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1. Electrophysiological properties of cat motoneurones were measured using intracellular electrodes, after which Procion dye was injected iontophoretically into the neurone through the recording pipette.

1. Measurements of the specific membrane properties and neuronal geometry of cat motoneurones were used to calculate the excitatory postsynaptic potentials (e.p.s.p.s) produced by unit (quantal) conductance changes occurring at various locations on the dendritic tree.

The lumbar spinal cord of rats and cats has been used as a model system to study the epileptogenic effects of penicillin. Within a few minutes after the application of penicillin, segmental myoclonus develops. Intracellular recording from cat motoneurons demonstrates that penicillin induces periodic large spontaneously occurring depolarizing synaptic potentials. Either these responses or directly applied intracellular current pulses evoked prolonged depolarization of the motoneuron soma, which represent an alteration in membrane properties of motoneurons. The prolonged depolarization has a threshold for termination by a hyperpolarizing current.

Penicillin was applied to the cat spinal cord and the changes in membrane properties of motoneurons measured. Just prior to the appearance of the facilitated spontaneous synaptic potentials, there is a diminution of the resting potential of the motoneuron. This is not associated with a detectable change in membrane resistance or in time constant. The after-hyperpolarization of the action potential is decreased. The simplest explanation for these changes is a change in the potassium equilibrium potential (Ek). To test the possibility that the change in Ek is causally related to the appearance of the prolonged depolarization, the intracellular potassium of normal motoneurons was displaced with either choline or tetramethylammonium ions. In both cases a prolonged depolarization occurred similar to that produced by penicillin, and, moreover, this response was evoked by directly applied intracellular currents.

The action potential evoked from inferior olivary neurons of the cat by orthodromic, antidromic, or intracellular stimulation has a large prolonged depolarization, frequently with several superimposed smaller spikes. The all-or-nothing unitary response appears to be a property of the cell, and the later spikes are not secondary to synaptic excitation by recurrent axon collaterals.

This superbly prepared monograph is a complete detailed description of the structure of cerebellar cortex as we understand it today. Separate chapters discuss each of the six neuron types in cerebellar cortex, the Structure of the two cortical afferent fiber systems, and the cortical neuroglia. The book ends with a chapter on the optical and electron microscopic methods used by the authors. Each chapter includes a relevant discussion of classical morphology and recent contributions of others before presenting the authors' evidence and their interpretation of the structure under discussion. The book summarizes the authors' extensive publications on cerebellar cortex and includes many observations not yet available in the literature. Short sections, throughout the book, attempt to relate the authors concept of cerebellar structure to function. They have judiciously selected material from the recent explosion of physiological studies to emphasize the functional importance of their observations. The authors have either presented