Volume 17, Number 21,
Issue of November 1, 1997
pp. 8550-8565
Copyright ©1997 Society for Neuroscience
Response Properties of Corticotectal and Corticostriatal Neurons
in the Posterior Lateral Suprasylvian Cortex of the Cat
Received April 30, 1997; revised Aug. 7, 1997; accepted Aug. 18, 1997.
Takahiro Niida1,
Barry
E. Stein2, and
John G. McHaffie2
1 Department of Orthoptics and Visual Science, School
of Allied Health Sciences, Kitasato University, Sagamihara, 228 Japan,
and 2 Department of Neurobiology and Anatomy, Bowman Gray
School of Medicine, Wake Forest University, Winston-Salem, North
Carolina 27157
Lateral suprasylvian cortex (LS) is an important source of visual
projections to both the striatum and superior colliculus. Although
these two LS efferent systems are likely to be involved in different
aspects of visual processing, little is known about their functional
properties. In the present experiments, 86 neurons in
halothane-anesthetized, paralyzed cats were recorded along the
posterior aspects of the medial and lateral banks of LS (PMLS and
PLLS). Neurons were selected for analysis on the basis of antidromic
activation from electrodes chronically implanted in the superior
colliculus and caudate nucleus. The segregated nature of
corticostriatal and corticotectal neurons was apparent; in no instance
could a neuron be antidromically activated from both the superior
colliculus and the caudate nucleus. Many common features were revealed
between corticotectal and corticostriatal neurons; the majority of
neurons in both populations were binocular and contralaterally
dominant, showed similar responses to stationary flashed light, and
expressed within-field spatial summation and surround inhibition.
However, a number of information-processing features distinguished
between corticotectal and corticostriatal neurons; the former were
generally tuned to lower velocities than were the latter, and, for a
given eccentricity in visual space, corticotectal neurons had smaller
receptive fields than did corticostriatal neurons. Moreover, most
corticotectal neurons displayed a marked preference for movements
toward temporal visual space, whereas corticostriatal neurons revealed
no specialization for a particular direction of movement. In addition,
whereas corticotectal neurons were selective for receding stimuli,
corticostriatal neurons were selective for approaching stimuli. The
presence of these two corticofugal pathways is discussed in relation to
their presumptive functional roles in the facilitation of attentive and
orientation behaviors.
Key words:
basal ganglia;
caudate;
lateral suprasylvian;
orientation
behavior;
striatum;
superior colliculus