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Objective Assess practices supporting care transitions for infants and families in the neonatal intensive care unit (NICU) using a model of four key drivers: communication, teamwork, family integration, and standardization. Study design Single-day audit among NICUs in the Vermont Oxford Network Critical Transitions collaborative addressing policies and practices supporting the four key drivers during admission, discharge, shift-to-shift handoffs, within hospital transfers, and select changes in clinical status. Results Among 95 NICUs, the median hospital rate of audited policies in place addressing the four key drivers were 47% (inter-quartile range (IQR) 35–65%) for communication, 67% (IQR 33–83%) for teamwork, 50% (IQR 33–61%) for family integration, and 70% (IQR 56–85%) for standardization. Of the 2462 infants included, 1066 (43%) experienced ≥1 specified transition during the week prior to the audit. Conclusions We identified opportunities for improving NICU transitions in areas of communication, teamwork, family integration, and standardization.

Family involvement in newborn intensive care quality improvement dates back to the 1980s. In recent years, there has been an evolution of support for family partnerships at the bedside, transforming parents from being passively present to being active and engaged caregivers and team members. Through those same efforts, a transformational understanding of the power of the family perspective in system design and improvement has occurred. Even with the progression and deepening of this involvement, opportunities exist to learn from families and to improve the quality of neonatal care as a result of the unique family perspective.

OBJECTIVES: To determine if NICU teams participating in a multicenter quality improvement (QI) collaborative achieve increased compliance with the Centers for Disease Control and Prevention (CDC) core elements for antibiotic stewardship and demonstrate reductions in antibiotic use (AU) among newborns. METHODS: From January 2016 to December 2017, multidisciplinary teams from 146 NICUs participated in Choosing Antibiotics Wisely, an Internet-based national QI collaborative conducted by the Vermont Oxford Network consisting of interactive Web sessions, a series of 4 point-prevalence audits, and expert coaching designed to help teams test and implement the CDC core elements of antibiotic stewardship. The audits assessed unit-level adherence to the CDC core elements and collected patient-level data about AU. The AU rate was defined as the percentage of infants in the NICU receiving 1 or more antibiotics on the day of the audit. RESULTS: The percentage of NICUs implementing the CDC core elements increased in each of the 7 domains (leadership: 15.4%–68.8%; accountability: 54.5%–95%; drug expertise: 61.5%–85.1%; actions: 21.7%–72.3%; tracking: 14.7%–78%; reporting: 6.3%–17.7%; education: 32.9%–87.2%; P < .005 for all measures). The median AU rate decreased from 16.7% to 12.1% (P for trend < .0013), a 34% relative risk reduction. CONCLUSIONS: NICU teams participating in this QI collaborative increased adherence to the CDC core elements of antibiotic stewardship and achieved significant reductions in AU.

BACKGROUND: The Antimicrobial Use (AU) Option of the Centers for Disease Control and Prevention’s National Healthcare Safety Network (NHSN) is a surveillance resource that can provide actionable data for antibiotic stewardship programs. Such data are used to enable measurements of AU across hospitals and before, during, and after stewardship interventions. METHODS: We used monthly AU data and annual facility survey data submitted to the NHSN to describe hospitals and neonatal patient care locations reporting to the AU Option in 2017, examine frequencies of most commonly reported agents, and analyze variability in AU rates across hospitals and levels of care. We used results from these analyses in a collaborative project with Vermont Oxford Network to develop neonatal-specific Standardized Antimicrobial Administration Ratio (SAAR) agent categories and neonatal-specific NHSN Annual Hospital Survey questions. RESULTS: As of April 1, 2018, 351 US hospitals had submitted data to the AU Option from at least 1 neonatal unit. In 2017, ampicillin and gentamicin were the most frequently reported antimicrobial agents. On average, total rates of AU were highest in level III NICUs, followed by special care nurseries, level II-III NICUs, and well newborn nurseries. Seven antimicrobial categories for neonatal SAARs were created, and 6 annual hospital survey questions were developed. CONCLUSIONS: A small but growing percentage of US hospitals have submitted AU data from neonatal patient care locations to NHSN, enabling the use of AU data aggregated by NHSN as benchmarks for neonatal antimicrobial stewardship programs and further development of the SAAR summary measure for neonatal AU.

To assess progress of neonatal intensive care units (NICUs) participating in the Vermont Oxford Network iNICQ 2015: Alarm Safety Collaborative in achieving Joint Commission 2014 alarm safety goals with respect to oximeters, and to compare patient-level oxygen saturation (SpO2) and oximeter alarm data to local policies. Prospective multicenter audits in February and August 2015 assessed implementation of policies addressing Joint Commission 2014 Alarm Safety goals, and ascertained SpO2 targets, oximeter alarm settings and compliance with policy-specified SpO2 targets and alarms. Eighty-six NICUs completed both audits. Of 13 policies addressing mandated goals, median (interquartile range) 8 (5, 9) policies were implemented at audit 1 and 9 (6, 11) at audit 2 (P=0.004). At audit 1, 28 NICUs had implemented ⩾9 policies versus 47 at audit 2. For 794 infants 97% was less frequent than when high alarm was not set to policy (10.1% vs 21.5%, P=0.006). Participating NICUs showed significant progress between audits in their implementation of Joint Commission Alarm Safety goals for oximeter monitoring. Oximeter high alarm not set per local policy is associated with increased hyperoxemia in preterm infants. Recommendations to standardize oxygen saturation targets for infants at risk for oxygenation-related outcomes have not been widely adopted.

Background The prevalence of substance use, both prescribed and non-prescribed, is increasing in many areas of the world. Substance use by women of childbearing age contributes to increasing rates of neonatal abstinence syndrome (NAS). Neonatal opioid withdrawal syndrome (NOWS) is a newer term describing the subset of NAS related to opioid exposure. Non-pharmacological care is the first-line treatment for substance withdrawal in newborns. Despite the widespread use of non-pharmacological care to mitigate symptoms of NAS, there is not an established definition of, and standard for, non-pharmacological care practices in this population. Evaluation of safety and efficacy of non-pharmacological practices could provide clear guidance for clinical practice. Objectives To evaluate the safety and efficacy of non-pharmacological treatment of infants at risk for, or having symptoms consistent with, opioid withdrawal on the length of hospitalization and use of pharmacological treatment for symptom management. Comparison 1: in infants at risk for, or having early symptoms consistent with, opioid withdrawal, does non-pharmacological treatment reduce the length of hospitalization and use of pharmacological treatment? Comparison 2: in infants receiving pharmacological treatment for symptoms consistent with opioid withdrawal, does concurrent non-pharmacological treatment reduce duration of pharmacological treatment, maximum and cumulative doses of opioid medication, and length of hospitalization? Search methods We used the standard search strategy of Cochrane Neonatal to search CENTRAL (2019, Issue 10); Ovid MEDLINE; and CINAHL on 11 October 2019. We also searched clinical trials databases and the reference lists of retrieved articles for randomized controlled trials (RCTs), quasi-RCTs, and cluster trials. Selection criteria We included trials comparing single or bundled non-pharmacological interventions to no non-pharmacological treatment or different single or bundled non-pharmacological interventions. We assessed non-pharmacological interventions independently and in combination based on sufficient similarity in population, intervention, and comparison groups studied. We categorized non-pharmacological interventions as: modifying environmental stimulation, feeding practices, and support of the mother-infant dyad. We presented non-randomized studies identified in the search process narratively. Data collection and analysis We used standard methodological procedures expected by Cochrane. We used the GRADE approach to assess the certainty of evidence. Primary outcomes in infants at risk for, or having early symptoms consistent with, opioid withdrawal included length of hospitalization and pharmacological treatment with one or more doses of opioid or sedative medication. Primary outcomes in infants receiving opioid treatment for symptoms consistent with opioid withdrawal included length of hospitalization, length of pharmacological treatment with opioid or sedative medication, and maximum and cumulative doses of opioid medication. Main results We identified six RCTs (353 infants) in which infants at risk for, or having symptoms consistent with, opioid withdrawal participated between 1975 and 2018. We identified no RCTs in which infants receiving opioid treatment for symptoms consistent with opioid withdrawal participated. The certainty of evidence for all outcomes was very low to low. We also identified and excluded 34 non-randomized studies published between 2005 and 2018, including 29 in which infants at risk for, or having symptoms consistent with, opioid withdrawal participated and five in which infants receiving opioid treatment for symptoms consistent with opioid withdrawal participated. We identified seven preregistered interventional clinical trials that may qualify for inclusion at review update when complete. Of the six RCTs, four studies assessed modifying environmental stimulation in the form of a mechanical rocking bed, prone positioning, non-oscillating waterbed, or a low-stimulation nursery; one study assessed feeding practices (comparing 24 kcal/oz to 20 kcal/oz formula); and one study assessed support of the maternal-infant dyad (tailored breastfeeding support). There was no evidence of a difference in length of hospitalization in the one study that assessed modifying environmental stimulation (mean difference [MD) -1 day, 95% confidence interval [CI) -2.82 to 0.82; 30 infants; very low-certainty evidence) and the one study of support of the maternal-infant dyad (MD -8.9 days, 95% CI -19.84 to 2.04; 14 infants; very low-certainty evidence). No studies of feeding practices evaluated the length of hospitalization. There was no evidence of a difference in use of pharmacological treatment in three studies of modifying environmental stimulation (typical risk ratio [RR) 1.00, 95% CI 0.86 to 1.16; 92 infants; low-certainty evidence), one study of feeding practices (RR 0.92, 95% CI 0.63 to 1.33; 49 infants; very low-certainty evidence), and one study of support of the maternal-infant dyad (RR 0.50, 95% CI 0.13 to 1.90; 14 infants; very low-certainty evidence). Reported secondary outcomes included neonatal intensive care unit (NICU) admission, days to regain birth weight, and weight nadir. One study of support of the maternal-infant dyad reported NICU admission (RR 0.50, 95% CI 0.13 to 1.90; 14 infants; very low-certainty evidence). One study of feeding practices reported days to regain birth weight (MD 1.10 days, 95% CI 2.76 to 0.56; 46 infants; very low-certainty evidence). One study that assessed modifying environmental stimulation reported weight nadir (MD -0.28, 95% CI -1.15 to 0.59; 194 infants; very low-certainty evidence) and one study of feeding practices reported weight nadir (MD -0.8, 95% CI -2.24 to 0.64; 46 infants; very low-certainty evidence). Authors' conclusions We are uncertain whether non-pharmacological care for opioid withdrawal in newborns affects important clinical outcomes including length of hospitalization and use of pharmacological treatment based on the six included studies. The outcomes identified for this review were of very low- to low-certainty evidence. Combined analysis was limited by heterogeneity in study design and intervention definitions as well as the number of studies. Many prespecified outcomes were not reported. Although caregivers are encouraged by experts to optimize non-pharmacological care for opioid withdrawal in newborns prior to initiating pharmacological care, we do not have sufficient evidence to inform specific clinical practices. Larger well-designed studies are needed to determine the effect of non-pharmacological care for opioid withdrawal in newborns.

BACKGROUND AND OBJECTIVE: Care for neonatal abstinence syndrome (NAS), a postnatal drug withdrawal syndrome, remains variable. We designed and implemented a multicenter quality improvement collaborative for infants with NAS. Our objective was to determine if the collaborative was effective in standardizing hospital policies and improving patient outcomes. METHODS: From 2012 to 2014, data were collected through serial cross-sectional audits of participating centers. Hospitals assessed institutional policies and patient-level data for infants with NAS requiring pharmacotherapy, including length of pharmacologic treatment and length of hospital stay (LOS). Models were fit, clustered according to hospital, to evaluate changes in patient outcomes over time. RESULTS: Among 199 participating centers, the mean number of NAS-focused guidelines increased from 3.7 to 5.1 of a possible 6 (P < .001), with improvements noted in all measured domains. Among infants cared for at participating centers, decreases occurred in median (interquartile range) length of pharmacologic treatment, from 16 days (10 to 27 days) to 15 days (10 to 24 days; P = .02), and LOS from 21 days (14 to 33 days) to 19 days (15 to 28 days; P = .002). In addition, there was a statistically significant decrease in the proportion of infants discharged on medication for NAS, from 39.7% to 26.5% (P = .02). After adjusting for potential confounders, standardized NAS scoring process was associated with shorter LOS (–3.3 days,95% confidence interval, –4.9 to –1.4). CONCLUSIONS: Involvement in a multicenter, multistate quality improvement collaborative focused on infants requiring pharmacologic treatment for NAS was associated with increases in standardizing hospital patient care policies and decreases in health care utilization.

In June 2005, the Association of Women's Health, Obstetric and Neonatal Nurses launched a multiyear initiative to address the unique physiologic and developmental needs of near-term infants (NTIs) defined as those born between 34 and 37 weeks post-menstrual age. The Optimizing Care for the Near-Term Infant Conceptual Model integrates the concepts of neonatal physiologic functional status, nursing care practices, care environment, and the essential role of the family both in the hospital and beyond. The elements of the model will serve to guide program and resource development within the Near-Term Infant Initiative. Goals of the initiative are to raise awareness of the NTI population's unique needs, emphasize the need for research, encourage development and adoption of evidence-based guidelines to promote safe care, and provide resources that assist nurses and other health care professionals in risk-based assessment of NTIs.

Importance Hospitals use rates from the best quartile or decile as benchmarks for quality improvement aims, but to what extent these aims are achievable is uncertain. Objective To determine the proportion of neonatal intensive care units (NICUs) in 2014 that achieved rates for death and major morbidities as low as the shrunken adjusted rates from the best quartile and decile in 2005 and the time it took to achieve those rates. Design, Setting, and Participants A total of 408 164 infants with a birth weight of 501 to 1500 g born from January 1, 2005, to December 31, 2014, and cared for at 756 Vermont Oxford Network member NICUs in the United States were evaluated. Logistic regression models with empirical Bayes factors were used to estimate standardized morbidity ratios for each NICU. Each ratio was multiplied by the overall network rate to calculate the 10th, 25th, 50th, 75th, and 90th percentiles of the shrunken adjusted rates for each year. The proportion in 2014 that achieved the 10th and 25th percentile rates from 2005 and the number of years it took for 75% of NICUs to achieve the 2005 rates from the best quartile were estimated. Main Outcomes and Measures Death prior to hospital discharge, infection more than 3 days after birth, severe retinopathy of prematurity, severe intraventricular hemorrhage, necrotizing enterocolitis, and chronic lung disease among infants less than 33 weeks’ gestational age at birth. Results Of the 756 hospitals, 695 provided data for 2014. The mean unadjusted infant-level rate of death before hospital discharge decreased from 14.0% in 2005 to 10.9% in 2014. In 2014, 689 of 695 NICUs (99.1%; 95% CI, 97.4%-100.0%) achieved the 2005 shrunken adjusted rates from the best quartile for death prior to discharge, 678 of 695 (97.6%; 95% CI, 95.8%-99.6%) for late-onset infection, 558 of 681 (81.9%; 95% CI, 77.2%-86.6%) for severe retinopathy of prematurity, 611 of 693 (88.2%; 95% CI, 81.7%-97.0%) for severe intraventricular hemorrhage, 529 of 696 (76.0%; 95% CI, 71.8%-81.2%) for necrotizing enterocolitis, and 286 of 693 (41.3%; 95% CI, 36.1%-45.6%) for chronic lung disease. It took 3 years before 445 NICUs (75.0%) achieved the 2005 shrunken adjusted rate from the best quartile for death prior to discharge, 5 years to achieve the rate from the best quartile for late-onset infection, 6 years to achieve the rate from the best quartile for severe retinopathy of prematurity and severe intraventricular hemorrhage, and 8 years to achieve the rate from the best quartile for necrotizing enterocolitis. Conclusions and Relevance From 2005 to 2014, rates of death prior to discharge and serious morbidities decreased among the NICUs in this study. Within 8 years, 75% of NICUs achieved rates of performance from the best quartile of the 2005 benchmark for all outcomes except chronic lung disease. These findings provide a novel way to quantify the magnitude and pace of improvement in neonatology.

T HE i-STAT PORTABLE blood analyzing system (Princeton, N J) is a small, portable, hand-held device that performs a panel of blood tests in 90 seconds on two to three drops of whole blood (Fini, 1994). This technological innovation, which combines silicon chip manufacturing with classical electrochemistry, facilitates the instantaneous reporting of critical laboratory parameters. Blood analysis for sodium, potassium, chloride, ionized calcium, urea nitrogen, glucose, hematocrit, and blood gases are readily available with the current technology. Serum bilirubin soon will be added to the menu. The testing can be performed by physicians, nurses, or other trained assistive personnel and is performed at the bedside, eliminating the costs associated with transporting specimens to a remote central laboratory. This technology has been successfully applied in a variety of clinical settings that include high-acuity patients requiring rapid stabilization and management. These settings include but are not limited to the neonatal intensive care unit, pediatric intensive care unit, PICU, postanesthesia, critical care unit, emergency, dialysis, and outpatient settings. The use of this system on transport also could further expedite early recognition and treatment of acid base

Premji S, Chessell L. Continuous nasogastric milk feeding versus intermittent bolus milk feeding for premature infants less than 1500 grams. Cochrane Database Syst Rev 2001;(1):CD001819 (latest version Nov 22 2001). . QUESTION: In premature infants weighing < 1500 g, how effective is continuous compared with intermittent bolus nasogastric milk feeding? Studies were identified by searching Medline, CINAHL, HealthSTAR, and the Cochrane Controlled Trials Register up to June 2000; and by reviewing abstracts, conference proceedings, and references from relevant publications. Studies were selected if they were randomised or quasi-randomised controlled trials that enrolled infants < 1500 g with no major congenital anomalies that might interfere with feeding tolerance; evaluated continuous nasogastric compared with intermittent bolus tube feedings of breast milk or formula; and assessed days to full feeds, feeding tolerance, time to regain birth weight, somatic growth, days to discharge, or complications such as necrotising enterocolitis and apnoea. 2 reviewers independently extracted data on methodological quality, patient characteristics, intervention type, …

Summary The long secondary dendrites of mitral cells in the olfactory bulb are well developed in the mammalian neonate and show a considerable degree of interweaving and coiling characteristic of dendrite bundles. In a number of other areas throughout the central nervous system, we have made a provisional correlation between the appearance of these bundles and the development of specific items of output performance characteristic of the areas involved. On this basis we have suggested that the dendrite bundles may serve as a repository for the central program shaping the response. This hypothesis is explored further in the case of the olfactory bulb. Mechanisms are suggested whereby rudimentary appetitive programs already encoded along facing dendrite membrane pairs within the specialized intrafascicular milieu, may trigger and control nipple search and suckling in the still blind and only primitively mobile neonate.

The methods of Golgi in conjunction with cresyl violet and Bielschowsky techniques have been used to study the precentral gyri of seven patients aged 74 to 102 years, with special reference to the giant pyramidal cells of Betz. These large neurons appear especially vulnerable to the process of aging and senescence. Age-related changes include irregular swelling of the cell body and principal dendrite shafts with progressive loss of dendrite spines; shortening, disruption, and progressive disappearance of the numerous circumferential (basilar) dendrites which characterize these cells during the period of vigorous adult life; the frequent engulfing of these cells during their senescent phase by astroglia; and the eventual loss of all dendrite shafts including the apical element prior to disappearance of the cell body. A semiquantitative survey of our material indicates that 75% or more of Betz cells show age-related changes by the eighth decade of life compared to less than 30% of the more numerous surrounding non-Betz pyramids. The function of these giant cells increasingly appears to be one of temporary relaxation of extensor muscle tone across weight-bearing joints preceding a specific motor action. Because of the very limited total number of Betz neurons, we suggest that their high incidence of age-related pathology and loss results in a clinically significant decrease in the capacity for rapid initial lysis of antigravity tone in extensors. Symptoms and signs of pain, stiffness, and slowing in activities affecting the lower extremities and hips, so common in aging and senescent individuals, may be, in part, a function of this loss of extensor inhibition and the resulting necessity to force motor patterns upon weight-bearing muscle systems in some degree of constant, unrelieved muscle tone.

Golgi studies of the sagittally sectioned brain stem of the cat show that the longitudinal organization of the superior olive (medial or accessory, and lateral or S segment) differs markedly from that revealed by cross sections. Olivopetal fibers from the cochlear nuclei terminate in sheets of neuropil arranged parallel to the long axis of the stem. Each sheet appears to be made up of the terminal elaborations of several afferent fibers, partially overlapped. Olivary neurons lie embedded in these sheets, their longitudinally elaborated dendrite systems densely covered by plexus terminals. The characteristic flame-shaped arbors and elongated bipolar neurons familiar from previous histological studies, appear to represent the end-on view of an essentially two-dimensional neuropil system. Some putative functional consequences of this organizational pattern are discussed.

Golgi analysis of the various subnuclei of the raphe complex of the brain stem's reticular core reveals an apparently special neurovascular relationship for two of them. Cells of the n. raphe pontis and n. linealis rostralis which have been recognized for some time as forming paired systems are now seen to lie closely applied along the surface of raphe vessels which ascend from the basilar artery on each side of midline. Both cells and dendrites of these two neuronal ensembles ascend along the vessels, the dendrites frequently appearing to bear specialized expansions en passage or terminally, with which to relate to the vascular walls. Histochemical and electron microscopic techniques have been used in efforts to determine the actual nature of this relationship. It has been suggested that the role of the two raphe systems might include: (i) neurosecretion, releasing some active principle into the underlying vascular system; (ii) chemosensor function, responding to specific circulating substances, (iii) mechanoreceptor function, responding to changes in tone and/or diameter of the vessel wall. Introductory studies appear to make the first unlikely, although all possibilities need further evaluation. If these nuclei should be shown to fulfill the second or third roles, it would make it less likely that raphe neurons themselves represent the original triggr for the onset of slow wave sleep, but rather, act in response to a distant pacemaker.

Most dendrites of motoneurons in the spinal cord of mature cats and monkeys have been shown to be grouped in tightly packed bundles. In the lumbosacral cord, bundles begin to appear at postnatal day, 12 to day 14 coincident with the earliest appearance of reciprocal activity in flexor-extensor muscle pairs and development of stepping-walking-weight-bearing capability in the hind limb. We suggested that the central program responsible for controlling integrated patterns of limb activity may be generated in motoneuron dendrite bundles. In the kitten, treading motions of the front legs associated with suckling appear almost immediately after birth. In addition to a generally more advanced state of development in cervical cord, motoneuron dendrite bundles can be identified in the neonatal cervical ventral horn. This can be interpreted as offering further support to the view that dendrite bundles provide the central program for reciprocal activity of leg muscle pairs in coordinated motor activity.

Summary The organization of the ventral anterior (VA) nucleus of the thalamus has been examined in Golgi stained sections from approximately 750 mice, rats, and cats. The study was motivated by physiological evidence suggesting that VA may play a prominent role in recruitment mechanisms and the projection of the thalamic non-specific system upon the cortex. A variety of neuron types and a group of presynaptic neuropil fields of diverse nature, arranged lateral to medial, attest to the complex nature of VA. In general terms, the lateral sectors of VA receive much of the pallido-thalamic projection while the most medial portion (sector a) contains a powerful collateral projection from the non-specific thalamic radiation. Since part of the pallido-thalamic projection (caudate loop) also projects upon the medial fields, sector a, gains special significance as an integrative center gating the play of thalamic activation and caudate inhibitory mechanisms upon the cortex. A substantial part of the rostrally projecting fibers of the non-specific radiation

Dendrite systems of most neurons in the brain stem reticular core undergo two significant changes between birth and maturity. The shaggy spinelike excrescences (heteromorphic protospines) which cover each dendrite and soma at birth, are lost completely, resulting in smooth, spineless reticular dendrites in the adult nervous system. It is suggested that these spinelike structures and their associated presynaptic terminals are concerned with primitive needs of the internal milieu and are replaced by a secondary system of terminals which provide substrate for more complex core functions. In contrast to the familiar radiative aspect of reticular dendrites in newborn organisms, dendrite shafts are rearranged into bundles which surround the fascicles of axons running longitudinally through the reticular formation. The bundles of dendrites are marked by closeness of apposition of the shafts and continuous change in the dendritic elements comprising them. On the basis of previous work, it is suggested that these bundles are the repository for central programs mediating certain stereotyped repetitive output patterns such as respiration and the rest-activity cycle.

A number of variants of the Golgi method have been used to examine neuropil patterns and input-output arrangements of the nonspecific (intralaminar) thalamic complex in adult cats. In comparison with previously used newborn material, it is clear that maturation brings with it considerable change in dendritic and axonal circuitry in both specific and nonspecific systems. The latter provides an extensive second projection system to cerebral cortex in parallel with specific sensory channels. In addition, its connections enable it to exert powerful modulatory forces on the entire dorsal thalamus. It is suggested that the caudally directed axonal path from nucleus reticularis thalami, in conjunction with the midline system, tune and shape those rhythmic slow wave processes which characterize thalamo-cortical operations.

The phenomenon of antidromic inhibition in the spinal cord is generally considered to depend on a population of intercalated interneurons which are cholinergically activated by motoneuron collaterals

An unusual axonless cell of very small size has been found in the ventral nuclei and intralaminar complex of the thalamus in adult cats. As revealed by variants of the rapid Golgi method, the cell shows characteristics which are different from any known neuron or neuroglial type although its general appearance is somewhat suggestive of cerebellar granules or small glial cells. Functional similarities to retinal amacrine cells are postulated if the element is, in fact, neuronal in nature. Its consistent absence in descriptions of perinatal thalamus suggests that its appearance or maturation (or both) occur rather late in the postnatal period, thereby providing an example of a cellular element comming “on line” well after thalamic activity is underway.

During the process of maturation, dendrite shafts have been found to rearrange themselves into bundles in various parts of the nervous system including the ventral horn of the spinal cord, brain stem reticular core, nucleus reticularis thalami, cerebral cortex, and possibly in basal ganglia and certain cranial nerve nuclei. In some cases, the appearance of bundle complexes seems closely time-locked to the initial development of discrete items of motor performance. An inferential cause and effect relationship has been suggested whereby the dendrite bundles are assumed to harbor representational analogues of the specific output. An hypothesis is advanced on the mechanism by which the proposed central program may be inscribed within the bundle. Reasoning from the extended membrane concept of Lehninger, it is suggested that the intrafascicular spaces within the bundle, and especially those between closely apposed pairs of dendrite shafts, provide a sheltered milieu with special properties. Cation-mediated lin...

A number of variants of the Golgi method have been used to examine neuropil patterns and input-output arrangements of the nonspecific (intralaminar) thalamic complex in adult cats.

The hypothalami of old mice were studied with Golgi methods. Our observations showed progressive disruption of hypothalamic architecture, paralleled by deterioration and loss of dendritic surface. Even though these changes were found in all hypothalamic regions studied, they were not evenly distributed. These patterns of distribution plus their possible functional importance are significant in relationship to neuroendocrinological changes in the aged. Emphasis is placed on the aging hypothalamus as an integrator of information originating in similarly aging limbic structures.

Structural maturation of the somatosensory thalamus in several laboratory mammals has been studied with the use of the Golgi methods. The period covered extends from approximately 1 week before term to 90 days after birth with emphasis on the immediate postnatal period. Although all systems appear immature at birth, the data indicate that those ascending and descending axon systems playing upon the ventrobasal complex tend to mature more quickly than certain significant elements in the neuropil of the receptive field. Those elements are particularly the small dendritic structures (for example, excrescences, tufts, etc.) which enter into the formation of synaptic glomeruli and are probably involved in the dendrodendritic linkages which abound in this part of the thalamus. The possible significance of the earlier maturation of thalamopetal afferents compared to the intrinsic thalamic neuropil whose processing operations they modulate, is discussed.