Memory

Question 1

Space-occupying lesion causing a mass effect on the medial frontal lobes. Patient has difficulty associating emotion to memories.

Discuss the pathway for associative memory - the circuit of Papez (9)

Answer 1

Information from the cingulate gyrus (½) is transported via the cingulum (½) into the entorhinal cortex (½) of the parahippocampal gyrus (½). From there the entrorhinal cortex feeds into the subiculum (½) of the hippocampal formation (½). Information sent into the dentate gyrus (½) and then to the hippocampus proper (½). The alveus collects the information from the hippocampus proper (½) and sends it via the medially converging fibres of the alveus (½) - the fimbria (½) along the fornix (crurae (½), body (½), columns (½)) to synapse with the mammillary bodies (½) of the hypothalamus. From there, the mammillothalamic tract (½) sends the information to the anterior nucleus of the thalamus (½) to complete the circuit (½).

Question 2

Using a short summary or flow diagram, describe the various component parts of the fornix and its associated structures (9)

Answer 2

Arises from the hippocampus as the alveus (white matter; fibres) (left & right)

Folds medially to form the fimbria,

Condenses at the point where the hippocampus ends, into the crus of the fornix

Continues superiorly into the lateral ventricle, superior to the thalamus as the body of the fornix,

Dives down, forming the interventricular foramen, into the wall of the hypothalamus as the columns of the fornix.

Synapses in the mammillary bodies.