Cab Drivers Experience Neurogenesis in Posterior Hippocampi, but Lose Performance For Other Tasks

Three to four years later, however, the researchers found an increase in gray matter in the posterior hippocampi, or the back part of the hippocampus, among the 39 trainees who ultimately qualified as taxi drivers. This change was not observed in the non-taxi drivers or trainees who had failed the exams. [...]

Qualified taxi drivers showed better memory performance for London-based information during the follow-up testing than controls or those who failed the test; however, they displayed “surprisingly poorer learning and memory for certain types of new visual information,” compared with controls, the researchers write online today in the journal Current Biology, “suggesting there might be a price to pay for the acquisition of their spatial knowledge.” (via.)

Learning, Gamma Rhythm, and Speed

Rhythms in the brain that are associated with learning become stronger as the body moves faster, UCLA neurophysicists report in a new study. The research team, led by professor Mayank Mehta, used specialized microelectrodes to monitor an electrical signal known as the gamma rhythm in the brains of mice. This signal is typically produced in a brain region called the hippocampus, which is critical for learning and memory, during periods of concentration and learning.

The researchers found that the strength of the gamma rhythm grew substantially as running speed increased, bringing scientists a step closer to understanding the brain functions essential for learning and navigation. (via.)

Kleine-Levin Syndrome: Sleep 10 days at a time? You might have it.

“I was hallucinating and after that I don’t remember anything. All of a sudden it just went blank and I just slept for 10 days. I woke up and I was fine again.” [...]

“I was hallucinating and after that I don’t remember anything. All of a sudden it just went blank and I just slept for 10 days. I woke up and I was fine again.” [...]

Louisa is unusual as KLS usually affects teenage boys, who can also exhibit hypersexuality and inappropriate behaviour.

As well as excessive sleeping, symptoms include behaviour changes, irritability, feeling in a dream-like state and binge eating, symptoms that can be mistaken for normal teenage behaviour. [...]

The change in behaviour before and during a sleep episode is one of the most upsetting things for Louisa’s parents, who take it in turns to remain with her. Doctors have told the family it’s crucial to wake Louisa once a day to feed her and get her to the bathroom.

But Lottie admits it can take a while to get her to come round. “I’ve tried before to literally force her to wake up but she just starts swearing and gets so agitated and aggressive.” [...]

Many sufferers have abnormalities in their temporal lobe, the area of the brain involved in behaviour and memory. A scan of Louisa’s brain function revealed she does have abnormalities in her frontal lobe but there are no signs that this has affected her behaviour or memory. (via.)

Brain-Derived Neurotrophic Factor & Serotonin Effects on Aging, Plasticity & More

BDNF and 5-HT: a dynamic duo in
age-related neuronal plasticity and
neurodegenerative disorders

Brain-derived neurotrophic factor (BDNF) and serotonin (5-hydroxytryptamine, 5-HT) are known to regulate synaptic plasticity, neurogenesis and neuronal survival in the adult brain. These two signals co-regulate one another such that 5-HT stimulates the expression of BDNF, and BDNF enhances the growth and survival of 5-HT neurons. Impaired 5-HT and BDNF signaling is central to depression and anxiety disorders, but could
also play important roles in the pathogenesis of several age-related disorders, including insulin resistance syndrome, Alzheimer’s disease and Huntington’s disease.
Enhancement of BDNF signaling may be a key mechanism whereby cognitive stimulation, exercise, dietary restriction and antidepressant drugs preserve brain function during aging. Behavioral and pharmacological manipulations that enhance 5-HT and BDNF signaling
could help promote healthy brain aging. [...]

By promoting neurogenesis,
synaptic plasticity and cell survival, BDNF plays a pivotal
role in the development and plasticity of the brain. During
development of the cerebral cortex and hippocampus,
BDNF induces the differentiation of neural stem cells into
neurons and promotes the survival of newly generated
neurons [1–3]. BDNF signaling at synapses enhances
long-term potentiation (LTP), a process of synaptic
strengthening associated with learning and memory;
the effect of BDNF on LTP is apparently mediated by
cAMP-response-element-binding protein (CREB), which
regulates the expression of genes involved in LTP and
memory formation [4]. Levels of BDNF are increased in
the hippocampus of rats during and after performance
of a spatial learning task (a radial-arm maze), and both
acquisition and maintenance of spatial memory are
impaired when BDNF levels are decreased using antisense
methods [5]. In rats that had previously acquired
spatial memory by extensive training, suppression of
BDNF expression impaired both reference and working
memory [5]. Another study showed that mice lacking one
copy of the BDNF gene exhibit impaired spatial learning
in the Morris water maze [6]. BDNF also plays an important
role in preventing death of neurons during development,
and promotes cell survival during stressful conditions
such as ischemia and trauma in the adult brain [7]. [...]

[A]ctivation of 5-HT1A receptors can impair learning and
memory whereas 5-HT2A and 5-HT2C receptors facilitate
memory formation [10]. [...]

5-HT can
also promote the survival of neurons in the adult brain, as
demonstrated by the abilities of a 5-HT receptor agonist
and SSRI to protect neurons against excitotoxic and
ischemic injury in animal models [12,13]. There are therefore
several commonalities of function in the CNS for
BDNF and 5-HT in terms of their effects on synaptic
plasticity, neurogenesis and cell survival. [...]

Conversely, BDNF
can stimulate the growth and sprouting of 5-HT neuron
axons innervating the cerebral cortex, thereby presumably
increasing the number of 5-HT synapses in this brain
region [14]. (via: pdf.)

“Exhaustion Syndrome” & Depression

Certain personality traits heighten susceptibility to psychiatric disorders. Therefore a research team at Umeå University wanted to study whether this patient group had any susceptibility factors that could explain the development of their disorder. The patient group is distinguished by being anxious and pessimistic, with a weak sense of self, which is common in many psychiatric disorders. What was special about this group was that they stood out as persistent, ambitious, and pedantic individuals.

Being ambitious, fastidious, and overachieving also appears to make a person more prone to exhaustion syndrome. According to Agneta Sandström’s dissertation, individuals with exhaustion syndrome demonstrate impaired memory and attention capacity as well as reduced brain activity in parts of the frontal lobes. Regulation of the stress hormone cortisol is also impacted in the group, with altered sensitivity in the hypothalamic-pituitary-adrenal axis (HPA axis). [...]

The HPA axis in the patient group shows reduced sensitivity in the pituitary, with less secretion of adrenocorticotropic hormone (ACTH) following stimulation with corticotropin (CRH), as well as heightened sensitivity in the adrenal cortex, with increased release of cortisol in relation to the amount of ACTH secreted. There is also a difference in the diurnal rhythm of cortisol, with the patients presenting a flatter secretion curve than the other two groups. The researchers could not detect any reduction in the volume of the hippocampus in the patient group. The proportion of individuals with measurable levels of the pro-inflammatory cytokine interleukin 1 is higher in the patient group. (via.)

Good news! “Zoning out” a crucial mental state

  • Stop Paying Attention: Zoning Out Is a Crucial Mental State – “When our minds wander, we lose touch with the outside world [...] we are more likely to make mistakes, fail to encode memories, or miss a connection. [...] [Scientists] tested the effect of zoning out by having a test group read a Sherlock Holmes mystery in which a villain used a pseudonym. As people were reading the passages discussing this fact, the researchers checked their state of attentiveness. Just 30 percent of the people who were zoning out at the key moments could give the villain’s pseudonym, while 61 percent of the people who weren’t zoning out at those moments succeeded. [...] The regions of the brain that become active during mind wandering belong to two important networks: [the executive control system, and the default network.]“

Both of these networks are used for thinking about goal directed behavior and the future. The article suggests that mind-wandering may lead to those Eureka!-like moments of spontaneous insight that may not occur when attentive to the present.

Mnemosyne – Spaced Repetition Memorization

So, I’m back in school as a biology major. I’ve got a lot of hardwork ahead of me, and one of the methods I’m using to attempt to make sure I remember what I’ve studied, and test well is I’m using a “spaced repetition” flash card program.

Mnemosyne is open source, and thus free, but it is based off of the supermemo algorithm which Piotr Wozniak built off of legitimate memory research, which essentially found that the most efficient way to study is to rehearse things just before we forget them. So, based off of his research, he created an algorithm and memory card program to do just this.  You may learn more about Piotr, and supermemo in his wired article:

Want to Remember Everything You Learn? Surrender to this Algorithm.

So my goal this year? To be able to know my classes well enough to not even have to study for my finals. Wish me luck, I’m signed up for some hard ones.