From the Guidelines
The subiculum is a critical component of the hippocampal formation, and its dysfunction has been implicated in several neurological conditions, including Alzheimer's disease, as evidenced by hippocampal sclerosis and TDP-43 inclusions, which can be observed in the context of AD neuropathologic change 1.
Subiculum Structure and Function
The subiculum is located between the hippocampus proper and the entorhinal cortex, playing essential roles in spatial navigation, memory processing, and emotional regulation. It receives information from the CA1 region of the hippocampus and projects to various brain regions including the entorhinal cortex, prefrontal cortex, nucleus accumbens, and hypothalamus.
Clinical Implications
Dysfunction of the subiculum has been implicated in several neurological and psychiatric conditions, including Alzheimer's disease, epilepsy, and schizophrenia. Hippocampal sclerosis, defined by pyramidal cell loss and gliosis in CA1 and subiculum, can be observed in the context of AD neuropathologic change, frontotemporal lobar degeneration (FTLD), and vascular brain injury (VBI) 1. TDP-43 immunoreactive inclusions are also commonly observed in the subiculum, particularly in cases of hippocampal sclerosis, and can be associated with various neurodegenerative diseases, including AD and frontotemporal lobar degeneration 1.
Key Findings
- The subiculum plays a crucial role in episodic memory formation and consolidation, helping to transform short-term memories into long-term ones.
- Hippocampal sclerosis and TDP-43 inclusions in the subiculum are associated with various neurodegenerative diseases, including Alzheimer's disease and frontotemporal lobar degeneration 1.
- The subiculum's pyramidal neurons have unique properties that allow them to generate burst-firing patterns, which may be crucial for its role in information processing and memory formation.
From the Research
Subiculum Brain Structure and Functions
- The subiculum is a pivotal structure positioned between the hippocampus proper and entorhinal and other cortices, as well as a range of subcortical structures 2.
- It plays a key role in the mediation of hippocampal-cortical interaction and has a range of electrophysiological and functional properties which are quite distinct from its input areas 2, 3.
Roles of the Subiculum in Neurocognitive Functions
- The subiculum participates in a wide range of neurocognitive functions, including spatial information processing, memory, motivation, and the temporal control of behaviour 4.
- It provides a relatively coarse representation of space and participates in, and supports certain aspects of, memory (particularly in the dynamic bridging of temporal intervals) 4.
- The subiculum also participates in the response to fear, stress, and anxiety, and in the generation of motivated behaviour (particularly the behaviour that underlies drug addiction and the response to reward) 4.
Dorso-Ventral Segregation of Function within the Subiculum
- There is a dorso-ventral segregation of function within the subiculum, with the dorsal subiculum relatively more concerned with space and memory, and the ventral subiculum concerned with stress, anxiety, and reward 4, 3.
- The dorsal component appears principally concerned with the processing of information about space, movement, and memory, whereas the ventral component appears to play a major regulatory role in the inhibition of the HPA axis 3.
Research on the Subiculum
- Despite its importance, the subiculum is an under-investigated region, and further research is needed to clarify its unique contribution to hippocampal formation processing 2.
- Recent studies have highlighted the importance of the subiculum in cognitive functions and pathological deficits of the hippocampal formation 5.