Biomedical subjects

D F Sisson

Publications and source records attributed to D F Sisson.

5 recordsLinked to original sources

PubMed1993

Augmenting and reducing of visual evoked potentials in Roman high- and low-avoidance rats.

Human and cat high sensation seekers tend to show increasing amplitudes (augmenting) of the P1 and N1 components of the visual evoked potential (VEP) to increasing intensities of light flash, whereas low sensation seekers show VEP reducing. Roman high-avoidance (RHA) and Roman low-avoidance (RLA) rats have behavioral traits comparable to human and cat high and low sensation seekers, respectively. RHA rats show greater exploration, activity, and aggression than do RLA rats. Rats of each Roman line and Wistar rats were anesthetized with chloral hydrate and maintained at a stable moderate anesthetic level. VEPs to each of five flash intensities were computer averaged for each rat. The slopes of P1 amplitudes as a function of flash intensity were significantly greater in the RHA than the RLA rats. RHA rats were clear augmenters; RLA rats had almost flat amplitude-intensity functions. The Wistar rats had slope functions that were similar to those of the RLA rats. This study shows that the relationship between sensation-seeking behavior and VEP augmenting and reducing has a heritable base and extends across species from human, cat, and rat. In addition, we demonstrate a rat model of this relationship that yields advantages of genetic homogeneity and a short generational time, and provides access to a wealth of behavioral data and experimental manipulations available for the rat.

Animals↗

PubMed1991

Are the differential effects of chloral hydrate on hooded rats vs. albino rats due to pigmentation or strain differences?

Effects of chloral hydrate anesthesia on EEG power spectra and VEP components were examined as a function of both pigmentation and strain differences in rats. Ten albino Westenberg Long Evans rats (WLE A) were compared to ten pigmented Westenberg Long Evans rats (WLE P), and to ten Wistar albino (Wis A) rats. Albino rats required less chloral hydrate to reach a deep level of anesthesia than pigmented rats. Wistar rats remained anesthetized longer than WLE rats. During deep levels of anesthesia, the lowest EEG frequency band contained more power in Wistar rats than in WLE rats. During moderate levels of anesthesia, frequencies less than 4 Hz lost power while frequencies greater than 13 Hz gained across all rats. Wistar rats had more power in the frequencies less than 8 Hz than did WLE rats; pigmented rats had more power in the frequencies greater than 13 Hz than did albinos. VEP component latencies of pigmented rats were shorter than albinos. Component amplitudes were not significantly different between groups.

Anesthesia↗

PubMed1989

Psychophysically derived visual mechanisms in turtle. I--Spectral properties.

Two-color increment thresholds were measured in turtle using a behavioral avoidance paradigm. Four visual mechanisms were isolated, and their spectral sensitivities were compared to action spectra of photoreceptors known to occur in this animal. One visual mechanism appears to be mediated by rods and red-sensitive cones at low background intensities, a second mechanism by coupled red- and green-sensitive cones at intermediate levels, a third and fourth mechanism by red-sensitive, and green-sensitive single cones, respectively, acting alone at high background intensities.

Adaptation, Ocular↗

PubMed1989

Psychophysically derived visual mechanisms in turtle. II--Spatial properties.

Visual mechanisms isolated in Pseudemys by the two-color threshold technique of Stiles show peak wavelength sensitivities at 650 nm (red light) and 540 nm (green light). Ricco critical areas were measured for the two test wavelengths under three conditions: dark, moderate and intense backgrounds. As expected, critical spatial areas decreased with light adaptation. Under dark adaptation only rods and red-sensitive cones were operative, and one photon per 12 rods was sufficient for green-light threshold, as was one photon per four red-sensitive cones for red-light threshold. Rods apparently pool their information among the several receptors within the threshold area. Under light adaptation, rods were not functional and thresholds were determined by red-sensitive and green-sensitive cones alone. Cones did not share information over many receptors, requiring close to one photon per receptor to function at threshold.

Adaptation, Ocular↗

PubMedDate not supplied

Chloral hydrate anesthesia: EEG power spectrum analysis and effects on VEPs in the rat.

This paper describes the use of EEG power spectrum analysis as a tool in identifying and controlling the state of an animal, a major source of variability in evoked potential (EP) data. Also described is a procedure of anesthetic administration combined with on-line EEG power spectrum analysis that permits an animal to be maintained in a stable, moderately anesthetized state during which VEP's are qualitatively comparable to those seen in the unanesthetized animal. Anesthesia level in acute preparations was varied by IV injections of chloral hydrate, and the EEG and light-flash VEP's were recorded from visual cortex. Under deep anesthesia, EEG activity was concentrated in the 0.1 Hz to 3 Hz band with very little contribution from frequencies higher than 10 Hz. After this period of deep anesthesia, EEG frequency distribution became bimodal with peaks in the 0.1-3 Hz and 5-7 Hz ranges, and a minor frequency band between 10 and 30 Hz. This moderate anesthetic state persisted for about 30 min. Two distinct forms of VEP's were highly correlated with these EEG frequency distributions. VEP's associated with the moderate anesthetic state were comparable to those reported from awake, chronic preparations. In VEP's associated with deep anesthesia, negative components were greatly attenuated or entirely absent; amplitudes of the positive components were increased as were the latencies of all components.

Animals↗