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Neural substrate of defensive behavior in the midbrain tectum
M L Brandão1, S H Cardoso, L L Melo
1Laboratório de Psicobiologia, Faculdade de Filosofia Ciências e Letras-USP, Brazil.
Neuroscience and Biobehavioral Reviews
|January 1, 1994
Summary
Electrical stimulation of brain regions like the dorsal periaqueductal gray (DPAG) induces defensive behaviors and autonomic changes in rats. These responses, part of the brain's aversion system, can be modulated by neurotransmitters.
Area of Science:
- Neuroscience
- Behavioral Neuroscience
Background:
- The brain's aversion system involves interconnected regions including the dorsal periaqueductal gray (DPAG), deep layers of the superior colliculus (DLSC), and inferior colliculus.
- Electrical stimulation of these midbrain tectum areas in rats elicits progressive defensive behaviors like arousal, freezing, and escape.
Purpose of the Study:
- To investigate the neural substrates and mechanisms underlying aversion and defensive behaviors.
- To explore the role of different neurotransmitter systems in modulating these responses.
Main Methods:
- Electrical stimulation of specific brain regions (DPAG, DLSC, inferior colliculus) in rats.
- Observation and recording of behavioral responses (arousal, freezing, escape).
- Measurement of autonomic parameters (mean arterial blood pressure, heart rate, respiration).
Main Results:
- Progressive increases in stimulation intensity led to dose-dependent aversive behavioral and autonomic responses.
- Behavioral and autonomic changes were accompanied by increased blood pressure, heart rate, and respiration.
- Minor tranquilizers attenuated these responses, suggesting a role for GABAergic neurotransmission.
Conclusions:
- The DPAG-DLSC, periventricular gray, amygdala, and inferior colliculus form a critical neural network for aversion.
- GABAergic, opioid, serotonergic, and excitatory amino acid systems are implicated in the control of defensive behaviors within this aversion system.