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Biomedical subjects

F H Duffy

Publications and source records attributed to F H Duffy.

At least 91 records · Page 5Linked to original sources
PubMed1975

Eye movement-related inhibition of primate visual neurons.

The influence of saccadic eye movements (EM) upon spontaneous neuronal activity was studied in the lateral geniculate nucleus (LGN) and striate visual cortex (VC) of encéphale isolé monkeys. EM were spontaneous and occurred in total darkness to eliminate the effects of retinal image displacement. The activity of LGN cells was not altered in association with EM. In contrast, 76% of cells studied in VC displayed a period of inhibition related to spontaneous EM in total darkness. EM-related inhibition of VC neurons was directionally specific; for each cell there was one quadrant of EM direction for which inhibition was most prominent. The majority of VC neurons showed inhibition in relation to EM directed into only one quadrant of the visual field. Reliable detection of EM-related inhibition required the formation of average histograms of neuronal firing time-locked to EM. For individual EM (even of optimum direction), a consistent degree of inhibition was not seen. The time course of EM-related inhibition of VC neurons is consistent with that reported for saccadic suppression. These results support the concept of a central mechanism (corollary discharge) acting at the cortical level being of significance in saccadic suppression.

Action Potentials↗
PubMed1971

Somatosensory system: organizational hierarchy from single units in monkey area 5.

The receptive fields of single cells in area 5 of monkey parietal cortex were studied by extracellular recording. Cells were driven primarily by gentle manipulation of multiple joints residing on one or more limbs. Both excitatory and inhibitory convergence were demonstrated. It is postulated that the multijoint receptive fields of area 5 are the result of convergence from single-joint cells of the primary receiving area. An analogy is drawn between the modification of information in the visual and somatosensory systems.

Animals↗
PubMedDate not supplied

The pattern of age-related differences in electrophysiological activity of healthy males and females.

Age-related differences in quantified electrophysiological measures were examined in 202 subjects (109 females; 93 males) ages 30-80 all of whom were judged to be optimally healthy on a wide variety of criteria. The study utilized both absolute and relative measures from EEG spectral analysis as well as additional measures from long latency-evoked potentials. The same findings were noted for the 109 newly studied females as were reported for 63 previously studied male subjects. Results indicate that there is a broad trend for decreased EEG slow and increased fast activity with age, however, some of the measures change linearly and others are best represented by nonlinear functions. There is no decade where activities remain stable. Overall the pattern of change for males and females is similar, however, gender differences in both the EEG and EP data were present. The females had higher magnitudes for almost all absolute spectral and fast relative spectral measures. However, females demonstrated lower absolute alpha amplitude, lower relative slow activity, and lower late-latency EP data. Moreover, the absolute slow activity measure showed a gender X age interaction, indicating that the females had a different change in pattern of activity with increasing age than the males. Thus, gender-related findings were complex and could not be expressed as simple differences in overall amplitude. Age-related change is not a simple linear process but differs for differing EEG spectral bands, relative, and absolute spectral measures and for males and females. The overall findings contradict the common wisdom that EEG and alpha slow with age and that age related EEG change is on a continuum with findings in Alzheimer's disease where increased slowing predominates.

Adult↗