Orlando J. Andy

QUANTITATIVE COMPARATIVE NEUROANATOMY OF PRIMATES: AN ATTEMPT AT A PHYLOGENETIC INTERPRETATION

All primates as well as many, if not all, recent orders of placental mammals have their phylogenetic origin in insectivorelike ancestors. This conclusion has been derived from paleontological studies on fossils. Although the brains of the early forerunners of mammals have not been preserved, clues to the shape of the brain and its surface pattern, to its size and to that of some of its individual subdivisions may be obtained from natural or artificial endocranial casts of fossil skulls. In this way, a direct study of the phylogenetic development of certain characteristics of the brain is possible. Edinger has brought this branch of scientific research, known as paleoneurology, to world-wide recognition. The amount of information that can be obtained from endocranial casts is necessarily restricted. Generally, statements concerning the finer structural details of the brain, especially those that are not represented on the surface, cannot be made. It would therefore be impossible to acquire any knowledge about the p h y b genetic development of such particulars without additionally employing the indirect method of comparing the brains of recent species now in existence. The results of this scientific approach, which is known as comparative neuroanatomy, can be used to a certain degree in the interpretation of phylogenetic relationships, if the comparisons are based on the insectivores. The recent representatives of the insectivores (to which comparative neuroanatomical investigations are necessarily restricted) are not uniform with regard to brain development. Using quantitative methods, we have tried (since 1956) to identify the species with the most primitive cerebral pattern. We have grouped together these primitive forms as “basal insectivores”.t To this group belong representatives of the tenrecs (Tenrecidae) , hedgehogs (Erinaceidae) and shrews (Soricidae) . The primitivity of the brains of the basal insectivores is reflected in the fact that all progressive structures

Thalamic Stimulation for Control of Movement Disorders

and complexes of cerebral structures, respectively, are quantitatively the least developed. With regard to the quantitative composition of the brain, the basal insectivores represent a fairly uniform type. In contrast, the remainder of the insectivores reveal distinct marks of higher

Parafascicular-Center Median Nuclei Stimulation for Intractable Pain and Dyskinesia (Painful-Dyskinesia)

Chronic recurrent thalamic stimulation has been effective in alleviating a variety of movement disorders. In contrast to thalamic lesions, it is preferred for the treatment of intractable motor disorders in low-risk elderly patients and patients with diffuse brain lesions secondary to trauma. Abnormal diencephalic electrical discharges have been observed and thought to be associated, in some way, with either generating or sustaining the movement abnormalities. The beneficial effects are ascribed to an electrophysiologic functional ablation of the discharging systems. This interpretation is based on the observation that the diencephalic discharges are attenuated by the applied stimulation and that the beneficial effects are reversible even after several months of applied therapeutic stimulation.

The effect of thalamic stimulation in processing of verbal stimuli in dichotic listening tasks: A case study

Medial thalamus stimulation was used to treat chronic intractable pain associated with dyskinesia. Relief from both the pain and the motor disorder occurred concomitantly. However, maximum pain reduction was attained at a relatively faster rate than maximum reduction from the motor disability. It is postulated that pathologic changes in the center median nucleus secondary to lenticulo-striate-internal capsular lesions account, in part, for both the pain and the dyskinesia. Electrical stimulation of the center median(n) parafascicular nuclear complex presumably simultaneously activates both the neurohumeral and tertiary sensory pain inhibitory system for pain control, and the suprasegmental gamma system for motor control.

Stuttering acquired from subcortical pathologies and its alleviation from thalamic perturbation

In dichotic listening tasks, the (dominant) right ears superiority in processing verbal stimuli has been attributed to its direct anatomic connection with the left dominant hemisphere. The role played by extralinguistic factors, such as attention and functional tuning of the associated cortical structures, has not been carefully examined. This investigation was undertaken to evaluate the effects of the left thalamic electric stimulation on the processing (recognition and recall) of dichotically presented CVC verbal stimuli in a patient being treated for chronic pain. We report the positive effects of electric stimulation (confirmed by increased subcortical metabolic activity using SPECT, a brain imaging technique) on the processing of dichotically presented verbal stimuli.

Alleviation of acquired stuttering with human centremedian thalamic stimulation.

Acquired stuttering subsequent to subcortical pathology of mesothalamus was observed in four neurosurgical subjects. The patients suffered from chronic pain, seizures, and somatosensory disorders. They also exhibited unpredictable and uncontrollable speech, spasmodic blocks which were devoid of accessory features, and adaptation effect. Therapeutic mesothalamic stimulation, used as a treatment of last resort to relieve the pain and associated symptoms, also had an ameliorating effect on the stuttering. Spontaneously occurring focal abnormal EEG discharges were anatomically delineated and used as a guide for therapeutic stimulation electrode placement. Attentuation of the abnormal discharges was followed by alleviation of symptoms. This investigation examines the clinical characteristics of stuttering in four neurosurgical patients and suggests an electropathologic basis for their mesothalamic-generated speech dysfluencies. The cooccurrence of pain, seizures, somatosensory disorders, and stuttering, and their concurrent amelioration, suggests that both chronic pain and stuttering may be implicated by similar or related reticular electropathologic generators, couched in overlapping reticular networks extending from the brain stem to the thalamus, and that the acquired stuttering may be recruited as one component of a larger syndrome complex.

Language Representation in the Human Brain: Evidence from Cortical Mapping☆

Despite many investigations, the cerebral mechanism for stuttering remains unknown. Recently, increased attention has been paid to acquired stuttering of adult onset in the hope that the events associated with it might provide clues to the biological mechanism underlying stuttering. This attention has focused exclusively on the cortical substrates. We present our observations of acquired dysfluency, presumably of subcortical origin in a neurosurgical subject with intractable pain. The stuttering was relieved by thalamic electric stimulation. The effect of thalamic stimulation on the stuttering suggests that the pathophysiology of transient asynchronisation in the balancing and sequencing of multiple impulses is amenable to a diffusely orchestrated functional tuning of the thalamic and brainstem implicated subcortical structures and pathways.

The human amygdala. I. Electrophysiological responses to odorants

The manner in which the human brain processes grammatical-syntactic and lexical-semantic functions has been extensively debated in neurolinguistics. The discreteness and selectivity of the representation of syntactic-morphological properties in the dominant frontal cortex and the representation of the lexical-semantics in the temporo-parietal cortex have been questioned. Three right-handed adult male neurosurgical patients undergoing left craniotomy for intractable seizures were evaluated using various grammatical and semantic tasks during cortical mapping. The sampling of language tasks consisted of trials with stimulation (experimental) and without stimulation (control) from sites in the dominant fronto-temporo-parietal cortex The sampling of language implicated a larger cortical area devoted to language (syntactic-morphological and lexical-semantic) tasks. Further, a large part of the fronto-parieto-temporal cortex was involved with syntactic-morphological functions. However, only the parieto-temporal sites were implicated with the ordering of lexicon in sentence construction. These observations suggest that the representation of language in the human brain may be columnar or multilayered.

Duration and frequency patterns of the after-discharge from septum and amygdala

Nine patients had an amygdalotomy for attempted relief of intractable seizures and, as an aid for localization, recordings were made from the amygdala and later computer analyzed. The background activity is 3-18 c/sec; in response to odorants sinusoidal bursts are seen, synchronous with inspiration at 12-24 c/sec, but mainly 40-70 c/sec. Each odorant is associated with a given group of frequency components. However, for many different odorants the number of these components is restricted and the hypothesis is presented that odor discrimination in mans amygdala is not determined by which components are present, but the patterning of the components according to their amplitude. Odorants within the same odor class produced similar patterns of response. Epileptiform activity was recorded in two different forms, one in response to odors, similar in frequency to the slower bursts, except for sharper configurations, at times progressing to clinical seizures and the second as an insertion discharge from an advancing electrode, similar in frequency to the faster bursts. These latter data suggest that the repertoire of a given neural system or structure may be limited to specific frequencies but the configuration or patterning of these frequencies define the different states of the structure.

Amygdaloid propagation to the brain stem (electrophysiological study)

Abstract 1. 1. After-discharges were induced in nineteen adult cats by repetitive electrical stimulation of the septum, amygdala and septum plus amygdala (overlapped S.A. seizures). Frequency and duration patterns were analyzed. 2. 2. Discharge durations were shortest for the amygdala, intermediate for the septum and longest for the overlapped septum-amygdala electrographic seizures. 3. 3. Durations of repeated, overlapped seizures increased at a faster rate than those of non-overlapped seizures. Durations of septum after-discharges displayed a moderate increase in relation to time whereas durations of amygdaloid seizures revealed very little change. 4. 4. Septum and S.A. after-discharge frequency patterns were characterized by predominantly slow, fast or mixed frequencies with modes at 5–7, 15 and 20 c/sec. Amygdala after-discharge frequency patterns were characterized by predominantly slow frequencies with a mode at 1–4 c/sec. In the overlapped S.A. discharges, the amygdala appeared to potentiate the frequency and duration patterns of the septum after-discharges.