Uncovering Neural Pathways to Alzheimer’s Disease

Breaking Down Connectomics

Connectomics is essentially the study of connectomes. Connectomes are complete maps of the neural connections in the brain. Our brain has a 100 trillion neural connections! That’s 1000x the number of stars in the galaxy.

Neural Plasticity

Neural connections are the connections that occur when neurons transmit information. The human brain is known to have neural plasticity. This means that the connections in the brain are constantly changing.

Developments in Connectomics

These wiring diagrams have a goal of mapping the molecular connections between neurons. Except, we’re not very far into the process. Currently, we only have a complete connectome of the roundworm C. elegans. This animal is a free-living, transparent nematode which only has 300 neurons and 7000 synaptic connections.

Roundworm C. Elegans

Why do we need connectomics?

The purpose of these connectomes is to better under the organization of neural interactions in the brain and attempt to relate brain structures to their functions to understand what parts give us certain abilities.

The Human Connectome Project

The Human Connectome Project (HCP) is a group of projects by researchers aiming to understand the major brain pathways, compare essential circuits, zoom into specific regions, and understand the functions of the brain in depth. The Human Connectome Project is essentially the Human Genome Project, but for the brain.

The Human Connectome Project

Mapping the human brain

These connections are mapped through the use of electron microscopes. These electron microscopes spend months collecting millions of slices of a specific region of the brain, which are nanometers thick. Then, they’re assembled into a 3-D structure using specific software.

Wiring Diagram of Mouse Brain

Understanding Alzheimer’s Disease

Alzheimer's disease (AD) is a neurodegenerative disorder resulting in accumulative neuron death. AD currently affects 500,000 people in the geriatric population in Canada.

Affects of Alzheimer’s

Patients with Alzheimer’s disease tend to lose many of their essential functions. Including, loss of memory, reduced motor function, loss of cognitive ability, and the ability to perform daily tasks.

Functional Connectomes and Alzheimer’s

Through the use of functional connectomics and different imaging modalities including sMRI, diffusion MRI, EEG, and fMRI, researchers have discovered abnormal connectivity in the AD brain.

The Future of Connectomics

Connectomics is continuing to make major advancements. Google has recently rendered a high-resolution connectome of the fly brain.

Key Takeaways

  • Connectomes are complete maps of the neural connections in the brain.
  • We only have a complete connectome of the roundworm C. elegans.
  • Developing the human connectome will help shed light on anatomical and functional connectivity within the healthy human brain, to produce data sets which can be used to facilitate research into neurological disorders.
  • The Human Connectome Project aims to understand the major brain pathways, compare essential circuits, zoom into specific regions, and understand the functions of the brain in depth.
  • Alzheimer’s disease is associated with an excessive amount of amyloid plaques, neurofibrillary tangles, buildup of micorglia, and the formation of vascular conditions.
  • Brain imaging and functional connectomics has been used to discover abnormal connectivity in the AD brain.

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