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Biomedical subjects

U Jürgens

Publications and source records attributed to U Jürgens.

14 recordsLinked to original sources
PubMed1992

Brain stimulation-induced changes of phonation in the squirrel monkey.

In 11 squirrel monkeys (Saimiri sciureus), the brain stem was systematically explored with electrical brain stimulation for sites affecting the acoustic structure of ongoing vocalization. Vocalization was elicited by electrical stimulation of different brain structures. A severe deterioration of the acoustical structure of vocalization was obtained during stimulation of the caudoventral part of the periaqueductal grey, lateral parabrachial area, cortico-bulbar tract, nucl. ambiguus and surrounding reticular formation, facial nucleus, hypoglossal nucleus, solitary tract nucleus and along the fibres crossing the midline at the level of the hypoglossal nucleus. It is suggested that these structures are part of, or at least have direct access to, the motor coordination mechanism of phonation. Complete inhibition of phonation was obtained from the raphe and raphe-near reticular formation.

Animals↗
PubMed1992

Postmortem concentrations of phenytoin in different regions of the brain and in the serum: analysis of autoptic specimens from 24 epileptic patients.

Postmortem concentrations of phenytoin (PHT) were determined by high-performance liquid chromatography in the serum (total and free) and in specified areas of the brain (frontal, temporal, occipital cortex and white matter, as well as cerebellum) of 18 epileptic patients who died following chronic diseases (group A) and of six otherwise healthy epileptic patients who died suddenly and unexpectedly (group B). The free concentrations in the serum correlated considerably better (r = 0.987) than the total concentrations in the serum (r = 0.871) with the concentrations in the frontal cortex. The concentrations in the frontal cortex were about nine times that of the free serum concentrations. The data show that the PHT concentrations in the frontal, temporal and occipital cortex largely agree. The concentrations in the white matter were significantly higher (frontal region 54%, temporal region 30%, occipital region 36%) than in the cortex. The concentrations in the cerebellar hemisphere (neocerebellum) were nearly identical with those in the frontal cortex. Regression analysis showed that on comparable total serum concentration the patients of group A had significantly higher free serum concentrations and significantly higher concentrations in the frontal cortex than the patients of group B. In respect of the concentration ratios cortex to serum free and in regard of the local distribution of PHT in the brain no difference, however, was found between those patients who died from chronic diseases and those who died suddenly.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Vocalization-correlated single-unit activity in the brain stem of the squirrel monkey.

The brain stems of 17 squirrel monkeys (Saimiri sciureus) were systematically explored for vocalization-related single-unit activity during calls electrically elicited from the periaqueductal grey. Of 12,280 cells tested, 1151 fired in relation to vocalization. Of these, 587 reacted to external acoustic stimuli and started firing after vocalization onset. As most of these cells were located in classical auditory relay structures, they probably represent auditory neurones reacting indirectly to self-produced vocalization due to auditory feedback. Seven cells reacted to acoustic stimuli but fired in advance of self-produced vocalization. These cells were located in the pericentral inferior colliculus, dorsal nucleus of the lateral lemniscus, dorsomedial to the ventral nucleus of the lateral lemniscus and immediately lateral to the central grey. They are probably engaged in tuning the auditory system to process self-generated sounds differently from external sounds. 261 neurones reacted to nonphonatory oral movements (chewing, swallowing) and started firing after vocalization onset. These neurones were widely distributed within the brain stem, with the highest density in the spinal trigeminal nucleus and medially adjacent reticular formation. The majority of these cells seem to react to proprioceptive and tactile stimuli generated by phonatory and nonphonatory oral activities. Some of them may exert motor control on muscles that come into play at later stages of phonation. 57 neurones reacted to nonphonatory oral movements but fired in advanced of vocalization onset. These neurones were located mainly in the trigeminal motor nucleus, nucl. ambiguous, reticular formation around these nuclei, parabrachial region and lateral vestibular nucleus. Their role in motor control seems to be related to specific muscles rather than specific functions. 100 of the vocalization-related cells showed a correlation with respiration. Expiration-related cells were found in and around the rostral nucl. ambiguous and in the reticular formation dorsal to the facial nucleus. Inspiration-related cells were located in the rostral and caudal nucl. ambiguous regions, ventrolateral solitary tract nucleus and the lateral reticular formation below the trigeminal motor nucleus. Most of these cells probably represent premotor neurones of respiratory muscles and laryngeal motoneurones of the cricothyroid and posterior cricoarytenoid muscles. Finally, a last group of cells was found that was unresponsive to chewing and swallowing movements, quiet breathing and acoustic stimuli, but changed activity during vocalization. 38 of them became active before vocalization and cricothyroid activity, and 101 afterward.(ABSTRACT TRUNCATED AT 400 WORDS)

Acoustic Stimulation↗
PubMed1991

Respiratory muscle activity during vocalization in the squirrel monkey.

In order to find out which muscles are involved in the respiratory component of primate phonation, the activity of 17 abdominal and thoracic muscles was recorded during vocalization in the squirrel monkey. Vocalization-correlated activity was found in the musculi obliquus externus et internus, rectus et transversus abdominis, intercostalis externus et internus and intercartilagineus. It was lacking in the mm. iliocostalis, latissimus dorsi, longissimus dorsi rhomboideus, serratus posterior superior, trapezius, splenius capitis, sternocleidomastoideus, scalenus medius and pectoralis major. There was simultaneous activation of the rib-raising external and rib-lowering internal intercostal muscles during most vocalizations. It is hence concluded that the intercostals, rather than supporting expiratory efforts, serve to stabilize the thorax, thus providing an anchorage against which the abdominal muscles can act.

Abdominal Muscles↗
PubMed1991

[Effectiveness of bromide in therapy resistant epilepsy of dogs].

In therapy lasting between 8 and 79 (means = 31) months 22 epileptic dogs had been unsuccessfully treated with phenobarbital and/or primidone. Both drugs had been administered in their maximum dosages. In an add-on therapy, these dogs were given potassium bromide at a rate of 17 to 58 mg/kg daily for a period of 7 to 61 (means = 21) months. We could quantitatively evaluate the seizure data from 19 of the dogs: four became free of seizures; seven showed a greater than 50% reduction in seizure frequency; in two dogs, the seizures were reduced by greater than 50% but the number of seizure-days by less than 50%; in the remaining six dogs the therapy was unsuccessful. We achieved the best therapeutic results in animals that suffered only grand mal seizures. Grand mal in addition to other types of seizures and tonic seizures were affected to a lesser extent if at all. At the beginning of the therapy we saw temporary side effects--weakness in the hind limbs and sedation; these were temporary and dependent on the dosage. Serum concentrations differed even with the same dosage among individual dogs. The therapeutic range of bromide serum concentration was from 0.7 to 2.0 mg/ml. Most of the animals tolerated concentrations up to 1.5 mg/ml quite well. To begin an add-on therapy with potassium bromide we would recommend a daily dose of 30 to 40 mg/kg. During treatment, the dose should be determined for each individual dog.

Animals↗
PubMed1979

Role of the periaqueductal grey in vocal expression of emotion.

In 32 squirrel monkeys (Saimiri sciureus) the role of the periaqueductal grey has been investigated by combined stimulation/lesioning and by neuroanatomical experiments. The results are as follows. Firstly, periaqueductal lesions invading the laterally adjacent tegmentum abolish species-specific calls elicitable by electrical brain stimulation. This holds for stimulation sites rostral as well as caudal to this area. The only vocalizations which survive are phonations of an artificial character which can be evoked from the lateral medulla. Spontaneous vocalizations also seem to be abolished. Secondly, vocalizations elicited from the periaqueductal grey are not affected by bilateral lesions in vocalization-eliciting areas rostral to it, but are abolished by lesions in the dorsolateral pons and ventrolateral medulla. Thirdly, the periaqueductal grey receives direct projections from all vocalization-eliciting areas tested, viz. the precallosal cingulate gyrus, gyrus rectus, medial amygdata, central amygdaloid nucleus/substantia innominata, nucleus striae terminalis, dorsal hypothalamus, midline thalamus, periventricular grey, dorsolateral and ventrolateral midbrain tegmentum. Fourthly, the periaqueductal grey projects directly to the nucleus ambiguus, the site of the laryngeal motoneurones. The course of the main bulk of fibres corresponds to the lesion sites effective in abolishing periaqueductally elicited vocalizations. From these results, it was concluded that the caudal periaqueductal-lateral tegmental area is a necessary relay station for all external and internal stimuli capable of inducing species-specific calls. Its position within the stimulus-response loop seems to be on the output side, immediately above the level of motor-corrdination but below that of stimulus recognition.

Animals↗
PubMed1979

The cingular vocalization pathway in the squirrel monkey.

In 39 squirrel monkeys (Saimiri sciureus), the effects of various brain lesions on vocalizations elicited from the precallosal cingulate gyrus were tested. It was found that lesions abolishing the "cingular vocalization" completely can be traced from the stimulation site continuously down to the laryngeal motoneurons in the nucleus ambiguus. The pathway thus determined (Fig. 4) travels from the precallosal cingulate gyrus through the frontal white matter and enters the internal capsule from a dorsolateral position. The pathway then follows this structure in a medio-caudal direction down to the caudal diencephalon. Here, the effective lesions leave the corticospinal tract and ascend dorsally into the periaqueductal grey. The pathway follows this structure to its end where it sweeps lateral through the parabrachial area and then descends through the lateral pons and ventrolateral medulla to the nucleus ambiguus. In nine of the animals, in addition, the effects of bilateral anterior cingular lesions on vocalizations elicited in other brain areas were tested. It was found that the only vocalization-eliciting area which becomes ineffective after destruction of the anterior cingulate gyrus is the postero-medial orbital cortex.

Animals↗
PubMed1977

The effect of superior temporal lesions on the recognition of species-specific calls in the squirrel monkey.

Eleven squirrel monkeys (Saimiri sciureus) were trained to discriminate species-specific calls from non-species-specific complex sounds in a go, no-go procedure with social contact as positive reinforcement. The task required that the animals not only responded to a particular call but that this response should be generalized to any squirrel monkey call, whether or not it had been presented previously in training. After having reached a performance level of 75% correct responses in three consecutive sessions, seven animals received bilateral lesions of the auditory cortex; the other four animals served as controls. It was found that small lesions within the superior temporal gyrus did not interfere with the discrimination task. Lesions destroying about three quarters of the auditory cortex led to loss of retention; during retraining the animals did not reach criterion, but performed significantly above chance. These animals were able, however, to master a simplified version of the task where one species-specific call had to be discriminated from one non-species-specific sound. Animals with almost total ablation of the auditory cortex were capable of mastering neither the generalized task nor the simplified version. From these results, together with those of the literature, it is concluded 1) that recognition of complex sounds is not possible after complete auditory cortex ablation, probably because of interference with gestalt-formation processing, and 2) that species-specific calls are processed in the auditory system in the same way as other complex sounds.

Agnosia↗
PubMed1977

Convergent projections of different limbic vocalization areas in the squirrel monkey.

The projections of four different sub-areas within the anterior limbic cortex, all yielding vocalization when electrically stimulated, were compared in six squirrel monkeys by the autoradiographic tracing technique. Areas of convergence of the projections from all four vocalization loci were the cortex within the anterior cingulate sulcus, a zone following the inferior thalamic peduncle from the central amygdaloid nucleus through the substantia innominata into the midline thalamus, a second zone following the periventricular fibre system from the anterior diencephalon to the caudal midbrain and dorsolateral pontine tegmentum and, finally, the tail of the caudate nucleus. Except for the latter, all of these brain structures produce vocalization when electrically stimulated. The call types elicitable from these projection areas are sometimes different from those elicitable from the anterior limbic cortex. It is hypothesized that the anterior limbic cortex controls vocalization directly, independently of the specific motivational state underlying it.

Animals↗
PubMed1976

[On the evolution of voice (author's transl)].

The paper gives a short survey of the phylogenetic development of the laryngeal and supralaryngeal apparatus from amphibians to man. The increasing differentiation of vocal behaviour, paralleling the differentiation of the vocal apparatus, is outlined and special reference is made to the non-verbal component in human language. It is stressed that animal vocal repertoires can be extremely rich, but in contrast to human verbal behaviour they are generated almost exclusively by laryngeal modulations and only to a minimal degree by supralaryngeal activity (i.e. articulation). A phylogenetic development can also be seen in the cerebral organization of vocal behaviour. In amphibians, reptiles and lower mammals, the dorsal midbrain-pons transitional zone seems to be the only area responsible for the production of vocal utterances. This area probably serves in integrating vocal fold movements, expiration, intra- and extra-oral muscle activity into species-specific vocal patterns; its destruction results in mutism. In higher mammals, including man, this area does not lose its original function but is brought under the control of the cortex around the anterior sulcus cinguli (supplementary motor area and anterior cingulate gyrus). The latter seems to play an essential role in the initiation of vocal utterances in situations which do not have a rigid stimulus-response characteristic, i.e. in voluntary vocal behaviour. The highest level of voice production, finally is represented by the cortical face area, the destruction of which is without consequence to the innate vocal behaviour of animals but produces dysarthria in man. This area (together with its associated structures, such as the cortex-pontine nuclei-cerebellum-thalamus-cortex circuit) seems to be essential for the production of verbal or, more generally, learned vocal behaviour.

Amphibians↗
PubMed1976

Reinforcing concomitants of electrically elicited vocalizations.

In 38 squirrel monkeys 251 vocalization-producing electrode positions were tested for their positive and negative reinforcing properties. Two groups of vocalization-producing brain areas could be distinguished: One group in which the electrically elicited vocalization was independent of the accompanying reinforcement effect, and a second group in which vocalization and reinforcement effect were correlated. The first group included the anterior cingulate gyrus, the adjacent supplementary motor area, gyrus rectus, ventromedial edge of the capsula interna, caudal periaqueductal gray and adjacent parabrachial region. The second group consited of the caudatum, septum, substantia innominata, amygdala, inferior thalamic peduncle, stria terminalis, midline thalamus, ventral and periventricular hypothalamus, substantia nigra, rostral periaqueductal gray, dorsolateral midbrain tegmentum and lateral medulla. It is hypothesized that the first group contains predominantly or exclusively "primary" vocalization substrates; the second group is thought to be composed mainly of structures whose stimulation yields vocalization secondarily due to stimulus induced motivational changes.

Animals↗
PubMed1976

Projections from the cortical larynx area in the squirrel monkey.

The projections from the cortical vocal fold area were studied in five squirrel monkeys (Saimiri sciureus) with the aid of the autoradiographic tracing technique. The location of the cortical vocal fold area was determined by exploring the exposed frontal cortex with roving electrodes while examining the larynx for vocal fold adduction. The following projections were found: To the orbital cortex (area 11), dorsomedial frontal cortex (areas 6 and 8), Broca's area (area 44), lower fronto-parietal cortex (areas 6, 4, 3 and 1), fronto-parietal operculum (area 50), insula (areas 14 and 13), caudatum, putamen, claustrum nucl. reticularis th., nucl. ventralis anterior, nucl. ventralis lateralis, nucl. ventralis posteromedialis, nucl. centralis inferior, nucl. centralis lateralis, nucl. medialis dorsalis, nucl. pulvinaris medialis, griseum pontis, nucl. parabrachialis medialis and lateralis, nucl. tr. spinalis n. trigemini and nucl. tr. solitarri. A comparison of the projection system with a previous mapping study for vocalization (Jürgens and Ploog, 1970) revealed that there are two areas yielding vocalization when electrically stimulated which receive direct projections from the cortical larynx area, namely, the cortex around the anterior sulcus cinguli and the parabrachial nuclei at the pons-midbrain transition. The possible relevance of these structures for vocalization is discussed.

Afferent Pathways↗
PubMed1976

Projections from the 'cingular' vocalization area in the squirrel monkey.

In 5 squirrel monkeys the anatomical projections from the 'cingular' vocalization area were studied by the autoradiographic tracing technique. The 'cingular' vocalization area lies around the sulcus cinguli at the level of the genu of the corpus callosum; its electrical stimulation yields purring and cackling calls. The following efferent connections were found: corticocortical fibers could be traced into the orbital cortex (areas 10 and 11), dorsomedial frontal cortex (areas 9, 8 and 6), limbic cortex (areas 25, 24 and 23), Broca's area (area 44), frontal operculum (area 50), insula (areas 13 and 14), and auditory association cortex (area 22). Subcortical terminal fields within the telencephalon were found in the nucleus caudatus, putamen, claustrum, globus pallidus, olfactory tubercle, preoptic region and nucleus centralis and basolateralis amygdalae. Fibers reached most of these structures along different trajectories. In the diencephalon terminal fields lay in the dorsal hypothalamus, the subthalamus, lateral habenular nucleus, and the following thalamic nuclei: nucleus reticularis, ventralis anterior, centralis medialis, centralis superior lateralis, centralis inferior, submedius, medialis dorsalis and centrum medianum. In the midbrain, the periaqueductal gray was the only projection area, extending into the parabrachial nuclei at the pontomesencephalic transition. The most caudal terminal field was found in the medial pontine gray. No terminals were detected in the nucleus ambiguus, nucleus n. hypoglossi or in any other cranial motor nucleus involved in phonation processes. A comparison of this projection system with the whole of structures producing vocalization when electrically stimulated yielded only partial overlap. Not all vocalization areas lie within the 'cingular' projection system, and inversely, not the whole projection system yielded vocalization. Overlap took place in the anterior limbic cortex, preoptic region, central amygdaloid nucleus, midline thalamus, dorsal hypothalamus, periaqueductal gray and parabrachial nuclei. These structures are considered to compose a functionally coherent vocalization system. The projections into Broca's area, nucleus ventralis anterior thalami, frontoopercular cortex within the lateral fissure, pontine nuclei and superior temporal gyrus are discussed in their possible relationship to vocalization processes.

Animals↗