Search PubMed⌕ Search

Biomedical subjects

G L Humphrey

Publications and source records attributed to G L Humphrey.

16 recordsLinked to original sources
PubMed1981

Effects of changes in cortical arousal and of auditory cortex cooling on neuronal activity in the medial geniculate body.

The activity of cells in the medial geniculate body (MGB) of adult cats was recorded during different states of cortical arousal with and without cooling of the auditory cortex. In the absence of auditory cortex cooling, the overall mean unit spontaneous discharge rate was 49% higher during desynchroized Electrocorticogram (ECoG) periods (high cortical arousal). Responses to sound were somewhat more prominent vis-à-vis the spontaneous activity during periods of high arousal. Changes in spontaneous discharge rate associated with arousal shifts were significantly reduced during auditory cortex cooling. When the ECoG changed from desynchronized to synchronized activity, MGB cells showed a change in discharge pattern, typically characterized by an increase in both high-rate bursts and long-interval pauses. These changes were duplicated for most cells by cooling of the auditory cortex. Corticofugal fiber discharge thus has an effect on MGB neuronal activity which is dependent on the level of cortical arousal. This effect is most likely a result of direct corticogeniculate activity, though indirect auditory cortex - brainstem - MGB routes may also be involved.

Animals↗
PubMed1979

Association between raw milk and human Salmonella dublin infection.

Between 1971 and 1975 the mean annual incidence of human Salmonella dublin infection in California increased more than five-fold. Investigation of the increase showed an association with exposure to raw milk in 44 out of 113 cases. Of these 44 patients, 35 had used certified raw milk from a single dairy. Faecal swabs confirmed S dublin infection in the dairy herd and the milk, and so a pasteurisation order was issued. S dublin appears to be an unusually invasive and life-threatening salmonella serotype: 65% of isolations were obtained from non-faecal specimens (mainly blood cultures), 89 patients (80%) were admitted to hospital and 22 patients died. Almost three-quarters of the patients were aged 20 or over, and half had serious underlying diseases, particularly leukaemias and lymphomas. Five patients presented with infected vascular lesions that included aneurysms with abscesses and infections of previous arterial graft sites. The public's increasing desire for a "health food" such as raw milk should be tempered with an appreciation of its attendant risk to health.

Adolescent↗
PubMed1972

Response decrements in the cochlear nucleus of decerebrate cats during repeated acoustic stimulation.

In the cochlear nucleus of decerebrate, paralyzed cats, multiple-unit responses to an acoustic stimulus showed significant decrements when the stimulus was repeatedly presented once every 5 seconds. These decrements developed in the absence of peripheral receptor adaptation. The responses recovered to the level prior to stimulation when stimulation was withheld for 5 to 10 minutes. Dishabituation by somatic stimulation of the forepaw, however, was less effective than in the intact cat. The continued development of response decrements after strychnine blockade of peripheral olivocochlear influences and central postsynaptic inhibition suggests a mechanism of decreased synaptic effectiveness, which has previously been postulated for neuronal habituation in brainstem and spinal cord.

Animals↗
PubMed1968

Epidemiology of leptospirosis in California: a cause of aseptic meningitis.

Twenty-one cases of leptospirosis, including three that were fatal, were reported in California during 1961-1965. An additional 18 cases were detected for the same period by screening sera from patients with central nervous system (CNS) disease of suspected viral origin. This finding supports a hypothesis that leptospirosis frequently is not considered in the differential diagnosis of CNS disease in which viral infection is suspected. The 39 patients, six of them females, ranged in age from six to 66 years. Most infections occurred in the summer. A history of exposure to animals or of swimming in potentially contaminated waters was obtained from 32 of the 39.

California↗
PubMedDate not supplied

Removable, conforming device for cooling the cortical surface.

A technique for cooling the cerebral cortex is described. It makes use of a neoprene bladder through which cold fluids is circulated. The flexible bladder is contained within a cylinder permanently attached to the skull. The bladder itself can be quickly installed and removed and conforms to the cortical surface with minimal pressure.

Animals↗