Inferior Body Research Articles

Dendritic orientation and laminar architecture in the rabbit auditory thalamus.

A laminar organization composed of the dendritic fields of principal neurons and afferent axonal arbors has been proposed as the anatomical substrate for the frequency map at several levels of the mammalian central auditory system, including the inferior colliculus and medial geniculate body (MGB). In contrast to the auditory thalamus in most mammals, the ventral division of the rabbit medial geniculate body (MGV) has cellular laminae visible in routine Nissl stains, allowing a direct comparison of the laminar organization with the dendritic architecture and frequency organization. In total 30 presumptive relay neurons in the MGV were labeled with the juxtacellular recording method, and their dendritic arbors were fully reconstructed from serial sections with the aid of a computer microscope. The spatial organization of MGV dendritic fields was analyzed using the dendritic prism, dendritic stick, and fan-in projection methods. Quantitative spatial analyses revealed that, for MGV neurons in the central pars lateralis subdivision, the major axis of the dendritic fields (approximately 29 degrees relative to the horizontal plane) was closely aligned with that of the Nissl laminae (approximately 25 degrees). Both were oriented orthogonally to the tonotopic axis. In contrast, cells in the pars ovoidea had their major axis of orientation parallel to the anteroposterior axis of the brain. Although a bitufted dendritic field was the norm, it was not uncommon for MGV neurons to have pronounced spatial asymmetries in their dendritic fields. A model is presented that incorporates cellular laminae and oriented dendritic growth to form frequency-related slabs within the MGV.

Do position and soft tissue affect distraction vector? An in vitro investigation

Objectives: The purpose of this investigation was to provide an in vitro evaluation of the effects of soft tissue and position on vector during distraction. Materials and Methods: A polyurethane skull and mandible replica (Synbone, Landquart, Switzerland) was used in this study along with an internal distraction device (Synthes Maxillofacial, Paoli, PA). The first portion of the investigation evaluated the effects of distractor position (inferior body, midbody, and superior body) on distraction vector. The second portion of the investigation used polyethylene straps to simulate the suprahyoid muscles and muscles of mastication, and polysulfide to simulate periosteum and mucosa. A laser light source attached to the synthetic mandible was projected on a grid 7.1 m from the construct to measure deflection from the starting point. The distractor was advanced 8.0 mm for each trial. Five trials each for inferior, middle, and superior, with and without simulated soft tissues (N = 30) were performed. Vertical and horizontal deflection along with absolute distance were measured and recorded. Means and standard deviations were derived for groups, and compared for statistical significance (P <.05) with a 1-way analysis of variance for the effects of position with and without simulated soft tissue, and with a paired t-test for the effects of simulated soft tissue within groups of similar distractor position. Results: Statistically significant differences (P <.05) for distractors without simulated soft tissues were only noted for vertical deflection between the inferior and superior distractor groups. Statistically significant differences were noted for all measures, for all distractor positions with simulated soft tissues. Statistically significant differences were noted for all measures between similar distractor positions with and without simulated soft tissues. Distractors without simulated soft tissues were deflected lateral to the y-axis and above the x-axis. Distractors with simulated soft tissues were deflected lateral to the y-axis, but below the x-axis. For distractors with simulated soft tissues, the closer to the inferior border, the less the deflection from the x-axis. Conclusion: Position alone had minimal effects on distraction vector. Simulated soft tissues affected the vector of distraction. The combination of position and simulated soft tissues affected distraction vector. © 2002 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 60:149-155, 2002

Neural correlates of sensory gating in the rat: decreased Fos induction in the lateral septum

In the P 50 gating or conditioning-testing paradigm in the rat, two identical click stimuli are presented with an inter-click interval of 500 ms. The reaction towards the second click, as measured with evoked potentials, is reduced in respect to that towards the first click; this phenomenon is called sensory gating. In the present experiments, the inter-click interval was varied systematically and auditory evoked potentials were measured. Sensory gating was found to occur only at intervals between 500 and 1000 ms, but not at longer intervals. Fos immunohistochemistry was then performed using two groups of rats exposed to double clicks: the inter-click interval was 500 ms in the experimental group and 2500 ms in the control group. Fos induction was analyzed in selected brain structures. In the auditory pathways, Fos-immunoreactive neurons were found in both groups of rats in the inferior colliculus and medial geniculate body. Fos-immunoreactive cells were also examined in the septum and hippocampus. In the ventral part of the lateral septal nucleus, the labeled neurons were significantly fewer in the experimental animals compared to the control group. Smaller and non-significant quantitative differences of Fos-positive neurons were documented in the medial septum and hippocampal CA1 region. These data point out a selective decrease in the lateral septum of Fos induced by auditory sensory gating, and suggest an involvement of this structure, and possibly of other parts of the septo-hippocampal system, in sensory gating mechanisms. The results might be relevant for theories on sensory gating deficits in schizophrenia.

Modulation of responses and frequency tuning of thalamic and collicular neurons by cortical activation in mustached bats.

In the Jamaican mustached bat, Pteronotus parnellii parnellii, one of the subdivisions of the primary auditory cortex is disproportionately large and over-represents sound at approximately 61 kHz. This area, called the Doppler-shifted constant frequency (DSCF) processing area, consists of neurons extremely sharply tuned to a sound at approximately 61 kHz. We found that a focal activation of the DSCF area evokes highly specific corticofugal modulation in the inferior colliculus and medial geniculate body. Namely a focal activation of cortical DSCF neurons tuned to, say, 61. 2 kHz with 0.2-ms-long, 100-nA electric pulses drastically increases the excitatory responses of thalamic and collicular neurons tuned to 61.2 kHz without shifting their best frequencies (BFs). However, it decreases the excitatory responses of subcortical neurons tuned to frequencies slightly higher or lower than 61.2 kHz and shifts their BFs away from 61.2 kHz. The BF shifts are symmetrical and centrifugal around 61.2 kHz. These corticofugal effects are larger on thalamic neurons than on collicular neurons. The cortical electrical stimulation sharpens the frequency-tuning curves of subcortical neurons. These corticofugal effects named "egocentric selection" last </=2.5 h after the cessation of a 7-min-long cortical electrical stimulation. In the mustached bat, corticofugal modulation serves to increase the contrast in neural representation of sound at approximately 61 kHz, which is an important component of an echo bearing velocity information. It is also most likely that the corticofugal system plays an important role in plasticity of the central auditory system. Another subdivision of the auditory cortex of the mustached bat is called the FM-FM area. This area consists of delay-tuned combination-sensitive neurons, called FM-FM neurons, and has the echo-delay axis for the systematic representation of target distances. A focal electric stimulation of the FM-FM area evokes changes in the responses of collicular and thalamic FM-FM neurons. These changes are basically the same as those described in the present paper. Therefore corticofugal modulation takes place for frequency domain analysis in exactly the same way as it does in time domain analysis.

Can the sagittal lumbar curvature be closely approximated by an ellipse?

For the sagittal lumbar curvature, existing spinal models are based only on the anthropomorphic radiographic characteristics of one individual, or, at best, of only a few individuals. This raises questions of applicability of the modeling results to clinical situations. Because spinal coupling and loads on spinal tissues have been shown to be functions of the initial static posture, a rigorously derived neutral lumbar lordosis would be important for clinicians and spine researchers. This study presents modeling of the sagittal lumbar spine in the shape of an ellipse. Vertebral body and disc heights, derived from digitized lateral lumbar radiographs of 50 normal subjects, were used to create an ellipse along the posterior body margins from the inferior of T12 to the superior sacral base. Additional data to create an elliptical lumbar model were determined from a least-squares analysis of passing ellipses through the digitized posterior body points. This confirmed that an elliptical model closely fit the lumbar curvature with a least-squares error of 1.2 mm per digitized point. The elliptical model is approximately an 85 degrees portion of a quadrant. The semi-major and semi-minor axes, a and b, are parallel to the posterior body margin of T12 and parallel to the inferior body endplate of T12, respectively, with a semi-minor to semi-major radio of b/a=0.39. The elliptic model has a height-to-length ratio of H/L=0.963, where height is the vertical distance from inferior T12 to superior S1 and length is the arc length along George's line (along the posterior longitudinal ligament) from T12 to S1.

The significance of Calvin' s anthropology for preaching on ethical themes

In this article the author highlights Calvin's anthropology. A main feature of this anthropology is his dualistic view on man. Calvin was very much influenced by the ancient Greek philosophy, which argued that man had two parts: a superior soul and an inferior body. The author argues that this perception is at odds with a Biblical image of man. According to the Bible no part of man is inferior or superior to any other part of his personhood. The article indicates that a Biblical perspective on anthropology will draw different conclusions in ethics compared to a dualistic perception of the nature of man. A correct appreciation of the anthropology of man is therefore needed to guide decisions in ethics, where the focus is constantly anthropological.

Ergonomic factors influencing handwriting performance

Handwriting is one of the first things children are taught at school and need to perform in an efficient manner throughout life. Various studies have indicated that handwriting skills are related to many different variables including ergonomic factors. The purpose of this study was to investigate the differences between children with good and poor handwriting on ergonomic factors that underlie handwriting (e.g. body and paper positioning, pencil-grip and pressure) and to examine the relationship between the handwriting legibility and speed and these ergonomic factors. The study included 209 students in Grades 2 and 3 in Israel. The students were identified as good (N=116) and as poor handwriters (N=103) by their teachers. The Hebrew Handwriting Evaluation (HHE) was used to collect data on handwriting quality and speed as well as on ergonomic factors. A Chi square procedure was used to compare the differences between the handwriting groups. Discriminant analysis determined the percent of correct discrimination of subjects with poor or good handwriting based on the ergonomic factors. Finally, Spearman correlation coefficients were employed between the ergonomic variables and speed and quality of handwriting. The results indicated that children with poor handwriting had inferior pencil, paper and body positioning, stabilization of paper and consistency of pressure, compared to children with good handwriting. The implications of the results in general, and specifically for clinical practice are discussed. Finally, further research related to this topic is suggested.

Lymphatic flow and neural plexus invasion associated with carcinoma of the body and tail of the pancreas.

Lymph node status and neural plexus invasion are the most important prognostic factors that may be amenable to surgery for carcinoma of the body and tail of the pancreas. The pattern of lymphatic spread and neural plexus invasion were evaluated by analysis of various clinicopathologic factors. Twenty patients with carcinoma of the body and tail of the pancreas underwent pancreatectomy with systemic regional lymph node dissection at Kanazawa University Hospital. A precise evaluation of their lymph node involvement and neural plexus invasion was determined. Sixteen of 20 patients (80%) had lymph node involvement. The lymph nodes with a high metastatic rate were those along the splenic artery (50%), the inferior body lymph nodes (35%), the lymph nodes around the common hepatic artery (25%), and the paraaortic lymph nodes (20%). There was no relationship between tumor size, histologic type, and lymph node involvement. Plexus invasion was observed in 14 patients (70%). The most frequent site was the splenic plexus, but between 15% and 20% of the patients had celiac or superior mesenteric plexus invasion. There was no relationship between tumor size, histologic type, and neural plexus invasion. Based on these results, extended lymphadenectomy including the paraaortic lymph nodes, celiac lymph nodes, and superior mesenteric lymph nodes may improve the prognosis for patients with carcinoma of the body and tail of the pancreas. Extrapancreatic neural plexus dissection, especially of the celiac plexus and superior mesenteric plexus, also is necessary.

Postmodern, Post-Cartesian Positionings on the Subject of Psychology

Descartes's philosophical position, founded upon a mind/body dualism, has had a strong influence on psychology. His dualistic system has supported the creation of a discipline in which individuals are viewed both as systems affected by mechanistic bodily emanations and as self-regulating agents replete with self-awareness and the capacity for moral responsibility. The purpose of Harwood Fisher's (1995) paper is to demonstrate that this Cartesian view is crucial to the continuation of a psychological science, which has this form of being as its subject. The major antagonists of these goals are those involved in the postmodern move in psychology, and he focuses especially on the work of Kenneth Gergen, Rom Harré and John Shotter. My attempt here is to expose the manner in which Fisher masks his desire as reason, and to invite him to accept his desires as a foundationless, a priori commitment. Further I contend that possibilities other than chaos among faceless automatons can result from the erasure of the Cartesian legacy from psychological theory. On the contrary, my feminist postmodern reframing holds that a system that enforces a hierarchy within which the rational (mind/soul) elements are designated as the masters of the inferior body (emotions) reproduces the male/female dichotomy. This polarity, a hallmark of patriarchal history, is deeply problematic from the position of postmodern feminism. Finally I pose the possibility of relational selves as an alternative to the Cartesian self as the subject of psychology.

Influence of period length of light/dark cycles on the body weight and food intake of young rats

The purpose of this work is to test whether physiological factors, such as body weight or food intake, are related to the period of environmental cycles under which animals are kept. We studied body weight increase, daily food intake and efficiency (i.e. relationship between body weight increase and food intake) of 7 groups each containing 20–24 male rats. Measurements were recorded every 4 days from the day of weaning (25 days old) during 64 days. Each group of rats was kept under a symmetrical LD cycle. The period of the cycles studied were: 22, 23, 24, 25, 26, 27 and 28 hours (T22, T23…T28). Results show differences in the three variables studied for groups T25 and T26. These animals show an inferior body weight, less food intake and less efficiency. It would seem that the difference between the period of the external LD cycle and the endogenous period of the animals rhythm induces changes in the energetic needs of the organism.

Ciliary Body Neurilemoma: Unusual Clinical Findings Intimating the Diagnosis

Neurilemomas (schwannomas) rarely occur intraocularly. When present, they pose a diagnostic dilemma for the physician and often are mistaken as a malignant lesion, resulting in enucleation. The authors report the clinical findings of a 46-year-old man with a slowly progressive growing mass of the anterior chamber, associated with glaucoma and the development of cataract. To further delineate the tumor's features, ancillary techniques, including ultrasonography, computed tomography, and magnetic resonance imaging, were conducted. A definitive anterior chamber biopsy of the tumor was performed with histologic examination and electron microscopy. Ultrasonography, high-resolution computed tomography and magnetic resonance imaging showed a well-delineated mass of the inferior ciliary body involving nearly 5 clock hours of the angle. Two clinical features that suggested a longstanding tumor were brilliant transillumination of the mass (leading to the impression of a "cystic mass," not corroborated by ultrasonography) and retrodisplacement of the involved iris root. The histology, and particularly the electron microscopic features, confirmed the diagnosis of a neurilemoma, a benign tumor of the anterior segment. Intraocular neurilemomas are extremely rare tumors. Few are well documented with modern ancillary techniques. Clinical findings in conjunction with radiographic and ultrasonic features may support the diagnosis of a benign tumor. For this patient, confirmation via biopsy permitted combined cataract and glaucoma surgery to rehabilitate the eye, which retains 20/20 visual acuity 3 years after the procedure.

Auditory evoked potentials in a patient with a unilateral lesion of the inferior colliculus and medial geniculate body

Brain-stem, middle latency and late auditory evoked potentials (BAEPs, MLAEPs and LAEPs, respectively) were recorded in a patient 2 months after removal of a tumor affecting the quadrigeminal plate. Simultaneously, MRI showed a left unilateral lesion involving the inferior colliculus, brachium colliculi and the medial geniculate body (MGB). On dichotic listening, there was complete extinction of the right ear input, without subjective auditory disturbance. BAEPs were abnormal after stimulation of the right ear alone. Wave V was delayed and reduced in amplitude, and the I–V interval was augmented. Above all, MLAEPs of both ears were very abnormal. The Pa and Na components over the left hemisphere were abolished (Pa) or very reduced in amplitude or abolished (Na) whereas both Pa and Na components over the right hemisphere were normal. LAEPs were asymmetrical, with reduced P1N1P2 complex over the left hemisphere and absence of polarity reversal over the mastoid. It has been demonstrated that a lesion affecting only the inferior colliculus and MGB unilaterally and not extending beyond the MGB can abolish Na and Pa ipsilaterally. Any discussion of Na and Pa sources should take into account the output of the MGB to the auditory radiations, the MGB, the brachium colliculi and the inferior colliculus.

養魚飼料のタンパク質源‐ＩＶ ハマチに対する大豆油粕栄養価の加熱時間に伴う変化

In order to elucidate changes in the nutritive value of defatted soybean meal with the duration of heating time, the general and amino acid composition and trypsin inhibitor (TI) activity of several types of meal heated at 108°C for 0-40 min were determined, and the growth, feed conversion, protein digestibility, and body composition of young yellowtail Seriola quinqueradiata were also compared by feeding them with diets containing about 20% of each meal. The nutritive value of raw defatted soybean meal was extremely low: it had a high TI activity and high nitrogen solubility index, resulting in a low protein digestibility; its feeding caused weight loss in fish with inferior hematological characteristics and body composition. The nutritive value of the meal was markedly improved by heating it for 20 min, and was maximized by heating it for 30 min, but it decreased slightly after being heated for 40 min. The heating treatment hardly improved the general and amino acid composition of the soybean meal, while it caused a rapid inactivation of TI together with a marked improvement in protein digestibility, indicating that the improvement of its nutritive value by heating could be mainly attributed to an elimination of heat-labile growth inhibition factors such as TI. Also, the comparison in nutritive value between these heated soybean meals and soy protein concentrates suggests the continuing existence of heat-stable growth inhibition factors in the heated meal.

Adverse effects of a high-glucose diet on body weight and plasma calcium and 1,25-dihydroxyvitamin D 3 levels in calcium-deficient growing rats

We tested the hypothesis that dietary calcium would lead to greater impairment of body weight gain and calcium homeostasis if rats are fed a diet with a high glucose content compared with our standard diet in which the carbohydrate is supplied by whole wheat flour. Groups of female rats at 21 days of age were given either of two equivalent calcium-deficient diets with carbohydrate supplied either by glucose (LCaG) or by wheat flour (LCaW). Control rats were fed the wheat-flour diet containing 0.4% calcium. Since previous studies indicated divergent effects of glucose-based and flour-based diets on body weight in vitamin D-deficient rats, we designed a parallel study with vitamin D-deprived rats. Compared with rats fed the LCaW diet, the rats fed the LCaG diet had inferior body weight gain and more severe hypocalcemia (1–2 mg/ml lower) over a 40-day period, and no significant elevation of the plasma 1,25(OH) 2D 3 level at 61 days of age. Rats fed the LCaW diet maintained a 3-fold elevation of plasma 1,25(OH) 2D 3 relative to the level of control rats fed the 0.4% calcium diet. The dry weight and percent ash of tibias were similarly reduced in the two calcium-restricted groups compared to the control group. Among the vitamin D-deprived rats, those fed the glucose diet had poorer weight gain than those fed the wheat flour diet. However, both groups had similarly depressed serum calcium level, tibia ash content and 1,25(OH) 2D 3 level. Thus, a glucose diet combined with calcium restriction or vitamin D deprivation appears to accentuate the impairment of body weight gain and, when combined with calcium restriction, it also accentuates the impairment of calcium homeostasis and interferes with the adaptive increase in plasma 1,25(OH) 2D 3.

Trajectory architecture of the trabecular bone between the body and the neural arch in human vertebrae.

The cancellous structure of vertebrae has been studied to investigate the direction of trabeculae and thus the lines of stress. The trabecular bone of the pedicle, connecting the body to the lamina, differed in different regions of the vertebral column. At C2 level, it was found that trabeculae are involved in transfer of th column. At C2 level, it was found that trabeculae are involved in transfer of the compressive forces from the superior articular surface to the inferior articular process and body. Throughout the thoracic region, trabeculae in the pedicle were inclined anteriorly towards the body, indicating that compressive forces in the thoracic spine are transferred from the neural arch to the body. In the lower lumbar region, trabeculae run from the body towards the neural arch. Trabeculae in the thoracic transverse processes extend from the costal facet to the lamina, suggesting that weight brought by the ribs to the costotransverse articulations is transmitted to laminae through transverse processes.

Scintigraphic diagnosis of sacral fractures

The H- or butterfly-pattern of uptake in the sacrum on Tc-99m-methylene diphosphonate bone scintigraphy is typical of fractures of the body of the sacrum that involve the sacral alae. This report describes four patients with a focal linear or curvilinear pattern of uptake in sacral fractures without alae involvement. This pattern differs from that associated with metastases in the sacrum, which typically has a random pattern. Recognition of this scintigraphic linear dot pattern of uptake in horizontal fractures in the inferior body of the sacrum is useful for detecting fractures without alae involvement that are not readily apparent on radiographs.

Hearing loss in dogs after lesions of the brachium of the inferior colliculus and medial geniculate.

Seven dogs were tested for their sensitivity to pure tones following lesions of the brachium of the inferior colliculus and medial geniculate body. Bilateral section of the brachium of the inferior colliculus consistently resulted in an average hearing loss of as much as 37 dB in the midrange of the animals' audiograms. Lesions of the medial geniculate appear to produce a similar hearing loss if the ventral division of the medial geniculate is completely destroyed.

The scanning electron microscopy of compressed spinal units

Histology and scanning electron microscopy were used to evaluate the rhesus monkey spinal unit following controlled compression. Indications of cortical and end plate damage to the compressed vertebral units were present on radiographs following testing, and more extensive damage was observed with microscopy. The cartilaginous end plate was separated from the underlying bone of the vertebral body. The superior body of the spinal unit was more severely damaged than the inferior body, due largely to the direction of compression loading. Even relatively low strain rates (8.89×10−5 m/s) should be considered detrimental to the integrity of the spinal unit based on the observations of this study.

Mesencephalic areas controlling pulsatile oxytocin release in the suckled rat.

Experiments were performed on anaesthetized lactating rats to investigate the effects of radiofrequency lesions of the mesencephalon on the milk-ejection reflex. In lesioned and control rats, intramammary pressure recordings were used to estimate oxytocin release (number and relative amplitude of the intermittent milk-ejection responses) during a 3-h suckling test with ten pups. Bilateral lesions (diameter 0·5–1·5 mm) of the lateral tegmentum (near the brachium of the inferior colliculus and medial geniculate body) seriously disrupted the milk-ejection reflex, reducing the number of rats ejecting milk (two out of ten v. all 12 controls, P&lt;0·001) and the amount of oxytocin they released (1·35±0·35 (s.e.m.) v. 15·52±2·19 mu. for controls, P&lt;0·05). Unilateral lesions of the lateral tegmentum also impaired milk ejection and, if the suckling stimulus was restricted only to the contralateral nipples, oxytocin release was virtually abolished. Bilateral lesions placed more medially in the intermediate tegmentum were far less disruptive (eight out of nine rats ejected milk), though the amount of oxytocin released in this group (8·64±1·88 mu.) was still significantly (P&lt;0·05) lower than controls. All rats with lesions of the central grey (nine) or ventral tegmentum (eight) displayed reflex milk ejection, as did those with multiple lesions of the tectum, central grey and ventral tegmentum (seven); in these three groups the amounts of oxytocin released (13·88±2·68, 13·10±1·90 and 11·04±1·95 mu. respectively) did not differ significantly from controls. Damage to the ventral tegmentum produced an irregular pattern of milk ejection characterized by occasional abnormally short (&lt;2 min) milk-ejection intervals, though the overall number of responses in 3 h was less than that of controls (20·83±1·82 v. 14·50±1·30 mu., P&lt;0·05). In conclusion, these results delineate two mesencephalic areas of particular importance in the milk-ejection reflex: (a) the lateral tegmentum, which appears to be concerned with transmission of the suckling stimulus from the contralateral nipples and is indispensable for oxytocin release, and (b) the ventral tegmentum which, although not an essential component of the reflex, may contribute to the timing of the intermittent milk-ejection responses.

Midbrain pathways of audiogenic seizures in [formula omitted] mice

The effects on audiogenic seizures of bilateral electrolytic lesions at levels of the inferior colliculus (IC), superior colliculus (SC), or medial geniculate body were determined for inbred DBA 2 mice. Of 88 control mice (surgical and nonsurgical), 82% displayed the full seizure syndrome when exposed to intense sound: wildrunning attacks progressed to clonic convulsions and then tonic convulsions. All remaining control animals displayed at least wild-running attacks. In 27 of 49 mice with IC-level lesions, either no seizure activity was observed or the syndrome terminated at the wild-running stage. In these mice, lesions consistently damaged the central IC nucleus (ICC) and sometimes adjacent midbrain tegmentum. In the 12 IC-lesion mice that displayed the full seizure syndrome, IC damage was generally lateral, primarily involving the external IC nucleus (ICX). In SC-lesion mice, absence of wild-running was observed in only 3 of 23 mice, but termination of seizures at wild-running or clonic stages was often seen (14 of 23 mice). Attenuation of seizure activity was correlated with damage to the deep SC and tegmentum, including the central gray. Little or no effect on audiogenic seizures was found with lesions of the dorsal SC or medial geniculate body. Analysis of the time course of components of the seizure syndrome revealed that IC-lesion mice attaining only the wild-running stage had increased latencies to onset of this behavior. In SC-lesion mice, time to onset of wild-running did not differ significantly from controls. Progression from wild-running attacks to onset of clonic convulsions was slowed by lesions at both IC and SC levels. The data indicate that the primary pathway of audiogenic seizure activity includes the ICC, deep SC, and adjacent tegmentum. Wild-running attacks appear to be mediated at the IC level, whereas progression to clonic and tonic convulsions may require more rostral levels.