Diffusion tensor imaging (DTI) is sensitive to structural ordering in brain tissue particularly in the white matter tracts. Diffusion anisotropy changes with disease and also with neural development. We used high-resolution DTI of fixed rabbit brains to study developmental changes in regional diffusion anisotropy and white matter fiber tract development. Imaging was performed on a 4.7-tesla Bruker Biospec Avance scanner using custom-built solenoid coils and DTI was performed at various postnatal ages.
The recent failure of many clinical trials of neuroprotective compounds may be due in part to poor animal models of human stroke. We have developed an endovascular stroke model in nonhuman primates that is compatible with serial magnetic resonance imaging (MRI) monitoring. Using cynomologous macaques (n = 4), a microcatheter was navigated transarterially (under fluoroscopic guidance) from the femoral artery to the middle cerebral artery (MCA). The microcatheter was wedged in a branch of the MCA for 3 hours to cause focal cerebral ischemia, as verified angiographically.
OBJECTIVE: To use functional MRI (fMRI) to investigate whether hippocampal activation during a memory task can predict cognitive decline in individuals with mild cognitive impairment (MCI).
Neuroimaging studies using angry or contemptuous human facial photographic stimuli have suggested amygdala hyper-responsivity in social anxiety disorder (SAD). We sought to determine if an angry "schematic face" (simple line drawing) would evoke exaggerated amygdalar responses in SAD patients compared with healthy control (HC) subjects. Angry, happy, and neutral schematic faces were overtly presented to matched cohorts of 11 SAD and 11 HC subjects for passive viewing, whereas brain functional magnetic resonance imaging signal was measured at 1.5 Tesla.
Recent researchers have suggested that a region of right temporo-parietal junction (RTPJ) selectively subserves the attribution of beliefs to other people (Saxe R, Kanwisher N. 2003. People thinking about thinking people: fMRI investigations of theory of mind. NeuroImage. 19:1835-1842; Saxe R, Powell LJ. 2006. It's the thought that counts: specific brain regions for one component of theory of mind. Psychol Sci. 17:692-699; Saxe R, Wexler A. 2005. Making sense of another mind: the role of the right temporo-parietal junction. Neuropsychologia. 43:1391-1399).
In this protocol we describe how to perform the Multi-Source Interference Task (MSIT), a validated functional magnetic resonance imaging (fMRI) task that reliably and robustly activates the cingulo-frontal-parietal cognitive/attention network (CFP network) within individual subjects. The MSIT can be used to (i) identify the cognitive/attention network in normal volunteers and (ii) test its integrity in people with neuropsychiatric disorders.
People can consciously re-experience past events and pre-experience possible future events. This fMRI study examined the neural regions mediating the construction and elaboration of past and future events. Participants were cued with a noun for 20s and instructed to construct a past or future event within a specified time period (week, year, 5-20 years). Once participants had the event in mind, they made a button press and for the remainder of the 20s elaborated on the event.
Recent functional neuroimaging studies have shown that multiple cortical areas are involved in memory encoding and retrieval. However, the underlying anatomical connections among these memory-related areas in humans remain elusive due to methodological limitations. Diffusion tensor imaging (DTI) is a technique based on detecting the diffusion of water molecules from magnetic resonance images. DTI allows non-invasive mapping of anatomical connections and gives a comprehensive picture of connectivity throughout the entire brain.
BACKGROUND: Corticostriatal circuitry has been implicated in the pathophysiology of obsessive-compulsive disorder (OCD). The serial reaction time (SRT) task, a paradigm that tests implicit sequence learning, has been used with imaging to probe striatal function. Initial studies have indicated that OCD patients exhibit deficient striatal activation and aberrant hippocampal recruitment compared with healthy control (HC) subjects.
We investigated the prevalence and specificity of category-selective regions in human visual cortex. In the broadest survey to date of category selectivity in visual cortex, 12 participants were scanned with functional magnetic resonance imaging while viewing scenes and 19 different object categories in a blocked-design experiment. As expected, we found selectivity for faces in the fusiform face area (FFA), for scenes in the parahippocampal place area (PPA), and for bodies in the extrastriate body area (EBA). In addition, we describe 3 main new findings.
