Biomedical subjects

A Crider

Publications and source records attributed to A Crider.

11 recordsLinked to original sources

PubMed1986

A selective attention deficit in the rat following induced dopamine receptor supersensitivity.

In the blocking paradigm, prior training to one conditioned stimulus (CSA) blocks the ability to attend to a second conditioned stimulus (CSB) when the two form a compound (CSAB) in subsequent training. Blocking is an associative process by which animals learn to ignore CSB because it contains no new information regarding the reinforcing event. In Experiment 1, dopamine (DA) receptor supersensitivity was induced in rats by prolonged pretreatment with haloperidol. The animals with DA receptor supersensitivity failed to show blocking by responding equivalently to both elements of the CSAB compound. This effect was replicated in Experiment 2, which also tested for an arousal interpretation of disrupted blocking by introducing a novel stimulus following training. Supersensitive rats were no more responsive to this novel stimulus than were control animals, which supports a selective attention deficit interpretation of disrupted blocking with DA receptor supersensitivity. This attentional deficit resembles behavioral perseverations induced by DA agonists.

Animals↗

PubMed1983

Interaction of tail-pressure stress and d-amphetamine in disruption of the rat's ability to ignore an irrevelant stimulus.

Rats received either 0 or 30 preexposures to a tone that was later used as a warning stimulus in a two-way active avoidance task. Consistent with previous data, tone preexposure resulted in retarded acquisition of the conditioned avoidance response (CAR) in saline control animals and in animals that received chronic administration of a low dose of d-amphetamine. Similarly, animals that received tail-pressure stress prior to stimulus preexposure also showed retarded acquisition of the CAR. However, animals that received a combination of tail pressure and d-amphetamine did not show retarded CAR acquisition following stimulus preexposure. These results suggest an interaction between environmental stressors and d-amphetamine in producing attentional deficits.

Animals↗

PubMed1982

Disruption of selective attention in the rat following chronic d-amphetamine administration: relationship to schizophrenic attention disorder.

In the blocking paradigm, prior training to one conditioned stimulus (CSA) blocks the ability to attend to a second conditioned stimulus (CSB) when the two form a compound (CSAB) in subsequent training. Blocking is an associative process by which animals learn to ignore CSB because it contains no new information regarding the reinforcing event. Experiment 1 showed that d-amphetamine disrupted rats' ability to ignore the irrelevant CSB: The animals responded equally to both elements of the CSAB compound following five dialy administrations of 4 mg/kg d-amphetamine. In Experiment 2 the disruption of blocking by d-amphetamine was eliminated by concomitant administration of 0.02 mg/kg haloperidol. These results are consistent with previous research showing that d-amphetamine disrupts rats' ability to ignore repeated presentations of a single nonreinforced stimulus in the latent inhibition paradigm. The inability of amphetamine-treated animals to ignore one element of a dual-element compound bears some resemblance to selective attention deficits seen among schizophrenic patients.

Animals↗

PubMed1981

Disrupted latent inhibition in the rat with chronic amphetamine or haloperidol-induced supersensitivity: relationship to schizophrenic attention disorder.

Latent inhibition (LI) is an attentional process by which animals learn to ignore a stimulus that is repeatedly presented without reinforcement. This ability to tune out a motivationally irrelevant stimulus is disrupted by pharmacological manipulations producing hyperdopaminergic states. In Experiment I, LI was disrupted following five daily administrations of 4 mg/kg d-amphetamine. In Experiment II the disruptive effects of d-amphetamine were eliminated by concomitant administration of chlorpromazine. Experiment III showed that LI could also be disrupted with 1 mg/kg d-amphetamine coupled with dopamine receptor supersensitivity produced by prolonged pretreatment with haloperidol. These data suggest that pharmacological disruption of LI may provide an animal analogue of the defective stimulus filtering thought to characterize at least some forms of schizophrenia.

Animals↗

PubMed1975