Recent advances in magnetic resonance imaging (MRI) technology now allow the tracing of developmental changes in the brains of children. We applied computer-matching algorithms and new techniques for measuring cortical thickness (in millimeters) to the structural MRI images of 45 children scanned twice (2 yr apart) between the ages 5 and 11. Changes in brain size were also assessed, showing local brain growth progressing at a rate of ϳ0.4 -1.5 mm per year, most prominently in frontal and occipital regions. Estimated cortical thickness ranged from 1.5 mm in occipital regions to 5.5 mm in dorsomedial frontal cortex. Gray matter thinning coupled with cortical expansion was highly significant in right frontal and bilateral parieto-occipital regions. Significant thickening was restricted to left inferior frontal (Broca's area) and bilateral posterior perisylvian (Wernicke's area on the left) regions. In the left hemisphere, gray matter thickness was correlated with changing cognitive abilities. For the first time, developmental changes in gray matter thickness, brain size, and structure-function relationships have been traced within the same individuals studied longitudinally during a time of rapid cognitive development.

We have traced central nervous pathways controlling bird song in the canary using a combination of behavioral and anatomical techniques. Unilateral electrolytic brain lesions were made in adult male canaries whose song had been previously recorded and analysed on a sound spectrograph. After several days of postoperative recording, the birds were sacrificed and their brains processed histologically for degeneration staining with the Fink-Heimer technique. Although large lesions in the neostriatum and rostral hyperstriatum had no effect on song, severe song deficits followed damage to a discrete large-celled area in the caudal hyperstriatum ventrale (HVc). Degenerating fibers were traced from this region to two other discrete nuclei in the forebrain: one in the parolfactory lobe (area X, a teardrop-shaped small-celled nucleus); and a round large-celled nucleus in the archistriatum (RA). Unilateral lesion of X had no effect on song; lesions of RA, however, caused severe song deficits. Degenerating fibers from RA joined the occipitomesencephalic tract and had widespread ipsilateral projections to the thalamus, nucleus intercollicularis of the midbrain, reticular formation, and medulla. It is of particular interest that direct connections were found onto the cells of the motor nucleus innervating the syrinx, the organ of song production. Unilateral lesions of n. intercollicularis (previously implicated in the control of vocal behavior) had little effect on song. One bilateral lesion of HVc resulted in permanent (9 months) and complete elimination of the audible components of song, although the bird assumed the posture and movements typical of song. Preliminary data suggest that lesions of the left hemisphere result in greater deficits than lesions of the right one. This finding is consistent with earlier reports that the left syrinx controls the majority of song components. Results reported here suggest a localization of vocal control in the canary brain with an overlying left hemispheric dominance.

A stereotaxic atlas of the telencephalon, diencephalon and mesencephalon of the canary, Serinus canaria, was prepared for use in anatomical and behavioral experiments. Canaries have a complex vocal and behavioral repertoire many of whose components are under hormonal control in the male, and are therefore useful for many physiological and anatomical experiments. They are available commercially, breed easily in captivity, are quite hardy and respond well to anesthetic and surgical procedures.The atlas consists of 30 frontal plates from the frontal pole to the level of the motor nucleus of the trigeminus. One sagittal plate is included for reference purposes. Six birds (three males and three females) with marking lesions were used to make the atlas. Their brains were embedded in albumin-gelatin media, cut at 50 and 25 P and stained with cresyl violet for cell bodies, Weil stain for myelinated fibers and the Fink-Schneider method for unmyelinated fibers. Plates were drawn from the cresyl violet series and labeled using all three stains.The completed atlas was tested for accuracy by making 12 small lesions in a number of predetermined discrete loci in several birds and evaluating their placement. Eleven of these lesions were found to be within the targeted structure. The results of this test, combined with the results of experiments in over 50 birds, have shown the atlas to be accurate in 80% of all cases.In recent years there has been growing interest in the anatomy, physiology and hormonal mechanisms of birds. They are interesting from a comparative and evolutionary standpoint as well as particularly useful in the study of sensory control over learned and species-specific behaviors. Songbirds have a complex vocal repertoire, which in some species is learned and monitored through auditory feedback (reviews in Nottebohm, '70, '72; Marler and Mundinger, ' 7 2 ) . We have been investigating the neural pathways and hormonal systems underlying the output of vocal behavior (Zigmond et al., '73, and in preparation). A system of stereotaxic coordinates was required to place small lesions that would induce deficits in song production. The atlas contained in the following pages was prepared for this purpose.Although the original experiments in our investigation were on the European chaffinch, Fringilla coelebs, the present em-J. COMP. NEUR., 156: 337-374. bargo on importation of foreign birds forced us to use a more available species, the canary. We have found it to be a most satisfactory experimental bird and we would recommend it to other investigators with interests in sensory systems. Canaries have highly complex vocal and behavioral repertoires which facilitate the detection of small post-operative deficits. Several pure bred strains are commercially available and canaries are easy to keep and breed in captivity; they are quite hardy and respond well to anesthetic and surgical procedures. METHODSSelection of plane of section and design of a headholder. The technology of preparing a n atlas has grown considerably...

Between 3 and 6 per cent of children who are otherwise unimpaired have extreme difficulties producing and understanding spoken language. This disorder is typically labelled specific language impairment. Children diagnosed with specific language impairment often have accompanying reading difficulties (dyslexia), but not all children with reading difficulties have specific language impairment. Some researchers claim that language impairment arises from failures specific to language or cognitive processing. Others hold that language impairment results from a more elemental problem that makes affected children unable to hear the acoustic distinctions among successive brief sounds in speech. Here we report the results of psychophysical tests employing simple tones and noises showing that children with specific language impairment have severe auditory perceptual deficits for brief but not long tones in particular sound contexts. Our data support the view that language difficulties result from problems in auditory perception, and provide further information about the nature of these perceptual problems that should contribute to improving the diagnosis and treatment of language impairment and related disorders.

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In this study, we examined the neuroanatomy of dyslexic (14 males, four females) and control (19 males, 13 females) children in grades 4-6 from a family genetics study. The dyslexics had specific deficits in word reading relative to the population mean and verbal IQ, but did not have primary language or motor deficits. Measurements of the posterior temporal lobe, inferior frontal gyrus, cerebellum and whole brain were collected from MRI scans. The dyslexics exhibited significantly smaller right anterior lobes of the cerebellum, pars triangularis bilaterally, and brain volume. Measures of the right cerebellar anterior lobe and the left and right pars triangularis correctly classified 72% of the dyslexic subjects (94% of whom had a rapid automatic naming deficit) and 88% of the controls. The cerebellar anterior lobe and pars triangularis made significant contributions to the classification of subjects after controlling for brain volume. Correlational analyses showed that these neuroanatomical measurements were also significantly correlated with reading, spelling and language measures related to dyslexia. Age was not related to any anatomical variable. Results for the dyslexic children from the family genetics study are discussed with reference to dyslexic adults from a prior study, who were ascertained on the basis of a discrepancy between phonological coding and reading comprehension. The volume of the right anterior lobe of the cerebellum distinguished dyslexic from control participants in both studies. The cerebellum is one of the most consistent locations for structural differences between dyslexic and control participants in imaging studies. This study may be the first to show that anomalies in a cerebellar-frontal circuit are associated with rapid automatic naming and the double-deficit subtype of dyslexia.

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The central gustatory pathways of the albino rat have been traced using a combined electrophysiological-neuroanatomical technique.Gustatory responses in the medulla were recorded in the region of the solitary nucleus which receives the seventh nerve primary afferents. Fibers traced from lesions of these recording sites did not cross as expected into the medial lemniscus, but instead travelled rostrally to terminate ipsilaterally in a small celled area dorsal and ventral to the brachium conjunctivum as it enters the pons.Since gustatory responses could be recorded in this region it represents a previously undescribed secondary "pontine taste area." Lesions of PTA result in degeneration of a bilateral ascending pathway travelling in the dorsomedial tegmentum to terminate in the classical gustatory nuclei of the thalamus. Other fibers in this pathway continue rostrally and distribute in the subthalamus, dorsolateral hypothalamus and subpallidal gray in the ventral forebrain.These findings in a mammal resemble those established nearly three quarters of a century ago by Herrick ('05) in the carp, and confirm his prediction that "broad lines of similarity [would be found1 between both the peripheral and central gustatory paths in all vertebrates."