Defense-Like Behaviors Evoked by Pharmacological Disinhibition of the Superior Colliculus in the Primate
ABSTRACT Stimulation of the intermediate and deep layers of superior colliculus (DLSC) in rodents evokes both orienting/pursuit (approach) and avoidance/flight (defense) responses (Dean et al., 1989). These two classes of response are subserved by distinct output projections associated with lateral (approach) and medial (defense) DLSC (Comoli et al., 2012). In non-human primates, DLSC has been examined only with respect to orienting/approach behaviors, especially eye movements, and defense-like behaviors have not been reported. Here we examined the profile of behavioral responses evoked by activation of DLSC by unilateral intracerebral infusions of the GABA(A) receptor antagonist, bicuculline methiodide (BIC), in nine freely moving macaques. Across animals, the most consistently evoked behavior was cowering (all animals), followed by increased vocalization and escape-like behaviors (seven animals), and attack of objects (three animals). The effects of BIC were dose-dependent within the range 2.5-14 nmol (threshold dose of 4.6 nmol). The behaviors and their latencies to onset did not vary across different infusion sites within DLSC. Cowering and escape-like behaviors resembled the defense-like responses reported after DLSC stimulation in rats, but in the macaques these responses were evoked from both medial and lateral sites within DLSC. Our findings are unexpected in the context of an earlier theoretical perspective (Dean et al., 1989) that emphasized a preferential role of the primate DLSC for approach rather than defensive responses. Our data provide the first evidence for induction of defense-like behaviors by activation of DLSC in monkeys, suggesting that the role of DLSC in responding to threats is conserved across species.
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ABSTRACT: To better reveal the pattern of corticotectal projections to the superficial layers of the superior colliculus (SC), we made a total of ten retrograde tracer injections into the SC of three macaque monkeys (Macaca mulatta). The majority of these injections were in the superficial layers of the SC, which process visual information. To isolate inputs to the purely visual layers in the superficial SC from those inputs to the motor and multisensory layers deeper in the SC, two injections were placed to include the intermediate and deep layers of the SC. In another case, an injection was placed in the medial pulvinar, a nucleus not known to be strongly connected with visual cortex, to identify possible projections from tracer spread past the lateral boundary of the SC. Four conclusions are supported by the results: 1) all early visual areas of cortex, including V1, V2, V3, and the middle temporal area, project to the superficial layers of the SC; 2) with the possible exception of the frontal eye field, few areas of cortex outside of the early visual areas project to the superficial SC, although many do, however, project to the intermediate and deep layers of the SC; 3) roughly matching retinotopy is conserved in the projections of visual areas to the SC; and 4) the projections from different visual areas are similarly dense, although projections from early visual areas appear somewhat denser than those of higher order visual areas in macaque cortex.Eye and Brain 09/2014; 2014(6):121-137. DOI:10.2147/EB.S53613
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ABSTRACT: Given the increasing rates of stroke and our aging population, it is critical that we continue to foster innovation in stroke rehabilitation. Although there is evidence supporting cognitive rehabilitation in stroke, the set of cognitive domains effectively addressed to date represents only a small subset of the problems experienced by stroke survivors. Further, a gap remains between investigational treatments and our evolving theories of brain function. These limitations present opportunities for improving the functional impact of stroke rehabilitation. The authors use a case example to encourage the reader to consider the evidence base for cognitive rehabilitation in stroke, focusing on four domains critical to daily life function: (1) speech and language, (2) functional memory, (3) executive function and skilled learned purposive movements, and (4) spatial-motor systems. Ultimately, they attempt to draw neuroscience and practice closer together by using translational reasoning to suggest possible new avenues for treating these disorders. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.Seminars in Neurology 11/2014; 34(5):496-503. DOI:10.1055/s-0034-1396003 · 1.78 Impact Factor
University of Lorraine, 12/2014, Degree: PhD