Somatic Representation Research Articles

Relational perspectives on the body

Part 1 Relational Constructions of the Body: The Clinical Body and the Reflexive Mind Psychic Envelopes and Sonorous Baths - Siting the Body in Relational Theory and Clinical Practice Polyglot Bodies -Thinking Through the Relational. Part 2 Linking Mind and Body: The Embodiment of Desire - Relinking the Bodymind Within the Analytic Dyad The Body-Mind - Psychopathology of Its Ownership. Part 3 The Material Body in the Relational Matrix: Cancer as a Factitious Disorder (Munchausen Syndrome) Related to Body Self-Image and Object Relations in a Borderline Patient Dissociation and Physical Difference - the Case of the Transformed Short Person Breast Cancer in the Analyst. Part 4 The Place of Bodily Experience in the Psychoanalytic Process: Listening to the Body - Somatic Representations of Dissociated Memory Mama, Why Don't Your Feet Touch the Ground? - Staying With the Body and the Healing Moment in Psychoanlaysis Re-Membering the Body - a Psychoanalytic Study of Presence and Absence of the Lived Body Psychic Elaboration of Musculoskeletal Back Pain - Ellen's Story.

Ministrokes in rat barrel cortex.

Many stroke models in rats are based on occlusion of the middle cerebral artery, which supplies a significant portion of multifunctional cortical and deep structures in the cerebral hemisphere. The purpose of this study was to develop a model for direct observation in real time of blood flow in and around focal ischemic regions of the cortex of known function. Cranial windows were placed over the parietal cortex of adult Wistar and Sprague-Dawley rats anesthetized with ketamine and xylazine. Whisker barrel cortex responding to stimulation of the contralateral whiskers was identified by an intrinsic optical signal. Transits of vital dyes were recorded by videomicroscopy before and after ligation of three to six branches and major collaterals of the middle cerebral artery through the dura. Infarcts were demonstrated with triphenyl-tetrazolium chloride staining; their relation to barrel cortex was determined by Nissl and cytochrome oxidase histology. Reduced blood flow in small ischemic regions was outlined by patient blue violet in the surrounding nonischemic area; arteriovenous latencies increased more than four times in ischemic cortex. Infarcts,typically 3 mm or less, were seen at 24 hours in 8 of 16 Wistar and 9 of 9 Sprague-Dawley rats. The ministrokes were confirmed by histology to be in the somatosensory cortex. This model of local ischemia, produced deliberately in the functionally defined barrel cortex in rats, leads to ministrokes. Changes can be followed by videomicroscopy as they develop, and processes of recovery can potentially be monitored. Infarcts are confirmed by histology for their location and extent in the somatic representation.

Individual variation and lateral asymmetry of the rat primary somatosensory cortex

We have evaluated the interindividual variability and lateral symmetry of a major cortical area by comparing the primary somatosensory cortex (S1) of adult rats. Our choice of the rat was dictated by the accuracy with which one can measure S1 and its component representations in the rodent brain; the importance of such measurements lies in understanding the rules that govern the allocation of cortical space and, ultimately, the consequences of differential allocation for behavior. With respect to interindividual differences, the major somatic representations in S1 are surprisingly variable in size. The area of the whiskerpad representation, for example, ranged from 3.72 to 6.84 mm2 in a sample of 53 rats; other components of S1 showed comparable differences among animals. With respect to lateral symmetry, the average area of each major representation was similar for the right and left hemispheres; thus, we found no consistent bias in the size of S1 or its elements in the sample as a whole. Within individual animals, however, the sizes of the major somatic representations were often quite different in the two hemispheres. The magnitude of the lateral differences averaged 7.9 +/- 0.8% (mean +/- SEM) for the whisker pad representation, 11.6 +/- 1.3% for the upper lip, 15.4 +/- 1.6% for the furry buccal pad, 13.9 +/- 1.4% for the lower jaw, and 13.3 +/- 1.2% for the forepaw. These results show that the amount of cortical space allocated to corresponding functions in individual rats--or in the two hemispheres of a particular rat--are often different. Such variations are likely to be reflected in somatosensory performance.

Functional significance of the mu rhythm of human cortex: an electrophysiologic study with subdural electrodes

The existence of the mu rhythm and its general anatomical and physiological relationships are well known. There are few data, however, regarding the details of its anatomical and physiological specificity. We implanted fronto-temporal subdural electrode grids in 9 patients with intractable epilepsy to facilitate their surgical management. A 7–11 Hz cortical mu rhythm was observed in 5–16 electrodes located over the sensorimotor cortex as mapped by electrical stimulation. The mu rhythm was blocked by contralateral face and arm movements, passive movements of contralateral arm, and by ipsilateral arm movements. There was correspondence between the body area movement of which blocked the mu at a given site and the body region that was affected by stimulation at the same site. Power spectral analysis showed an overall decrease in power in all frequency bands. This was less prominent in the 14–100 Hz band resulting in a relative increase in high frequency power in association with movement. We conclude that both the presence and blocking of mu rhythm are specific to the somatic representation of the cortex from which it is recorded. Its functional significance may be similar to other sensory rhythms like the occipital alpha rhythm.

Climbing fiber representation of the renal afferent nerve in the vermal cortex of the cat cerebellum

In order to understand how the cerebellum may participate in various autonomic functions, it is necessary to first determine the occurrence and distribution of the various visceral inputs in the cerebellar cortex and their relation to other cerebellar afferents. This study examines the organization of climbing fiber responses (complex spikes) of Purkinje cells elicited by electrical stimulation of the renal afferent nerve and their relationship to climbing fiber responses representing the body surface. Visceral and somatic afferent responses were mapped in the lateral vermal cortex of lobules V to VII in chloralose-anesthetized cats. Extracellular single-unit recordings were made from 628 Purkinje cells, of which 14% had climbing fiber responses induced by renal afferent nerve stimulation. Except for one Purkinje cell, the renal climbing fiber input converged with somatic induced climbing fiber input. Tactile stimulation also elicited 54% of cells, which were unresponsive to the renal afferent nerve stimulation. The occurrence and distribution of the climbing fiber responses elicited by renal afferent nerve stimulation varied between lobules V, VI, and VII for the proportion of responsive units, the onset latencies, and topological organization. More renal responsive units were encountered in lobules V (18%) and VII (17%) than in lobule VI (6%), the average latency of renal climbing fiber responses was significantly longer in lobule VII than in lobules V and VI, and the latencies were also different among various parasagittal planes in lobules V and VII. The proportional representation of various body areas for cells with renal and somatic convergent input was different than for cells with only somatic representation. Proportionally, the forelimb had the greatest representation in lobule V, split receptive fields were frequently represented in lobule VI, and the face was well represented in lobule VII. The results of this study, in conjunction with studies showing climbing fiber representation of the vagal and splanchnic nerves, further substantiate role of the cerebellum in autonomic functions.

Rudimentary determinants of attitudes: II. Arm flexion and extension have differential effects on attitudes.

In the pain-flexor reflex, arm extension is temporally coupled with the onset of the unconditioned aversive stimulus, whereas flexion is associated with its offset; when retrieving desirable stimuli, arm flexion is more closely coupled temporally to the acquisition or consumption of the desired stimuli than arm extension. It was posited that these contingencies foster an association between arm flexion, in contrast to extension, and approach motivational orientations. Six experiments were conducted to examine this hypothesis. Ideographs presented during arm flexion were subsequently ranked more positively than ideographs presented during arm extension, but only when the Ss' task was to evaluate the ideographs when they were presented initially. Arm flexion and extension were also each found to have discernible attitudinal effects. These results suggest a possible role for nondeclarative memory in attitude formation. In general, we should not be terribly surprised that it is so difficult to change attitudes and preferences by cognitive methods. These methods do not reach the motor system and other somatic representational systems of the organism. They only deal with one representational system—the one that exists in the form of associative structures, images, and other subjective states. Since attitudes contain such a substantial affective component, they are likely to have multiple representations—and somatic representations are probably among the more significant ones. (Zajonc & Markus, 1982, p. 130) The term attitude comes from the Latin words apto (aptitude or fitness) and acto (postures of the body), both of which have their origin in the Sanskrit root ag, meaning to do or to act (Bull, 1951). The connection between attitude and action carried into the 18th century, when attitude referred to a physi

Growth of the rat somatic sensory cortex and its constituent parts during postnatal development

We have compared the size and arrangement of the primary somatic sensory cortex (SI) and its constituent parts in juvenile (1 week old) and mature (10-12 weeks old) rats using succinic dehydrogenase histochemistry and digital image analysis. Our goal was to determine whether some regions of the maturing cortex grow more than others. To this end, we examined (1) the growth of barrels and the surrounding (interbarrel) cortex, (2) the growth of the major somatic representations within SI, and (3) the overall growth of SI compared to the neocortex as a whole. With respect to the first of these issues, SI barrels and barrel-like structures grow more than the intervening cortex. The growth of these elements varies according to region: barrels in the head representation more than double in size, whereas the barrel-like structures in the paw representations increase by only about half this amount. The growth of the major somatic representations within SI is also heterogeneous, the representation of the head enlarging to a greater extent than the representations of the paws. Thus, the ratio of the total area of head representation to the combined paw representation is 15% greater in adults than in juveniles. Finally, the primary somatic sensory cortex grows to a somewhat greater extent than the neocortex as a whole. These observations demonstrate that postnatal cortical growth is not uniform; it varies among cortical barrels and the immediately surrounding (interbarrel) cortex, among the representations of different body parts, and between SI and the rest of the neocortex. As an explanation of this differential growth, we suggest that the neuropil of metabolically (and/or electrically) more active cortical regions grows to a greater extent during maturation than that of less active regions.

Vagal and somatic representation by the climbing fiber system in lobule V of the cat cerebellum

The organization of the climbing fiber representation of the vagal afferents and the body surface in the vermal and intermediate zones of lobule V was examined in cats anesthetized with α-chloralose. Extracellular single-unit recordings were made from 428 Purkinje cells. Electrical stimulation of the vagus nerve elicited climbing fiber responses in 40% of the cells, most of which had convergent somatic input. Activation of A σ vagal afferent fibers accounted for 65% of the responses, whereas the A β fibers involved 27% and the C fibers included 8% of the responses. The responses driven by vagal nerve stimulation were encountered throughout the lobule, although a significantly increased representation of the vagus was identified for 3 longitudinal 0.5 mm wide sectors (two in the vermis and one in the intermediate region). In the vermis, the fine-grain organization consisted of a mixture of representations of the various parts of the body surface with and without convergent vagal input, although there was little convergence in the medial vermis where many of the responses were elicited by only vagal nerve stimulation. In the intermediate cortex, most of the vagal climbing fiber representation was convergent with forelimb input. These results suggest that vagal input into the cerebellum could have important modulatory effects on the cerebellar somatosensory input.

Neuromagnetic somatosensory homunculus: A non-invasive approach in humans

The somatosensory homunculus has been identified during stimulation of median (at wrist and elbow), femoral, tibial and pudendal nerves of the left hemibody via the neuromagnetic imaging technique. The somatic representations of different body districts have been localized in the somatosensory cortex, by means of an equivalent dipole localization algorhythm. Dipole locations agree with the well-known somatotopic organization obtained with invasive techniques. The proposed method is, therefore, an important investigating tool for studies on normal and diseased subjects.

Connections of the ventral granular frontal cortex of macaques with perisylvian premotor and somatosensory areas: anatomical evidence for somatic representation in primate frontal association cortex.

In macaque monkeys with injections of tritiated amino acids or horseradish peroxidase in the ventrolateral granular frontal cortex, we observed extensive anterograde and retrograde labeling of the premotor and somatosensory cortex in and around the lateral sulcus. Comparable labeling was not present with large and small control injections of the dorsal granular cortex. Cytoarchitectonic evaluation of the perisylvian cortex in the three cases examined in detail indicated that labeled areas included the ventral premotor cortex (area 6V); the precentral opercular and orbitofrontal opercular areas (PrCO and OFO); the second somatosensory area (S-II); the opercular cortex immediately anterior to S-II, possibly corresponding to area 2 of the S-I complex; and the central part of the insular cortex, including portions of the granular and dysgranular insular fields (Ig, Idg). Labeling was particularly dense and extensive in areas 6V, S-II, and OFO. Lighter labeling was also present in the rostral inferior parietal lobule (areas 7b and POa). The distribution of label within perisylvian areas was not uniform: certain parts were heavily labeled, while other parts were lightly labeled or unlabeled. Comparison of label distribution with published accounts of the somatotopy of these areas indicates that forelimb and orofacial representations were selectively labeled. Further, our results, taken together with other recent anatomical findings (e.g., Matelli et al.: Journal of Comparative Neurology 251:281-298, 1987; Barbas and Pandya: Journal of Comparative Neurology 256:211-228, 1987) suggest strongly that there is a network of interconnected forelimb and orofacial representations in macaque cortex, involving the ventral granular frontal cortex, area 6V, OFO, opercular area 2, S-II, the central insula, and area 7b. Each injection of frontal cortex which labeled the perisylvian somatic cortex involved the cortex of the ventral rim of the principal sulcus (PSvr). The cortex surrounding the PSvr does not stand out as a distinct area in Nissl-stained material. However, examination of myelin-stained sections prepared from uninjected hemispheres with the Gallyas technique revealed the existence of a distinct zone centered on the PSvr. This myeloarchitectonic area, which we term area 46vr, is more heavily myelinated than the ventral bank and fundus of the principal sulcus (area 46v) but is less heavily myelinated than the ventral (inferior) convexity (area 12). Involvement of area 46vr in our injections was probably responsible for the strong labeling observed in perisylvian somatic areas.(ABSTRACT TRUNCATED AT 400 WORDS)

Edwin Barkley Boldrey, M.D., 1906-1988.

E DWIN Barkley Boldrey was born on July 17, 1906, in Morgantown, Indiana, the first son of a Methodist minister, Edwin Howe Boldrey, and Florence Barkley Boldrey (whose parents came from Scotland). He received an A.B. degree in English composition from DePauw University in 1927. He then gained an M.A. degree in anatomy and psychology from the University of Indiana in 1930, followed by the M.D. degree in 1932, with election to the Alpha Omega Alpha medical honor society. He came under the tutelage of a local neurologist, Dr. LaRue Carter, who inspired him to begin a career in the neurological sciences. He martied Helen Burns Eastland in 1932 and began postdoctoral training as an intern at the Montreal General Hospital, continuing there with general surgical training until 1935, when he was accepted for neurosurgical residency training at the Montreal Neurological Institute just as this institution came under the guidance of Drs. William V. Cone and Wilder Penfield. During this 5 years of intense work in the disciplines of neurology, neurophysiology, neuropathology, and neurosurgery, Dr. Boldrey developed the careful and meticulous surgical skills and the inquisitive but critical thoughtfulness coupled with absolute integrity that served him so well throughout his life. He received an M.Sc. degree from McGill University in 1936, with a thesis describing research work on the somatic motor and sensory representation in the human cerebral cortex. In April, 1940, Dr. Howard C. Naffziger persuaded him to join the faculty of the University of California Medical School in San Francisco, where he enjoyed an illustrious professional career for 48 years. He progressed through the academic ranks, serving as Chairman of the Department of Neurological Surgery from 1951 to 1956; he was appointed Professor in 1960 and Emeritus Professor in 1974. In 1983, the Edwin B. Boldrey Lectureship in Neurological Surgery was established in his honor at the University of California, San Francisco. Edwin Barkley Boldrey, M.D., 1906-1988

Organization of adult motor cortex representation patterns following neonatal forelimb nerve injury in rats

Somatotopic representation patterns in the motor cortex (MI) of rats that had a unilateral forelimb amputation on the first postnatal day were examined after 2-4 months of survival. Intracortical electrical stimulation and recording techniques were used to map the somatic representation in MI and in the somatic sensory cortex (SI). In normal rats, vibrissa, forelimb, and hindlimb areas comprise the bulk of the MI representation. Stimulation within the forelimb area elicits elbow, wrist, or digit movements at the lowest current intensities. The proximal limb representation appears to be contained within the distal forelimb area, since shoulder movements are nearly always evoked by stimulating at higher current intensities at some distal forelimb sites. In agreement with previous studies, the distal forelimb representation overlapped the adjacent part of the granular SI cortex. Following removal of the forelimb at birth, 3 novel features of MI organization were observed. First, the areas from which stimulation evoked movements of the vibrissa or the shoulder musculature were larger than normal. Stimulation thresholds were lower than those required for comparable movements in normal rats throughout these areas, suggesting that nerve section had not simply unmasked a high-threshold representation. Second, vibrissa movements were more commonly paired with movements of the proximal forelimb muscles at the same site. Third, stimulation in the adjacent granular SI cortex failed to evoke shoulder or trunk movements, although receptive-field mapping in this region showed that cells were responsive to cutaneous stimulation of the trunk and shoulder region. These results indicate that several organizational features develop differently in MI following perinatal nerve injury: certain remaining muscle groups have enlarged cortical representations, there is a strengthening of some normally weak connections from MI to the proximal musculature, and muscles are grouped in unusual combinations. These data demonstrate that the formation of MI representation patterns is strongly influenced by nerve injury during the perinatal period.

Microelectrode maps, myeloarchitecture, and cortical connections of three somatotopically organized representations of the body surface in the parietal cortex of squirrels.

Microelectrode mapping methods and anatomical procedures were combined in the same animals to reveal the cortical connections of three architectonically distinct representations of the body surface in the somatosensory cortex of grey squirrels. In individual experiments, microelectrode multiunit recordings were used to determine the somatotopic organization of regions of the cortex and to identify sites for injections of the anatomical tracer, wheat germ agglutinin conjugated to horseradish peroxidase. After the brains were perfused, the cortex was separated from the brainstem, flattened, and cut parallel to the flattened surface to facilitate comparisons of areal connection patterns, physiological data, and architectonic subdivisions. Recordings in the primary (S-I) and secondary (S-II) somatosensory fields confirmed earlier descriptions of the somatotopic organization of these fields (Sur et al.: J. Comp. Neurol. 179:425-450, '78; Nelson et al.: J. Comp. Neurol. 184:473-490, '79). In addition, recordings in the cortex caudal to S-I and ventral to S-II revealed a third representation of the body surface in parietal cortex, the parietal ventral area (PV). Neurons in PV were responsive to light tactile stimulation of skin and hairs. Multiple unit receptive fields of neurons in PV were larger than those for neurons in S-I but similar in size to those for neurons in S-II. PV represented the contralateral body surface in a somatotopic manner that can be roughly characterized as an inverted "homunculus" with the limbs directed medially, the trunk located ventrally, and the face congruent with the representations of the upper lip and nose in S-I. Neurons in some electrode penetrations in PV were also responsive to auditory clicks. Microlesions placed at physiologically determined borders allowed all three somatic representations to be related to myeloarchitectonically defined fields. S-I was architectonically distinct as a densely myelinated region. Within S-I, a lightly myelinated oval of the cortex between the representation of the hand and face, the "unresponsive zone" (Sur et al.: J. Comp. Neurol. 179:425-450, '78), was an easily recognized landmark. S-II and PV corresponded to less densely myelinated fields. Other subdivisions such as motor cortex, primary auditory cortex, and visual areas 17 and 18 were distinguished. Connections were revealed by placing injections within S-I, S-II, or PV.(ABSTRACT TRUNCATED AT 400 WORDS)

Ambiguities of aging: Japanese experience and perceptions of menopause.

The initial findings of this study indicate that menopause is regarded as a natural life-cycle transition in Japan in which the biological marker of cessation of menstruation is not considered to be of great importance. Symptom reporting among all respondents is generally low regardless of menopausal status, and symptoms such as shoulder stiffness and headaches, which are reported frequently, are not linked specifically to menopausal status (even though individual informants may perceive them to be so). Symptoms of hot flashes and sudden perspiration are higher among peri- and post-menopausal women, but their prevalence appears to be much lower than research findings from other areas to date. Reports by Japanese gynecologists emphasize that menopausal women are liable to present with numerous non-specific somatic complaints. This may well be an accurate representation of a clinical population, but the findings of this present study indicate that such a picture is by no means representative of the average middle-aged female population in Japan. While occupational differences do not contribute to variation in reported symptomatology (with the exception of lumbago and shoulder stiffness), there are nevertheless considerable differences in the subjective meaning of menopause, many of which can be accounted for by class and occupational differences. Presentation of these differences awaits a future publication, but there is one topic which is of concern to the majority of the respondents from each of the sub-samples. The present generation of women entering their 50's are the first where the majority must face later middle age in a nuclear family, along with their husbands, although both they and their husbands have been socialized for the more distant male/female relationships of an extended family. Japanese women cannot look forward, as they did in the past, to the power and comforts derived from running an extended family; on the contrary many can expect a late middle age of looking after bed-ridden parents or parents-in-law, and a lonely, isolated and often poverty-stricken old age (Steslicke 1984), since many pension programs are by no means adequate. Some of their fears about aging are expressed in their views on menopause, but these fears do not appear to be manifested at all prominently as either psychological or somatic representations. When asked to compare their lives with that of their own mothers, stories of incredible hardships from pre- and immediately post-war Japan are vividly portrayed.(ABSTRACT TRUNCATED AT 250 WORDS)

The silent brain infarct in carotid surgery.

The destructive potential of carotid artery disease is underestimated by the clinical classification that surveys only that part of the brain with clear somatic representation. Asymptomatic patients are found to have brain infarctions on CT scan for which there is no history or symptom. To assume "benign" behavior of a carotid lesion, a patient must be both asymptomatic and "asignomatic." Likewise, when the morbidity of carotid operations is reported, silent infarcts must somehow be taken into account. We investigated this "silent" disease in a prospective study of 100 carotid operations done on 91 patients over a 9-month period in our service. All patients had arch and four-vessel selective arteriography. Detailed neurologic examinations and CT scans were done before and after surgery. Of the 91 patients, 78 (86%) had a history of neurologic problems. Preoperative CT scans showed infarction in 21 patients, but only 57% of the infarctions correlated with symptoms and/or history. Among patients with a history of transient ischemic attack (TIA), 19% had an infarction seen on CT scan; however, among those patients who had lateralizing TIAs, the incidence of unsuspected infarction was higher (26%). Arteriography showed a lesion in all carotid systems supplying a symptomatic or infarcted hemisphere. Following 100 operations, four patients had neurologic abnormalities--two had transient hemianopsia and two had hemiparesis. CT scan showed a new infarct in all four patients as well as in eight other patients without neurologic findings; two of these silent postoperative infarctions were found in the hemisphere opposite the side of the operated carotid artery.(ABSTRACT TRUNCATED AT 250 WORDS)

The silent brain infarct in carotid surgery

The destructive potential of carotid artery disease is underestimated by the clinical classification that surveys only that part of the brain with clear somatic representation. Asymptomatic patients are found to have brain infarctions on CT scan for which there is no history or symptom. To assume “benign” behavior of a carotid lesion, a patient must be both asymptomatic and “asignomatic.” Likewise, when the morbidity of carotid operations is reported, silent infarcts must somehow be taken into account. We investigated this “silent” disease in a prospective study of 100 carotid operations done on 91 patients over a 9-month period in our service. All patients had arch and four-vessel selective arteriography. Detailed neurologic examinations and CT scans were done before and after surgery. Of the 91 patients, 78 (86%) had a history of neurologic problems. Preoperative CT scans showed infarction in 21 patients, but only 57% of the infarctions correlated with symptoms and/or history. Among patients with a history of transient ischemic attack (TIA), 19% had an infarction seen on CT scan; however, among those patients who had lateralizing TIAs, the incidence of unsuspected infarction was higher (26%). Arteriography showed a lesion in all carotid systems supplying a symptomatic or infarcted hemisphere. Following 100 operations, four patients had neurologic abnormalities—two had transient hemianopsia and two had hemiparesis. CT scan showed a new infarct in all four patients as well as in eight other patients without neurologic findings; two of these silent postoperative infarctions were found in the hemisphere opposite the side of the operated carotid artery. The clinical morbidity of this prospective series consisted of two TIAs (2%) and two strokes (2%). With CT evidence used as a criterion for infarction, the morbidity rate was 12%. CT scanning added to clinical studies of carotid disease and its surgical management shows that the morbidity of both is much greater than that inferred by traditional clinical assessment.

Topical organization of somatic projections in the fur seal cerebral cortex

To map somatic projections in the cerebral cortex of the fur sealCallorhinus ursinus multiple spike activity of cortical neurons evoked by tactile stimulation of different parts of the body surface was recorded in acute experiments. The region of somatic representation is bounded rostrally by the postcruciate and coronal sulci, caudally by the anterior suprasylvian sulcus, and dorsomedially by the ansate sulcus. The somatotopic map is oriented so that the projection of the head faces ventrolaterally, and that of the caudal part of the trunk faces dorsomedially; the projection region of the forelimb is buried in the coronal sulcus. The projection area of the head occupies the greatest area, and in it, the greatest area is occupied by the region of the superior labial vibrissae.

Central Nervous System Changes Related to the Reduction of Visual Input in a Naturally Blind Fish (Astyanax hubbsi)

Tectal anatomy and physiology of the blind cave characin, Astyanax hubbsi , have been compared with that of its sighted ancestor Astyanax mexicanus (the river fish) and with goldfish. Normal and experimental neuroanatomic methods have revealed that, with the exception of a greatly reduced retinotectal projection, connectivity and structure of cave fish tecta are similar to those described in sighted species. It appears that the rudimentary retinotectal input is nonfunctional, since no tectal evoked responses could be elicited with electrical or visual stimulation of the optic cyst, and all attempts to visually condition cave fish were unsuccessful. Attempts have also been made to record somatosensory, auditory and lateral line activity in the tecta of the blind and sighted fish. A sparse somatic representation was found in the deeper portion of the sighted fish tecta which contrasts with a dense, well-organized one in the cave fish. No tectal responses were found to auditory or lateral line stimuli. CNS plasticity is discussed in relation to studies of fish, amphibians, reptiles, birds and mammals, in which a reduction of sensory input by any one of a number of means has resulted in alterations of structure and function.

Electromyographic specificity during simple physical and attitudinal tasks: Location and topographical features of integrated EMG responses

Integrated electromyographic (IEMG) activity was recorded using surface mini-electrodes placed over the corrugator supercilii, zygomatic major, levator labii superioris, masseter, obicularis oris and superficial forearm flexors muscle regions while subjects imagined or performed simple physical or attitudinal tasks. In the physical tasks, subjects either imagined they lifted or actually lifted a 16 gram or 35 gram weight. In the attitudinal tasks, subjects adopted either an agreeable or disagreeable attitudinal set as they silently read neutral text or imagined reading an editorial. Each task was performed for 12 sec on five separate occasions, and tasks were ordered randomly across the experimental trials. Following each trial, subjects provided self-reports regarding the extent to which the task was stressful, arousing and vivid. Multivariate analyses of the topographical features of each IEMG response were performed to determine the effects of the tasks on changes in IEMG response waveforms, and univariate analyses were conducted to assess the features of the waveform that were altered by tasks. Results support the efficacy of electromyographic studies of covert affective processing given that subjects are generally quiescent, unobtrusively observed, unaware that somatic activity is being recorded and involved in the task. The implications of these data for the somatic representation of affect are discussed.

Subjective health assessments and the perceived outcome of minor surgery

A simple and standardised measure of perceived health status, the Nottingham Health Profile, was used to assess the effect on perceived health status of surgical intervention in a variety of non-acute medical disorders. Patients were assessed a few days before their operation and again two months later and were compared with a control group who had not undergone surgery. Results showed very little change in subjective health from before to after surgical intervention. The experimental group had similar perceived health scores to the control group on the pre- and post-tests. It is suggested that the period allowed to elapse after surgical intervention was too short, or that the level of problems experienced by patients prior to surgery was too low to show significant change. It is also possible that the particular presenting disorders were only one possible somatic representation of general feelings of minor ill-health in the group. The findings of this study point to the need to look at the differences between doctors and patients expectations of the outcome of surgery, the decision to seek care and the factors that govern wellbeing.