Neuro 🧠

Today we will be exploring the hippocampus, which associates with episodic and semantic memories.

There are 3 cognitive processes that are mediated by the hippocampus - associative representation, sequential organisation and relational networking.

Associative representation -

This is based on the idea that our memory is deconstructed into a series of sequentially organised events of memory from an unique experience. For example, in one specific memory, you might remember details of yourself as well as others, this therefore suggests that our episodic memory work closely in association with other memories to create an unique and complete picture of our memory which involves association with other aspects.

Sequential organisation -

This reflects how our memory is organised into specific orders. This is demonstrated in a study with rats which are presented with 5 odours, and findings showed that rats with lesions in the hippocampus failed to identify odours presented in orders,…

1) Compress brain tissue, as the growing mass presses against nearby brain structures, interfering with their function - can led to loss of functions in areas, e.g. motor movement

2) Increased Intracranial Pressure - tumor growth raises pressure inside it, as the skull is fixed space. Symptoms include - persistent headaches, nausea, and vomiting etc.

3) Disruption of electrical activity

Irritation at surrounding brain tissues would trigger abnormal electrical signals, leading to seizures

4: Region-specific dysfunction

Frontal lobe - personality changes, impaired judgement

Dementia is a group of conditions marked by cognitive decline, memory loss and imparied thinking. The most common type is Alzheimer's disease.

Let's look into what dementia does to the brain and how radiologists use MRI to identify Dementia:

1) Shrinking (brain atrophy) - this is especially in the hippocampus, temporal lobes and cortex

2) Cortical thinning - the brain's outer layer is the cortex. Automated volumetric analysis can compare a patient's brain size to a normal brain.

3) White matter lesions: associated with vascular dementia, in T2 MRI sequences, these bright spots may indicate small vessel disease and are common in vascular dementia.

Below is an example of brain atrophy:

Introduction to brain MRI:

There are 3 possible views of MRI, axial, coronal and sagittal.

There are also two main MRI views/sequences:

T1: better shows anatomy of soft tissues in the body

T2: more accurately show composition and placement of water molecules in tissues, highlighting cysts, fluids and swelling.