Functional magnetic resonance imaging (fMRI) has been used extensively to identify regions in the inferior temporal (IT) cortex that are selective for categories of visual stimuli. However, comparatively little is known about the neuronal responses relative to these fMRI-defined regions. Here, we compared in nonhuman primates the distribution and response properties of IT neurons recorded within versus outside fMRI regions selective for four different visual categories: faces, body parts, objects, and places. Although individual neurons that preferred each of the four categories were found throughout the sampled regions, they were most concentrated within the corresponding fMRI region, decreasing significantly within 1–4 mm from the edge of these regions. Furthermore, the correspondence between fMRI and neuronal distributions was specific to neurons that increased their firing rates in response to the visual stimuli but not to neurons suppressed by visual stimuli, suggesting that the processes associated w...

Uni-manual sensorimotor coordination performed at low movement rates is bi-stable, displaying a tendency towards either synchronization or syncopation. Under parametric increases in movement rate the syncopated pattern becomes unstable until at some critical frequency the system passes into a monostable regime and spontaneous switches to synchronized coordination ensue. Functional imaging studies have demonstrated robust differences in neural activity underlying these two coordination patterns when performed at movement rates well within the bistable regime. Such data suggest that neural networks distinguishing between coordination modes may be related to the relative differences in stability and contribute to the generation of behavioral transitions. Here we use blood oxygen level dependent (BOLD) functional magnetic resonance imaging to measure neural activity of the brain for the purpose of establishing a relationship between brain areas that distinguish between the two stable coordination patterns and ...

Introduction - Amyotrophic lateral sclerosis (ALS) is an horrific illness with rapid degeneration of motor neurons. Monitoring motor circuitry in ALS patients is difficult due to the inability of patients to perform even simple motor tasks at later stages. We utilized pharmacologic magnetic resonance imaging (phMRI) of a passive amphetamine challenge for longitudinal study of motor cortex/dopaminergic circuitry in FALS rats. Methods - Rats expressing SOD1G93A and wild-type (WT) littermates were studied. PhMRI experiments were run using a contrast agent to sensitize images to relative blood volume (rCBV), then amphetamine (2.5 mg/kg, i.v.) was injected. ROI analysis was used to assess regional rCBV changes. Five rats were scanned pre-symptomatically (85+/-28 days) and again after partial hind-limb paralysis (131+/-13 days). Results - The response to amphetamine produces a pattern that involves sensorimotor cortex (SMCx), caudate/putamen (CPu), and medial prefrontal cortex (MPFCx). The average rCBV (%) in CP...

Neuroimaging studies have often failed to observe activity in the hippocampal region during memory retrieval. Recently, two functional magnetic resonance imaging studies reported activity in the hippocampal region associated with recollective success. In both, participants studied pictures of objects and were given a recognition memory test with words that either did or did not name the studied objects. The recognition test was therefore cross-modal or associative in nature. These findings raise the question of what circumstances are required to observe activity in the hippocampal region during memory retrieval. Here, we report that robust hippocampal activity for targets relative to foils occurred during retrieval in a recognition memory task when single words were used at both study and test, as well as when pictures of single nameable objects were used at both study and test. The hippocampal region is involved not just in overtly associative tasks but more broadly in the recollection of recently occurri...

The baroreceptor reflex is not fully developed at birth. Hypotensive challenges in the adult cat elicit functional magnetic resonance imaging (fMRI) signal intensity declines in multiple medullary, cerebellar, insular and pontine regions, and signal increases in amygdala and hypothalamic areas. We used fMRI procedures to compare responses in neural sites involved in mediating the baroreceptor reflex in kittens with adult cats, and thus determine mechanisms underlying the incomplete baroreceptor responses in developing animals. A baroreceptor reflex was elicited in isofluorane-anaesthetized adult cats (n=7) and kittens (n=14; 14-25 days old) via i.v. sodium nitroprusside. FMRI image series were collected during 60 s baseline and 180 s challenge periods. Significant differences between signal intensity changes in adult cats and kittens were assessed on a voxel-by-voxel basis using SPM2, and by volume-of-interest analysis. Baseline arterial pressure increased and heart rate decreased with age, while barorecep...

The subthalamic nucleus (STh) is a small subcortical structure which is involved in regulating motor as well as cognitive functions. Due to its small size and close proximity to other small subcortical structures, it has been a challenge to localize and visualize it using magnetic resonance imaging (MRI). Currently there are several standard atlases available that are used to localize the STh in functional MRI studies and clinical procedures such as deep brain stimulation (DBS). DBS is an increasingly common neurosurgical procedure that has been successfully used to alleviate motor symptoms present in Parkinson's disease. However, current atlases are based on low sample sizes and restricted age ranges ([Schaltenbrand and Wahren, 1977][1]), and hence the use of these atlases effectively ignores the substantial structural brain changes that are associated with aging. In the present study, ultra-high field 7 tesla (T) magnetic resonance imaging (MRI) in humans was used to visualize and segment the STh in youn...

Functional magnetic resonance imaging (FMRI) was used to identify candidate language processing areas in the intact human brain. Language was defined broadly to include both phonological and lexical–semantic functions and to exclude sensory, motor, and general executive functions. The language activation task required phonetic and semantic analysis of aurally presented words and was compared with a control task involving perceptual analysis of nonlinguistic sounds. Functional maps of the entire brain were obtained from 30 right-handed subjects. These maps were averaged in standard stereotaxic space to produce a robust “average activation map” that proved reliable in a split-half analysis. As predicted from classical models of language organization based on lesion data, cortical activation associated with language processing was strongly lateralized to the left cerebral hemisphere and involved a network of regions in the frontal, temporal, and parietal lobes. Less consistent with classical models were (1) t...

Spinal cord injuries (SCI) lead to major handicaps affecting over 2.5 million people worldwide. Major shortcomings in therapeutic translation to clinics is due to many factors including species differences, development of predictive animal models and di...

SfN’s Pre-Conference Sessions occur before the official start of the annual meeting and provide an opportunity to learn from global experts on emerging scientific topics and techniques, advances in our understanding of neurobiological diseases, and rigorous and responsible conduct of scientific research. Space is limited and registration is required for Friday’s Short Courses. To attend, add the appropriate course to your annual meeting registration. Attendees of Meet the Experts sessions must be registered for the annual meeting but no separate registration or fee is required for these Saturday morning sessions. Space is limited and attendees are encouraged to arrive early for their priority session.

The main olfactory bulb (MOB) is the first olfactory center where the olfactory information is coded and processed. In addition to integrating the activity from the olfactory epithelium, the responsive behavior is regulated further by intrinsic bulbar circuits and the extrinsic pathways from other brain regions. We are using functional magnetic resonance imaging (fMRI) to visualize the integrative effects of the regulation mechanisms on bulbar responsive behavior in rats. Using iso-amyl acetate as stimulant, the effects of odorant concentration, exposure duration, and intervals between stimulations on the responsive properties of the MOB were examined at 7-Tesla with spatial resolution of 220x220x250 μm and temporal resolution of 8s to 1.5 s/image. When rat was repeatedly exposed to odors, its MOB was activated to higher degree in the first stimulation, but was suppressed in following exposures. With longer stimulation, or higher concentration, the adaptation is more prominent. Activity dropped to ∼40% of ...