Richard F. Martin

Primate neostriatal neurons containing tyrosine hydroxylase: Immunohistochemical evidence

We have detected, in monkey caudate nucleus and putamen, neuronal cell bodies containing tyrosine hydroxylase-like immunoreactivity, as revealed by peroxidase-antiperoxidase immunohistochemistry. Many of these cells are distributed in an outer rim of 1-2 mm throughout the anterior-posterior extent of the neostriatum near its borders with the corona radiata; others are embedded in the adjacent white matter, especially near the ventral putamen and nucleus accumbens. Light and electron microscopy indicate that they are small (8-12 micron), bipolar cells with large nuclei. Such neostriatal neurons, containing tyrosine hydroxylase-like immunoreactivity, number in the tens of thousands.

Nociceptive responses of trigeminal neurons in SII-7b cortex of awake monkeys

A cluster of trigeminal nociceptive neurons was located in the lateral sulcus on the upper bank of the frontoparietal operculum in a region bordering between cortical areas SII and 7b. These neurons were isolated in cortical cell layers IV and V-VI. All nociceptive neurons responded exclusively to noxious mechanical stimulation of cutaneous receptive fields on the face/head or intraoral tissue. Sustained noxious mechanical stimulation elicited slowly adapting responses that accurately encoded the duration of the stimulation. Prolonged discharges following removal of noxious stimulation were not observed. These nociceptive specific neurons poorly encoded graded noxious stimuli. Trigeminal somatosensory neurons within and surrounding the SII-7b cluster were not topographically organized according to divisions of the trigeminal nerve, laterality of receptive fields, or division of face/head and intraoral receptive fields. The thalamocortical, corticocortical and indirect corticolimbic connectivities of SII and area 7b and the possible role of SII-7b nociceptive neurons in learning, memory and avoidance behaviors are discussed.

Physiological properties of intradental mechanoreceptors

A major role of tooth receptors in signaling overt or impending tissue damage (nociception) has been previously established by substantial evidence from mechanical, thermal and chemical stimulation of exposed dentin. We report evidence showing that some intradental receptors in canine teeth of the cat detect mechanical transients applied to intact enamel. This new finding suggests that dental innervation may play an important non-nociceptive role in oral function such as detecting tooth contact during mastication and swallowing.

NeuroNames Brain Hierarchy.

The NeuroNames Brain Hierarchy is a structured system of neuroanatomical terminology that provides a comprehensive representation of virtually all human and nonhuman primate brain structures that are identifiable either grossly or in Niss1-stained histological sections. This system was devised for computer applications to address deficiencies in the brain terminology presented in Nomina Anatomica. English terms are listed for 783 structures in nine levels of hierarchical ranking. Abbreviations are provided for all superficial and primary volumetric structures. The substructures that constitute the total volume of every superstructure are identified. Superficial features of the brain are clearly distinguished from internal, volumetric brain structures. Structures found solely in either humans or macaques are identified. The purpose of the NeuroNames Brain Hierarchy is to bring greater standardization to the neuroanatomical terminology used by scientific investigators, clinicians, and students. This effort is consistent with the goals of the Unified Medical Language System program of the National Library of Medicine. It is hoped that the systematic construction of the NeuroNames Brain Hierarchy will facilitate use of the most widely accepted definitions of classical neuroanatomy in quantitative computerized neuroimaging applications. It should provide an accurate structural framework against which to reference the many other kinds of neuroanatomical information that are acquired by modern imaging, mapping, and histological labeling techniques.

A stereotaxic template atlas of the macaque brain for digital imaging and quantitative neuroanatomy.

A stereotaxic brain atlas of the longtailed macaque (Macaca fascicularis) is presented in a format suitable for use as a template atlas of the macaque brain. It includes most of the brain segmented to show the boundaries of landmark structures such that every point in the brain can be represented by a unique set of coordinates in three-dimensional space and ascribed unambiguously to one and only one primary structure. More than 400 structures are represented, including 360 volumetric structures, which constitute the substance of the brain, and 50 superficial features. To facilitate use with ventriculography, magnetic resonance imaging, and other noninvasive imaging techniques, the stereotaxic space is referenced to internal landmarks, viz., the anterior commissure and posterior commissure; the center of the anterior commissure at the midline is the origin of the stereotaxic axes. Reference of stereotaxis to this bicommissural space facilitates structural comparison with human brain atlases, which are commonly referenced to the biocommissural line. It also facilitates comparison of brains of different nonhuman primate species by providing a template brain against which to compare size and internal variability. Thirty-three coronal sections at 1-mm intervals from the spinomedullary junction to the rostral extreme of the caudate nucleus show most structures of the hindbrain, midbrain, and subcortical forebrain. Separately, four side views and 16 coronal sections show cortical structures. Structures are represented by outlines of their boundaries and labeled according to NeuroNames, a systematic English nomenclature of human and nonhuman primate neuroanatomy. Abbreviations are based on a protocol designed to facilitate cross-species comparisons. Instructions are provided for: (1) locating sites from the Template Atlas in the conventional stereotaxic space of an experimental animal, (2) locating sites identified by conventional stereotaxis in the Template Atlas, and (3) using the Template Atlas to collate, compare, and display image information (e.g., labeled cells, recording sites, stimulation sites, lesions) from multiple animals.

Dissociation of action and object naming: Evidence from cortical stimulation mapping

This cortical stimulation mapping study investigates the neural representation of action and object naming. Data from 13 neurosurgical subjects undergoing awake cortical mapping is presented. Our findings indicate clear evidence of differential disruption of noun and verb naming in the context of this naming task. At the individual level, evidence was found for punctuate regions of perisylvian cortex subserving noun and verb function. Across subjects, however, the location of these sites varied. This finding may help explain discrepancies between lesion and functional imaging studies of noun and verb naming. In addition, an alternative coding of these data served to highlight the grammatical class vulnerability of the target response. The use of this coding scheme implicates a role for the supramarginal gyrus in verb‐naming behavior. These data are discussed with respect to a functional–anatomical pathway underlying verb naming. Hum. Brain Mapping 24:1–10, 2005.

Transplant improves hemiparkinsonian syndrome in nonhuman primate: intracerebral injection, rotometry, tyrosine hydroxylase immunohistochemistry.

Publisher Summary This chapter describes the methods for creating a unilateral DA lesion by direct injection of neurotoxin into substantia nigra, and for collecting quantitative behavioral data using a rotometer, and using these methods to test the efficacy of fetal nigral cell-suspension transplants. The histopathological results reveal that there is no evidence of immune rejection of the grafts as judged by the absence of lymphocytes, neutrophils, or macrophages. The behavioral changes observed in the monkey are believed to be related to the transplant, but it is not known why the improvement occurred so soon after the transplant, or why it ended so quickly. It is impossible to state with any certainty that the excess dopamine (DA) cells on the lesioned and transplanted side represent surviving transplanted cells, which migrated from the original graft site toward the ventricle. However, it is possible that the lesion alone results in a transformation or induction of endogenous tyrosine hydroxylase-like immunoreactive (TH-LI) cells, but this question will require investigation of additional transplantation animals and lesion controls.

Server-based Approach to Web Visualization of Integrated Three-dimensional Brain Imaging Data

The authors describe a client-server approach to three-dimensional (3-D) visualization of neuroimaging data, which enables researchers to visualize, manipulate, and analyze large brain imaging datasets over the Internet. All computationally intensive tasks are done by a graphics server that loads and processes image volumes and 3-D models, renders 3-D scenes, and sends the renderings back to the client. The authors discuss the system architecture and implementation and give several examples of client applications that allow visualization and analysis of integrated language map data from single and multiple patients.

Shape-Based Cortical Surface Segmentation for Visualization Brain Mapping

We describe a knowledge-based approach to cortical surface segmentation that uses learned knowledge of the overall shape and range of variation of the cortex (excluding the detailed gyri and sulci) to guide the search for the grey-CSF boundary in a structural MRI image volume. The shape knowledge is represented by a radial surface model, which is a type of geometric constraint network (GCN) that we hypothesize can represent shape by networks of locally interacting constraints. The shape model is used in a protocol for visualization-based mapping of cortical stimulation mapping (CSM) sites onto the brain surface, prior to integration with other mapping modalities or as input to existing surface analysis and reconfiguration programs. Example results are presented for CSM data related to language organization in the cortex, but the methods should be applicable to other situations where a realistic visualization of the brain surface, as seen at neurosurgery, is desired.

Evaluating Spatial Normalization Methods for the Human Brain

Cortical stimulation mapping (CSM) studies have shown cortical locations for language function are highly variable from one subject to the next. If individual variation can be normalized, patterns of language organization may emerge that were heretofore hidden. In order to uncover these patterns, computer-aided spatial normalization to a common atlas is required. Our goal was to determine a methodology by which spatial normalization methods could be evaluated and compared. We developed key metrics to measure accuracy of a surface-based (Caret) and volume-based (SPM2) method. We specified that the optimal method would i) minimize variation as measured by spread reduction between CSM language sites across subjects while also ii) preserving anatomical localization of all CSM sites. Eleven subjects structural MR image sets and corresponding CSM site coordinates were registered to the colin27 human brain atlas using each method. Local analysis showed that mapping error rates were highest in morphological regions with the greatest difference between source and target. Also, SPM2 mapped significantly less type 2 errors. Although our experiment did not show statistically significant global differences between the methods, our methodology provided valuable insights into the pros and cons of each method