Annual Review of Neuroscience, vol. 14.

Annual Review of Neuroscience, Volume 14

Cowan WM, Shooter EM, Stevens GF, Thompson RF, eds. Palo Alto, CA 94303-0897, Annual Reviews Inc, 1991, hardback, 583 pp, illus, $40. A diverse collection of neuroscience topics, from the molecular to systems level of analyses, is included in this 14th volume of the Annual Review of Neuroscience. Twenty articles comprise this volume, and although they attest to the high degree of specialization that has evolved within the neurosciences, only 3 articles are likely to be of direct interest to the physical therapy researcher. The first of these, by Swedish investigators Grillner, Wallen, Brodin, and Lansner, is concerned with the neural circuitry and cellular processes underlying locomotion (swimming) in the "most primitive of vertebrate nervous systems," the lamprey. A succinct, clearly written overview of swimming behaviour, together with a general description of the basic motor patterns that characterize swimming, opens this review and is followed by more detailed accounts of specific neurons involved in the spinal circuitry and their possible interactions that may give rise to the motor patterns of swimming. The role of the brain stem in initiation of movement is also reviewed, along with mechanisms attributable to intersegmental coordination and the roles of transmitters and putative neurotransmitters in pattern generation. The concepts presented, although specific to lamprey swimming behaviour, should be of interest to anyone concerned with the general issues of central pattern generators and the interaction of centrally generated commands and peripheral afferent feedback in posture and locomotion. The somatotopic arrangements within the mammalian central nervous system (CNS) have given rise to the characterization of CNS organization in terms of sensory and motor maps. Questions have arisen concerning to these maps as a result of direct damage to specific regions of the CNS, interruption of inputs to these regions, or the disruption of peripheral end organs. The issues of CNS plasticity and reorganization of sensory and motor maps of the adult mammalian bran following experimentally induced lesions are reviewed by psychology professor Jon Kass of Vanderbilt University. A variety of animal models are considered, and results are presented for changes in somatosensory cortex, parietal association cortices, visual and auditory cortices, and subcortical (spinal cord and brain stem) structures. The extensive reorganization of both motor and sensory maps reported here dramatically exemplifies the mutability and plasticity of even the adult brain and is suggestive of the potential for restoration of function following injury. The author ends on a cautionary note by stating that even though dramatic changes can be observed at this basic level of organization, little evidence has been amassed relating the behavioral consequences of these map reorganizations. This final statement certainly should catch the interest of the physical therapy researcher concerned with restoration of function following CNS injury. Of most interest to the physical therapist should be the review by the neurophysiologist AP Georgopoulos of The Johns Hopkins University on functions of higher-order motor control. Higher-order motor control is defined here as ". . . processes that lead to the intiation of a motor response" (ie, prior to activation of motor cortex and associated descending brain-stem systems). The simplistic concept of top-down, serial processing of neural information from one "CNS center" to another, which for so long dominated many interpretations of hierarchical models, is rightfully downplayed. Emphasis is placed on the impotance of parallel activation of neural structures distributed throughot the CNS, which functions in the initiation of appropriate motor responses. Three aspects of motor function are reviewed: specification of motor variables, coordinate transformation,and cognitive process that may be active in planning of movement. For the reader unfamiliar with this literature and its associated jargon, grasping of specific concepts may prove difficult. A great deal of recent literature from both human psychophysical studies, as well as from neurophysiological studies in awake, behaving animals, is reviewed in a very compact format. The literature reviwed should offer a good starting point for journal club discussion of issues in motor control in general and of the issue of higher-center control specifically. The Annual Review of Neuroscience is an important addition to the libraries of physical therapy programs that offer advanced master's and doctoral degrees. Clinicians will find little benefit from this book. Carl G Kukulka, PhD, PT The University of Iowa Iowa City, Iowa