Abstract
This book is divided into two sections: Part I dealing with the functional neuro-anatomy of limbic and subcortical systems; and Part II being more concerned with clinical syndromes. In the Introduction, the editors note that some of the chapters present complex material requiring careful study and perhaps a second reading and indeed this would be the case with much of Part I, which is a review of the limbic system, the ventromedial temporal lobe, the thalamus, the accumbens and the neurobiology of fear responses based in the amygdala. The anatomical structures, and connections and projections and recent neurotransmitter developments are covered extensively in a series of essays.
Part II is devoted to clinical syndromes: Salloway and White review paroxysmal limbic disorders including complex partial epilepsy, psychogenic seizures, panic disorder, transient global amnesia, migraine and dissociative disorders, indicating the underlying limbic dysfunction. Fried discusses complex partial seizures and auras and experiential responses arising in the temporal lobes, noting the difficulties inherent in localisation and classification. Trimble, Mendez and Cummings discuss the Kluver-Bucy Syndrome and also posttraumatic seizures and other disorders: The Gastaut-Geschwind Syndrome is reviewed, noting the absence of absolute evidence to support its existence as a reflection of temporal lobe foci. Memory disturbance with dominant and non-dominant medial temporolimbic circuits is summarised along with the range of pathologies contributing to these deficits. Delusional thinking with temporolimbic disease and the concept of alternating psychosis is contrasted with hallucinatory behaviour originating with non-dominant pathology. Changes encountered in the temporolimbic system in schizophrenia are reviewed along with emotional and mood disorders and their association with dominant hemisphere frontal and temporal pathology. The association with rage and aggression with temporal lobe epilepsy and dominant pathology is contrasted with anxiety and dissociative states encountered with non-dominant pathology. The neurobiology of emotional experience is covered by Heilman. Emotional variance is accounted for by the dimensions of valence, arousal and control, and asymmetry of hemispheric function in the frontal lobes identifies depression with left hemisphere lesions and indifference and euphoria with right hemisphere lesions.
An interesting chapter on recovered memory by Zoler is worth attention and provides a reasoned account of the mechanisms likely to be involved and the nature of ongoing change, re-organisation and plasticity of memory. Using the Eileen Franklin case as an example, memory is presented as a dynamic process, changing over time and affected by new events and by the actual process of retrieval, the retrieved memory often being incomplete, distorted or false. While memory is distributed in the brain as a whole the medial temporal lobes provide a function of binding and assembling memories, although on occasions the medial temporal lobes may not be involved and the neocortex plays a role in re-organisation. Visual imagery may use a similar neural substrate.
A general review of the medial temporal lobe in schizophrenia is reported by Arnold covering structural changes and the results of functional neuroimaging, neurotransmitter changes and evoked potentials. Limbic cortical dysregulation as a proposed model for depression is discussed by Mayberg, and Koob and Nestler discuss the neurobiology of drug addiction in some detail.
An interesting chapter on the neural substrate of religious experience by Saver and Rabin extends to include epilepsy-related religious experiences and near death experiences. The distinction between mystical and psychotic states is addressed and the neurobiological basis to delusional thinking and associated delusional mood change.
The book is really a collection of essays, well referenced, but sometimes difficult to follow. Clinicians may find Part II of greater relevance with some quite stimulating ideas and theories. It highlights recent areas of research and it is perhaps surprising that other chapters were not added to the volume to include topics such as the role of the limbic system and aggression, links with sexuality and amnestic syndromes.