export_hippocampal formation Flashcards
What are the components of the limbic system
- Limbic cortex
- Subcortical limbic structures
- Fibers
What are the subcomponents of the limbic cortex
- Parahippocampal gyrus
- Hippocampal formation
- Dentate gyrus
- Cingulate gyrus
- Insula
- Orbitofrontal gyrus
What are the subcortical limbic structures involved in the limbic system
- Amygdala
- Hypothalamus
- Septal nuclei
- Habenular nuclei
- Anterior and dorsomedial thalamic nuclei
- Indusium griseum
What are the fibers/tracts involved in the limbic system
- Mamillothalamic tract
- Fornix
- Stria medullaris thalami
- Stria terminalis
What are the layers of the hippocampus
- Presubiculum
- Subiculum
- Prosubiculum
- Hippocampus
- Dentate gyrus
All of these layers are archipallum, that is they are composed of three layers - molecular, pyramidal and polymorphic.
The inferior parahippocampal gyrus is what type or cortex?
Isocortex - it has 6 layers.
What is the indusium griseum
Hippocampal remnants that course over the dorsal surface of the corpus callosum and connect the septal area with the hippocampus.
Composed of the subcallosal gyrus and the medial and lateral longitudinal striae.
Input to the hippocampal gyrus
- Entorhinal cortex –> hippocampal and dentate gyrus.
- Medial septal nucleus –> Fimbria
- Cingulate gyrus –> cingulum –> presubiculum/entorrhinal cortex –> hippocampus
What are the components of the fornix
- Fimbriae
- Crura
- Body
- Columns.
What are the output fibers/tracts located within the fornix
- Precommissural fornix –> caudate septal nucleus
- Postcommissural fornix –> mammillary bodies –> anterior thalamic nulcei –> cingulate gyrus
- Subiculum –> postcommissural fornix —> various structures.
Hippocampal output from the subiculum leaves via the postcommissural fornix and travels to the 5 following structures:
- Mammillary bodies
- Anterior thalamic nuclei
- Lateral septal area of the hypothalamus
- Medial frontal cortex
- Cingulate gyrus
What is the sole direct cortical projector/output of the hippocampus
The subiculum. Dentate fibers do not leave the hippocampus.
CA1 pyramidal cell axons project to the
Subiculum and fornix
CA3 pyramidal cell axons project to the
CA1 and fornix
What is the function of the hippocampus
Consolidation of short-term memory into long-term memory. Unilateral injury to mammillary bodies or the fornix does not seem to impair function but lesions to this area may cause psychomotor seizures.