Fear and the amygdala Flashcards
- What structures make up the limbic system?
- Cingulate cortex
- Neocortex
- Hypothalamus
- Hippocampus
- Amygdala
- How did Papez propose the limbic circuit interacts as the basis of emotional processing?
He proposed the cingulate cortex projects to the hippocampus, from the hippocampus to the hypothalamus via the fornix, then to the anterior nuclei of the thalamus, then back to the cingulate cortex. The cingulate cortex is responsible for the emotional experience, which interacts bidirectionally with the neocortex responsible for emotional colouring. The hypothalamic nuclei are responsible for emotional expression and the hippocampus for the role of memory in emotion
- Briefly describe the inputs and outputs of the amygdala
The amygdala receives input from two pathways: the direct thalamo-amygdala pathway which passes through the thalamus and arrives at the medial nucleus of the amygdala, and the indirect thalamo-cortico-amygdala pathway which passes through the thalamus, sensory cortex and hippocampus and arrives at the basal and lateral nuclei of the amygdala. The central medial nucleus of the amygdala sends projections to the paraventricular and lateral nuclei of the hypothalamus as well as the periaqueductal grey.
- Other than the amygdala model of auditory fear conditioning (AFC), which considers the amygdalas as the ‘root’ of AFC, which other neuroanatomical structure does Weinberger consider to be the ‘root’? Highlight the role of this structure by briefly outlining both the direct and indirect pathways of auditory fear conditioning.
The Medial Geniculate Nuclei (MGN) of the thalamus. The direct pathway, the thalamo-amygdala pathway, travels through the MGN of the thalamus to the lateral nucleus of the amygdala directly, whereas the indirect pathway passes through the auditory cortex and thus is called the thalamo-cortico-amygdala pathway. As a result both pathways pass through the MGN of the thalamus and the MGN matches all criteria of LTP, associativity, the convergence of the condition and unconditioned stimulus thus Weinberg considered the MGN as the root of auditory fear conditioning.
