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Biomedical subjects

R G Bout

Publications and source records attributed to R G Bout.

12 recordsLinked to original sources
PubMed2000

A single camera roentgen stereophotogrammetry method for static displacement analysis.

A new method to quantify motion or deformation of bony structures has been developed, since quantification is often difficult due to overlaying tissue, and the currently used roentgen stereophotogrammetry method requires significant investment. In our method, a single stationary roentgen source is used, as opposed to the usual two, which, in combination with a fixed radiogram cassette holder, forms a camera with constant interior orientation. By rotating the experimental object, it is possible to achieve a sufficient angle between the various viewing directions, enabling photogrammetric calculations. The photogrammetric procedure was performed on digitised radiograms and involved template matching to increase accuracy. Co-ordinates of spherical markers in the head of a bird (Rhea americana), were calculated with an accuracy of 0.12mm. When these co-ordinates were used in a deformation analysis, relocations of about 0.5mm could be accurately determined.

Animals↗
PubMed1998

Complex movement patterns: modifiability and constraints.

Most behaviours involve complex morphological systems and vice versa morphological systems are used by the organism in many different ways. During evolution and ontogeny changes in kinematics and function of skeletal and muscular systems must be coordinated with changes in their neural control. Neuromotor patterns are sometimes believed to be conserved in evolution, leading to diversification at the level of musculoskeletal design. Vertebrate motor patterns used in feeding are reviewed to examine this hypothesis. Stereotyped behaviour is not necessarily the result of phylogenetic constraints but may also result from the functional demands imposed by the mechanics of the jaw apparatus and the nature of the task performed. Sensory feedback and descending control not only contribute to 'online' control of movement but also shape the development of motor patterns and learning behaviour and indicate a potentially large flexibility. The neural and sensory apparatus that produces this flexibility will be subject to evolutionary modification. In the absence of a demand for flexibility motor patterns may become stereotyped in some species, while they are very flexible in others. To the extent that morphological systems perform independent movements during different behaviours, separate basic motor patterns may be required, which may be coordinated in different ways.

Animals↗
PubMed1997

Organization and efferent connections of the archistriatum of the mallard, Anas platyrhynchos L.: an anterograde and retrograde tracing study.

The intratelencephalic and descending connections of the archistriatum of the mallard were studied using anterograde and retrograde tracers. Autoradiography after injections of [3H]-leucine served to visualize the intratelencephalic and extratelencephalic efferent connections of the archistriatum. Horseradish peroxidase (HRP), HRP-wheatgerm agglutinin, and fluorescent tracers were used to identify the precise origin of the projections to the various terminal fields found in the anterograde experiments. Four main regions can be recognized in the archistriatum of the mallard: (1) the rostral or anterior part that is a source of contralateral intratelencephalic projections, in particular to the contralateral archistriatum; (2) the dorsal intermediate archistriatum that is the origin of a large descending fiber system, the occipitomesencephalic tract, with projections to dorsal thalamic nuclei, the medial spiriform nucleus, the intercollicular nucleus, the deep tectum, parts of the mesencephalic and bulbar reticular formation, and the subnuclei of the descending trigeminal tract. There are no direct projections to motor nuclei. This part corresponds to the somatic sensorimotor part as defined by Zeier and Karten (1971, Brain Res. 31:313-326); it also contributes to the ipsilateral intratelencephalic connections and, to a lesser degree, to contralateral intratelencephalic connections. (3) The ventral intermediate archistriatum is another region that is also a source of intratelencephalic projections, in particular of those to the lobus parolfactorius. The most lateral zone sends fibers to the septal area. (4) The caudoventral intermediate and posterior archistriatum is another region that is a source of the projections to the hypothalamus and thus corresponds to the amygdaloid part of the archistriatum as defined by Zeier and Karten; it also contributes a modest component to the occipitomesencephalic tract. The different cell populations are not spatially separated, which makes it impossible to recognize distinct subnuclei within the four main regions of the archistriatum of the mallard.

Animals↗
PubMed1997

An electromyographic technique for small animals.

An improved technique is proposed to record electromyographic (EMG) signals. The technique includes anesthesia with isofluothane and twisted bipolar electrodes that are glued with a sugar solution to longitudinally grinded hypodermic needles. The advantages of the technique are (1) minimal damage to the muscles; (2) removal of the injection needle with ease after insertion into the muscle; (3) the electrodes can be soldered onto the connector prior to the experiment; and (4) quick recovery of the animal. The technique is especially advantageous for EMG experiments with small animals.

Anesthesia↗
PubMed1997

Central connections of the nucleus mesencephalicus nervi trigemini in the mallard (Anas platyrhynchos L.).

BACKGROUND: In the mallard duck, functionally distinct groups of jaw muscles are each innervated by a different subnucleus of the main trigeminal (mV) or facial (mVII) motor nucleus. The other subnuclei of mV and mVII innervate several head muscles, including lingual muscles. The reticular premotor cells of the trigeminal and facial jaw motor subnuclei occupy different areas in the parvocellular reticular formation (RPc). The cell bodies of jaw muscle spindle afferents are situated in the mesencephalic nucleus (MesV). In the present study, the central connections of MesV with jaw motor subnuclei and their premotor areas are investigated. METHODS: In a first series of experiments, horseradish peroxidase (HRP) injections were made in electrophysiologically identified trigeminal and facial subnuclei. In a second series of experiments, HRP was delivered iontophoretically at different parts of RPc. Anterograde tracing with tritiated leucine was used to confirm the central connections of MesV. Double labeling with fluorescent tracers was used to investigate whether MesV collaterals reach both the rostral and caudal parts of RPc. RESULTS: MesV projects to only two of the five different subnuclei of the trigeminal motor nucleus. The subnuclei that receive spindle afferents innervate jaw adductor muscles (mV2) or pro- and retractors of the mandible (pterygoid muscles; mV1). The three other subnuclei innervate jaw-opener muscles or other head muscles. MesV fibers also project to the rostral part of the dorsolateral RPc (RPcdl), which serves as a premotor area for the motor subnuclei of adductor and pterygoid muscles. The intermediate part of RPcdl does not contain premotor cells of mV or mVII, and a clear projection of MesV to this area is absent. The caudal part of RPcdl projects to the mV and mVII subnuclei that innervate jaw-opener muscles. This part of RPc receives a projection from the same MesV cells as the rostral RPcdl. The MesV projection to RPc does not include premotor cells of mV and mVII in the ventromedial part of RPc (RPcvm). CONCLUSIONS: Spindle afferents from jaw-closer muscles project only to mV subnuclei innervating jaw-closer muscles (mV1, mV2) and to a population of premotor cells in the rostral RPcdl that innervates these subnuclei. The mixed population of premotor cells in RPcvm, which innervates both jaw-opener and jaw-closer subnuclei, does not receive a MesV projection. However, a premotor area for jaw-opener subnuclei in the caudal part of RPcdl does receive MesV input and may serve as a relay through which proprioceptive information from jaw closer spindles can reach jaw opener muscles.

Animals↗
PubMed1995

The composition of trigeminal nerve branches in normal adult chickens and after debeaking at different ages.

The long term effects of amputation of the tip of the beak were studied in adult hens that were debeaked on the day of hatching, at the age of 8 d and at 6 wk, by EM analysis of fibre spectra of the medial branch of the ophthalmic nerve and of the intramandibular nerve. Three categories of fibre were distinguished for further analysis, i.e. unmyelinated axons, small myelinated fibres and large myelinated fibres. In normal birds the ophthalmic nerve contains relatively more large fibres than the intramandibular nerve. Amputation consistently results in a reduction of the number of large fibres and a substantial increase in the number of small myelinated fibres. The proportion of unmyelinated axons is rather variable, but is not affected by beak trimming. Age at debeaking has no effect. The observations are inconclusive concerning the possibility of heightened nociception.

Aging↗
PubMed1994

The reticular premotor neurons of the jaw muscle motor nuclei in the mallard (Anas platyrhynchos L.).

The trigeminal and facial motor nuclei in the mallard comprise several subnuclei which innervate tongue, jaw and other head muscles. The premotor cells of the subnuclei innervating jaw muscles are distributed in two longitudinal cell columns within the parvocellular reticular formation (RPc). The ventromedial part of RPc contains cells projecting to subnuclei innervating either jaw-closer muscles or jaw-opener muscles. In the dorsolateral part of RPc three subdivisions may be recognized: a rostral part which projects to two trigeminal subnuclei innervating jaw-closer muscles, an intermediate part which does not serve as premotor area for any of the jaw motor subnuclei and a caudal part of RPcdl which projects to the trigeminal and facial motor subnuclei innervating jaw-opener muscles. Exteroceptive information from mechanoreceptors in the beak reaches all three parts of RPCdl. Muscle spindles in jaw-closer muscles may influence the activity of premotor cells of jaw-opener muscles through their projection upon the caudal part of RPcdl.

Animals↗
PubMed1991

Functional morphological interpretation of the distribution of muscle spindles in the jaw muscles of the mallard (Anas platyrhynchos).

The morphology and distribution of muscle spindles of jaw and tongue muscles in the mallard were examined in serial transverse sections of single muscles and in horizontal sections of a whole head. Our observations on spindle morphology are in agreement with previous descriptions of spindles in birds. Some spindles differ in their innervation and the pattern of intrafusal muscle fibers. The spindles of individual adductor and pterygoid muscles are distributed unevenly. Some adductor muscles lack spindles, whereas those of other muscles are confined to limited areas. Jaw opening muscles and extrinsic tongue muscles lack spindles. The stretch of extrafusal muscle fibers could be estimated from the difference in sarcomere length for birds with the beak open and closed. Not all muscle fiber groups are stretched evenly over the whole range of jaw opening. Only those fiber groups that are continuously stretched during jaw opening contain spindles.

Animals↗
PubMed1990

The identification of the motor nuclei innervating the tongue muscles in the mallard (Anas platyrhynchos); an HRP study.

Horseradish peroxidase (HRP) histochemistry was used to identify the motoneurons innervating the tongue muscles in the mallard. Four nuclei are involved: the intermediate motor nucleus of N.VII innervating the stylohyoid, serpihyoid and ceratohyoid muscles, the retrofacial nucleus of N.IX innervating the m. geniohyoideus and the n. intermedius or motor nucleus of N.XII that innervates the mm. ceratoglossus and hyoglossus anterior and obliquus. The m. intermandibularis is innervated by a trigeminal motor subnucleus. There is no clear intranuclear organization. The results are summarized in Table I and discussed in connection with the role of each of the muscles during movements of the tongue.

Animals↗
PubMed1986

Topographical representation of the jaw muscles within the trigeminal motor nucleus. An HRP study in the mallard, Anas platyrhynchos.

The location of the trigeminal motoneurons of the jaw muscles has been determined in the brainstem of the mallard utilizing retrograde axonal transport of horseradish peroxidase (HRP). Injections with HRP into the jaw muscles or application of HRP to the mandibular nerve showed that the trigeminal motor nucleus can be subdivided into five subnuclei, mV1-mV5. Three functional groups of jaw muscles are represented in separate subnuclei. The most lateral subnucleus mV2 innervates all but one adductor muscles, the intermediate mV1 innervates the pterygoid muscles + one adductor and the medial mV4 the two protractor muscles. The most ventral subnucleus mV3 contains the neurons innervating two extrinsic tongue muscles as well as some perikarya of adductor muscles. Subnucleus mV5 lies dorsomedial to mV4 and contains the motoneurons of the depressor muscle of the lower eye lid. Elements of the proprioceptive system, viz. presumptive gamma-neurons and mesencephalic trigeminal nucleus cells, could also be visualized. The topological and functional aspects of the subdivision of the motor nucleus are discussed.

Animals↗
PubMed1985

An HRP study of the central connections of the facial nerve in the mallard (Anas platyrhynchos L.).

The location of several facialis innervated muscles has been determined by injecting individual muscles with horseradish peroxidase. The depressors of the lower jaw are represented in the dorsal facial motor nucleus and the tongue retractor muscles in the intermediate facial motor nucleus. HRP was also directly applied to the rostral and caudal branch of the facial nerve. The afferent connections are described including two small projections to the principal sensory nucleus and n. interpolaris which were not found in birds before.

Animals↗