A diffuse neural projection system that, in response to stimulation, arouses the cortex.
Cluster of nerve cells and nerve fibers in the brainstem connecting nerves to and from the spinal cord, cranial nerves, and areas of the brain; it constantly monitors the state of the body and functions in the control of breathing, heart rate, level of consciousness, and many other functions.
A network of nerve pathways and nuclei throughout the brainstem, connecting motor and sensory nerves to and from the spinal cord, the cerebellum and the cerebrum, and the cranial nerves. It is estimated that a single neuron in this network may have synapses with as many as 25,000 other neurons.
A meshed structure formed of gray matter and interlacing fibers of white matter found in the medulla oblongata between the pyramids and the floor of the fourth ventricle of the brain. It is also present in the spinal cord, midbrain, and pons. Fibers from this structure are important in controlling or influencing alertness, waking, sleeping, and various reflexes. They are thought to activate the cerebral cortex independently of specific sensory or other neural systems. The reticular formation is part of the reticular activating (alerting) system.
A network of neurons through which the hypothalamus sends descending signals to the brain stem and the viscera to activate the fight-or-flight response; also serves as an ascending pathway of sensory information from the periphery to the thalamus.
A complex system of nerve cells dispersed throughout the brainstem, which is the neural pathway connecting the brain to the spinal cord.