Describe the Functional Brain Systems
Networks of neurons working together and spanning wide areas of the brain
Limbic System
&
Reticular Rormation
Describe the Limbic System
- Evolutionarily primitive parts of the forebrain, responsibilit for basic physiological drives, instincts, and emotions
- Electrical stimulation of certain areas of the limbic system can caues intense sensations of pleasure, pain, or rage
- Attaches emotinoal responses to odors (e.g., skunks smell bad)
- Located on medial aspects (deep) of cerebral hemispheres & diecephalon
What are the Limbic System structures?
Amygdala
Hippocampus
Cingulate gyrus
Hypothalamus
Anterior nucleus of the thalamus (plus other structures)
Where does right/left communication occur?
via the fornix and anterior commissure
Which structures of the limic system are especially important in emotions?
Amygdala
&
Cingulate gyrus
What does the amygdala do?
Deals with anger, danger, and fear responses and fear memory
e.g., if damaged, an animal cannot learn to be afraid of a stimulus
What does the Cingulate gyrus do?
plays a role in expressing emotions via gestures and resolves mental conflict
Which structure of the Limbic System is especially important in forming memory?
Hippocampus
What does the Hippocampus do?
Converts new information into long-term memories
Within the Limbic system, what is the relationship between emotion and cognition?
- The limbic system interacts with the prefrontal lobes, therefore:
- one can react emotionally to conscious understandings
- one is consciously aware of emotion in one’s life
- negative emotions impact the ability to form long-term memory
Describe Reticular Formation
Composed of three broad columns along the length of the brain stem:
Raphe nuclei, Medial group, Lateral group
Has extensive axonal connections with spinal cord, hypothalamus, thalamus, cerebellum
RAS = Reticular Activating System - sends impulses to the thalamus and cerebral cortex to keep it active and alert
How does the RAS or Reticular Activiting System work?
- Sends impulses to the thalamust and cerebral cortex to keep it conscious and alert
- keeps the resting potentials near threshold – thus, maintains wakefulness
- Filters out repetitive and weak stimuli, keeps the brain in a “ready” state (demo)
- Controls Motor function
- Controls Sleep and waking
Explain the Motor Function of the RAS?
- Autonomic centers regulate visceral motor functions
- BP, HR & breathing rate all increase or decrease in response to RAS input
How does RAS help control sleep and waking?
Sleep: need to minimuze inputs (lights down, noise down, etc.)
Awaken: need to increase inputs (lights on, sound volumen up, etc.)
What is Reticular Formation Damage?
- If the brain stem is damaged at midbrain or higher, reticular activity is not conveyed to the forebrain and the person is rendered comatose (unable to wake up)
- If the brain stem is damaged below the Reticular Formation, there will be normal sleep/wake patters (visual & auditory input unaffected) but will likely cause paralysis
