Summary: Researchers have identified how the brain shops and recalls visible image memory, essential for tasks like tracking and problem-solving. By studying macaques, they discovered that the anterior ventral temporal cortex ( aVTC ) and the orbitofrontal cortex ( OFC) work together in this process, with OFC regulating memory-related activities in aVTC neurons. The results may lead to novel approaches to treating delirium memory problems.
Important Information:
- The aVTC and OFC are important in visible object storage, with the OFC governing memory-related synapse activity.
- Their physical recall and perception were impacted by the OFC’s chemogenetic silencing in macaques.
- These results provide insight into dementia-related memory loss and point to potential therapeutic target.
Origin: National Institutes for Quantum Science and Technology
Physical thing memory refers to our brain’s ability to store, understand, and recall sensory information about objects we perceive. This ability is essential for dealing with the earth, influencing studying, problem-solving, routing, and social interactions.
Without effective visible item memory, these activities may be almost impossible. In response, a large number of researchers have dedicated efforts to find the causes of this crucial aspect of consciousness in both humans and animals.
The anterior ventral temporal cortex ( aVTC ) is a key component of visual object memory, according to numerous studies on primates engaged in memory-related tasks. This region’s ability to represent complex visual items suggests that neurons can work in visual image memory even without direct physical input, relying instead on higher cognitive regions ‘ regulatory signals.
Despite this knowledge, the details of this” top-down” rules and the broader efficient system that includes aVTC remain vague.
A Japanese research team conducted a thorough research to uncover this obscure topic in an effort to answer these questions. They carried out a variety of experiments on macaques performing visual memory tasks under the direction of Senior Research Scientist Toshiyuki Hirabayashi from the National Institutes for Quantum Science and Technology ( QST ).
Their latest report was  , published in , Nature Communications , on July 10, 2024 , and was co-authored by Takafumi Minamimoto from the Advanced Neuroimaging Center, QST.
Second, the researchers performed useful positron emission tomography scans on macaques as part of a sensory recall task, which revealed moment changes in blood flow that allowed them to identify brain regions with higher activity.
They combined these proportions with functional magnetic resonance imaging data, which was previously collected from a large number of macaques and used to analyze the communication between various brain regions. In this way, they identified specific nodes in the network that governs visual object memory as essential components of the aVTC and the orbitofrontal cortex ( OFC).
To concrete these observations, they conducted chemogenetic suppressing experiments. Just put, they used a popular vector to create specially created receptors to the cells to physically modify the OFC of macaques. These receptors only work in the presence of a very precise custom drug, which stops the neurons from firing.
When the OFC was biologically silenced, which did not in any way interfere with the monkeys ‘ visual perception, the group found that they performed significantly worse in the visual understand jobs.
However, the researchers wanted to take their research one step farther, and thus, they explored the small-scale details governing physical thing memory in the aVTC and OFC.
For a thorough knowledge of the community mechanisms that underlie thing memory, both the macro- and micro-scale recognition of brain network nodes and the subsequent micro- and macro-scale understanding of direct information flow along the identified nodes are necessary, says Hirabayashi.
To this end, they conducted single-neuron recordings in the aVTC of the same macaques used in previous experiments, assessing the memory-related activity and higher-order modulation in these neurons. They found that the memory-related activity of individual aVTC neurons, but not perception-related activity, was specifically attenuated by OFC silencing.
This was in line with the earlier behavioral evaluations. Additionally, when the monkeys performed a mnemonic error in the task prior to OFC silencing, the top-down inputs from the OFC supported behavioral relevance of the memory-related activity in individual aVTC neurons, which was consistent with the changes in neuronal activity.
These analyses together provided the team with a thorough understanding of the mechanisms that govern primates ‘ short-term visual object memory. The findings of this study may ultimately aid in better understanding ourselves given that our brains have many functional and structural similarities with those of these animals. Worth noting, this could have important implications in medicine.
According to Hirabayashi,” The network mechanisms that were discovered in non-human primates could provide a mechanistic understanding of related memory deficits that occur in human dementia.”
He adds that the artificial neuromodulation of the recently discovered network in patients with dementia might restore their visual memory functions.
Let’s hope that this research will pave the way for a more in-depth understanding of the human brain, the most complex object in the universe.
About this information on visual memory research
Author: International Affairs and Public Relations Section
Source: National Institutes for Quantum Science and Technology
Contact: International Affairs and Public Relations Section – National Institutes for Quantum Science and Technology
Image: The image is credited to Neuroscience News
Original Research: Open access.
Takafumi Minamimoto et al.,” Fronto-temporal top-down regulation for object memory in primates is analyzed through multiscale chemogenetic dissection..” Nature Communications
Abstract
Fronto-temporal top-down regulation for object memory in primates is analyzed through multiscale chemogenetic dissection.
The underlying neural mechanisms have been extensively studied, particularly in the anterior temporal cortex of primates, and visual object memory is a fundamental component of various cognitive abilities.
However, it is still difficult to determine the top-down regulation that this region receives for object memory at the macroscopic, large-scale functional network in which it is embedded and at microscopic neuron-level dynamics.
By combining whole-brain functional imaging during rest and a short-term object memory task in male macaques, we have found that the orbitofrontal node serves as a critical partner of the anterior temporal node for object memory.
During the task, local and remote orbitofrontal nodes were downregulated by focal chemogenetic silencing, in addition to worsening mnemonic but not perceptual performance.
Additionally, bottom-up perceptual signal remains unchanged despite the same monkeys performing the same task using imaging-guided neuronal recordings.
Furthermore, similar activity difference was also observed between correct and mnemonic error trials before silencing, suggesting its behavioral relevance.
These multifaceted but convergent results provide a multiscale causal understanding of the ventral fronto-temporal network’s dynamic top-down regulation that underlies short-term object memory in primates.
