Trends in self-poisoning with drugs in Newcastle, New South Wales, 1980-1982

A review has been carried out of 747 cases of self-poisoning with drugs which were treated in the three major Newcastle hospitals over the three-year period 1980-1982. The data obtained have been compared with earlier published data for the years 1976-1979. The number of patients who were admitted to hospital fell from 290 in 1980 to 226 in 1982. The most common drugs used were benzodiazepine (34.5% of cases) and antidepressant agents (9.1%), paracetamol (7.9%), barbiturates (7.1%) and phenothiazines (3.8%). Although this indicated a gratifying drop in the use of barbiturate drugs, the use of several drugs in combination in self-poisoning rose disturbingly. Five patients died in hospital; 23 who committed suicide with drugs were not admitted to hospital but were investigated by the Regional Forensic Pathologist.

Low-frequency septal stimulation increases tyrosine hydroxylase activity in the hippocampus

Rats were chronically implanted with recording electrodes in the dorsomedial subiculum and stimulating electrodes in the septal area. Low-frequency septal stimulation (regular inter-pulse interval = 130 msec) was used over a period of 10 days to drive the hippocampal theta rhythm at 7.7 Hz (a régime shown previously to proactively facilitate acquisition of barpressing and retard its extinction), and high frequency (77 Hz) stimulation was used to block theta rhythm (a régime shown previously to proactively retard acquisition of barpressing and facilitate its extinction). The activity of soluble tyrosine hydroxylase from hippocampus increased in animals killed 15-33 days after the end of the period of 7.7 Hz septal stimulation but not after high-frequency stimulation. Irregular low-frequency stimulation with a mean inter-pulse of 130 msec produced the same effect on tyrosine hydroxylase activity as regular 7.7 Hz theta-driving. The possible relations between the effects of low-frequency septal stimulation on hippocampal tyrosine hydroxylase and on behavior are discussed.

Handedness and alcoholism

One hundred thirty-six alcoholic men and 48 alcoholic women admitted consecutively to an adult alcohol and substance abuse unit were studied in an attempt to replicate previous reports of an association between alcoholism and handedness. Each individual received a structured admission interview, and handedness was determined by a modification of the Edinburgh Inventory. Left-handedness was more frequent in men with alcoholic fathers and in first-born men. These data are discussed in the context of a recent theory relating left-handedness, immune disease, developmental learning disorders, and fetal testosterone.

Proactive behavioral effects of theta-driving septal stimulation on conditioned suppression and punishment in the rat

In two experiments, a treatment phase of septal stimulation preceded the acquisition of free operant lever pressing on a random-interval 64-s reinforcement schedule. Male Sprague-Dawley rats, chronically implanted with a bilateral septal stimulating electrode and a unilateral bipolar hippocampal recording electrode, received (a) low-frequency (7.7-Hz) stimulation, which drove the hippocampal theta rhythm, or (b) random-pulse stimulation (average frequency = 7.7 Hz), which produced only nonregular waveforms in the hippocampus. Control animals were implanted but not stimulated. After 12 days of lever-press acquisition, animals were presented while lever pressing with an auditory signal associated with a particular schedule of shock delivery: In Experiment 1, shocks occurred despite the subject's response strategy; in Experiment 2, shocks were delivered only if the rat pressed the lever. In both experiments, lever pressing was suppressed by the auditory stimulus. Theta-driving but not random-pulse septal stimulation proactively increased behavioral tolerance to the effects of electric shock. These results reinforce the idea that proactive behavioral effects of septal stimulation are a consequence of the production of the hippocampal theta rhythm.

Proactive behavioral effects of theta-blocking septal stimulation in the rat

The induction of hippocampal theta rhythm using low-frequency septal stimulation has been shown to proactively (1) facilitate the acquisition and (2) increase resistance to extinction of a food-rewarded fixed-ratio (FR) bar-press response (Holt & Gray, Quarterly Journal of Experimental Psychology, 35B, 97-118, 1983). Both (1) and (2) are also seen after septal lesions. This suggests that Holt and Gray's (1983) results may have been due either to stimulation-produced theta waves (the "theta" hypothesis), or a small septal lesion produced by the stimulating current (the "lesion" hypothesis). Both hypotheses were tested in the present experiment using high-frequency septal stimulation. In one of two treatment conditions male Sprague-Dawley rats, chronically implanted with a bilateral septal stimulating electrode and a unilateral bipolar hippocampal recording electrode, received (1) trains of continuous pulses at 77 Hz which blocked the hippocampal theta rhythm, or (2) trains of pulses at 100 Hz interrupted by a 30-msec interval at a frequency of 7.7 Hz. Control animals were implanted but not stimulated. Acquisition of a discrete-trial bar-press response on a fixed ratio 5 reinforcement schedule immediately followed the treatment phase. After 15 days' acquisition all animals were extinguished over the subsequent 12 days. Results indicated that both types of septal stimulation reduced resistance to extinction of barpressing; theta-blocking stimulation produced the greater effect. Theta-blocking stimulation retarded the acquisition of bar-pressing in the early stages of training. These overall results are exactly opposite to those produced by low-frequency (7.7 Hz) theta-driving septal stimulation (Holt & Gray, 1983) and contrary to the predictions of the lesion hypothesis. Furthermore, these findings support the idea that long-term changes in behavior may depend on stimulation-produced changes in the hippocampal theta rhythm.

Septal driving of the hippocampal theta rhythm produces a long-term, proactive and non-associative increase in resistance to extinction

Previous experiments employing electrical or pharmacological induction, or instrumental reinforcement, of hippocampal theta rhythm in rats have reported subsequent performance changes in a number of learning situations. In all these studies theta induction took place either concurrent with or following the behaviour under investigation. In the present two experiments, a treatment phase of electrically-induced hippocampal theta (by septal stimulation at 7·7 Hz) preceded acquisition of a discrete trial, barpress response on a fixed ratio 5 reinforcement schedule. In one of three treatment conditions animals received electrical stimulation (1) on its own, or (2) in a classical conditioning relationship with food delivery as unconditioned stimulus, or (3) temporally uncorrelated with food delivery; controls were implanted with electrodes but not stimulated. After 15 days’ acquisition of barpressing, all animals were extinguished over the subsequent 12 days. Results indicated that theta-driving stimulation, independent of any association with food, resulted in increased resistance to extinction of barpressing. In addition, conditions (1) and (3) enhanced the speed of response during early acquisition. These findings cast doubt on a “memory consolidation” hypothesis of hippocampal theta function and demonstrate a non-associative, long-lasting, proactive effect of theta induction on behaviour.

Effects of rapid increase of phenylalanine intake in older PKU children

Twelve children formerly on strick low-phenylalanine diets were allowed to change to a moderate-protein diet over a five-week period. They were observed at home by parents, in school by teachers, and in the clinic by team members, and were evaluated periodically for phenylalanine intake, serum phenylalanine levels, activity, irritability, growth, and intelligence. Growth patterns were normal for age. Dietary phenylalanine increased sharply for all children at the end of three months, then dropped at about six months, after which it rose above the three month level. Serum phenylalanine levels followed dietary intakes, and in nine cases are staying at about 20 mg. per 100 ml. or less. The three subject above 20 mg. have serum phenylalanine of 21, 23, and 25 mg. per 100 ml. One of these has had behavioral problems and excessive weight gains in the past two years.