Biomedical subjects

C M Braun

Publications and source records attributed to C M Braun.

43 records · Page 3Linked to original sources

PubMed1983

Effects of brainstem lesions on tonic immobility in the rabbit (Oryctolagus cuniculus).

Lesions were placed in discrete brainstem areas implicated in the generation of both tonic immobility (T1) and paradoxical sleep (PS) to examine postulated state and event correspondences between these states in the rabbit. Lesions were concentrated in the region of the nucleus locus coeruleus (LC)-an area implicated in the mediation of muscular atonia during PS-but also included other reticular (pontine gigantocellular tegmental field: FTG), and nonreticular (vestibular, cerebellar, central grey, collicular) areas. Polygraphic recordings of EEG, EMG and EOG activities were taken during sleep-waking states and measures of the TI response were obtained before (1 day prior) and after (5 and 14 days) lesions were made. None of the lesions was followed by a sustained, significant variation in either frequency of induction or duration of TI. Following LC lesions, and to a lesser extent after FTG lesions, sleep patterns were fragmented, with a reduction or absence of PS and the occurrence of phasic motor activation at times when PS periods might be expected to occur. The absence of PS and persistence of TI following specific brainstem lesions indicate a fundamental difference in mechanisms underlying these states. It is suggested that a major determinant of these results is the activation of phasic activity during PS but not TI, and that the possibility remains that both states may share a common mechanism of tonic motor control.

Animals↗

PubMed1981

Effects of locus coeruleus lesions upon sleeping and waking in the rabbit.

The effects of radiofrequency lesions in the region of the locus coeruleus (LC) upon sleep--waking states and behaviors were investigated in chronically implanted New Zealand White rabbits. Polygraphic recordings were taken prior to and at 5- and 14-day intervals following lesioning. In animals exhibiting absence of paradoxical sleep and the presence of bizarre motor behavior, additional recordings were taken 30 days postlesion. Prelesion sleep-wakefulness pattern data were comparable to those previously observed in intact rabbits, including the recently reported absence of sustained PS-related nuchal muscle atonia. Lesions histologically localized to the area of the locus coeruleus were of two types, i.e., those effecting bilateral destruction of greater than or equal to 80% (n = 11) or 30-50% (n = 11) of the LC. A transient period of inactivity was present immediately following lesioning, but by two weeks postlesion animals had generally regained normal waking behavioral and physiological functioning, e.g., eating, drinking and grooming behaviors had returned and respiration, micturition and general urological functioning were normal. The more extensive LC lesions were followed by increases in the proportion of total recording time spent in wakefulness, but primarily in quiet rather than active wakefulness. Sleep was fragmented by phasic muscular activation in proportion to the amount of LC destroyed. In animals with the most extensive lesions, slow wave sleep was interrupted by brief, abrupt episodes of twitching, and episodes of marked phasic muscular activation, often violent in nature, occurred following periods of slow wave sleep. The postlesion occurrence of PS was inversely related to the degree of LC destruction and, accordingly, to the presence of episodes of phasic motor activation. These results did not confirm earlier reports in other species implicating the LC in urogenital functioning and respiration, but do corroborate previous findings indicating that neural elements in the LC regions are essential to the integrity of sleep and are especially important to the control of motor mechanisms during sleep.

Animals↗

PubMedDate not supplied

Refutation of Poffenberger's inference: an existence proof and a countermodel.

Interhemispheric relay time (IHRT) is inferred from simple (visual) reaction time (SRT) by subtracting SRTs in ipsilateral hand-field conditions from SRTs in contralateral hand-field conditions. This index, the "crossed-uncrossed differential" (CUD) is a synonym of IHRT in the current literature. The CUD has been shown to be significantly moderated by experimental variables, including attentional. One reason the CUD = IHRT hypostasy persists today is that no experimental manipulation has yet been able to generate a significantly negative CUD in a subject manifesting a significant positive CUD in classical conditions. We implemented an experimental manipulation, in SRT, consisting of increasing complexity of the response after the initial key press required at detection. In a very large scale single-case experiment, we found that the CUD thus went from significantly positive in classical SRT to significantly negative in the increased response load condition.

Attention↗

PubMedDate not supplied

Prevalence, and intellectual outcome of unilateral focal cortical brain damage as a function of age, sex and aetiology.

Neurologists and neuropsychologists are aware that aging men are more at risk than women for brain damage, principally because of the well known male-predominant risk for cardiovascular disease and related cerebrovascular accidents. However, a disproportion in prevalence of brain damage between the sexes in childhood may be less suspected. Furthermore, sex-specific risk for other aetiologies of brain damage may be little known, whether in the pediatric or adult populations. Proposals of a sex difference in cognitive recovery from brain damage have also been controversial. Six hundred and thirty five "consecutive" cases with cortical focal lesions including cases of all ages and both sexes were reviewed. Aetiology of the lesion was determined for each case as was postlesion IQ. Risk was highly male prevalent in all age groups, with a predominance of cardiovascular aetiology explaining much of the adult male prevalence. However, several other aetiological categories were significantly male prevalent in juveniles (mitotic, traumatic, dysplasic) and adults (mitotic, traumatic). There was no sex difference in outcome (i.e., postlesion IQ) of these cortical brain lesions for the cohort as a whole, after statistical removal of the influence of lesion extent, aetiology and presence of epilepsy. Mechanisms potentially responsible for sex differences in prevalence, aetiology of brain damage, and recovery, are reviewed and discussed.

Adolescent↗

PubMedDate not supplied

Does severe traumatic closed head injury impair sense of humour?

It is now known that closed head injury (CHI) impairs interpersonal skills, disturbs and/or blunts mood and compromises emotional discriminativeness. This study tried to test whether sense of humour is also impaired or disturbed following CHI. Subjects were 42 CHI patients and 42 normal controls, matched for age, education and paternal occupation. Humour performance measures included time taken to rank jokes according to funniness and to classify them, stability of funniness rankings at re-test and ability to correctly classify jokes into 'mutilated' and 'intact' categories. Non-performance measures included total number of non-verbal vocalizations, and mean percentage of appreciation of the jokes. The CHI patients were highly significantly impaired on all aspects of performance but did not differ from the normals on non-performance measures. However, when vocabulary (WAIS-R) was co-varied out of the analyses only time to rank funniness remained significant. The results were interpreted to suggest a severe impairment of sense of humour, an important cause of which is a narrow lexicon, poor lexical semantic processing, or some other reading dysfunction, some of which probably antedated the CHI. It was concluded that measures of humour, vocabulary, and of pure affective performance such as prosodic and/or facial emotion discrimination could contribute to the rehabilitation process in severe CHI.

Adolescent↗

PubMedDate not supplied

Processing of pragmatic and facial affective information by patients with closed-head injuries.

Although several affective impairments have been demonstrated to occur following closed-head injury (CHI), deficits of the communicative function of language, particularly sentenial and suprasentential pragmatic aspects, have been suggested, but not demonstrated, to occur. This study compared 31 normals and 31 severely closed-head injured patients matched for age, sex and education. The dependent measures consisted of a facial test of emotion (FTE) and a contextual test of emotion (CTE). The former task consisted of 36 slides representing facial expressions of the six emotions demonstrated by Ekman and colleagues to be transcultural, namely, job, sadness, fear, anger, surprise and disgust. The subject was required to name the appropriate emotion for each slide. The latter task consisted of correctly identifying the appropriate emotion for each of 36 brief verbal narratives representing contexts connotative of the same six transcultural emotions. The CHI patients were impaired overall on the FTE but not the CTE. However, the ability to identify anger was significantly impaired on both tasks when considered in isolation from the other emotions. It was concluded that a processing deficit of primary emotional material, particularly anger, does exist following CHI, but that this deficit is not necessarily independent of task and/or modality parameters. It was also concluded that evidence of a pragmatic deficit of the language function following CHI remains to be provided at this time.

Adult↗

PubMedDate not supplied

[Hypothalamic hamartoma: detailed presentation of a case].

We describe a seven year old child with a hypothalamic hamartoma. Classical symptoms of hypothalamic hamartoma include gelastic epileptic laughter, precocious puberty, aggressiveness, and progressively worsening epilepsy. After a normal first few years of life, this case presents all these symptoms except the precocious puberty. He has a markedly morbid personality disorder: he assaults strangers and relatives, bites people, spits in their faces unpredictably, is coprolalic and coprophagic, has gelastic laughter, puts pencils, erasers, and other non-comestible objects in his mouth, chews and ingests them, has tics (plays noisily with his saliva, empty chewing, compulsive spitting) and is self-injurious. None of the medications attempted to date have been of any help. Medical prognosis is somber, and this case is difficult to institutionalize, the more "congenial" institutions being insufficiently equipped to protect him and the beneficiaries and staff from his aggressive behavior. MRI showed the typical profile of hypothalamic hamartoma, and the diagnosis was confirmed with partial resection. This case illustrates that a tiny lesion, the size of a small cherry, can have extremely morbid psychological consequences. Detailed neuropsychological evaluation, certain unusual electroencephalographic traits and neurosurgical issues are discussed.

Child↗