Midline Surface Research Articles

Automatic Brain Midline Surface Delineation on 3D CT Images With Intracranial Hemorrhage.

Brain midline delineation plays an important role in guiding intracranial hemorrhage surgery, which still remains a challenging task since hemorrhage shifts the normal brain configuration. Most previous studies detected brain midline on 2D plane and did not handle hemorrhage cases well. We propose a novel and efficient hemisphere-segmentation framework (HSF) for 3D brain midline surface delineation. Specifically, we formulate the brain midline delineation as a 3D hemisphere segmentation task, and employ an edge detector and a smooth regularization loss to generate the midline surface. We also introduce a distance-weighted map to keep the attention on the midline. Furthermore, we adopt rectification learning to handle various head poses. Finally, considering the complex situation of ventricle break-in for hemorrhages in bilateral intraventricular (B-IVH) cases, we identify those cases via a classification model and design a midline correction strategy to locally adjust the midline. To our best knowledge, it is the first study focusing on delineating the brain midline surface on 3D CT images of hemorrhage patients and handling the situation of ventricle break-in. Extensive validation on our large in-house datasets (519 patients) and the public CQ500 dataset (491 patients), demonstrates that our method outperforms state-of-the-art methods on brain midline delineation.

Cortical Afferents of Area 10 in Cebus Monkeys: Implications for the Evolution of the Frontal Pole.

Area 10, located in the frontal pole, is a unique specialization of the primate cortex. We studied the cortical connections of area 10 in the New World Cebus monkey, using injections of retrograde tracers in different parts of this area. We found that injections throughout area 10 labeled neurons in a consistent set of areas in the dorsolateral, ventrolateral, orbital, and medial parts of the frontal cortex, superior temporal association cortex, and posterior cingulate/retrosplenial region. However, sites on the midline surface of area 10 received more substantial projections from the temporal lobe, including clear auditory connections, whereas those in more lateral parts received >90% of their afferents from other frontal areas. This difference in anatomical connectivity reflects functional connectivity findings in the human brain. The pattern of connections in Cebus is very similar to that observed in the Old World macaque monkey, despite >40 million years of evolutionary separation, but lacks some of the connections reported in the more closely related but smaller marmoset monkey. These findings suggest that the clearer segregation observed in the human frontal pole reflects regional differences already present in early simian primates, and that overall brain mass influences the pattern of cortico-cortical connectivity.

Applied anatomy for tibial intraosseous access in adults

Intraosseous access is a method for providing vascular access in resuscitation of critically ill and injured patients when traditional intravenous access is difficult or impossible. There is a lack of detailed description for the landmark for the insertion point in the literature. The aim of this study was to determine the exact location for intraosseous access. Radiographic computed tomography (CT) images of a total of 50 dry tibia bones were obtained. With 5-mm intervals, for all transverse images and by selecting transverse section, measurements were taken from the thickness of the cortex at anterior margin and mid-line medial surface, distance from anterior margin, and mid-line medial surface of the tibia to the posterior wall of medullar cavity, distance from anterior margin and mid-line medial surface of the tibia to the posterior surface of the tibia. The thinner part of the cortex of the tibia and the larger width of the medullar cavity is at 0.5 cm below the tibial tuberosity in the midline of the medial surface. The application region for proximal tibia access and landmark and most suitable insertion point for intraosseous infusion should be at level 0.5 cm below the tibial tuberosity in the midline of the medial surface. It was recommended that standard length for intraosseous canule should be 17 mm except for the thickness of skin. In conclusion, presented study provides certain localization for intraosseous access and standard length for intraosseous canule and this will be more effective in using this technique. Clin. Anat. 31:593-597, 2018. © 2017 Wiley Periodicals, Inc.

Understanding the Impact of Stroke on Brain Motor Function: A Hierarchical Bayesian Approach

ABSTRACTStroke is a disturbance in blood supply to the brain resulting in the loss of brain functions, particularly motor function. A study was conducted by the UCI Neurorehabilitation Lab to investigate the impact of stroke on motor-related brain regions. Functional MRI (fMRI) data were collected from stroke patients and healthy controls while the subjects performed a simple motor task. In addition to affecting local neuronal activation strength, stroke might also alter communications (i.e., connectivity) between brain regions. We develop a hierarchical Bayesian modeling approach for the analysis of multi-subject fMRI data that allows us to explore brain changes due to stroke. Our approach simultaneously estimates activation and condition-specific connectivity at the group level, and provides estimates for region/subject-specific hemodynamic response functions. Moreover, our model uses spike-and-slab priors to allow for direct posterior inference on the connectivity network. Our results indicate that motor-control regions show greater activation in the unaffected hemisphere and the midline surface in stroke patients than those same regions in healthy controls during the simple motor task. We also note increased connectivity within secondary motor regions in stroke subjects. These findings provide insight into altered neural correlates of movement in subjects who suffered a stroke. Supplementary materials for this article are available online.

Brain structural changes in women and men during midlife

Brain development during childhood and adolescence differs between boys and girls. Structural changes continue during adulthood and old age, particularly in terms of brain volume reductions that accelerate beyond age 35 years. We investigated whether brain structural change in mid-life differs between men and women. 43 men and 28 women from the Northern Finland 1966 Birth Cohort underwent MRI brain scans at age 33–35 (SD=0.67) and then again at age 42–44 (SD=0.41). We examined sex differences in total percentage brain volume change (PBVC) and regional brain change with FSL SIENA software. Women showed significant PBVC reduction compared with men between the ages of 33–35 and 42–44 years (Mean=−3.21% in men, Mean=−4.03% in women, F (1, 68)=6.37, p<0.05). In regional analyses, women exhibited greater brain reduction than men in widespread areas. After controlling for total percent brain volume change, men show greater relative regional brain reduction than women in bilateral precentral gyri, bilateral paracingulate gyri, and bilateral supplementary motor cortices. The results indicate sex differences in brain changes in mid-life. Women have more total brain reduction, and more reduction on the outer brain surface than men, whereas men exhibit more brain reduction on the mid-line surface than women after co-varying for total brain volume loss. These changes could contribute to sex differences in midlife behaviour and health.

Neuroimaging in normal pressure hydrocephalus.

Normal pressure hydrocephalus (NPH) is a syndrome characterized by the triad of gait disturbance, mental deterioration and urinary incontinence, associated with ventriculomegaly and normal cerebrospinal fluid (CSF) pressure. The clinical presentation (triad) may be atypical or incomplete, or mimicked by other diseases, hence the need for supplementary tests, particularly to predict postsurgical outcome, such as CSF tap-tests and computed tomography (CT) or magnetic resonance imaging (MRI). The CSF tap-test, especially the 3 to 5 days continuous external lumbar drainage of at least 150 ml/day, is the only procedure that simulates the effect of definitive shunt surgery, with high sensitivity (50-100%) and high positive predictive value (80-100%). According to international guidelines, the following are CT or MRI signs decisive for NPH diagnosis and selection of shunt-responsive patients: ventricular enlargement disproportionate to cerebral atrophy (Evans index >0.3), and associated ballooning of frontal horns; periventricular hyperintensities; corpus callosum thinning and elevation, with callosal angle between 40º and 90º; widening of temporal horns not fully explained by hippocampal atrophy; and aqueductal or fourth ventricular flow void; enlarged Sylvian fissures and basal cistern, and narrowing of sulci and subarachnoid spaces over the high convexity and midline surface of the brain. On the other hand, other imaging methods such as radionuclide cisternography, SPECT, PET, and also DTI or resting-state functional MRI, although suitable for NPH diagnosis, do not yet provide improved accuracy for identifying shunt-responsive cases.

Thickness of the Palatal Masticatory Mucosa with Reference to Autogenous Grafting: A Cadaveric and Histologic Study

The aims of this study were to measure the thickness of the palatal masticatory mucosa and determine its histologic characteristics with reference to autogenous grafting. Thirty-two fully dentate, cadaver hemimaxillae were examined (from 13 men and 3 women; mean age, 57.1 years). The thickness of the palatal masticatory mucosa was assessed at 24 standard measurement points on the sectioned specimens after decalcification, and then the specimens were processed for embedding in paraffin, sectioned, and stained with hematoxylin and eosin. The thickness of the palatal masticatory mucosa varied by tooth site as follows: 3.55 ± 1.09 mm (mean ± SD; distal canine), 3.51 ± 0.99 mm (distal first premolar), 3.28 ± 1.07 mm (distal second premolar), 2.83 ± 1.00 mm (midline first molar), 2.92 ± 1.03 mm (distal first molar), and 3.15 ± 1.66 mm (distal second molar). The thickness also varied according to distance from the cementoenamel junction (CEJ): 2.35 ± 0.79 mm at 3 mm below the CEJ, 2.65 ± 0.77 mm at 6 mm, 3.52 ± 0.94 mm at 9 mm, and 4.29 ± 1.14 mm at 12 mm. Histologic analysis showed that the thickness of the lamina propria decreased toward the posterior palatal area and midpalatal suture, while that of the submucosa increased. These results suggest that the most appropriate donor site for gingival autogenous grafting is the region 3 to 9 mm below the CEJ between the distal surface of the canine and the midline surface of the first molar.

Mood‐induced variations of mandible and tongue postures

Twelve young adults in a good general health were observed during habitual posture of tongue and jaw in different emotional conditions induced by watching three video sequences. The position of the mandible was tracked by the displacements of an electromagnetic sensor glued to the chin. The tongue-to-palate distance was obtained by 2-D location of three electromagnetic sensors placed on the tongue upper midline surface. Head displacements were evaluated with a sensor fixed to an upper central incisor and were subtracted from corresponding displacements of tongue and chin sensors to obtain the real tongue and mandible positions during continuous recording sequences. Emotional conditioning by a fear movie influenced the vertical position of the mandible: the mean interarch distances during the fear movie (2·34 ± 0·24 mm) were significantly different from those measured during the tender (3·13 ± 0·35) and neutral (3·42 ± 0·80) movies, respectively (anova repeated measure, SNK; P < 0·05). anova repeated measure indicated that the tongue-to-palate distance differed significantly when the subjects were watching the conditioning movies (P = 0·003), the tip of the tongue taking a lower position during the fear movie than during the tender and neutral movies.

Parafalcine and midline arteriovenous malformations: surgical strategy, techniques, and outcomes

Parafalcine arteriovenous malformations (AVMs) have a midline plane in common, but differ in their location (anterior, middle, or posterior) and depth (superficial or deep). Surgical management varies with AVM location and depth in terms of patient position, head position, craniotomy, and surgical approach. This study examined surgical strategies, patient outcomes, and regional factors influencing results. Patients with AVMs located on the medial surface of the cerebral hemisphere were identified retrospectively from a consecutive, single-neurosurgeon series that is registered prospectively as part of the UCSF Brain Arteriovenous Malformation Study Project. During a 12-year period, 443 patients with AVMs were treated surgically. Of these 443 patients, 132 (30%) had parafalcine AVMs, which were distributed in zones as follows: superficial-anterior, 25 (18.9%); superficial-middle, 26 (19.7%); superficial-posterior, 39 (29.5%); deep-anterior, 25 (18.9%); deep-posterior, 17 (12.9%). Five different surgical strategies were used depending on AVM zone. Complete AVM resection was achieved in 123 (93.2%) of 132 patients. Overall, neurological condition improved in 74 patients (56.1%) and remained unchanged in 41 patients (31.1%). Neurological condition deteriorated in 12 patients (9.1%), and 5 patients (3.8%) died. Patients with AVMs in the superficial-middle zone had the highest rate of neurological deterioration (26.9%). Parafalcine AVMs lie on a midline surface that, when exposed with a bilateral craniotomy across the superior sagittal sinus and a wide opening of the interhemispheric fissure, makes them superficial. However, unlike convexity AVMs, which are approached perpendicularly, parafalcine AVMs are approached tangentially. Gravity retraction is useful with deeply located AVMs (those in the deep-anterior and deep-posterior zones), because it widens the interhemispheric fissure and accesses deep arterial feeding vessels from the anterior and posterior cerebral arteries. Surgical risks were increased in the superficial-middle zone, which is likely explained by the proximity of sensorimotor cortex. The authors' regional classification of parafalcine AVMs may serve as a guide to surgical planning.

A mechanical model of vocal-fold collision with high spatial and temporal resolution.

The tissue mechanics governing vocal-fold closure and collision during phonation are modeled in order to evaluate the role of elastic forces in glottal closure and in the development of stresses that may be a risk factor for pathology development. The model is a nonlinear dynamic contact problem that incorporates a three-dimensional, linear elastic, finite-element representation of a single vocal fold, a rigid midline surface, and quasistatic air pressure boundary conditions. Qualitative behavior of the model agrees with observations of glottal closure during normal voice production. The predicted relationship between subglottal pressure and peak collision force agrees with published experimental measurements. Accurate predictions of tissue dynamics during collision suggest that elastic forces play an important role during glottal closure and are an important determinant of aerodynamic variables that are associated with voice quality. Model predictions of contact force between the vocal folds are directly proportional to compressive stress (r2 = 0.79), vertical shear stress (r2 = 0.69), and Von Mises stress (r2 = 0.83) in the tissue. These results guide the interpretation of experimental measurements by relating them to a quantity that is important in tissue damage.

Analysis of factors affecting vocal fold impact stress using a mechanical model

High mechanical stress levels in the vocal folds likely contribute to pathological changes to the tissue such as vocal nodules. Vocal fold collision during phonation was modeled as a dynamic contact problem in order to calculate stress levels during impact. The model incorporated a 3-D, linear elastic, finite element representation of a single vocal fold, a rigid midline surface, and a simplified aerodynamic waveform. The effects of fold geometry, material properties, and sub-glottal pressure on peak impact stress were calculated. Impact stress time course and the relationship between sub-glottal pressure and peak impact stress agree with published experimental measurements [Jiang and Titze, J. Voice 8, 132–144 (1994)]. Identification of high-stress configurations will promote better understanding of the etiology, persistence, and treatment of certain pathological voice changes. [Work supported by the Whitaker Foundation.]

New insights into critical events of avian gastrulation.

The formation and progression of the primitive streak are key events of avian gastrulation. We examine these processes in detail, using various morphological approaches. We show that formation of the primitive streak occurs locally at the caudal midline of the area pellucida, as cells in the caudal midline undergo an epithelial-to-mesenchymal transformation, and that extensive migration of delaminated cells arising from more rostral or peripheral areas of the blastoderm is not involved in streak formation. Instead, such delamination occurs earlier and is restricted to the process of hypoblast formation. Moreover, we provide evidence that progression of the primitive streak involves two processes: convergent-extension movements within the streak per se, and progressive delamination of midline epiblast cells in a caudal-to-rostral sequence. We have identified a subpopulation of primitive-streak cells located at its dorsal midline surface that undergoes extensive rostral displacement concomitant with streak progression. The fact that these cells are located only dorsally and do not elongate ventrally as do adjacent ingressing cells, suggests that these cells retain their residency within the primitive streak, at least until regression of the primitive streak occurs. Finally, by following labeled cells over time we establish the timing of movement of epiblast cells toward and into the primitive streak, providing direct evidence that cell-cell intercalation occurs within the primitive streak during its progression. Collectively, our results provide new insight into complex and central events of avian gastrulation.

Anatomy and targets of Dorsal Unpaired Median neurones in the Terminal Abdominal Ganglion of the male cockroach Periplaneta americana L.

The morphology of the Dorsal Unpaired Median (DUM) neurones in the Terminal Abdominal Ganglion (TAG) of the adult male cockroach Periplaneta americana were described based on wholemount preparations and paraffin sections and by using anterograde and retrograde cobalt mapping, octopamine-like immunohistochemistry, and double immunofluorescence technique with both conjugated gamma-aminobutyric acid (GABA) and octopamine antisera. Among 60 +/- 6 neurones with large somata (diameter 40 to 60 microns) on the dorsal midline surface of the TAG that were stained with toluidine blue, about 36 efferent DUM neurones exhibited octopamine-like immunoreactivity. The DUM neurones were arranged in three clusters (anterior, median and posterior) corresponding to the 7th-11th abdominal ganglia of the fused TAG. Anterior efferent DUM neurones with one, two, and four pairs of lateral neurites entered segmental nerves VIIB; VIIB and phallic nerves; IXB and phallic nerves; VIIIA, IXA, X, and IX, respectively. Three octopamine-like immunoreactive DUM neurones innervating heart chambers via segmental nerves (VIIA, VIIIA, and IXA) in the last abdominal segments occurred within abdominal ganglia 7, 8, and 9. Together with octopamine-like immunoreactive efferent DUM neurones, GABA-like immunoreactive dorsal midline neurones with small somata (10 to 20 microns) also occurred within the median group. The spatial distribution of DUM neurones in the TAG suggested that they had their origins in the median neuroblast, as for DUM neurones in the grasshopper.

Discrimination of speech-like contrasts in the auditory thalamus and cortex.

The neurophysiologic discrimination of acoustic contrasts was investigated as reflected by the mismatch negativity (MMN) response. Evoked responses were recorded from guinea pig thalamus (medial geniculate nucleus) and epidural surface in response to synthesized speech contrasts /ga/-/da/ and /ba/-/wa/. From the caudomedial portion of the medial geniculate nucleus, /ba/-/wa/ elicited a strong mismatch response, whereas /ga/-/da/ did not. Neither stimulus contrast elicited an MMN from the ventral, or primary, portion of medial geniculate. Both stimulus contrasts elicited an MMN from the midline surface. Neither contrast elicited an MMN from the surface over the temporal lobe. Results indicate a hierarchy of processing of the spectrotemporal changes which characterize formant transitions. Also, results indicate that the nonprimary portions of the auditory pathway contribute substantially to the MMN.

Morphogenesis of the murine node and notochordal plate

Development of the node and formation of the notochordal plate in gestational day 7-9 mice (Theiler stages 10-14) has been documented principally with scanning electron microscopy (SEM) and cell fate analyses utilizing DiI and/or CFSE as a cell label. With SEM, cells composing these two populations are initially identifiable at stage 10 at the ventral midline of the rostral half of the embryo. They can be recognized by their relatively small ventral surface area, as compared to that of the peripherally adjacent prospective gut endodermal cells, and by the presence on the ventral side of each cell of a prominent single, central cilium, which is lacking on endodermal cells. At stage 10, the node is located at the apex of the cup-shaped embryo. It represents the rostral end of the primitive streak (although its structure differs from that of the rest of the streak), and it consists of a localized two-layered area (i.e., epiblast and the most caudal aspect of the notochordal plate). By stage 11, the notochordal plate constitutes a relatively broad, circular area (at the level of the node) that tapers rostrally into a narrower midline strip (beneath the future floor plate of the neural tube). The tip of the notochordal plate terminates rostrally at the much broader prechordal plate, which underlies the future forebrain level of the neuraxis. The prechordal plate cells, like the ventral node and notochordal plate cells, each have a relatively small ventral surface area and displays a single central cilium on their ventral surface. The most caudal aspect of the notochordal plate remains morphologically distinct on the dorsal, midline surface of the open gut through stage 13; the more rostral levels progressively fold off from the roof of the gut to form the definitive notochord. Videomicroscopy reveals that the cilia extending from the ventral surfaces of the cells of node and of the prechordal and notochordal plates are motile. The potential significance of this motile behavior remains unknown. Labeling studies, which marked cells in both the dorsal and ventral layers of the node, reveal that the stage-10 node contributes cells to the notochordal plate and overlying midline ectodermal cells of the neural plate, the future floor plate of the neural tube.(ABSTRACT TRUNCATED AT 400 WORDS)

Nonprimary auditory thalamic representation of acoustic change

1. The mismatch response, or mismatch negativity (MMN), is a neurophysiologic response to stimulus change. In humans and other animals, the MMN may underlie the ability to discriminate acoustic differences, a fundamental aspect of auditory perception. 2. This study investigated the role of the thalamus in the generation of a tone-evoked MMN in guinea pigs. Electrodes were placed in the caudomedial (nonprimary) and ventral (primary) subdivisions of the auditory thalamus (medial geniculate nucleus). Surface epidural electrodes were placed at the midline and over the temporal lobe. The MMN was elicited by a deviant stimulus (2,450-Hz tone burst) embedded in a sequence of standard stimuli (2,300-Hz tone bursts). 3. A tone-evoked MMN was present in nonprimary thalamus but was absent in the primary thalamus. Surface-recorded MMNs were measured at the midline but not over the temporal lobe. The correspondence between nonprimary thalamic responses and midline surface potentials, and between primary thalamic responses and temporal surface potentials, is consistent with data reported for the auditory middle latency responses in guinea pigs. 4. The results demonstrate that the nonprimary auditory thalamus contributes to the generation of a tone-evoked MMN in the guinea pig. Furthermore, the data indicate that the guinea pig is a feasible model for investigating central auditory processes underlying acoustic discrimination.

Subcortical and cortical components of the MLR generating system

The contributions of the auditory thalamo-cortical pathway, mesencephalic reticular formation, and inferior colliculus to the surface recorded auditory middle latency response (MLR) were assessed by selective inactivation of these areas with lidocaine. Evoked responses were recorded simultaneously from these areas and from the cortical surface. Lidocaine-induced changes were compared across recording sites. In the guinea pig, surface components measured from over the temporal lobe (waves A, B and C) and the midline (waves M− and M+) have been previously shown to reflect the activity of two distinct generating mechanisms. Effects of lidocaine injections corresponded to selective changes in components from these two systems. Injections in the medial geniculate body (MGB) were associated with total disruption of surface potentials measured over the temporal lobe, auditory cortex (AC) responses, and local activity in MGB. Thus the thalamo-cortical pathway appears to be important for the generation of MLRs recorded from the surface of the temporal lobe. These injections generally did not alter the surface midline responses or activity obtained from either the mesencephalic reticular formation (mRF) or the inferior colliculus (IC). Lidocaine injections within AC did not alter the basic response morphology of surface potentials, nor were significant changes measured within AC. Lidocaine injections into the mRF produced changes in all surface temporal potentials, the M+ midline surface potential, and in local potentials recorded from MGB and mRF. Injections into the IC changed surface and subcortical responses at all sites. This was the only injection to affect activity at the latency of surface midline wave, M−. This wave may be the animal analogue for human wave Na. Control experiments indicated that the effects observed were specific to the neural inactivation of target areas. The MLR generating system appears to consist of contributions and interactions from multiple areas including the auditory thalamo-cortical pathway, mRF and IC. The animal model and e experimental strategy described appear promising for linking the contributions from specific brain areas to surface MLR waves.

Electrical stimulation over the human vertebral column: which neural elements are excited?

Supramaximal percutaneous electrical stimuli applied over the human cervical verterbral column produced maximal compound muscle action potentials (CMAPs) in abductor digiti minimi. It is important to know which neural elements are excited by these stimuli and experiments were performed to answer this question. With stimulating electrodes placed progressively lateral to the midline, submaximal CMAPs with the same latency are produced. With shocks over the cervical vertebrae in the midline, the threshold for excitation of arm muscles is much lower than for excitation of leg muscles. Comparison of conduction time from the cervical column to more distal sites on the ulnar nerve by direct measurement and by F wave latency determination shows that the latter exceeds the former by 1.6 msec. Collision experiments in which paired shocks were given at the wrist and Erb's point or the wrist and cervical column showed that recovery from blocking as interstimulus interval lengthened was similar for the two sites, and that it was possible to detect F waves from the proximal stimulus. The latency of CMAPs evoked from midline surface stimuli was identical to that from a needle stimulus near the C8 root. It is concluded that electrical stimuli applied over the cervical vertebrae in the midline excite the motor roots at their exit from the spinal canal. This finding has implications for clinical studies of pyramidal tract and proximal peripheral nerve conduction.

Lingual vibrotactile testing: A Modified nonclamping procedure

Lingual vibrotactile thresholds were obtained from the anterior midline surface of the tongue for 20 subjects during test and retest conditions. Measurements were made at five frequencies (60, 100, 150, 200, and 250 Hz) using a new procedure which did not compress the lingual tissue. Modifications also included using a series of logic modules to program stimulus control and to track threshold sensitivity at frequency while simultaneously adding and subtracting attenutation in the manner of Bekesy audiometry. Procedures previously used by the author and his associates clamped the tongue and consistently obtained a summating response suggestive of frequency selective mechanoreceptors. Present test‐retest results showed a flat configuration across frequency which agrees with the Duplex Theory of Mechanoreception [R. T. Verrillo, in The Skin Senses, edited by D. Kenshallo (Thomas, Springfield, 1968) pp. 139–159]. The authors conclude that previously using clamping techniques may have distorted lingual tissues so as to excite ventrally based frequency responsive mechanoreceptors.

The effects of linear and logarithmic data transformations upon observed patterns of lingual vibrotactile sensitivity

Vibrotactile thresholds were obtained from the anterior midline surface of the tongue on three groups of normal-speaking young adults. A different frequency condition was employed for each of the groups tested. Threshold values were initially recorded in millivolts and subsequently converted to microns of displacement and decibels. Data comparisons showed a differential response to frequency for both kinds of transformations. This finding was discussed in terms of its implications concerning the nature and type of mechanoreceptors present in the cutaneous surface tissue of the tongue. Some suggestions for further research in this area were made.