Inhibitory Neurons May Hold the Key to Spatial Learning and Memory

Summary: A new study explores how the brain quickly learns and remembers important locations by focusing not on excitatory neurons, but on inhibitory ones called parvalbumin interneurons (PVs). These PVs act like circuit breakers, briefly reducing their activity to allow learning-related neurons to strengthen connections.

Using optogenetics and virtual reality mazes in mice, researchers found that learning was blocked when PV inhibition didn’t decrease at the right time. The findings challenge the idea that more brain activity always equals more learning and could reshape approaches to Alzheimer’s and memory enhancement.

Key Facts:

• Dynamic Inhibition: Parvalbumin interneurons reduce activity just before learning moments, allowing memory-related circuits to strengthen.
• Predictive Signal: The decrease in inhibition predicted a reward before it occurred, revealing how the brain primes itself for learning.
• Clinical Implications: Improper timing of inhibition may explain memory impairments in Alzheimer’s and learning disorders.                Source: Georgia Institute of Technology

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Our Hiding Consciousness

The neuron, the specialized cell type that makes up much of our brains, is at the center of today’s neuroscience. Neuroscientists explain perception, memory, cognition and even consciousness itself as products of billions of these tiny neurons busily firing their tiny “spikes” of voltage inside our brain.

These energetic spikes not only convey things like pain and other sensory information to our conscious mind, but they are also in theory able to explain every detail of our complex consciousness.

At least in principle. The details of this “neural code” have yet to be worked out.

While neuroscientists have long focused on spikes travelling throughout brain cells, “ephaptic” field effects may really be the primary mechanism for consciousness and cognition. These effects, resulting from the electric fields produced by neurons rather than their synaptic firings, may play a leading role in our mind’s workings.

In 1943 American scientists first described what is known today as the neural code, or spike code. They fleshed out a detailed map of how logical operations can be completed with the “all or none” nature of neural firing—similar to how today’s computers work. Since then neuroscientists around the world have engaged in a vast endeavor to crack the neural code in order to understand the specifics of cognition and consciousness—to little avail.     READ MORE...

Human Neurons and Mammels

Human neurons have fewer ion channels, which might have allowed the human brain to divert energy 

to other neural processes.

Neurons communicate with each other via electrical impulses, which are produced by ion channels that control the flow of ions such as potassium and sodium. In a surprising new finding, MIT neuroscientists have shown that human neurons have a much smaller number of these channels than expected, compared to the neurons of other mammals.


The researchers hypothesize that this reduction in channel density may have helped the human brain evolve to operate more efficiently, allowing it to divert resources to other energy-intensive processes that are required to perform complex cognitive tasks.


“If the brain can save energy by reducing the density of ion channels, it can spend that energy on other neuronal or circuit processes,” says Mark Harnett, an associate professor of brain and cognitive sciences, a member of MIT’s McGovern Institute for Brain Research, and the senior author of the study.

MIT neuroscientists analyzed pyramidal neurons from several different mammalian species, including,

from left to right, ferret, guinea pig, rabbit, marmoset, macaque, and human. 

Credit: Courtesy of the researchers

Harnett and his colleagues analyzed neurons from 10 different mammals, the most extensive electrophysiological study of its kind, and identified a “building plan” that holds true for every species they looked at — except for humans. They found that as the size of neurons increases, the density of channels found in the neurons also increases.

However, human neurons proved to be a striking exception to this rule.

“Previous comparative studies established that the human brain is built like other mammalian brains, so we were surprised to find strong evidence that human neurons are special,” says former MIT graduate student Lou Beaulieu-Laroche.

Beaulieu-Laroche is the lead author of the study, which was published on November 10, 2021, in Nature.  READ MORE...

Our Consciousness

When I see red, it’s the most religious experience. Seeing red just results from photons of a certain frequency hitting the retina of my eye, which cascades electrical and biochemical pulses through my brain, in the same way a PC runs. But nothing happening in my eye or brain actually is the red colour I experience, nor are the photons or pulses. This is seemingly outside this world. Some say my brain is just fooling me, but I don’t accept that as I actually experience the red. But then, how can something out of this world be in our world? Andrew Kaye, 52, London.

What’s going on in your head right now? Presumably you’re having a visual experience of these words in front of you. Maybe you can hear the sound of traffic in the distance or a baby crying in the flat next door. Perhaps you’re feeling a bit tired and distracted, struggling to focus on the words on the page. Or maybe you’re feeling elated at the prospect of an enlightening read. Take a moment to attend to what it’s like to be you right now. This is what’s going on inside your head.

Or is it? There’s another, quite different story. According to neuroscience, the contents of your head are comprised of 86 billion neurons, each one linked to 10,000 others, yielding trillions of connections.

A neuron communicates with its neighbour by converting an electrical signal into a chemical signal (a neurotransmitter), which then passes across the gap in between the neurons (a synapse) to bind to a receptor in the neighbouring neuron, before being converted back into an electrical signal. From these basic building blocks, huge networks of electro-chemical communication are built up.  TO READ ENTIRE ARTICLE, CLICK HERE...