Coordinated Eye and Body Movements Evoked by Brainstem Stimulation in Decerebrated Cats

Balancing energetic and cognitive resources: Memory use during search depends on the orienting effector

“…In addition, for a given gaze shift amplitude, there appears to be considerable individual variability in the extent to which head movements are recruited (Fuller, 1992). It is clear then, that what we might consider the 'default' mode of coordination emerging from brainstem circuits is subject to considerable modulation from higher order inputs ranging from cortex to the basal ganglia (Isa & Sasaki, 2002), a point foreshadowed by the observation that superior colliculus (SC) stimulation in decerebrated cats lead to increased rates of coordinated motor activity as compared to stimulation of SC in intact animals, implicating a prominent role for cortical afferents in contextually regulating the extent to which eye and head movements are coordinated (Faulkner & Hyde, 1958).…”

Forced Movement Resulting from Midbrain Stimulation in the Rat

“…Nonreciprocal ac tion cannot, however, be related entirely to anesthesia as such, because of methodological confounding. In most studies demonstrating reciprocity, postures or movements have been produced by brain stem stimulation alone [3,4,7,13,14,16,17,19,22,25,26,30,33,37,39,40], while in most investigations demonstrating nonreciprocal effects, the measured muscular or neuronal activity has been elicited from some source other than brain stem stimulation [2,5,23,27,34,36]. The possibility is sug gested that two overlapping organizations exist in the brain stem: (a) medial and lateral systems that nonreciprocally inhibit or facilitate the spinal reflex pathways, and (b) medial and lateral systems capable of di rect reciprocal action on the motoneurons, producing ipsiversive or contraversive postures.…”

“…Hence, stimulation should be delivered in a variety of controlled situations, (d) The importance of connections above the mid brain to reciprocity from reticular stimulation is not clear. Reciprocal ef fects are usually seen with brain stem stimulation below a transection [6,7,8,13,14,17,22,33,36,39], but inhibition of tone or bilateral exten sion have been observed. The loci producing these effects may be inter mingled with reciprocal points [33] or may be grouped into discrete areas [22], Nonreciprocity in these cases may be dependent on intense stimula tion [33] and the increased probability that more than one zone will bo activated, (e) Electrode size may be critical at least to direction of move ment.…”

“…More recent experiments involving stimulation of unanesthetized in tact cats have replicated the tegmental response and localized it to the ventromedial midbrain tegmentum, with possible inclusion of the red nu cleus [7,17,25,26,30,40], In addition, Skultety has demonstrated a dorsolateral zone which produces contraversive turning, with ipsilateral extension and contralateral flexion of the forelimbs [30], The latter sug gests similar reciprocal organizations in the midbrain and medulla [33].…”

On the Physiologic Decussation Concerned with Head Turning

“…Skultety [18] described «circus movement» in cats upon central gray stimulation of cat midbrain. He concentrated on the contra lateral response and stated that only one previous study, namely that by Faulkner and Hyde [3] mentioned contralateral turning from the midbrain (as opposed to ipsilateral). Several previous communications from our laboratory emphasized the presence of both contralateral and ipsilateral responses from the midbrain and postulated the exis tence of an oculomotor decussation in the midbrain [16,24].…”