We Just Moved One Step Closer To Understanding (and Defeating) Alzheimer’s

Most cones don’t really see color

We see color because of specialized light-sensing cells in our eyes called cones. One type, L-cones, sees the reds of strawberries and fire trucks; M-cones detect green leaves, and S-cones let us know the sky is blue. But vision scientists have now discovered that not all cones sense color (see video). The finding was made possible because, for the first time, scientists were able to look at individual photo-sensing cells.

Stephanie Kwolek was born #OTD in 1923. She’s most famous for inventing the bulletproof polymer Kevlar: wp.me/p4aPLT-3dv

- Carl Sagan, Cosmos.

(Giphy)

Quote from #JaneGoodall primatologist and anthropologist. More quotes like this to inspire you in my new journal I Love Science, in stores March but ready for preorder now! #womeninscience #ilovescience #anthropology #scientificliteracy

 Poison in the Brain: Toxic Structures in Neuronal Nuclei of Alzheimer’s Patients 

Spherical structures in the nucleus of nerve cells, so-called nuclear spheres, are suspected to trigger Alzheimer’s disease. A team headed by Dr Thorsten Müller from the research group Cell Signaling in Neurodegeneration has for the very first time demonstrated the presence of the presumably toxic protein aggregates in the human brain. The researchers from Ruhr-Universität Bochum have published their article in the journal Neurobiology of Aging.

The team compared brain samples from Alzheimer’s patients with those of the healthy individuals in the same age group. The result: in the samples taken from Alzheimer’s patients, the number of nuclear spheres was much higher than in those taken from healthy study participants.

Moreover, the group from Bochum analysed in what way nuclear spheres are generated. It was demonstrated in experiments with cell cultures that the amyloid precursor protein (APP) plays a crucial role in this process. APP has long been associated with Alzheimer’s disease. The researchers observed that nuclear sphere generation preferably takes place, if the amyloid precursor protein carries no phosphate group in a specific amino acid. An APP cleavage product, moreover, is contained in the nuclear spheres.

“Extensive nuclear sphere generation in the human Alzheimer’s brain” by Katharina Kolbe, Hassan Bukhari, Christina Loosse, Gregor Leonhardt, Annika Glotzbach, Magdalena Pawlas, Katharina Hess, Carsten Theiss, and Thorsten Müller in Neurobiology of Aging. Published online August 18 2016 doi:10.1016/j.neurobiolaging.2016.08.016

Thorny life of new-born neurons

Even in adult brains, new neurons are generated throughout a lifetime. In a publication in the scientific journal PNAS, a research group led by Goethe University describes plastic changes of adult-born neurons in the hippocampus, a critical region for learning: frequent nerve signals enlarge the spines on neuronal dendrites, which in turn enables contact with the existing neural network.

Practise makes perfect, and constant repetition promotes the ability to remember. Researchers have been aware for some time that repeated electrical stimulation strengthens neuron connections (synapses) in the brain. It is similar to the way a frequently used trail gradually widens into a path. Conversely, if rarely used, synapses can also be removed – for example, when the vocabulary of a foreign language is forgotten after leaving school because it is no longer practised. Researchers designate the ability to change interconnections permanently and as needed as the plasticity of the brain.

Plasticity is especially important in the hippocampus, a primary region associated with long-term memory, in which new neurons are formed throughout life. The research groups led by Dr Stephan Schwarzacher (Goethe University), Professor Peter Jedlicka (Goethe University and Justus Liebig University in Gießen) and Dr Hermann Cuntz (FIAS, Frankfurt) therefore studied the long-term plasticity of synapses in new-born hippocampal granule cells. Synaptic interconnections between neurons are predominantly anchored on small thorny protrusions on the dendrites called spines. The dendrites of most neurons are covered with these spines, similar to the thorns on a rose stem.

In their recently published work, the scientists were able to demonstrate for the first time that synaptic plasticity in new-born neurons is connected to long-term structural changes in the dendritic spines: repeated electrical stimulation strengthens the synapses by enlarging their spines. A particularly surprising observation was that the overall size and number of spines did not change: when the stimulation strengthened a group of synapses, and their dendritic spines enlarged, a different group of synapses that were not being stimulated simultaneously became weaker and their dendritic spines shrank.

“This observation was only technically possible because our students Tassilo Jungenitz and Marcel Beining succeeded for the first time in examining plastic changes in stimulated and non-stimulated dendritic spines within individual new-born cells using 2-photon microscopy and viral labelling,” says Stephan Schwarzacher from the Institute for Anatomy at the University Hospital Frankfurt. Peter Jedlicka adds: “The enlargement of stimulated synapses and the shrinking of non-stimulated synapses was at equilibrium. Our computer models predict that this is important for maintaining neuron activity and ensuring their survival.”

The scientists now want to study the impenetrable, spiny forest of new-born neuron dendrites in detail. They hope to better understand how the equilibrated changes in dendritic spines and their synapses contribute the efficient storing of information and consequently to learning processes in the hippocampus.

Crystals of the female hormone oxytocin

In women this hormone is secreted naturally by the pituitary gland. Oxytocin causes contractions of the uterus during labour, and it also stimulates the flow of milk in women who are breast-feeding.

5 sleep disorders you didn’t know existed

Ever shouted at your partner while you slept, or woken up unable to move? From apnoea to exploding heads, here are some strange things that go bump in the night.

Sleep apnoea

A surprisingly common condition in which you stop breathing for 10 seconds or more as you sleep. The lack of oxygen causes your brain to wake you up, or pull you into much lighter sleep. Either way, it can have a profound effect on the quality of your sleep – and that of any bedfellow, as it’s often accompanied by loud snoring.

Sleep paralysis

A terrifying experience, where the body, which naturally becomes paralysed duringREM sleep, is still paralysed when you wake. You are fully conscious but cannot move or speak, sometimes for several minutes. Some people also feel as if they are choking or their chest is being crushed and they may have visual hallucinations. The condition can be exacerbated by sleep deprivation, some drugs, and disorders such as sleep apnoea.

Hypnagogic jerks

Those jumps or twitches you experience as you nod off, often accompanied by the sensation of falling. The cause remains a mystery. One idea is that you start dreaming before your body becomes paralysed. Another is that the twitches are a by-product of your nervous system relaxing as you drift off.

REM sleep disorder

If you’ve ever punched or shouted at your partner in the night, only to remember nothing next morning, you may have been in the grip of this condition. Here, the body isn’t fully paralysed during REM sleep, so people act out their dreams. Thistends to happen only with bad dreams.

Exploding head syndrome

This entails the sensation of a loud noise, like an exploding bomb or a gunshot, as you drift off or wake up. It affects about 1 in 10 of us and it tends to start around age 50. Nobody knows what causes it– perhaps physical changes in the middle ear, or a minor seizure in the brain’s temporal lobe. Despite its name, the condition is harmless.

Image Credit: Toby Leigh

Source: New Scientist (By Catherine de Lange)