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A D Craig

Publications and source records attributed to A D Craig.

65 records · Page 4Linked to original sources
PubMed1985

A dorsal spinal neural network in cat. III. Dynamic nonlinear analysis of responses to random stimulation of single type 1 cutaneous input fibers.

The input/output characteristics of a subset of dorsal horn neurons in laminae 3 and 4 [( L3,4:SA1,X], see INTRODUCTION; output cells) of cat have previously been examined in the resting unperturbed condition using single or paired input pulses introduced once every three seconds on single slowly adapting type 1 (SA1) cutaneous mechanoreceptor afferent fibers (1, 27, 28). The present study extends this description to the dynamic condition by use of a random-stimulation method developed for the characterization of multiport pulse-input/pulse-output nonlinear systems. A total of 58 SA1 receptor input channels to 29 [L3,4:SA1,X] network output cells were tested individually in 15 spinal cats with several random train stimuli of differing mean input rates [5, 10, 20, 30, 50 pulses per second (pps)]. Simultaneous stimulation of two input channels with independent random trains was performed in 16 units. In each case, zero-, first-, and second-order descriptions of network behavior were obtained; the second-order characteristics of interest were expressed in the form of excitability functions, which are directly comparable with those obtained from condition-test results. Preliminary testing with multiple input pulses suggested that, in addition to the strong second-order effects previously identified, third- and higher-order nonlinearities and effects with long time constants could generate significant rate effects. Nonetheless, first-order response characteristics obtained in the dynamic condition at the lowest mean input rate used (5 pps) were in each case qualitatively identical, though slightly smaller in magnitude, to the poststimulus time histograms (PST) obtained in the unperturbed condition. Second-order excitability functions were generally, but not always, similar to condition-test results in the eight cases in which comparisons were made. Furthermore, use of a complete second-order characterization to predict the output response to a different random input in five cases resulted in an average correlation with the observed output that was a 50% improvement over the linear model predictions. These results indicate strong second-order and weaker higher-order nonlinearities in the [L3,4:SA1,X] network. Three classes of channel-specific second-order excitability characteristics were identified into which the previous descriptions (28) can be incorporated. The general pattern was initial facilitation followed by inhibition. This was observed for both the early and late response components in about half the channels (class I).(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗
PubMed1983

The distribution of afferent fibers from the gastrocnemius-soleus muscle in the dorsal horn of the cat, as revealed by the transport of horseradish peroxidase.

The transganglionic transport of horseradish peroxidase (HRP) was used to examine the distribution of afferent fibers from the gastrocnemius-soleus (GS) muscle in the dorsal horn of the cat. Intense labeling was consistently observed in lamina I (in segments L4 to S3) and in the lateral portion of lamina V (segments L6 and S1-3), but not to any significant extent in laminae II-IV. These terminal fields were ascribed to the small-diameter (group III/IV) GS afferent fibers.

Afferent Pathways↗
PubMed1982

The thalamo-cortical projection of the nucleus submedius in the cat.

The cortical projection of the nucleus submedius (Sm) was studied in the cat with the autoradiographic and horseradish peroxidase (HRP) methods. The results indicate that Sm projects topographically on to layer 3 of a distinct agranular cortical field that occupies the posterolateral gyrus proreus, the adjacent fundus of the rhinal sulcus, and the postero-ventral portion of the medial wall of the presylvian sulcus. This cortical field is denoted the ventrolateral orbital cortex (VLO), consonant with previous nomenclature in the rat (Krettek and Price, '77a). The more ventral part (VLO beta) is cytoarchitectonically distinct from the dorsal part (VLO alpha); the former receives input from the anterior part of Sm (Sma), while the latter receives input from the dorsal and ventral parts of Sm (Smd and Smv). A light input to superficial layer 1 of VLO probably also arises from Sm, and there may be an input to layers 5 and 6. The corticothalamic projection from VLO to Sm reciprocates the ipsilateral thalamocortical projection and also has a moderate contralateral component. A dense, subpial layer 1 input to VLO arises from cells of the ventromedial nucleus (VM) subjacent to Sm. The present experiments also indicate that clusters of cells in VM probably provide input to layer 3 of the cortex in the fundus of the presylvian sulcus, as well as area 6a beta in the lateral wall of the presylvian sulcus and the ventral bank of the cruciate sulcus. Results from the HRP experiments additionally indicate that VLO beta and the anteroventral (Smv) portion of VLO alpha are reciprocally connected with the ventral agranular insular cortex and the cingulate cortex, ipsilaterally, while the posterodorsal (Smd) portion of VLO alpha is instead connected wih specific portions of the somatosensory cortical areas bilaterally. All portions of VLO alpha appear to project to the ventrolateral periaqueductal gray. In light of the recent suggestion that Smd is involved with nociception (Craig and Burton, '81), the present results suggest that the related portion of VLO alpha may serve as a cortical representation for noxious stimuli.

Afferent Pathways↗
PubMed1981

Spinal and medullary lamina I projection to nucleus submedius in medial thalamus: a possible pain center.

1. Results obtained with the anterograde horseradish peroxidase (HRP) and autoradiographic techniques have revealed a dense and compact spinal and trigeminal projection to the dorsal portion of the nucleus submedius (Sm) in the medial thalamus of the cat. A homologous projection was observed in two cases in the monkey and in three cases in the rat with the anterograde HRP method. 2. The projection to Sm in topographically organized rostrocaudally, with trigeminal terminations located caudally and spinal terminations rostrally. The rostrocaudal extent of the trigeminal field in Sm (ca. 1 mm) is larger than that of the spinal field (ca. 0.8 mm). There is a considerable ipsilateral trigeminal projection, whereas there is a minimal uncrossed spinal projection to Sm. 3. Retrogradely labeled cells were analyzed in cases with small injections of HRP in medial thalamus in the cat. The results indicate that the projections to Sm identified in the anterograde experiments arise from lamina I cells of the spinal and medullary dorsal horm, probably exclusive of lamina V and other spinothalamic cells. The retrograde results corroborate the topographic observations made in the anterograde experiments. 4. These results suggest that Sm may be critically involved in specific nociception.

Animals↗
PubMed1979

The lateral cervical nucleus in the cat: anatomic organization of cervicothalamic neurons.

The morphology of the lateral cervical nucleus (LCN) and the organization of the cervicothalamic projection neurons were studied in cats which had received thalamic injections of horseradish peroxidase (HRP). The boundaries of the LCN were defined following very large thalamic (HRP injections. Roughly 92-97% of LCN cells project contralaterally to thalamus; an additional 1.5% project ipsillaterally. Computer-assisted measurements of perikaryal areas demonstrated that there are two sizes of LCN cells, large (175-900 micrometer 2) and small (less than 175 micrometer 2); the small cells are localized in the medial third of the LCN. LCN cells which are not labeled after large thalamic HRP injections are predomininantly small, medially-located neurons. Small HRP injections into physiologically identified regions of ventroposterior thalamus demonstrated that cervicothalamic neurons are organized in a topography consistent with that observed physiologically in the LCN (Craig and Tapper, '78). Dorsolateral LCN cells are retrogradely labeled from nucleus ventroposterolateralis, pars lateralis (VPL1), ventromedial LCN cells are labeled from pars medialis (VPL m), and a few medial cells are labeled from nucleus ventroposteromedialis (VPM). A few cells in the medial portion of the LCN are also labeled from each part of ventroposterior thalamus. Some interspersion was observed even in the cases with the most well-restricted labeling. We conclude that the LCN maintains a basic somatotographic organization with an inherent variability, certain aspects of which are consistently demonstrable both physiologically and anatomically. Evidence was also obtained suggestive of a rostrocaudal inversion in the cervicothalamic projection. The cervicothalamic projection, the differentiation of the medial LCN subpopulation, and the possible redefinition of the LCN are discussed in light of these results.

Animals↗
PubMed1979

Efferent projections from temperature sensitive recording loci within the marginal zone of the nucleus caudalis of the spinal trigeminal complex in the cat.

The efferent projections from nucleus caudalis of the spinal trigeminal complex in cats were studied with retrograde and anterograde axonal transport techniques combined with localization of recording sites in the thalamus and marginal zone of nucleus caudalis to innocuous skin cooling. Results showed brainstem projections from nucleus caudalis to rostral levels of the spinal trigeminal complex, to the ventral division of the principal trigeminal nucleus, the parabrachial nucleus, cranial motor nuclei 7 and 12, solitary complex, contralateral dorsal inferior olivary nucleus, portions of the lateral reticular formation, upper cervical spinal dorsal horn and, lateral cervical nucleus. Projections to the thalamus included; a dorsomedial region of VPM (bilaterally) and to the main part of VPM and PO contralaterally. Neuronal activity was recorded in the dorsomedial region of VPM to cooling the ipsilateral tongue. HRP injections in this thalamic region retrogradely labeled marginal neurons in nucleus caudalis. These results show that marginal neurons of nucleus caudalis provide a trigeminal equivalent of spinothalamic projections to the ventroposterior nucleus in cats.

Animals↗
PubMed1978

Spinal and medullary input to the lateral cervical nucleus.

The distributions of spinal and medullary cells projecting to the lateral cervical nucleus (LCN) have been investigated in young cats and dogs using the retrograde horseradish peroxidase (HRP) technique. Labeled spinal cells, whose axons contribute to the spinocervical tract (SCT), were found at all levels of the spinal cord ipsilateral to the injection sites. No significant differences were found between cat and dog, nor between cases with single injections at different levels of the LCN. SCT cells were found predominantly, if not exclusively, within lamina IV, with some extension into medial lamina V. No apparent mediolateral or dorsoventral density gradient was observed within lamina IV; cells of all sizes were labeled. Cells in cervical laminae I and V-VII were occasionally labeled; these, however, were considered to be propriospinal, supplying afferent fibers to the C1-2 dorsal horn. Cells of origin of spinocerebellar fibers consistently remained unlabeled in cases with restricted HRP injections and minimal fiber damage in the dorsolateral funiculus (DLF) around the injection sites. These results, therefore, corroborate and refine the findings of electrophysiological studies of the SCT and the LCN. Labeled medullary cells were located in the caudoventral and rostral portions of the dorsal column nuclei (DCN; stellate and fusiform cells), the underlying n. medullae oblongatae centralis, subnucleus dorsalis (parvicellular medullary reticular formation), the marginal and magnocellular layers (both large and small cells) of the n. trigeminalis spinalis pars caudalis and also in pars interpolaris; a cluster of cells was also consistently labeled in the lateral reticular formation just ventral to pars caudalis. The projection from the DCN to the LCN was confirmed with the anterograde Nauta technique. Fiber degeneration was observed in the entire ipsilateral LCN, although it was less abundant than that observed in the adjacent C1-2 dorsal horn. These results indicate that neurons in the rostral portions of the DCN not only may affect the input to the LCN (at the level of the dorsal horn), but also the output of the LCN itself. These data also suggest the possibility of both noxious and non-noxious facial input to the LCN.

Animals↗
PubMed1978

Lateral cervical nucleus in the cat: functional organization and characteristics.

1. The lateral cervical nucleus (LCN) was investigated with extracellular recordings in the anesthetized cat. A total of 556 LCN units were characterized; the locations of most of these were histologically verified. Half of these had receptive fields on the rostral third of the ipsilateral body surface including the face; 14% had fields on the thorax or abdomen, 33% had fields on the hindlimb or tail, and about 3% had receptive fields larger than one limb. 2. The LCN was observed to be somatotopically organized in experiments using angled microelectrode penetrations. Hindlimb units were dorsolateral, forelimb units ventromedial, and face units most medial within the LCN. In regions where LCN cells were present only in the medial portion of the dorsolateral funiculus, they were all forelimb units. 3. A special subpopulation (17%) of cells were clustered most ventromedially in the LCN. These units had large or disjoint receptive fields, and/or responded to deep, visceral, or noxious stimulation. A third of these did not project in the medial lemniscus (ML); many were synaptically activated by stimulation of the ML. Those that did project in the ML had significantly longer latencies than all other LCN units. It is suggested that this subpopulation contains local LCN interneurons. 4. The specific mechanoreceptor inputs were identified for each of 121 projecting LCN units. Receptor inputs were uniform across each receptive field; that is, each unit that responded to a given receptor type was observed to respond to receptors of that type throughout its receptive field. Input from large-fiber-diameter, velocity-sensitive mechanoreceptors was predominant. The absence of input from slowly adapting type I and II receptors and from joint receptors was confirmed. A significant number of units (17.3%) could be driven by only one receptor type. The LCN sample profile agrees closely with the receptor representation in the hindlimb portion of the spinocervical tract. It is concluded that these data that anatomic specification of convergence occurs in the LCN with respect to receptor connectivity, and that this specification originates in lamina IV of the dorsal horn. 5. Stimulation of the dorsal column nuclei synaptically excited 23% of the LCN units tested. In two cases it was possible to demonstrate, by collision, that this occurred via collaterals of spinocervical tract axons. It is concluded that some spinocervical axons have collaterals terminating in the rostral parts of the dorsal column nuclei.

Animals↗
PubMedDate not supplied

A thalamic nucleus specific for pain and temperature sensation.

The existence of a posterolateral thalamic relay nucleus for pain and temperature sensation was postulated in 1911, on the basis of the stroke-induced analgesia and thermanaesthesia found paradoxically in patients with thalamic pain syndrome. Pain or temperature sensations can be evoked in humans by electrical stimulation in a vaguely defined region of the posterolateral thalamus. Here we use anterograde tracing and single unit recordings to demonstrate that there is a distinct nucleus in the posterior thalamus of the macaque monkey that receives a dense, topographic input from spinothalamic lamina I neurons and in which almost all neurons are nociceptive- or thermoreceptive-specific. Immunohistochemical staining showed that this nucleus is defined by a dense calbindin-positive fibre plexus in the macaque, so we applied the same staining method to sections of human thalamus. We found a nearly identical fibre plexus localized within a distinct nucleus that is cytoarchitectonically homologous to the lamina I relay nucleus in the macaque thalamus. The stereotaxic coordinates of this nucleus and its location relative to the main somatosensory representation fit clinical descriptions of the pain-producing region in humans. We conclude that this is a specific thalamic nucleus for pain and temperature sensation in both monkey and human.

Animals↗