Research reveals that neuron diversity affects memory

Neurons in key regions of the brain have different functions based on their precise genetic identities, and understanding this diversity may lead to a better understanding of the brain. “Cornell University researchers report in a new study that computational flexibility and memory capacity may help disease treatment options.

Pyramidal cells in the CA1 region of the hippocampus, once thought to be a homogeneous population of neurons, have recently been found to be highly diverse. However, the role of this diversity in cognitive function has not previously been investigated in detail.

“Most memory research assumes that the hippocampus and cortex are something like a black box: a monolithic structure, a homogeneous set of neurons,” said co-senior authors. Antonio Fernandez Ruiz, Assistant Professor of Neurobiology and Behavior, and Investigator of the Nancy and Peter Meinig Family of Life Sciences at the College of Arts and Sciences (A&S). “Essentially, there are two black boxes of hers communicating with each other, but he doesn’t know exactly what the components of these two boxes are.”

“Hippocampal Cortical Circuits for Selective Memory Encoding, Routing, and Replaywas published in the May 16th journal Neuron. Co-senior author orange blossom oliveAssistant Professor of Neurobiology and Behavior (A&S).

In experiments in rats, Fernandez Ruiz and his team found that CA1 neurons simultaneously encoded task-related information, but then whether the neurons were deep or superficial in the hippocampus. It was to send impulses to different targets accordingly.

“We discovered that there are at least two different ways these structures communicate with each other,” he said. “And there are specialized circuits united by different types of cells that encode different types of information and send them to different parts of the brain.”

The study used rats undergoing both a memory task and sleep, and examined large numbers of neurons recorded simultaneously using high-density silicon probes. The probe detects cell-encoded activity coordinated by synchronized oscillations known as sharp-wave ripples.

As they found in an earlier study, CA1 pyramidal cells (named for their shape) have different physiological properties depending on where they are located within the hippocampus (deep, middle or superficial). different parts. Fernandez Ruiz said this diversity is key to memory development.

A key finding in this study: deep CA1 pyramidal cells are primarily responsible for the alignment and assembly dynamics, whereas superficial cells were specifically recruited during replay of new experiences and facilitated memory formation.

“When we learn something new, these aspects of the experience are segregated and encoded by specialized neuronal populations, which are then sent to different areas dedicated to processing different kinds of information. ‘ he said. We believe this is important as it makes the system more flexible. “

The researchers also characterized previously unknown circuits involving the hippocampus and cortex that play a role in memory consolidation. Oliva said a better understanding of neuronal diversity in the hippocampus could help target areas affected by dementia.

“Diseases like Alzheimer’s are characterized by impaired communication between the hippocampus and cortex,” she says. more affected.

“If we can identify which aspects of memory are being disrupted, perhaps we can trace it back to the specialization of different cell types, allowing us to adopt new, more targeted treatments.”

Co-authors include postdocs Ryan Harvey and Heath Robinson. and Can Liu, a PhD student in neurobiology and behavior.All authors are members Brain Computation and Behavior Labco-led Fernandez-Ruiz and Oliva.

Support for this research came from the National Institutes of Health, the Sloan Foundation, the Whitehall Foundation, and a Klingenstein-Simmons Fellowship.