SUMMARY1. Electrical stimuli applied in the locus coeruleus/subcoeruleus (LC/SC) and raphe nuclei produce a profound depression of transmission in reflex pathways from group II muscle afferents. The present experiments were performed to determine whether presynaptic inhibitory mechanisms contribute to these effects.2. Changes in the excitability of afferent terminals to electrical stimuli have been used as an indication of primary afferent depolarization (PAD) produced by conditioning stimuli applied within the LC/SC and raphe nuclei and, for comparison, in the nucleus ruber. Group II afferents originating from ankle flexor muscles and terminating in the midlumbar segments were used for testing.3. Clear changes in excitability were observed in fourteen of nineteen group II fibres in which the effects of conditioning stimuli applied in the LC/SC were tested and in twelve of seventeen fibres in which the effects of stimuli applied within the raphe nuclei were tested. By comparison, only one of the twelve fibres tested with conditioning stimuli applied to the nucleus ruber was found to be influenced. These effects matched those of the same conditioning stimuli on field potentials evoked by group II afferents at the location at which the terminals of group II fibres were stimulated.4. Stimuli applied in the LC/SC and in the raphe nuclei both produced a mean decrease in threshold stimulus current of 19 %. These effects are comparable to those produced by the most effective volleys in peripheral afferents which, in the same fibres, produced a mean decrease in threshold stimulus current of 24%.5. In all cases (twelve) in which the effects of stimuli applied in the LC/SC and raphe nuclei were tested on the same group II fibre, either both or neither were found to be effective. This strengthens previous indications that some populations of neurones might be activated by stimuli applied in each of these regions of the brain.6. In contrast to group II afferents, group I a afferents investigated in the same experiments were only exceptionally affected. Of seven fibres tested with stimuli applied in the LC/SC, six with stimuli applied in the raphe nuclei and seven with stimuli applied in the nucleus ruber, only one fibre showed any clear change in

EIDE, E., L. FEDINA, J. JANSEN, A. LUNDBERG and L. VYRLICKY. Properties of Clarke's column neurones. Acta physiol. scand. 1969. 77. 125-144. Mechanisms responsible for the high efficacy of synaptic actkation of the dorsal spinocerebellar tract (DSCT) was investigated with intracellular recording from Clarke's column cells in anesthetized spinal cats. The spike potential is brief (mean duration 0.57 msec) and followed by a delayed depolarization. Our observations suggest a high safety for impulse transmission from the initial segment to the soma and from the soma to the dendrites. The afterhyperpolarization is small ( < 2 mV), shortlasting (30-50 msec) and has a high sensitivity to hyperpolarizing currents. There is only a small conductance change during the afterhyperpolarization. The monosynaptic group I EPSP has a mono-exponential decay, the time course of which is explained by the passive properties of the membrane. I t is postulated that the transmitter action is brief. Possible mechanisms for multiple discharges evoked by group I volleys in DSCT cells are discussed. Injected currents evoke maintained firing and within a wide range there is a linear relation between frequency and current strength (mean slope constant 4.8 imp/sec/mV) . Depolarization produced by muscle stretch and injected current have equivalent effect on the firing rate. The properties of DSCT cells seem well adapted to their function to transfer sensory signals and operate over a wide frequency range

This paper starts with a review the economics of criminal behavior. Then, the authors discuss the theory of public enforcement. The economic analysis of criminal behavior and criminal law has been a hugely successful enterprise. As an academic enterprise, it has achieved the goal of research-it has generated a large and growing literature. More important than academic success, however, has been the influence of this branch of learning on actual practice. The understanding of deterrence effects and rational responses by criminals has substantially changed the purpose and functioning of the criminal justice system.

EIDE, E., L. FEDINA, J. JANSEN, A. LUNDBERG and L. VYKLICKY. Unitary components in the activation of Clarke's column neurones. Acta physiol. scand. 1969. 77. 145-1 58.I n response to muscle stretch unitary EPSPs were recorded from group I activated dorsal spinocerebellar tract (DSCT) neurones. The size of the different unitary EPSP varied appreciably, the largest was about 5 mV. The rise time and decay times of the unitary EPSPs varied only between 0.2-1 msec and 1-3 msec respectively. The estimate of the number of primary afferent fibres converging on to each second order neurone ranged from 12 to 16. The distribution of amplitudes of individual unitary EPSPs was symmetrical with a coefficient of variation as low as 0.10. This suggests that a large number of quanta are released by each impulse in the primary afferent fibres. Acta physiol. scand. Val. 77: 1-2 10493003.

Intracellular recording from motoneurones was made in cats with intact dorsal roots and in chronically de‐afferented cats. Stimulation of the gray matter was performed with electrodes inserted into the spinal cord. Large excitatory and inhibitory post‐synaptic potentials were evoked by these stimuli in alpha motoneurones after a latency of about 0.5 msec. It is concluded that excitatory and inibitory interneurones were activated and that the synaptic delay at inhibitory and excitatory synapses is the same.