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Biomedical subjects

R C Frysinger

Publications and source records attributed to R C Frysinger.

25 records · Page 2Linked to original sources
PubMed1983

Interaction between motor commands and somatosensory afferents in the control of prehension.

In 1931, Hughlings Jackson made a distinction between voluntary and automatic movements. According to Jackson the former are varied and purposeful gestures, whereas the latter include stereotyped movements largely under immediate sensory control. In this regard it may be said that the motor function of the primate hand includes both voluntary as well as automatic responses. Phillips and Porter (1977) noted that injury to the nervous system may often disrupt tactile exploration and skilled manipulation, although the same lesion may fail to interfere with automatic prehension used in posture and locomotion. The effects of selective brain destruction as well as the results from single-cell recordings from moving animals have indicated some of the different contributions made by various parts of the cerebello-thalamo-cortical motor system. Prehension offers a unique opportunity in which the interactions between motor commands and somatosensory afferents may be studied.

Afferent Pathways↗
PubMed1982

Multiple unit activity recorded from amygdala central nucleus during Pavlovian heart rate conditioning in rabbit.

Using a Pavlovian heart rate conditioning paradigm, a rapid development of short latency increases in the multiple unit activity of the amygdala central nucleus were observed in response to a tone conditioned stimulus. In some cases the increase in multiple unit response showed a parallel development with the conditioned decelerative heart rate response and were significantly correlated with it. These results suggest a direct role for the central nucleus in the expression of conditioned heart rate responding in rabbit.

Amygdala↗
PubMed1980

beta-Adrenergic manipulation in amygdala central n. alters rabbit heart rate conditioning.

The present study was conducted to assess the effects of beta-adrenergic manipulation within the central nucleus of the amygdala on Pavlovian heart rate conditioning in the rabbit. Administration of the beta-adrenergic antagonist dl-propranolol into the central nucleus impaired the acquisition of conditioned heart rate responding compared to a vehicle injected control group. No significant effects of dl-propranolol on either baseline heart rate or on the heart rate orienting response were observed. The effect of dl-propranolol on conditioning exhibited stereospecificity, and animals receiving combined intracerebral injections of dl-propranolol and the beta-adrenergic agonist 1-isoproterenol did not exhibit comparable conditioning impairments. In addition, dl-propranolol administration dorsal to the central nucleus or into amygdala sites anterior or posterior to the central nucleus was less effective. These results support the interpretation that beta-adrenergic activity within the central nucleus region of the amygdala complex contributes to the acquisition of classically conditioned heart rate responding.

Amygdala↗
PubMed1978

Alcohol influence on hemisphere differences and signal detection thresholds.

Six right- and six left-handed subjects were run in a repeated measures design to determine the influences of alcohol on hemiretina detection thresholds. Stimuli were presented tachistoscopically to the hemiretinae at blood alcohol concentrations (BACs) of 0, 50, and 100 mg%. The nasal hemiretinae had higher thresholds than the temporal hemiretinae and this difference was independent of alcohol. Alcohol interacted with visual field and handedness. The results showed that the highest alcohol dose (100 mg%) raised detection thresholds more for the hemifield contralateral to the subject's preferred hand than the ipsilateral hemified. Results are discussed in terms of lateral dominance and attention.

Adolescent↗
PubMedDate not supplied

Correlation of unit recordings with regional cell counts in epileptogenic human temporal lobe.

The previously reported diminished incidence of neuronal activity recorded from areas ipsilateral to a seizure focus may result from either cell loss or pathophysiologic changes in hippocampus and related structures. We examined records of single-cell discharge from 471 electrode bundles in 62 patients who later had cell counts taken from samples of resected tissue. Analysis of variance showed that amygdala and parahippocampal gyrus had more activity than hippocampus and the subicular complex and that the resected side had less activity overall. Only the posterior subicular complex showed more high-amplitude (> 50 microV) activity on the epileptogenic side; all other areas showed more activity contralaterally. Activity between 25 and 50 microV did not differ across sides or structures. Percentage of maximal cell count was correlated with the number of electrodes with high-amplitude activity only in the subicular complex. Low-amplitude activity in nonresected hippocampus, however, was strongly negatively correlated with cell counts on the resected side, perhaps owing to compensatory mechanisms. Cell counts in hippocampus correlated negatively with high-amplitude unit activity in resected amygdala, suggesting reciprocity between these areas. These results suggest that the amount of cell activity recorded from mesiotemporal structures involves bilateral factors more complex than simple cell loss.

Amygdala↗
PubMedDate not supplied

Cardiac and respiratory correlations with unit discharge in epileptic human temporal lobe.

We recorded respiratory activity and electrocardiogram (ECG) together with single cell activity from the amygdala and hippocampus of epileptic patients who later received anterotemporal lobectomy. Cross-correlation histograms were used to test for neuronal discharge timing relationships with inspiration or ECG. Linear regression was used to test for correlations of inspiratory time, respiratory period, and heart rate (HR) with tonic unit rate for each breath. Of 129 cells from 16 patients who later had resection, 89 were contralateral and 40 were ipsilateral to the resected lobe. Of the contralateral cells, 19% had a timing relationship with the cardiac cycle and only 1% had such a relationship with the respiratory cycle. Tonic correlations with HR were noted in 22% and with respiratory period and inspiratory time in 11 and 6%. Neither these percentages nor mean discharge rate differed between structures, although variance in rate was much higher on the resected side. Amygdala cells on the resected side showed more correlations with the cardiac cycle (55 vs. 20%), respiratory period (46 vs. 3%), and inspiratory time (27 vs. 7%) and were more likely to show several types of correlation. The results suggest a selective loss of ipsilateral amygdala cells and/or afferents, favoring relationships with cardiac- and respiratory-related systems and a possible synaptic reorganization of remaining cardiorespiratory afferents.

Cardiovascular System↗