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P W Graham

Publications and source records attributed to P W Graham.

15 recordsLinked to original sources
PubMed1992

Taste-potentiated odor aversion learning: role of the amygdaloid basolateral complex and central nucleus.

The present study examined the relative contributions of the amygdaloid basolateral complex (ABL) and central nucleus (CN) to taste-potentiated odor aversion (TPOA) learning--an associative learning task that is dependent on information processing in two sensory modalities. In Experiment 1, rats with neurotoxic lesions of these systems were trained on the TPOA task by presenting a compound taste-odor conditioned stimulus, which was followed by LiCl administration. Results showed that ABL damage caused an impairment in potentiated odor aversion learning but no deficit in the conditioned taste aversion. In contrast, rats with CN damage learned both tasks. Experiment 2 examined the effects of ABL damage on TPOA and odor discrimination learning. The odor discrimination procedure used a place preference task to demonstrate normal processing of olfactory information. Results indicated that although ABL-lesioned animals were impaired on TPOA, there was no deficit in odor discrimination learning.

Animals↗
PubMed1992

N-methyl-D-aspartate antagonist D-APV selectively disrupts taste-potentiated odor aversion learning.

Two experiments examined the effects of the competitive N-methyl-D-aspartate (NMDA) antagonist D-APV (D-2-amino-5-phosphonovalerate) on rats' ability to acquire potentiated aversions to the odor element of a taste-odor compound. In Experiment 1, pretreatment with D-APV (2.5 micrograms/side icv) caused stereospecific deficits in potentiated odor aversion learning but left simple taste and odor aversion learning intact. In Experiment 2, pretreatment with D-APV had no effect on rats' acquisition of an illness-based odor discrimination task. These results parallel those previously obtained using a noncompetitive NMDA antagonist (Robinson, Crooks, Shinkman, & Gallagher, 1989) and show that interference with NMDA receptors can selectively impair potentiated odor aversion learning. These results suggest that NMDA receptors play a critical role in some, but not all, forms of learning and memory.

2-Amino-5-phosphonovalerate↗
PubMed1990

The amygdala central nucleus and appetitive Pavlovian conditioning: lesions impair one class of conditioned behavior.

Rats with neurotoxic lesions of the amygdala central nucleus (CN) were trained using appetitive Pavlovian conditioning procedures. Conditioned responses (CRs) that are representative of 2 classes of behavior were monitored. One type of CR resembled the orienting responses that were elicited by the conditioned stimuli (CSs) prior to pairing with food reinforcement: the other type of CR resembled the behavior elicited by food reinforcement itself. Holland (1977, 1984) has referred to these as CS-generated and unconditioned stimulus (US)-generated CRs, respectively. During differential conditioning, some lesioned and unlesioned rats received reinforced presentations of a visual cue and nonreinforced presentations of an auditory cue, and the others in each lesion condition received reinforced auditory and nonreinforced visual cue presentations. Relative to the control group, the CN-lesioned rats were impaired in the acquisition of CS-generated CRs to both visual and auditory CSs. Orienting responses and habituation to the CSs were, however, comparable for the lesion and control groups. Moreover, rats with CN lesions readily acquired the US-generated CRs. Thus, a specific class of conditioned behavior was impaired by CN damage. Many studies using aversive Pavlovian procedures have suggested that CN lesions impair fear conditioning. The present results suggest another role for CN in the conditioning of orienting/attentional responses.

Amygdala↗
PubMed1989

Upper gastrointestinal endoscopy. Findings in an isolated rural general practice.

Results of 646 consecutive oesophagogastroscopies performed by general practitioners in an isolated rural practice were analysed and compared with a larger series (1409) of 'open access' endoscopies performed by gastroenterologists. Positive findings were recorded in 49.3 per cent of the series. The 'open access' gastroenterologist series reported 61 per cent positive findings.

Aged↗