This funny little man is proportioned according to the touch receptors in the body. As you can see, the hands, the face, the feet have more than their fair share of nerves. Stimulation to these areas will send many more signals to the brain than will stimulation to the torso or arm or legs. And there are correspondingly disproportionate areas of the brain that receive the incoming signals.

Fidgeting, holding and playing with things, becomes an obsession with many people who have dementia, and the sensory feedback to the brain is at least part of the reason why. It is not entirely different from babies and small children being obsessed with exploring with their hands and mouths. It is important to provide tactile stimulation to those in your care. Hand and foot and face massages provide passive tactile stimulation. A barefoot walk in the grass and a sensory box like I showed earlier are excellent active stimulations.

This is an overhead view of the brain. The frontal lobe is pointing up in the picture. At the very back of the frontal lobe is the motor cortex, here in that off-red color; that’s the part of the brain that controls voluntary muscle activity. Just behind the motor cortex in the parietal lobe is the somatosensory cortex, pictured in blue. The somatosensory cortex receives electrical impulses coming in from different parts of the body, providing us with our sense of touch.

Here is another look at our friend Homunculus. His rather disconnected body is spread across a section of the motor cortex. Homunculus’ face is aligned with a large section of that motor cortex which controls facial movement, his elbow with a rather smaller section, etc. You can see that the volume of brain dedicated to controlling the face and hands is again disproportionately large. This can be a little hard to see at first… <This might be a little unclear and need some explanation. Draw on the monitor, etc.>

And here is Homunculus spread across the somatosensory cortex. You can see how the area of the brain that controls movement in a part of the body is closely relates to the area that receives messages and feedback from that part.  Nerves in the fingers send messages to the somatosensory cortex which communicates with the motor cortex which then sends instructions back to the fingers about what to do next. These connections between different lobes and sections are crucial to our functioning.

And now things get really interesting. Until very recently the mature brain was thought to be relatively immutable. Neurologists told us that the brain structure didn’t really change once we reached adulthood. We go on learning, synaptic connections are created, but new brain cells just didn’t happen. Some new discoveries have changed the way we think about that. We now know that the brain does change and reorganize itself, that it can actually increase in mass depending on need and use. This phenomenon is called brain plasticity, and is one of the most exciting new areas in neuroscience. Brain plasticity is fueled by how the brain is stimulated.

As humans we have an intimate relationship to music. Listening to music is an excellent sensory stimulation; who doesn’t enjoy music? Playing music is even more stimulating. Creating music – not composing but creating the sounds – is multi-sensory. It involves hearing and somatic senses. Instrumental musicians have become favorite subjects for brain studies, and these studies have reached some exciting conclusions. One is that pianists and violinists have enlarged areas of their somatosensory and motor cortices when compared to non-musicians. It is not just that they are more able to discern tone and pitch, or recognize harmony and dissonance, but their brains have actually grown as a result of their practice. Furthermore, the right motor cortex is more changed in violin players, whose left hands are more active. The cortex is enlarged on the left in piano players, who are more active with their right hands.


One more study, this one involving mice brains. A group at MIT put mice into a water maze. The mice would swim around randomly until they found a hidden platform which allowed them to get out of the water. Soon the mice were able to swim directly to the platform. Then the researchers did something that was not so nice – they gave the mice Alzheimer’s disease. Back in the maze the mice swam around randomly once again. They forgot their training.

The investigators then put half of the demented mice into an enriched environment with a running wheel and other colorful toys, an environment one of the researchers called “Disneyland for mice.” The control group was kept in their cages with little for stimulation but the food they got at mealtimes. After a time both groups were re-tested in the maze. The control group performed as expected; they had no idea where the platform was. However, the mice who had gone to Disneyland swam to the platform pretty much as they had before their memories had been altered.

Even this laboratory hardened group of researchers was amazed. They had assumed that their procedure had erased all memory of the training, just as we assume that Alzheimer’s disease erases memory. The scientists had to re-examine their assumption and they concluded that it was not the memory that was lost but access to the memory was destroyed. And it is entirely possible that Alzheimer’s works like that, erasing connections and not memories. Could enough of the right type of stimulation help reconnect to lost memories?

I know what you are thinking, and no, I don’t want you to teach your 92 year old grandmother to play the violin, unless she really wants to and shows some aptitude. I also don’t suggest a running wheel. And by all means don’t let her drive in London. There are more appropriate ways to provide sensory and brain stimulation. I was able to get enough of these Brainpaths from the manufacturer for everyone here. This simple device provides similar sensory feedback as fingering violin strings. The idea for it is actually based on some of these recent discoveries in neuroscience. Tracing the grooves in this plastic disk with your fingers stimulates the 3000 or so receptors in each fingertip which, as we have seen, stimulates the somatosensory cortex, which in turn signals the motor cortex.

And here is a picture of the somatosensory cortex being stimulated by this activity. This is a functional magnetic resonance imaging scan of the brain of someone using one of these Brainpaths. Compare this to the image we saw earlier of the somatosensory cortex…

The red spots in the fMRI scan indicate high activity. Notice how closely those spots correspond to the position of Homunculus’ hand on the somatosensory cortex. Our contention that sensory stimulation is brain stimulation is further substantiated. Furthermore – – – I find it amazing that we can image the brain like that, don’t you?!
It is an exciting time for the science of neurology and brain study. I read recently that we have learned more about the brain in the last five years than in the five thousand years previous. Recent advances in brain-imaging technology have given us some incredible tools for studying this most complex structure in the known universe: tools like the fMRI, the EEG, SPECT scan, and CT scan and the PET scan. I’m sure that many of you know more than I do about these machines. Some of you could probably even tell me what those letters stand for – because I’d like to know. Anyway, these special tools allow us to watch electrical activity and blood flow in the brain as it responds to different stimuli and situations.

This image from the brain on Brainpaths is a good example of how this new technology can help us study the brain. In this picture we see how a simple somatic input affects the corresponding part of the somatosensory cortex. Sensory input, however, is rarely this simple. Looking at a painting, especially a well done piece, can light up the brain like a Christmas tree. Art can trigger responses in creative centers, emotional centers, the prefrontal cortex which makes judgements, and more. Art can also evoke memories and reminiscences.

When you read a book more than just language and visual centers are stimulated, as this image illustrates. If you read about running, the parts of your brain associated with running are activated. If the protagonist in your book is cooking and describing the odors in the kitchen, the olfactory centers of your brain can be activated.


Interestingly, here is a comparative picture from an fMRI scan showing the brain while surfing the internet. Little wonder we waste so much time doing so. And the positive effects often last for days and weeks. I think I have another image here, one of the brain while watching situation comedy on TV. Yes…

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