Comparison of Commonly Carried Liquids Against Commercial Ultrasound Gel for Use in the Backcountry Setting.

INTRODUCTION: Point-of-care ultrasound (POCUS) is utilized in austere environments because it is lightweight, durable, battery powered, and portable. In austere settings, weight and space constraints are limitations to carrying dedicated ultrasound gel. Few studies have assessed commonly carried liquids as gel alternatives. The study objective was to assess the suitability of common food and personal care products as ultrasound coupling agents compared with that of commercial gel. METHODS: A noninferiority study compared 9 products to commercial gel. Each substance was independently tested on 2 subjects by 2 sonographers covering 8 standardized ultrasound windows. Clips were recorded, blinded, and independently graded by 2 ultrasound fellowship-trained physicians on the ability to make clinical decisions and technical details, including contrast, resolution, and artifact. A 20% noninferiority margin was set, which correlates to levels considered to be of reliably sufficient quality by American College of Emergency Physicians' guidelines. The substances included water, soap, shampoo, olive oil, energy gel, maple syrup, hand sanitizer, sunscreen, and lotion. RESULTS: A total of 300 of 318 (94%) clips met the primary endpoint of adequacy to make a clinical decision. All media, except sunscreen, were noninferior to commercial gel in the ability to make a clinical decision (α=0.05). In terms of secondary outcomes, resolution, artifact, and contrast, all substances were noninferior to commercial gel (α=0.05). The sonographers concluded that all gel alternatives' usability performed similarly to commercial gel, with the exception of energy gel. CONCLUSIONS: Of the 9 substances tested, 8 were noninferior to commercial gels for clinical decisions. Our study indicates that several POCUS gel substitutes are serviceable to produce clinically adequate images.

Cognitive-behavioral therapy increases prefrontal cortex gray matter in patients with chronic pain.

UNLABELLED: Several studies have reported reduced cerebral gray matter (GM) volume or density in chronic pain conditions, but there is limited research on the plasticity of the human cortex in response to psychological interventions. We investigated GM changes after cognitive-behavioral therapy (CBT) in patients with chronic pain. We used voxel-based morphometry to compare anatomic magnetic resonance imaging scans of 13 patients with mixed chronic pain types before and after an 11-week CBT treatment and to 13 healthy control participants. CBT led to significant improvements in clinical measures. Patients did not differ from healthy controls in GM anywhere in the brain. After treatment, patients had increased GM in the bilateral dorsolateral prefrontal, posterior parietal, subgenual anterior cingulate/orbitofrontal, and sensorimotor cortices, as well as hippocampus, and reduced GM in supplementary motor area. In most of these areas showing GM increases, GM became significantly higher than in controls. Decreased pain catastrophizing was associated with increased GM in the left dorsolateral prefrontal and ventrolateral prefrontal cortices, right posterior parietal cortex, somatosensory cortex, and pregenual anterior cingulate cortex. Although future studies with additional control groups will be needed to determine the specific roles of CBT on GM and brain function, we propose that increased GM in the prefrontal and posterior parietal cortices reflects greater top-down control over pain and cognitive reappraisal of pain, and that changes in somatosensory cortices reflect alterations in the perception of noxious signals. PERSPECTIVE: An 11-week CBT intervention for coping with chronic pain resulted in increased GM volume in prefrontal and somatosensory brain regions, as well as increased dorsolateral prefrontal volume associated with reduced pain catastrophizing. These results add to mounting evidence that CBT can be a valuable treatment option for chronic pain.

Predictive relationships between chronic pain and negative emotions: a 4-month daily process study using Therapeutic Interactive Voice Response (TIVR).

This article examines temporal relationships between negative emotions and pain in a cohort of 33 patients with chronic musculoskeletal pain enrolled in a telephone-based relapse prevention program (Therapeutic Interactive Voice Response [TIVR]), after 11 weeks of group cognitive behavioral therapy (CBT). Patients were asked to make daily reports to the TIVR system for 4 months after CBT. Patients' daily reports were analyzed with path analysis to examine temporal relationships between 3 emotion variables (anger, sadness, and stress) and 2 pain variables (pain and pain control). As expected, same-day correlations were significant between emotion variables and both pain and pain control. The lagged associations revealed unidirectional relationships between pain and next-day emotions: increased pain predicted higher reports of sadness the following day (P < .05). Conversely, increased pain control predicted decreased sadness and anger the following day (P < .05). Unlike some previous studies, this study did not reveal that an increase of negative emotions predicted increased next-day pain. We speculate that CBT treatment followed by the relapse prevention program teaches patients how to modulate negative emotions such that they no longer have a negative impact on next-day pain perception. The clinical implications of our findings are discussed.

Early history of IBRO: the birth of organized neuroscience.

To celebrate the thirtieth anniversary of the founding of the International Brain Research Organization (IBRO), a symposium was organized for the III Congress of the World Federation of Neuroscientists in Montreal to present, on 7 August 1991, the recollections of some of the early participants in IBRO's history and to place it in the context of other significant world organizations. Edited and slightly condensed transcripts of the talks together with the discussions are presented. L. Marshall reviewed the antecedent conferences that led to the Moscow Colloquium in 1958 and the subsequent formation of IBRO with UNESCO support. The ambience of that period for scientific organization on an international level was discussed by W. A. Rosenblith who emphasized how IBRO goals fitted into the rising interest in brain and behavior research. The scientific careers of six past executive secretaries were briefly reviewed by P. Gloor, with special tribute to the first, Herbert Jasper. One of IBRO's major achievements, the world survey of resources and needs in brain research, was described first-hand by G. Krauthamer. To discuss IBRO's image, C. Blakemore invoked the travails of reorganization and recovery from a period of inactivity. Finally, placing IBRO in a national and international context, S. Cozzens presented the perspective of the historian of sociology on an upbeat note.

Putative cholinergic neurons of the pedunculopontine tegmental nucleus projecting to the superior colliculus consist of sensory responsive and unresponsive populations which are functionally distinct from other mesopontine neurons.

We examined the sensory properties of putative cholinergic neurons of the pedunculopontine tegmental nucleus projecting to the superior colliculus. Projection neurons were identified by antidromic activation from the contralateral posterior superior colliculus; stimulation of the anterior half was essentially ineffective. Identified neurons fell into two groups, one with a somatosensory input (39%) and one without a sensory input. Somatosensory responsive projection neurons were low threshold and rapidly adapting. Receptive fields were contralateral (94%) and predominantly orofacial (57%). Sensory responsive and unresponsive projection neurons were intermingled within the pedunculopontine tegmental nucleus as identified histologically by reduced nicotinamide adenine dinucleotide phosphate diaphorase or acetylcholinesterase. The properties of neurons outside the nucleus differed significantly. They could not be activated antidromically from the superior colliculus; many had ipsi- or bilateral receptive fields (75%) and wide dynamic range or nociceptive response patterns (52%). The presence of two functionally distinct groups of projection neurons implies a dual or more complex modulation of tectal neurons by the pedunculopontine tegmental nucleus. The pedunculopontine tegmental nucleus has been implicated in a multiplicity of behaviors and, in particular, in rapid eye movement sleep and alerting or arousal functions. By virtue of its many connections with the basal ganglia, limbic system and reticular structures, the projection to the superior colliculus of two distinct groups may provide an important differentiating element of the tectal organization of orienting and spatial cognitive behavior.

Somatosensory input and thalamic projection of pedunculopontine tegmental neurons.

The cholinergic pedunculopontine tegmental area of the anesthetized rat was explored for single units responsive to somatosensory stimulation. Units projecting to the intralaminar thalamus were identified by antidromic stimulation. Approximately one half of the somatosensory units consisted of low threshold units responsive to light tapping and stroking; the others were high threshold mechanoreceptive units. Most receptive fields were trigeminal and contralateral. These results suggest that somatosensory information is an important element in a subcortical system linking this area with the basal ganglia, superior colliculus and thalamus.

Effect of superior colliculus lesions on sensory unit responses in the intralaminar thalamus of the rat.

The effects of kainic acid lesions of the intermediate and deep layers of the superior colliculus on the sensory input to the intralaminar thalamus of the rat were determined. Ipsiversive circling and contralateral sensory neglect were consistently seen after lesion placement. Two to 7 days later, the intralaminar thalamus was systematically explored for extracellular mechanoreceptive unit responses to high threshold and low threshold stimuli. On the side ipsilateral to the lesion the number of responsive units was reduced by 51%. The loss was particularly marked for nociceptive units (80%), and low threshold and complex units with orofacial receptive fields (73%). This effect may involve a partial deafferentation of the intralaminar thalamus as well as altered excitatory thresholds of thalamic neurons. It is suggested that the functionally distinct direct tectothalamic projection as well as the indirect tecto-reticulo-thalamic pathway are implicated.

Sensory responses of intralaminar thalamic neurons activated by the superior colliculus.

The intralaminar thalamus of anesthetized rats was explored for neurons activated by stimulation of the superior colliculus and responsive to sensory inputs. Neurons activated by stimulation of the intermediate and deep collicular layers were distributed throughout the intralaminar thalamus. Approximately one half of them responded to tectal as well as sensory inputs. The majority were nociceptive or had a more complex response pattern including responses to auditory stimulation. A small population of low threshold units had contralateral orofacial receptive fields and responded to light taps; these units were preferentially localized anteriorly in the central lateral and paracentral nuclei. Neurons responsive to tectal and sensory stimulation were randomly intermingled with other neurons which had no detectable sensory input. The results indicate that ascending projection neurons of the intermediate and deep layers of the superior colliculus provide an input to functionally diverse subpopulations of intralaminar thalamic neurons. In view of its projections to motor cortex and basal ganglia, the intralaminar thalamus appears directly implicated in basal ganglia and superior colliculus related mechanisms of attention, arousal and postural orienting.

Somatosensory neurons projecting from the superior colliculus to the intralaminar thalamus in the rat.

Neurons of the rat superior colliculus projecting to the intralaminar thalamus were tested for their responses to somatosensory stimulation. They were identified by antidromic stimulation of the parafascicular nucleus and central lateral nucleus. To establish the existence of descending as well as ascending axon collaterals antidromic stimulation was applied to the upper cervical spinal cord in some cases. Somatosensory receptive fields were delineated and their laminar location in the superior colliculus was noted. Units were distributed throughout the intermediate and deep tectal layers, none were located in the superficial layers. Units with somatosensory receptive fields could be classified as low threshold, high threshold, wide dynamic range or complex. The majority of the peripherally responsive units (52%) were low threshold somatosensory units with contralateral receptive fields. All units were distributed throughout the intermediate and deep layers. Their distribution reflected the typical somatotopic organization of the superior colliculus. These results indicate that the intralaminar thalamus receives some sensory information by way of the tectum. In turn, the basal ganglia may gain direct access to this information by way of the thalamoneostriatal projection.

Vibrissa-responsive neurons of the superior colliculus that project to the intralaminar thalamus of the rat.

Responses to deflection of vibrissae were studied in neurons of the superior colliculus projecting to the intralaminar thalamus. Forty-two percent were activated by deflection of several vibrissae. Some units showed habituation and directional sensitivity but no other feature extraction was noted. All responsive units were located in the intermediate and deep layers in a roughly somatotopic distribution and intermingled with other projecting and non-projecting units.

Superior collicular projection to intralaminar thalamus in rat.

The superior collicular (SC) cells which project to the intralaminar thalamus (IT; nuclei centralis lateralis, CL; paracentralis, PC; parafascicularis, Pf) in the rat were identified by means of retrograde transport of wheatgerm agglutinin conjugated horseradish peroxidase (WGA-HRP). SC-IT cells were located throughout the mediolateral and rostrocaudal extents of the tectum ipsilateral to the thalamic injection. In this SC, they had a primarily bilaminar distribution in the lower one-half of the stratum griseum intermediale (SGI) and upper portion of the stratum griseum profundum (SGP). In these laminae, SC-IT cells were arranged in clusters or patches similar to those which have been described for many inputs to the deep SC laminae. A small number of SC-IT cells were also observed in the deep laminae of the tectum contralateral to the thalamic injection. Double labelling experiments using True Blue (TB) and Diamidino Yellow (DY) demonstrated that less than 1% of the contralaterally projecting SC-IT cells also innervated ipsilateral IT. Anterograde tracing with [3H]leucine demonstrated further that SC projected heavily to CL, PC and Pf. This projection also extended into the medial portion of the posterior thalamus (PO).

Organization of the intercollicular pathway in rat.

The intercollicular pathway of the rat was studied using autoradiographic (ARG) and horseradish peroxidase (HRP) tracing techniques. The HRP experiments demonstrated that the cells of origin of the intertectal pathway were located primarily in the rostral stratum griseum intermediale ( SGI ), stratum album intermedium (SAI) and stratum griseum profundum (SGP). Intertectal neurons were in most cases multipolar and had average somal diameters which ranged between 8 and 33 micron. Only a small number of superficial layer neurons contributed axons to the intercollicular pathway. ARG tracing showed that the intertectal pathway terminated in the deep layers of the rostral one half of the colliculus. The primary terminal zone was SGP. In addition, labeled axons left this region and coursed dorsally to terminate in a series of patches in the lower SGI and upper SAI. A small number of labeled fibers also reached the stratum opticum (SO) and lower stratum griseum superficiale (SGS).

A wide field electron microscopic analysis of the fiber constituents of the major splanchnic nerve in cat.

The fiber composition of the left major splanchnic nerve was studied in cats by electron microscopy. Comparisons were made between normal and partially degenerated nerve specimens following ventral rhizotomy (T3-L1), or spinal nerve division (T3-L1). Normal, major splanchnic nerves contained 2,500-4,000 myelinated and 10,000-15,000 unmyelinated fibers. Preganglionic fibers included approximately 90% of the finely myelinated (1-7 micrometers) and over 50% of the unmyelinated fibers. Removal of the sensory and preganglionic components by spinal nerve division revealed a third postganglionic fiber category. This included 13-38 small myelinated (1-5 micrometers) and 1,645-7,619 unmyelinated fibers. Finally, a comparison of normal and partially degenerated nerve specimens of both groups (ventral rhizotomy and spinal nerve cut) indicated that splanchnic afferents are made up of virtually all of the 120-350 large myelinated (8-14 micrometers) and 10% of the small myelinated (1-7 micrometers) fibers. A preliminary estimate indicated that about 10-20% of the unmyelinated fibers were sensory. The implications of these findings are discussed.

Paravertebral origin of postganglionic sympathetic fibers in the major splanchnic and distal coeliac nerves as demonstrated by horseradish peroxidase (HRP) retrograde transport method.

A significant number of sympathetic neurons in the lower thoracic paravertebral ganglia (lateral chain ganglia) were retrogradely labeled when the central cut end of the ipsilateral major splanchnic nerve was exposed to horseradish peroxidase (HRP) in the cat. HRP-labeled perikarya were found in all ganglia of that region of the chain from which the splanchnic nerve has its origin but they are most numerous in the last thoracic paravertebral ganglion, that adjacent to the T13 segment of the cord. The number of HRP-positive cell diminished rapidly in more rostral ganglia. Labeled cell bodies of postganglionic splanchnic neurons in the paravertebral ganglia were fusiform to oval in shape with cell diameters averaging between 25 to 45 micrometer. These results demonstrate that the splanchnic nerve contains, in addition to visceral afferents and preganglionic sympathetic constituents, many postganglionic fibers with cell bodies in the paravertebral ganglia. These splanchnic postganglionic axons pass through the coeliac ganglion and continue into distal coeliac nerves.

The organization of visceral sensory neurons in thoracic dorsal root ganglia (DRG) of the cat studied by horseradish peroxidase (HRP) reaction using the cryostat.

The organization of visceral sensory neurons in thoracic dorsal root ganglia (DRG) was studied by retrograde transport of horseradish peroxidase (HRP) from the central cut end of the left major splanchnic nerve of the cat. The majority of HRP-labeled cells were concentrated between T5 and T11. Within a DRG, labeled splanchnic neurons were found in all sectors. There was no consistent pattern of localization within the ganglion although clustering of visceral cell bodies was apparent. It may be that each clustered group of cells innervates individual viscera or reflects a degree of functional segregation.

Behavioral alterations and loss of caudate modulation in the centrum medianum--parafascicular complex of the cat following electrolytic lesions of the substantia nigra.

Extracellular activity in the centrum medianum--parafascicular complex was examined following electrolytic lesions of the substantia nigra in the cat. Three major changes were observed in the activity of these polysensory medial thalamic neurons: (1) normally quiescent in the intact animal, about 70% of the neurons now displayed spontaneous activity; (2) many of these spontaneously active neurons no longer responded to caudate stimulation and the responses to sensory stimulation were not changed; and (3) while caudate stimulation alone did inhibit some neurons, such stimulation in a conditioning test procedure often failed to inhibit the test response to limb stimulation which 'broke through' the inhibitory period. All of these changes were correlated with the extent of damage to the ipsilateral substantia nigra. Additionally, a noticeable change was observed in the behavior of the lesioned animals; intense circling, contralateral to the side of the lesion, persisted for several days following surgery. Other symptoms were arrest reactions, abnormal rhythmic pawing and sluggishness of movement. The results indicate that the substantia nigra is an important element in funneling caudatofugal activity to the centromedian--parafascicular complex where it interacts with, and modulates incoming sensory activity. The loss of this modulation and the removal of a tonic background inhibition, indicated by the increased proportion of spontaneously active neurons, may be important factors in producing the observed behavioral abnormalities.

Intracellular responses in the centrum medianum-parafascicular complex of the cat following medial and lateral caudate, substantia nigra and peripheral stimulation.

Caudate, nigral and somatosensory stimulation generates brief EPSPs followed by prolonged IPSPs in thalamic neurons of the centromedian-parafascicular complex. A 300 msec long hyperpolarization and inhibition of neuronal excitability represents the predominant effect by virtue of its duration, intensity and constancy. The brief excitatory response which precedes the inhibition is more variable, depending largely upon the site of basal ganglia stimulation. EPSPs tend to remain subthreshold for lateral caudate stimulation whereas medial caudate, medial nigral and somatosensory stimulation usually generates an action potential prior to the inhibitory phase. Double shock stimulation of basal ganglia and limbs at variable intervals demonstrates the predominance of powerful inhibitory interactions between striatonigral and sensory inputs. The existence of these interactions indicates the importance of temporal factors in determining the momentary response of medial thalamic neurons.

Segmental organization of sympathetic preganglionic neurons of the splanchnic nerve as revealed by retrograde transport of horseradish peroxidase.

Spinal nerves were transected at selected thoracic levels on the left side and the central cut end of the left major splanchnic nerve was exposed to horseradish peroxidase (HRP) in order to study the preganglionic sympathetic organization in the spinal cord of the cat. In three animals, a total of 4235 HRP labeled neurons were observed (uncorrected counts) in five regions: intermediolateral nucleus (IML) (82.8%), lateral funiculus (LF) (14.7%), intercalatus nucleus (IC) (2.1%), central autonomic (CA) (0.3%) and the anterior horn (AH) (0.1%). The neuronal distribution indicates that sympathetic preganglionic neurons in the thoracic spinal cord are segmentally organized.

The afferent projections to the centrum medianum of the cat as demonstrated by retrograde transport of horseradish peroxidase.

The afferent projections of nucleus centrum medianum (CM) of the thalamus were studied, in the cat, by means of retrograde transport of electrophoretically ejected horseradish peroxidase. Several variations of method--survival time, fixatives, substrates, etc.--were tried to improve the amount of visible reaction product. Labeled neurons were localized primarily in two categories of nuclei in the brain. The first consisted of structures making up or closely related to the basal ganglia: the entopeduncular nucleus, the pars reticulata of the substantia nigra, and motor cortex. The second category was made up of nuclei closely related to postural and orienting functions: the deep layers of the superior colliculus ipsilaterally, and the medial and lateral vestibular nuclei bilaterally. Other nuclei containing retrogradely labeled neurons were the periaqueductal gray and locus coeruleus. Brain stem reticular projections were sparse and widely scattered. These results identify CM as an important element in the loop system linking medial thalamus and neostriatrum; the probable attention and orientation related functions of this system are discussed.