amygdala-hippocampus activation to the subject to reinforce mood induction. Activation of predominantly left amygdala-hippocampus during sad mood induction was observed in all subjects and in 77 % of single trials. This activation does not appear to diminish with repeated mood induction. The linear correlation between the intensity of amygdala-hippocampus activation and self-rating increased with repeated scanning, possibly reflecting adaptation to the mood induction procedure. These results suggest that amygdala...

The purpose of this study was to investigate the volumetric development of medial temporal lobe structures in rhesus macaques using non-invasive magnetic resonance imaging (MRI) techniques. Four infant macaques (2 males, 2 females) were scanned in the coronal plane using a Fast Spin Echo Inversion Recovery protocol at 3-4 and 6 months of age. Three adult males (3 years old) were also scanned using identical procedures. We began our analysis by measuring the volume of the hippocampal formation (HF) using the Image J software. Surface area of the left and right HF were obtained from each image where the HF could be seen and were ultimately combined with image thickness (1.5 mm) to calculate the total HF volume for each subject. Data were analyzed using repeated measures ANCOVAs to adjust for total cerebral volume (3-4 months vs. 6 months comparison) or one-way ANOVAs (6 months vs. 3 years). The left and right HF volume did not differ at any age studied. However, the HF volume increased between 3-4 months and...

Neural activity that occurs during the creation of a new memory trace can be observed using functional magnetic resonance imaging (fMRI). Event-related designs have been used to demonstrate that activity in prefrontal and medial temporal lobe areas is associated with successful memory storage. Here we contrasted activity associated with encoding success and encoding effort. Participants viewed a series of 150 words but attempted to remember only half of them. Encoding effort was manipulated using a cue in the form of a letter (R or F) presented after each word to instruct participants either to remember or to forget that word. Increased activity in left inferior prefrontal cortex was observed when words were followed by the cue to remember. In contrast, increased left medial temporal lobe activity was observed for words that were successfully recalled later. These results show that fMRI correlates of the intention to encode a word are different from fMRI correlates of whether that encoding is successful. P...

The pathologic hallmark of spinal cord (SC) injury is a progressive tissue decay at the damage site. Understanding the stages of the progression of pathology would be very helpful in developing strategies for SC injury repair. The evolution of pathology in the transection injury has been described. Longitudinal studies, ex vivo by histology [PNAS(1996)93:111791] and in vivo by MRI, of the transection site in rat SC suggest that an intrinsic reparative repertoire is activated after injury. However, by the end of the 3rd wk postinjury (PI) the repair is aborted and chronic inflammation/decay take over yielding a widening cavity. These data point to the existence of a window of opportunity for developing strategies for preventing the onset of tissue decay, eg, radiation therapy at this critical period can facilitate natural repair in sectioned SC1. The focus now is on contusion which is more similar to the human SC injury. Here we obtained by MRI a dynamic in vivo view of the events' progression at the lesion...

In 1990, Keele and Ivry considered the cerebellum as to be an 'internal clock' supporting temporal computations, both, in the motor and in the perceptual domain. Durational parameters contribute to speech perception. A previous study (Ackermann et al., 1997) found bilateral cerebellar disorders to compromise the identification of lexical items exclusively differing in a durational measure, i.e., intersyllabic silent period (occlusion time). The same subjects, however, showed intact categorical distinctions for the voice onset time (VOT). To further delineate contribution of the cerebellum to speech perception, activation in response to two series of items were studied by means of functional magnetic resonance imaging (fMRI): Boten / Boden (engl.: messenger / floor) utterances exclusively differing in (a) the intersyllabic occlusion time (27-167ms) or (b) in the intrasyllabic VOT (9-69ms), respectively. Randomized blocks requiring identification of the intersyllabic time measure yielded significantly higher...

Brain imaging studies have suggested regional reduction in gray matter content in bipolar patients in key anatomical regions involved in mood regulation. Most studies have utilized region-of-interest based methodologies, in which a particular brain structure is chosen a priori, traced, and then compared among different groups. As a different approach, voxel-based morphometry can potentially identify gray matter changes across the whole brain. We examined structural T1-weighted 1.5 T MR images of 26 bipolar disorder patients (age±S.D.= 35.2±10.4 years) and 39 healthy subjects (age±S.D.= 36.6±9.7 years). SPM99 was utilized to normalize the images to the MNI brain template, segment, smooth, and generate a statistical map of the differences between the groups, with age as covariate. Statistical significance was set at p<0.01 (voxel-level, uncorrected). Compared with the healthy control group, the bipolar subjects presented decreased gray matter density in an area in the left temporal lobe encompassing the limb...

The assessment of hemispheric dominance for language is being carried out after intracarotid administration of sodium amytal (Wada Test). This highly invasive method is not free of risks and is also distressing to the patient. Recent studies in adults have shown a good correlation between language dominance and lateralisation on fMRI. Here we present preliminary data in 6 consecutive patients who underwent Wada testing and fMRI scanning prior to epilepsy surgery. FMRI was performed on a 1.5T Siemens Vision system using a whole brain 3D EPI sequence. Two scans each with a total of 120 data sets were collected. During scanning the subjects silently generated verbs in response to auditory presentation of nouns. fMRI activations (analysed using SPM96b) included: the left inferior frontal gyrus (Broca’s area), premotor cortex and superior temporal gyrus bilaterally. The Wada test was not completed in 2 patients. One patient did not show language-related activation in any of 4 scans performed. Of the remaining 4...