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P M Milner

Publications and source records attributed to P M Milner.

32 records · Page 2Linked to original sources
PubMed1982

Development of brain stimulation reward in the medial prefrontal cortex: facilitation by prior electrical stimulation of the sulcal prefrontal cortex.

Electrical stimulation of the medial prefrontal cortex (MC) in rats delivered daily for seven days causes a marked improvement in the rate of acquisition of a self-stimulation response. In the present experiment, we looked at whether we could get the same facilitatory effect on self-stimulation of the MC by delivering pre-training stimulation to other points in the brain anatomically related to the MC. Electrical stimulation of the lateral hypothalamus was without effect. However, electrical stimulation of the sulcal prefrontal cortex (SC) either contralateral or ipsilateral to the MC electrode did facilitate acquisition of self-stimulation of the MC. Thus the Sc and MC would appear to be part of the same substrate controlling the development of positive reinforcement in the MC.

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PubMed1982

Elimination of medial prefrontal cortex self-stimulation following transection of efferents to the sulcal cortex in the rat.

Intracranial self-stimulation (ICSS) of the medial prefrontal cortex (MFC) was not affected by lesions of the medial forebrain bundle, the nucleus accumbens or medialis dorsalis. However, bilateral, parasagittal knife cuts that transected fibers interconnecting the medial and sulcal cortices eliminated ICSS from the MFC with no apparent recovery over a 21 day test period. Similar knife cuts produced only transient effects on lateral hypothalamic ICSS. These data suggest that the neural substrates of frontal cortex ICSS are very different than those that subserve ICSS along the medial forebrain bundle.

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PubMed1982

Strength-duration characteristics of lateral hypothalamic and periaqueductal gray reward-path neurons.

Behaviorally measured strength-duration curves were plotted for reward related neurons stimulated by electrodes in the lateral hypothalamus (LH) and ventral periaqueductal gray (PG). The average curves for the two groups were only marginally different, suggesting that similar neural populations mediate self-stimulation at the two sites. Analysis of the data for both groups indicates that stimulating pulses shorter than 0.1 msec stimulate mainly a short time-constant substrate with an average time-constant of about 0.1 msec. This is the same time-constant that has been reported in the literature for myelinated axons having a wide range of conduction velocities. It is suggested that the marked departure of behaviorally determined strength-duration curves from the approximately exponential form usually exhibited by single elements is due to the stimulation of unmyelinated elements by long (but not by short) stimulation pulses.

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PubMed1982

Fiber pathways associated with cerebellar self-stimulation in the rat: a retrograde and anterograde tracing study.

Intracranial self-stimulation (ICSS) was obtained from an area of cerebellum just rostro-ventral to the fastigial nucleus. The acquisition of cerebellar ICSS was slow, although this depended in part on the type of operant task required. The afferent and efferent fiber connections of the region of cerebellum supporting ICSS were identified using silver-degeneration and horseradish peroxidase tracing techniques. Two major pathways, one ascending to the ventromedial thalamus and one descending to the paramedian reticular formation and the region of the solitary nucleus, are discussed as possible substrates of ICSS at sites in the cerebellum as well as from other pontine and medullary regions.

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PubMed1977

Schedule control of behavior reinforced by electrical stimulation of the brain.

Electrical stimulation of the brain was used to train rats to respond on random interval schedules. Stimulation was either delayed for 0.5 second and preceded by a brief signal, delayed and unsignaled, or presented contiguously with the response. In every case, responding was maintained on schedules and showed resistance to extinction typical of food-reinforced responding. Priming was never necessary. These data cast doubt on the generality of beliefs about the behavioral effects of brain stimulation reinforcement.

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PubMed1977

Effects of dopamine supersensitivity on lateral hypothalamic self-stimulation in rats.

Dopamine (DA) receptor supersensitivity was demonstrated by potentiated d-amphetamine stereotype after a three-day treatment regimen in which the DA receptor blocker pimozide (4.0 mg/kg) was administered twice daily. Similarly-induced DA supersensitivity produced a significant increase in the rate of lever-pressing for lateral hypothalamic (LH) intracranial self-stimulation (ICSS) and a significant decrease in ICSS thresholds. No change from pretreatment baselines was observed in vehicle-treated control animals. Following three-day treatment with the noradrenaline--(NA) and DA-receptor blocker, haloperidol (4.0 mg/kg twice daily), a single injection of the alpha-adrenergic agonist clonidine (0.15 mg/kg) caused increased running behavior. In contrast clonidine decreased running in rats pretreated with chronic pimozide or vehicle. These results indicate an increase in the sensitivity of central NA receptors following chronic haloperidol but not chronic pimozide. Taken together, these findings were interpreted as a potentiation in the reinforcing properties of LH-ICSS after chronic pimozide treatments due to increases in the sensitivity of DA and not NA receptors.

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PubMedDate not supplied

The discovery of self-stimulation and other stories.

The author's recollections of the events leading to the discovery of rewarding brain stimulation at McGill University in 1953, with a history of his subsequent attempts to find a learning theory congruent with the phenomenon.

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