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Distractibility following simultaneous bilateral lesions of the superior colliculus or medial frontal cortex in the
Abstract:
Hooded rats with bilateral lesions of the superior colliculus or medial frontal cortex were compared with controls for locomotor guidance in shuttling back and forth between goal-doors at two opposite ends of a large arena. Colliculectomized rats accomplished this with great accuracy. When flashing distractor lights were introduced midway down the runway, frontal corticals and controls were severely disrupted but colliculars continued to run normally. This result was obtained both when all training occurred postoperatively (Experiment 1) and when runway performance had been stabilized preoperatively (Experiment 2), thus after a long or short postoperative recovery interval. The results offer support for previous studies with rats which have demonstrated sensory 'neglect' but good locomotor guidance after collicular ablation. Frontal corticals differed from controls only in terms of their elevated rate of repeat door-pressing upon postoperative resumption of testing in Experiment 2. Despite the similarity between effects reported elsewhere of collicular and frontal lesions made unilaterally, bilateral deficits clearly demonstrable after collicular ablation were absent here after frontal lesions. The results imply that the functional responsibilities of superior colliculus and frontal cortex in the rat are separable; at least, they have different rates of functional recovery.
Insights
Rats with superior colliculus lesions navigated accurately, even with distracting lights. Medial frontal cortex lesions impaired navigation, suggesting separable functions and recovery rates for these brain regions in locomotor guidance.
Area of Science:
- Neuroscience
- Behavioral Neuroscience
- Comparative Psychology
Background:
- Locomotor guidance is crucial for navigation.
- The superior colliculus and medial frontal cortex are implicated in sensory processing and motor control.
- Understanding the distinct roles of these brain regions is essential for comprehending complex behaviors.
Purpose of the Study:
- To investigate the roles of the superior colliculus and medial frontal cortex in locomotor guidance in hooded rats.
- To compare the effects of bilateral lesions in these areas on navigation accuracy and response to distractors.
- To determine if functional recovery differs between collicular and frontal lesions.
Main Methods:
- Bilateral lesions of the superior colliculus or medial frontal cortex were induced in hooded rats.
- Locomotor guidance was assessed in a shuttling task between goal-doors in a large arena.
- Distractor lights were introduced midway down the runway to test sensory processing.
- Experiments were conducted with both postoperative training and preoperative training to assess recovery intervals.
Main Results:
- Rats with superior colliculus lesions showed accurate locomotor guidance, unaffected by distractor lights.
- Rats with medial frontal cortex lesions and control rats were significantly disrupted by distractor lights.
- Frontal cortex-lesioned rats exhibited an elevated rate of repeat door-pressing postoperatively.
- Bilateral collicular lesions caused deficits not observed with bilateral frontal lesions, suggesting distinct functional roles.
Conclusions:
- The superior colliculus and medial frontal cortex have separable functional responsibilities in locomotor guidance.
- Superior colliculus plays a key role in maintaining navigation accuracy despite sensory distractions.
- Functional recovery rates differ between the superior colliculus and medial frontal cortex following bilateral lesions.