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J Cranney

Publications and source records attributed to J Cranney.

16 recordsLinked to original sources
PubMed1999

Dopamine antagonists in the orbital prefrontal cortex reduce prepulse inhibition of the acoustic startle reflex in the rat.

Schizophrenia is characterized by, among other things, (a) information processing deficits that have been indexed by a number of measures, including deficits in prepulse inhibition (PPI) of the acoustic startle reflex; and (b) pathophysiology of the frontal lobe. Recent studies have implicated the prefrontal cortex (PFC) in the modulation of PPI in rats. These studies suggest that dopamine (DA) ablation of the PFC (using 6-OHDA) leads to disruption of PPI. To better understand the role of DA type 1 (D1) and type 2 (D2) receptors in the modulation of PPI, we investigated the effects of two pharmacologically distinct DA antagonists on the modulation of PPI. Microinjection of SCH23390 (a D1 antagonist) into the orbital PFC markedly decreased PPI (at 0.1, 0.5, and 1.5 microg), whereas raclopride (a D2 antagonist) decreased PPI at some doses (0.1 and 0.5 mg/ml) but not at others (5.0 microg). We conclude that both D1 and D2 receptors mediate the cortical modulation of PPI.

Acoustic Stimulation↗
PubMed1992

Immediate-startle stimulus presentation fails to condition freezing responses to contextual cues.

Twenty-eight male Wistar rats were placed in a novel and distinctive environment. Eighteen of these received an intense startle-eliciting white noise stimulus. Animals that experienced a 60-s delay between placement and the startle stimulus demonstrated significant freezing in the context, both poststartle (Session 1) and on a later startle-free test (Session 2). Animals that received immediate startle, however, did not differ on either occasion from animals that did not experience the startle stimulus. The amplitude of the startle response was not affected by this manipulation, which indicates a dissociation between freezing and startle responses with immediate- versus delay-startle presentation. The findings are consistent with Fanselow's (1986) conditioned stimulus-based associative explanation of the immediate-shock freezing deficit.

Animals↗
PubMed1990

Potentiation of the acoustic startle response by a conditioned stimulus paired with acoustic startle stimulus in rats.

The hypothesis that the standard acoustic startle habituation paradigm contains the elements of Pavlovian fear conditioning was tested. In a potentiated startle response paradigm, a startle stimulus and a light conditioned stimulus (CS) were paired. A startle stimulus then was tested alone or following the CS. Freezing behavior was measured to index conditioned fear. The startle response was potentiated on CS trials, and rats froze more in CS than in non-CS periods. In Experiment 1, response to a previously habituated, weak startle stimulus was potentiated. In Experiment 2, response to the same stimulus used as the unconditioned stimulus (US) in training was potentiated. This CS-potentiated response retarded the course of response decrements over training sessions as compared with an explictly unpaired control group. Conditioned fear is a standard feature of this habituation paradigm, serves to potentiate the startle response, and provides an associative dimension lacking in the habituation process per se.

Animals↗
PubMed1989

Duplex perception: some initial findings concerning its neural basis.

Duplex perception is the simultaneous perception of a speech syllable and of a nonspeech "chirp," and occurs when a single formant transition and the remainder (the "base") of a synthetic syllable are presented to different ears. The current study found a slight but nonsignificant advantage for correct labeling of the fused syllable when the chirp was presented to the left ear. This advantage was amplified in the performance of a "split-brain" subject. A subject with a left pontine lesion performed at chance level when the chirp was presented to her left ear. These findings suggest that some, if not complete, ipsilateral suppression does occur in the dichotic fusion procedure, and that identification of the fused syllable is maximal when the left hemisphere fully processes the linguistic characteristics of the base (through contralateral presentation), and at least minimally processes the frequency transition information of the chirp (through ipsilateral presentation).

Adult↗
PubMed1989

Influence of long-term sensitization on long-term habituation of the acoustic startle response in rats: central gray lesions, preexposure, and extinction.

The relation between long-term decrements of the acoustic startle response in rats and the development of freezing behavior during habituation training was examined. Freezing behavior developed over the initial trials of habituation training, and the rate of long-term response decrements was found to be inversely related to the development of freezing. Manipulations (neurological or behavioral) that either reduced the level of freezing or retarded its development promoted startle response decrements. In Experiment 1, rats receiving electrolytic lesions of the ventrolateral periaqueductal gray demonstrated both accelerated long-term startle response decrements and retarded development of freezing behavior. In Experiment 2, preexposure to the startle apparatus (i.e., latent inhibition) accelerated long-term startle decrements and inhibited development of freezing. In Experiment 3, exposure to the startle apparatus following initial habituation training (i.e., extinction) reduced both freezing behavior and startle response amplitudes. The results are discussed in terms of the influence of Pavlovian fear conditioning on long-term habituation of the acoustic startle response.

Animals↗
PubMed1988

Effects of lesions of the cerebellar vermis on VMH lesion-induced hyperdefensiveness, spontaneous mouse killing, and freezing in rats.

In a series of independent experiments, we showed that lesions of the vermis of the cerebellum in rats blocked the hyperdefensiveness induced by lesions of the ventromedial hypothalamus (VMH), attenuated spontaneous mouse killing, and reduced unconditioned freezing and other signs of fear in the presence of a cat. The vermal lesions did not significantly affect foot-shock conditioned freezing. Control lesions of the cerebellar hemispheres did not affect VMH lesion-induced hyperdefensiveness or freezing in the presence of a cat. The hemispheric lesions did attenuate foot-shock conditioned freezing. The data are discussed in terms of the striking similarities and differences between the behavioral effects of cerebellar vermal lesions and amygdala lesions and the interaction of a number of brain areas in modulating agonistic behaviors. The results leave no doubt that the medial cerebellum is significantly involved in the control of species-specific agonistic behaviors. The specific dimension of agonistic behaviors and the details of the interactions with other brain areas remain a puzzle which we approached here by expanding the behavioral profile of animals with lesions of the cerebellar vermis.

Agonistic Behavior↗
PubMed1985

Reflex modification in the rat: the inhibitory effects of intensity and frequency changes in steady tones.

In laboratory rats (as in humans) a low-intensity tone that precedes a high-intensity burst of noise by approximately 100 ms can reduce the amplitude of the startle reaction elicited by the burst of noise. A series of four experiments with rats investigated the relation between the inhibitory effects of tonal frequency change and the length of the silent period (gap) preceding it. The major findings were the following: (a) A gap in an otherwise continuous pure tone inhibited startle when the gap occurred approximately 100 ms prior to the noise burst. (b) Although an increase in gap duration increased the inhibition afforded by the gap, the maximum inhibition was yielded by gaps of 100 ms and greater; this maximum was equivalent to the inhibition yielded by the presentation of a postgap tone alone. (c) A shift in tonal frequency across a 10-ms gap yielded more inhibition than did the same gap with no frequency shift; again the shift yielded equivalent inhibition to the presentation of the postgap tone alone. (d) An increase in the frequency shift increased inhibition when the shift occurred across a 10-ms gap, but not when the shift occurred across a 100-ms gap.

Acoustic Stimulation↗
PubMed1980

Seating preference, hypnotizability, and imagery ability.

The effects of a specific hemispheric mode of functioning as indexed by lateralized seating preference was tested separately for male and female subjects in terms of their performance on the Harvard Group Scale of Hypnotid Susceptibility, Form A, the Creative Imagination Scale, and Betts' Questionnaire Upon Mental Imagery. Males, but not females, who preferred right-side seating scored higher on the Harvard scale but not on the Creative Imagination Scale or Betts' imagery questionnaire. Findings provide some support the notion that hypnotizability is associated with the right hemisphere for right-handed persons.

Choice Behavior↗
PubMedDate not supplied

Startle responding and context conditioning. Naloxone pretreatment and stimulus intensity.

The possibility that acoustic startle stimuli could support a conditional response (freezing) to contextual stimuli was investigated. Rats were exposed to three acoustic startle stimuli on the first day, and one on the second day. On day 1, 20 rats received naloxone pretreatment and another 20 received saline (placebo) pretreatment. Half of each group received a high-intensity acoustic stimulus, the other half a low-intensity acoustic stimulus. Both the higher stimulus intensity and the naloxone pretreatment led to greater freezing behavior during the 3-minute test period before the single startle stimulus on day 2. These findings support the notion that increased actual or perceived intensity of the acoustic startle stimulus increases conditioning to contextual stimuli as indexed by freezing behavior.

Acoustic Stimulation↗