NEUROBIOLOGY Molecules, Cells and SystemsGary G. Matthews
About the Book
The second edition of Neurobiology: Molecules, Cells, and Systems incorporates numerous additions and improvements. For students, several new learning tools have been introduced. The Essential Background section at the beginning of each chapter lists the assumed background information for that chapter, with references to specific chapters when the material is covered in this book.
Key Points have been interspersed throughout the text, framed as questions that will be answered in each section. Review questions have been added at the end of each chapter to focus attention on the main points covered in the chapter.
New topics added to the second edition include a chapter devoted to the roles of the hypothalamus, including a description of recent advances in understanding the molecular basis of circadian rhythms. A chapter on language and cognition in the human brain has also been added.
Two new Advanced Topics have been included for students and instructors who wish to cover cellular aspects of neurobiology in a more quantitatively rigorous way. One advanced topic discusses ion channel kinetics, and the other describes the passive electrical characteristics of cell membranes.
The most obvious change from the first edition is the artwork, which has been completely redrawn to exploit the book's new four-color format. Each illustration was designed to illuminate a particular principle, and the drawings are integrated into the text discussion of each topic. The goal has been to make the figures accessible and readily comprehensible to beginning students of neurobiology, as well as visually attractive. In addition, animations of selected illustrations are available at this web site, as indicated by special icons next to the relevant figures.
Although the second edition incorporates many changes, the general approach to the field of neurobiology has not changed from the first edition.
Neurobiology is a diverse field. Although Neurobiology: Molecules, Cells, and Systems provides broad exposure to this field, the author has not attempted to cover all aspects of neuroscience. Instead of an encyclopedic survey, a subset of topics within neurobiology that illustrate the fundamentals of nervous system function have been selected. Within each selected topic, the author has chosen specific examples that lend themselves to explanations at the levels of molecules, cells, and neural systems. The intention is to provide a framework for further learning, which individual instructors and students can supplement with additional subject matter. Toward this end, suggested readings for each chapter are included at this web site, an approach that will help ensure that the readings are up-to-date.
Errata - Chapter 10 Summary
In this chapter, we have explored
some of the ways in which sensory
information is translated into motor output, using examples from the
mechanisms that control movement of the eyes. Sensory information is vital
for the proper performance of the motor output systems at all levels in
the
hierarchy. Within the brainstem, reflex systems rapidly translate
vestibular signals originating in the semicircular canals into motor
signals for the extraocular muscles, allowing eye movements to compensate
quickly for movements of the head. The main goal of these reflex circuits
is to maintain a stable image on the retina during locomotion.
Motion in the visual field
can also trigger reflexive movements of the
eyes, which match the speed of the moving object so that the image remains
in a constant location on the retina. These reflexive movements consist
of
a slow movement in the same direction as the moving object, followed by
a
fast resetting movement in the opposite direction to restore the eyes
to a
more centered position within the orbit.
Fast movements, called saccades,
are also made voluntarily to bring various
objects of interest within the visual field into the center of the field,
where the image will fall on the fovea of the retina. Saccades are
produced by neuronal circuits in the brainstem that operate in parallel
with the pathways of the vestibular reflex system. The brainstem saccade
generators are controlled by commands from the superior colliculus and
from
the frontal eye fields in the frontal lobes of the cerebral cortex. The
superior colliculus receives sensory information from the visual system,
which is used to construct a two-dimensional map of the visual fields
in
dorsal layers of the colliculus. In deeper layers of the superior
colliculus, this map of visual space is translated into a map of saccade
space, whose outputs trigger saccades of the proper direction and magnitude
to bring the fovea to a particular position in the visual field. In
primates, a similar mapping of visual space into saccade space also occurs
in parts of the parietal cortex.
The saccade circuits of the
superior colliculus are inhibited by inputs
from the substantia nigra. The frontal eye fields in the frontal cortex
trigger saccades, both by activating the circuits in the superior
colliculus and by activating neurons in the caudate nucleus that in turn
inhibit the inhibitory neurons of the substantia nigra.