title: Behavioral and electrophysiological estimates of visual thresholds in awake rats treated with 3,3',4,4',5-pentachlorobiphenyl (PCB 126).
abstract: Visual thresholds for luminance increments were obtained behaviorally and electrophysiologically from rats exposed to a polychlorinated biphenyl (PCB) during development. Male Long-Evans rats exposed to 0, 0.25, or 1.0 microg/kg/day of 3,3',4,4', 5-pentachlorobiphenyl (PCB 126) through gestation and weaning were trained as adults to perform a signal detection task. Estimates of threshold were derived from psychometric functions for each animal relating the proportion of hits to signal intensity. Thresholds derived under three luminance conditions did not differ significantly among the PCB-treated groups. After behavioral testing was completed, flash-evoked potentials were recorded from dark-adapted awake animals. Peak amplitudes increased linearly over approximately 3 log units of intensity. Extrapolations to 0 amplitude along the linear portion of the amplitude-log intensity functions produced estimates of absolute threshold of -5.44 to -5.53 log cd/m(2)-s. Waveforms recorded from awake animals had a large late negative component that was absent in previously reported anesthetized preparations. Developmental exposure to PCB 126 had no significant effect on absolute threshold or peak amplitudes and latencies.
authors.affiliation: Neurotoxicology Division, US EPA, Research Triangle Park, NC 27711, USA. geller.andrew@epamail.epa.gov
authors.forename: A M
authors.initials: AM
authors.lastname: Geller
authors.forename: P J
authors.initials: PJ
authors.lastname: Bushnell
authors.forename: D C
authors.initials: DC
authors.lastname: Rice
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D005074:Evoked Potentials, Visual / Q000187:drug effects; D005260:Female; D008297:Male; D010775:Photic Stimulation; D011078:Polychlorinated Biphenyls / Q000494:pharmacology*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D011597:Psychomotor Performance / Q000187:drug effects; D051381:Rats; D020318:Rats, Long-Evans; D012684:Sensory Thresholds / Q000187:drug effects; D013961:Thyroid Gland / Q000187:drug effects / Q000378:metabolism; D013974:Thyroxine / Q000097:blood / Q000187:drug effects; D014796:Visual Perception / Q000187:drug effects*; D014851:Wakefulness
chemical_list: D011078:Polychlorinated Biphenyls; D013974:Thyroxine; C023035:3,4,5,3',4'-pentachlorobiphenyl