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PubMed1988

Identification and characterization of neurons initiating patterned neural activity in the buccal ganglia of Aplysia.

Two patterns of neural activity were identified in excised buccal ganglia of Aplysia californica. Both are expressed in many cells, and each can be expressed independently. Using cells B4 and B5 as monitors of the activity patterns, we searched the buccal ganglia for cells initiating the patterns. Two electrically coupled cells, B31 and B32, can initiate what we termed pattern 2. The cells are active before pattern 2 is expressed. Stimuli initiating pattern 2 excite B31/B32. Depolarizing B31/B32 induces the pattern, while hyperpolarizing them can prevent its expression. The cells have unusual features. Their somata do not sustain conventional action potentials, and depolarization causes a regenerative response. B33 differs from B31/B32 in that its soma sustains conventional action potentials but otherwise has similar features. B34 also seems to be inexcitable but has weaker synaptic input than B31/B32 and appears unable to induce pattern 2. B35 and B36 have prominent regenerative capabilities. B35 is also able to initiate pattern 2. B37 is presynaptic to B31/B32 and can initiate pattern 2 via its effects on them. The newly identified cells provide a starting point for investigating factors that initiate and control different patterns of neural activity in the buccal ganglia. Since the buccal ganglia are involved in generating feeding behavior, further studies on the newly identified cells may provide insights into the neural control of feeding behavior, and provide a neural substrate for studying modulation of the feeding patterns by associative learning.

Animals↗
PubMed1994

Origin of the foveal granular pattern in entoptic viewing.

PURPOSE: To investigate the controversial origin of the foveal granular pattern at the center of the entoptic Purkinje vessel shadows. Both phenomena may be vividly elicited by oscillating a focused spot of light across the scleral surface of the eye in a circumferential direction. METHODS: The site and pattern of oscillation of the light spot were varied and were correlated with the appearance of the foveal granular pattern. Movement of the granular pattern relative to a foveal afterimage was also observed. RESULTS: Oscillation of the light in a meridional direction abolishes the granular pattern. Oscillating illumination through the central pupil can elicit Purkinje vessel shadows but not the characteristic foveal granular pattern. With transscleral illumination, the granular pattern oscillates with an "against" motion with respect to the motion of the Purkinje vessel shadows and with a "with" motion with respect to apparent motion of an afterimage serving as a fixed anatomic reference, and it is displaced from the center of the foveal avascular zone in the visual direction away from the source of illumination. CONCLUSIONS: These observations strongly suggest that the foveal granular pattern is a random moire pattern produced by spatial aliasing as the striated light pattern cast by the parafoveal nerve fiber elements sweeps over the photoreceptors in the form of a faint, high-spatial-frequency, irregular grating. An anatomic section of the fovea reveals the necessary geometry for production of such striated patterns, and the Nyquist frequency for the foveal photoreceptor mosaic supports the spatial aliasing effect. Also, a grating moving over a stationary random dot background demonstrates the origin of the "against" motion that is characteristic of the foveal granular pattern.

Fovea Centralis↗
PubMed2006

Distinct mechanisms underlie pattern formation in the skin and skin appendages.

Patterns form with the break of homogeneity and lead to the emergence of new structure or arrangement. There are different physiological and pathological mechanisms that lead to the formation of patterns. Here, we first introduce the basics of pattern formation and their possible biological basis. We then discuss different categories of skin patterns and their potential underlying molecular mechanisms. Some patterns, such as the lines of Blaschko and Naevus, are based on cell lineage and genetic mosaicism. Other patterns, such as regionally specific skin appendages, can be set by distinct combinatorial molecular codes, which in turn may be set by morphogenetic gradients. There are also some patterns, such as the arrangement of hair follicles (hair whorls) and fingerprints, which involve genetics as well as stochastic epigenetic events based on physiochemical principles. Many appendage primordia are laid out in developmental waves. In the adult, some patterns, such as those involving cycling hair follicles, may appear as traveling waves in mice. Since skin appendages can renew themselves in regeneration, their size and shape can still change in the adult via regulation by hormones and the environment. Some lesion patterns are based on pathological changes involving the above processes and can be used as diagnostic criteria in medicine. Understanding the different mechanisms that lead to patterns in the skin will help us appreciate their full significance in morphogenesis and medical research. Much remains to be learned about complex pattern formation, if we are to bridge the gap between molecular biology and organism phenotypes.

Animals↗
PubMed1999

Drosophila wing melanin patterns form by vein-dependent elaboration of enzymatic prepatterns.

BACKGROUND: Animal melanin patterns are involved in diverse aspects of their ecology, from thermoregulation to mimicry. Many theoretical models have simulated pigment patterning, but little is known about the developmental mechanisms of color pattern formation. In Drosophila melanogaster, several genes are known to be necessary for cuticular melanization, but the involvement of these genes in melanin pattern evolution is unknown. We have taken a genetic approach to elucidate the developmental mechanisms underlying melanin pattern formation in various drosophilids. RESULTS: We show that, in D. melanogaster, tyrosine hydroxylase (TH) and dopa decarboxylase (DDC) are required for melanin synthesis. Ectopic expression of TH, but not DDC, alone was sufficient to cause ectopic melanin patterns in the wing. Thus, changes in the level of expression of a single gene can result in a new level of melanization. The ontogeny of this ectopic melanization resembled that found in Drosophila species bearing wing melanin patterns and in D. melanogaster ebony mutants. Importantly, we discovered that in D. melanogaster and three other Drosophila species these wing melanin patterns are dependent upon and shaped by the circulation patterns of hemolymph in the wing veins. CONCLUSIONS: Complex wing melanin patterns are determined by two distinct developmental mechanisms. Spatial prepatterns of enzymatic activity are established late in wing development. Then, in newly eclosed adults, melanin precursors gradually diffuse out from wing veins and are oxidized into dark brown or black melanin. Both the prepatterning and hemolymph-supplied components of this system can change during evolution to produce color pattern diversity.

Animals↗
PubMed1979

Neurophysiological aspects of pattern-sensitive epilepsy.

The capacity of striped patterns (square-wave gratings) to induce paroxysmal EEG activity in a group of pattern-sensitive epileptic patients is shown to depend on: 1. The spatial frequency of the pattern. The optimum spatial frequency lies between 1 and 4 cycles/degree in every patient tested. 2. The orientation of the pattern. Although, for the patient group as a whole, no one orientation is consistently more likely to induce paroxysmal activity than any other, the responses of individual patients can show marked orientation selectivity. 3. The brightness contrast of the pattern. The probability of paroxysmal EEG activity increases dramatically as contrast is increased from 0.2 to 0.4. Red/green gratings at isoluminance fail to induce paroxysmal activity. 4. The size of the pattern. There is considerable variation between patients in the subtense of a centrally-fixated circular pattern necessary to induce paroxysmal activity with a given probability. However, for every patient an increase in the probability of paroxysmal activity from near zero to near unity is effected by an increase in the angular subtense of the pattern by a factor of two. Patterns other than square-wave gratings are capable of inducing paroxysmal activity but, in general, patterns that stimulate more than one orientation system are less epileptogenic. The above findings are compatible with the hypothesis of a seizure trigger in the striate cortex and are incompatible with a trigger confined to the lateral geniculate nucleus of the thalamus. Further evidence against a geniculate trigger is obtained from an investigation of the response of a pattern-sensitive patient to a diffuse (unpatterned) flickering field in which it is shown that the effects of counter-phase interocular flicker implicate binocular mechanisms.

Adolescent↗
PubMed2004

Cerebral microdialysis of patients with severe traumatic brain injury exhibits highly individualistic patterns as visualized by cluster analysis with self-organizing maps.

OBJECTIVE: To analyze patterns of cerebral microdialysis in patients with traumatic brain injury and, with a neural network methodology, investigate pattern relationships to intracranial pressure and cerebral perfusion pressure. DESIGN: Retrospective. SETTING: University hospital, adult neurosurgical intensive care unit. PATIENTS: Twenty-six patients with severe traumatic brain injury. All consecutive traumatic brain injured patients (Glasgow Coma Scale < or =8) with microdialysis monitoring, analyzing glutamate, lactate, pyruvate, and glucose in both penumbral and nonpenumbral tissue. INTERVENTIONS: None; patients received the unit's standard neurointensive care procedure. MEASUREMENTS AND MAIN RESULTS: We used 2084 hrs of complete microdialysis data sets (eight markers) to train Kohonen self-organizing maps. The self-organizing map algorithm is a data-clustering method that reduces high-dimensional information to a two-dimensional representation on a grid (map), retaining local relationships in the data. Maps were colored (overlaid) for intracranial pressure, cerebral perfusion pressure, and outcome, to explore relationships with underlying microdialysis patterns. The maps exhibited a striking clustering of patients, with unique microdialysis patterns that were recognizable throughout the analysis period. This also held true for most microdialysis patterns characteristic of ischemia. These patients with ischemic patterns can have good outcomes, suggesting a disparity between microdialysis values and severity of traumatic brain injury. CONCLUSION: Using an artificial neural network-like clustering technique, Kohonen self-organizing maps, we have shown that cerebral microdialysis, in traumatic brain injury, exhibits strikingly individualistic patterns that are identifiable throughout the analysis period. Because patients form their own clusters, microdialysis patterns, during periods of increased intracranial pressure or decreased cerebral perfusion pressure, will be found within these clusters. Consequently, no common pattern of microdialysis can be seen among patients within the range of our data. We suggest that these individualistic patterns reflect not only metabolic states of traumatic brain injury but also local gradients seen with small volume sampling. Future investigation should focus on relating these patterns, and movement within and from clusters, to metabolic states of the complex pathophysiology of traumatic brain injury.

Adolescent↗
PubMed2004

Identifying spatially similar gene expression patterns in early stage fruit fly embryo images: binary feature versus invariant moment digital representations.

BACKGROUND: Modern developmental biology relies heavily on the analysis of embryonic gene expression patterns. Investigators manually inspect hundreds or thousands of expression patterns to identify those that are spatially similar and to ultimately infer potential gene interactions. However, the rapid accumulation of gene expression pattern data over the last two decades, facilitated by high-throughput techniques, has produced a need for the development of efficient approaches for direct comparison of images, rather than their textual descriptions, to identify spatially similar expression patterns. RESULTS: The effectiveness of the Binary Feature Vector (BFV) and Invariant Moment Vector (IMV) based digital representations of the gene expression patterns in finding biologically meaningful patterns was compared for a small (226 images) and a large (1819 images) dataset. For each dataset, an ordered list of images, with respect to a query image, was generated to identify overlapping and similar gene expression patterns, in a manner comparable to what a developmental biologist might do. The results showed that the BFV representation consistently outperforms the IMV representation in finding biologically meaningful matches when spatial overlap of the gene expression pattern and the genes involved are considered. Furthermore, we explored the value of conducting image-content based searches in a dataset where individual expression components (or domains) of multi-domain expression patterns were also included separately. We found that this technique improves performance of both IMV and BFV based searches. CONCLUSIONS: We conclude that the BFV representation consistently produces a more extensive and better list of biologically useful patterns than the IMV representation. The high quality of results obtained scales well as the search database becomes larger, which encourages efforts to build automated image query and retrieval systems for spatial gene expression patterns.

Algorithms↗
PubMed2005

The genetics of ray pattern variation in Caenorhabditis briggsae.

BACKGROUND: How does intraspecific variation relate to macroevolutionary change in morphology? This question can be addressed in species in which derived characters are present but not fixed. In rhabditid nematodes, the arrangement of the nine bilateral pairs of peripheral sense organs (rays) in tails of males is often the most highly divergent character between species. The development of ray pattern involves inputs from hometic gene expression patterns, TGFbeta signalling, Wnt signalling, and other genetic pathways. In Caenorhabditis briggsae, strain-specific variation in ray pattern has provided an entree into the evolution of ray pattern. Some strains were fixed for a derived pattern. Other strains were more plastic and exhibited derived and ancestral patterns at equal frequencies. RESULTS: Recombinant inbred lines (RILs) constructed from crosses between the variant C. briggsae AF16 and HK104 strains exhibited a wide range of phenotypes including some that were more extreme than either parental strain. Transgressive segregation was significantly associated with allelic variation in the C. briggsae homolog of abdominal B, Cb-egl-5. At least two genes that affected different elements of ray pattern, ray position and ray fusion, were linked to a second gene, mip-1. Consistent with this, the segregation of ray position and ray fusion phenotypes were only partially correlated in the RILs. CONCLUSIONS: The evolution of ray pattern has involved allelic variation at multiple loci. Some of these loci impact the specification of ray identities and simultaneously affect multiple ray pattern elements. Others impact individual characters and are not constrained by covariance with other ray pattern elements. Among the genetic pathways that may be involved in ray pattern evolution is specification of anteroposterior positional information by homeotic genes.

Alleles↗
PubMed2002

Template-matching describes visual pattern-recognition tasks in the weakly electric fish Gnathonemus petersii.

Several insects use template-matching systems to recognize objects or environmental landmarks by comparing actual and stored retinal images. Such systems are not viewpoint-invariant and are useful only when the locations in which the images have been stored and where they are later retrieved coincide. Here, we describe that a vertebrate, the weakly electric fish Gnathonemus petersii, appears to use template-matching to recognize visual patterns that it had previously viewed from a fixed vantage point. This fish is nocturnal and uses its electrical sense to find its way in the dark, yet it has functional vision that appears to be well adapted to dim light conditions. We were able to train three fish in a two-alternative forced-choice procedure to discriminate a rewarded from an unrewarded visual pattern. From its daytime shelter, each fish viewed two visual patterns placed at a set distance behind a transparent Plexiglas screen that closed the shelter. When the screen was lifted, the fish swam towards one of the patterns to receive a food reward or to be directed back into its shelter. Successful pattern discrimination was limited to low ambient light intensities of approximately 10 lx and to pattern sizes subtending a visual angle greater than 3 degrees. To analyze the characteristics used by the fish to discriminate the visual training patterns, we performed transfer tests in which the training patterns were replaced by other patterns. The results of all such transfer tests can best be explained by a template-matching mechanism in which the fish stores the view of the rewarded training pattern and chooses from two other patterns the one whose retinal appearance best matches the stored view.

Animals↗
PubMed2005

Engineering gene networks to emulate Drosophila embryonic pattern formation.

Pattern formation is essential in the development of higher eukaryotes. For example, in the Drosophila embryo, maternal morphogen gradients establish gap gene expression domain patterning along the anterior-posterior axis, through linkage with an elaborate gene network. To understand the evolution and behaviour of such systems better, it is important to establish the minimal determinants required for patterning. We have therefore engineered artificial transcription-translation networks that generate simple patterns, crudely analogous to the Drosophila gap gene system. The Drosophila syncytium was modelled using DNA-coated paramagnetic beads fixed by magnets in an artificial chamber, forming a gene expression network. Transient expression domain patterns were generated using various levels of network connectivity. Generally, adding more transcription repression interactions increased the "sharpness" of the pattern while reducing overall expression levels. An accompanying computer model for our system allowed us to search for parameter sets compatible with patterning. While it is clear that the Drosophila embryo is far more complex than our simplified model, several features of interest emerge. For example, the model suggests that simple diffusion may be too rapid for Drosophila-scale patterning, implying that sublocalisation, or "trapping," is required. Second, we find that for pattern formation to occur under the conditions of our in vitro reaction-diffusion system, the activator molecules must propagate faster than the inhibitors. Third, adding controlled protease degradation to the system stabilizes pattern formation over time. We have reconstituted transcriptional pattern formation from purified substances, including phage RNA polymerases, ribonucleotides, and an eukaryotic translation extract. We anticipate that the system described here will be generally applicable to the study of any biological network with a spatial component.

Animals↗
PubMed1994

Role of DNA ploidy patterns in esophageal squamous cell carcinoma. An ultraviolet microspectrophotometric study.

BACKGROUND: Controversy still exists about the influence of DNA content on the prognosis for patients with esophageal squamous cell carcinoma. METHODS: DNA ploidy was determined by microspectrophotometric (MSPM) analysis of paraffin embedded malignant tissue from 78 patients with squamous cell carcinoma of the esophagus. The DNA distribution pattern was classified as diploid, low grade aneuploid (LGA), and high grade aneuploid (HGA) pattern. The relationships among DNA distribution patterns, pathologic features, clinical findings, and prognoses were investigated. Twenty-seven of 78 patients were also selected for analyses of the DNA ploidy pattern of lymph node metastases. RESULTS: Of 78 cancers, 20 (26%) were diploid, 15 (19%) LGA, and 43 (55%) HGA. The advanced carcinomas had the higher distribution of HGA pattern (55%), whereas the diploid pattern was more frequent in early stage (70%) or superficial (65%) esophageal cancer. In patients with the HGA pattern, there was a significantly higher frequency of lymph node metastases (79%) and marked lymphatic (74.4%) and vascular (69.8%) invasion compared with those exhibiting the LGA (33.3%) or diploid (25%) pattern. Five-year survival rates for patients with diploid carcinoma (57%) was significantly better than for those with the HGA pattern (14%). The distribution of nuclear DNA content was much narrower in the metastatic lymph node than in the corresponding primary cases. CONCLUSIONS: The HGA of DNA pattern based on spectrophotometry closely correlated with the factors generally indicative of the aggressive behavior of malignant tumors. Therefore, the role of the DNA ploidy pattern as a prognostic factor was emphasized.

Aged↗
PubMed1983

Correlation of in vitro culture pattern and Q-banded karyotype in acute nonlymphocytic leukemia.

Both cytogenetic abnormalities and in vitro growth patterns of leukemic cells have prognostic significance in acute nonlymphocytic leukemia (ANLL). The present study was undertaken to analyze the interrelationship between these two factors and response to therapy. Blast cells from 43 patients with de novo ANLL, four patients with secondary ANLL, and two patients with ANLL following a preleukemic phase were studied using both in vitro culture in methylcellulose and quinacrine chromosome banding techniques. In 19 patients with de novo ANLL, minimal growth in culture (less than or equal to 5 colonies without prominence of small clusters) was noted (Pattern I). Blast cells from the remaining 24 patients formed numerous abnormal clusters and colonies in a continuum distribution (Pattern II). Sixty-three percent of Pattern I patients had completely normal karyotypes (NN). Only 29% of Pattern II patients were NN. No Pattern I patient had only abnormal karyotypes (AA), while 25% of Pattern II patients were AA (p less than 0.05). All six patients with secondary leukemia or leukemia following a preleukemic phase demonstrated both Pattern II growth and cytogenetic abnormalities. Fifty-six percent of Pattern I patients with de novo ANLL responded to chemotherapy, 35% of Pattern II patients responded, and 0% of patients with secondary or post-preleukemic ANLL responded. The correlation between the presence of cytogenetic abnormalities in leukemic cells and a pattern of excessive, abnormal growth in vitro coupled with the trend toward poor prognosis in these patients suggests that cytogenetically abnormal cells may have a proliferative advantage both in vitro and in vivo.

Acute Disease↗
PubMed1994

Early development of the somatotopic map and barrel patterning in rat somatosensory cortex.

Several lines of evidence implicate a crucial role for thalamic afferents from the ventroposterior nucleus (VP) in the development of barrels and their characteristic pattern in the primary somatosensory cortex (S1) of rodents. We sought to determine the stage in development when VP thalamocortical afferents are first distributed in a periphery-related pattern and the sequence of events that culminate in a mature pattern. Using acetylcholinesterase (AChE) histochemistry, an early marker for VP thalamocortical afferents, and the anterograde axon tracer DiI, we show that VP thalamocortical afferents become distributed into a periphery-related pattern earlier than was previously reported, including their parcellation into a barrel-related pattern that mirrors the distribution of sensory hairs on the face. The earliest periphery-related patterning observed is transiently present in the deep cortical layers prior to the emergence of layer 4, the layer in which barrels later develop. AChE histochemistry reveals a clear sequence of maturation of the barrel pattern in the distribution of VP afferents: An initially patternless distribution of AChE-reactive afferents is followed by their distribution in a nascent trigeminal representation, from which rows subsequently emerge; barrel-related clusters of afferents then emerge from the rows. This process begins before birth, and the transition from row-related to barrel-related distributions of VP afferents is evident during the first postnatal day (P0). This demonstration of a periphery-related pattern in developing rat S1 precedes by about 2 days that revealed by any other marker reported to delineate barrels. These findings confirm that VP thalamocortical afferents are the first barrel component to have a periphery-related pattern and support the hypothesis that thalamocortical afferents provide to immature S1 the patterning information that initiates the formation of barrels and their characteristic array. Furthermore because these findings show an earlier onset for barrel formation than was previously realized, they necessitate a reevaluation of conclusions drawn from experiments examining developmental plasticity in barrel patterning.

Acetylcholinesterase↗
PubMed2003

Examination of passive ROM and capsular patterns in the hip.

BACKGROUND AND PURPOSE: The present study was conducted to examine passive hip range of motion (PROM) for patients with hip dysfunction, including pain, with or without hip osteoarthritis, to arrange and describe PROM patterns and to count the number of hips presenting Cyriax's and Kaltenborn's capsular patterns. METHOD: The study is theory-testing, observational, cross-sectional and descriptive. One hundred and sixty-eight patients (mean age 61.7 years, range 36-90 years), 50 with no hip osteoarthritis, 77 with unilateral hip osteoarthritis and 41 with bilateral osteoarthritis, based on radiological reports, were consecutively recruited by physicians in primary health care and orthopaedic settings. One examiner tested PROM bilaterally, by use of a goniometer and a standardized protocol. PROM limitations were calculated by comparing norms from the symptom-free hips (n = 100) in the study, from Kaltenborn and, in patients with unilateral hip osteoarthritis (n = 77), from the non-osteoarthritis hip. The limitations were arranged by size in PROM patterns. The patterns and the numbers of hips with patterns corresponding to Cyriax's and Kaltenborn's capsular patterns were counted. RESULTS: Between 68 and 138 PROM patterns were identified by use of different PROM norms for defining limitations. Few osteoarthritis hips showed Cyriax's capsular pattern and none Kaltenborn's capsular pattern. CONCLUSIONS: The concept of capsular pattern for the hip should be re-examined. No support was found in the present study for its existence. It is impossible to anticipate radiological evidence of hip osteoarthritis from the multitude of PROM patterns. Every patient should be regarded as unique.

Adult↗
PubMed1999

Clonal analysis of epidermal patterning during maize leaf development.

In plants, specialized epidermal cells are arranged in semiordered patterns. In grasses such as maize, stomata and other specialized cell types differentiate in linear patterns within the leaf epidermis. A variety of mechanisms have been proposed to direct patterns of epidermal cell differentiation. One class of models proposes that patterns of cellular differentiation depend on the lineage relationships among epidermal cells. Another class of models proposes that epidermal patterning depends on positional information rather than lineage relationships. In the dicot epidermis, cell lineage is an important factor in the patterning of stomata, but not trichomes. In this study, the role of cell lineage in the linear patterning of stomata and bulliform cells in the maize leaf epidermis is investigated. Clones of epidermal cells in juvenile leaves were marked by excision of dSpm from gl15-m and in adult leaves by excision of Ds2 from bz2-m. These clones were analyzed in relation to patterns of stomata and bulliform cells, testing specific predictions of clonal origin hypotheses for the patterning of these cell types. We found that the great majority of clones analyzed failed to satisfy these predictions. Our results clearly show that lineage does not account for the linear patterning of stomata and bulliform cells, implying that positional information must direct the differentiation patterns of these cell types in maize.

Anthocyanins↗
PubMed1996

FASTA-SWAP and FASTA-PAT: pattern database searches using combinations of aligned amino acids, and a novel scoring theory.

We introduce two new pattern database search tools that utilize statistical significance and information theory to improve protein function identification. Both the general pattern scoring theory with the specific matrices introduced here and the low redundancy of pattern databases increase search sensitivity and selectivity. Pattern scoring preferentially rewards matches at conserved positions in a pattern with higher scores than matches at variable positions, and assigns more negative scores to mismatches at conserved positions than to mismatches at variable positions. The theory of pattern scoring can be used to create log-odds pattern scores for patterns derived from any set of multiple alignments. This theoretical framework can be used to adapt existing sequence database search tools to pattern analysis. Our FASTA-SWAP and FASTA-PAT tools are extensions of the FASTA program that search a sequence query against a pattern database. In the first step, FASTA-SWAP searches the diagonals of the query sequence and the library pattern for high-scoring segments, while FASTA-PAT performs an extended version of hashing. In the second step, both methods refine the alignments and the scores using dynamic programming. The tools utilize an extremely compact binary representation of all possible combinations of amino acid residues in aligned positions. Our FASTA-SWAP and FASTA-PAT tools are well suited for functional identification of distant relatives that may be missed by sequence database search methods. FASTA-SWAP and FASTA-PAT searches can be performed using our World-Wide Web Server (http://dot.imgen.bcm.tmc.edu:9331/seq-search/Op tions/fastapat.html).

Algorithms↗
PubMed1990

Recurring discharge patterns in multiple spike trains. II. Application in forebrain areas related to cardiac and respiratory control during different sleep-waking states.

Simultaneously recorded spike trains were obtained using microwire bundles from unrestrained, drug-free cats during different sleep-waking states in forebrain areas associated with cardiac and respiratory activity. Cardiac and respiratory activity was simultaneously recorded with the spike trains. We applied the recurring discharge patterns detection procedure described in a companion paper (Frostig et al. 1990) to the spike and cardiorespiratory trains. The pattern detection procedure was applied to detect only precise (in time and structure) recurring patterns. Recurring discharge patterns were detected in all simultaneously recorded groups. Recurring discharge patterns were composed of up to ten spikes per pattern and involved up to four simultaneously recorded spike trains. Fourty-two percent of the recurring patterns contained cardiac and/or respiratory events in addition to neuronal spikes. When patterns were compared over different sleep-waking states it was found the the same units produced different patterns in different states, that patterns were significantly more compact in time during quiet sleep, and that changes in the discharge rates accompanying changes in sleep-waking states were not correlated with changes in pattern rate.

Action Potentials↗
PubMed1978

Comparison of firing patterns and sensory responsiveness between supraoptic and other hypothalamic neurons in the unanesthetized sheep.

Adult Southdown ewes were surgically prepared with pituitary stimulating electrodes, carotid and jugular cannulae, and a cranial platform-cylinder arrangement for chronic single unit recording. Isolated neurons (n = 112) in the region of the supraoptic nucleus (SON) were identified by pituitary stalk stimulastion as AD + (antidromically invaded) SON neuroendocrine cells (n = 75) or AD--(not antidromically invaded) SON neurons (n = 37). Spontaneous firing pattern distribution and sensory evoked behavior of these SON region neurons were compared with activity recorded from 112 randomly located non-identified neurons of extra-SON areas of the hypothalamus. Spontaneous discharge activity was categorized into six distinct firing pattern types: continuously active slow (CAS), continuously active fast (CAF), continuously active bursting (CAB), continuously active regular (CAR), low frequency bursting (LFB), and high frequency bursting (HFB). These 6 firing pattern types were characterized by computer analysis and their mean order independent statistical parameters compared. Bursting discharge patterns (LFB, HFB, and CAB) were compared with respect to mean burst duration, burst mean firing rate, and interburst interavls. Ninety-three per cent of all neurons maintained a stable discharge pattern in the absence of apparent stimuli. Occasionally CAS and CAF neurons spontaneously generated spike clusters sufficient to give the transient appearance of a bursting discharge pattern and LFB neurons lapsed spontaneously into CAS acitivity. All 6 firing pattern types recorded from non-identified extra-SON neurons were also recorded in the SON region. However, spontaneously discharging AD+ SON neurons exhibited only continuously active slow (CAS), continuously active fast (CAF), and low frequency bursting (LFB) activity. The total absence of high frequency bursting (HFB), continuously active regular (CAR), and continuously active bursting (CAB) patterns of discharge from AD+ SON neurons suggests that AD- SON neurons exhibiting these firing patterns may function as interneurons, pacemaker neurons, or receptor neurons. A significant number of LFB discharging neurons were recorded in widespread extra-SON regions of the hypothalamus, indicating this discharge pattern may not be unique to magnocellular neuroendocrine cells. AD+ SON LFB neurons sampled in this study demonstrated a significantly longer mean interburst interval (20.86 sec) compared to extra-SON LFB neurons (12.43 sec). No AD+ SON neuron tested was significantly sensitive to non-specific sensory arousal or sleep-waking state changes. In extra-SON areas of the hypothalamus, 11 of 75 neurons tested to sensory arousal and 6 of 19 neurons tested to sleep-waking changes responded with significant changes in mean firing rate (MFR); no significant difference between firing pattern types was demonstrated in arousal or sleep-waking sensitivity...

Animals↗