Physiology III
Neuroscience
Exam III - Essay #1

That which is in red was updated after input from Dr. Winterson...See below for her input.

Describe the original and modern Papez circuit. Explain the role each component in relation to memory, emotion, behavior and motivation.

Papez believed that the experience of emotion was primarily determined by the cingulate cortex and, secondly, by other cortical areas.  Emotional expression was thought to be governed by the hypothalamus. The cingulate gyrus projects to the hippocampus, and the hippocampus projects to the hypothalamus by way of the bundle of axons called fornix. Hypothalamic impulses reach the cortex via relay in the anterior thalamic nuclei.

Cingulate Gyrus
    Located on medial surface of the brain
    Principal fiber bundle connecting the two cerebral hemispheres
    Coordinates pleasant memories of previous emotions
    Participates in the emotional reaction to pain
    Participates in the regulation of aggressive behavior    
    Deals with feeling states (affect)

Hippocampus
    Located adjacent to olfactory cortex in the temporal lobe
    Involved consolidation of short term memory to long-term factual or declarative memory
    Suppresses rage response    
    The emotional aspects are more to aid the process of establishing the linkages
           
example, an emotional charged memory is more readily established and retrieved than one not colored by emotion, however the emotion is not necessarily specific to the event.

Hypothalamus
    Important output center of the limbic system
    Controls most vegetative & endocrine functions
    Controls many aspects of emotional behavior
    Deals with the expression of emotion
    Programmed response

Anterior Thalamic Nuclei
    Gateway to the cerebral cortex
    Computes the specific emotional response 
    modulation of emotional feelings or affect


Modern Papez Circuit

Modern belief is that there is more "interplay" between the original 4 areas as well as addition of more areas and pathways (see above graphic).  This provides for a more complex, fine-tuned emotional response.

Pathways Added To Circuit
    Bi-directional communication between the hippocampus and the association cortex
            Allows for comparison of old information and current stimulus
            Example "What you are think you are seeing really isn't scary at all"
            Blunts behavior response
    Input from the hypothalamus to the prefrontal cortex
            Executive decision making
                    Influences emotional response
                    "Pick Your Battles"

New Structures Added To Circuit
   
Amygdala
        Located deep inside temporal lobe
        Many bi-directional connections to hippocampus, hypothalamus, thalamus, cortex
        Projects current status in relation to both surroundings and thoughts
        The center for ID'ing danger (fundamental for self preservation)
        Involved in Fear conditioning
        Processes behavioral response
        Critical in long term memory
        "Window of the limbic system"

An important component of the learning is the emotion. 

The comments in this box are from Dr. Winterson.  They have been integrated into the essay outline above and highlited in red.
"The hippocampus can be better characterized as being involved in the consolidation of short term to long term factual or declarative memory. The emotional aspects are more to aid the process of establishing the linkages. So for example, an emotional charged memory is more readily established and retrieved than one not colored by emotion, however the emotion is not necessarily specific to the event.

On the other hand, the amygdala is more involved with "fear conditioning" per se. An important component of the learning is the emotion. I may have led you astray in the first lecture trying to convince you that emotions are important to learning.

Under anterior nucleus, since this nucleus projects to the cingulate gyrus its most immediate effects would likely be the modulation of emotional feelings or affect (not expression which implies some type of behavior).

Finally, you may want to add something about parts of the hypothalamus outside of the mammillary bodies."


Last Updated 04/10/00 12:27:17 PM
Return To The MNA2001 Homepage