Editing Brain (section)

=== Learning and memory ===
Almost all animals are capable of modifying their behavior as a result of experience—even the most primitive types of worms. Because behavior is driven by brain activity, changes in behavior must somehow correspond to changes inside the brain. Already in the late 19th century theorists like [[Santiago Ramón y Cajal]] argued that the most plausible explanation is that learning and memory are expressed as changes in the synaptic connections between neurons.<ref>{{cite journal |last=Ramón y Cajal |first=S |title=The Croonian Lecture: La Fine Structure des Centres Nerveux |journal=Proceedings of the Royal Society |volume=55 |issue=331–335 |pages=444–468 |year=1894 |doi=10.1098/rspl.1894.0063|doi-access=free |bibcode=1894RSPS...55..444C }}</ref> Until 1970, however, experimental evidence to support the [[synaptic plasticity]] hypothesis was lacking. In 1971 [[Tim Bliss]] and [[Terje Lømo]] published a paper on a phenomenon now called [[long-term potentiation]]: the paper showed clear evidence of activity-induced synaptic changes that lasted for at least several days.<ref>{{cite journal |last=Lømo |first=T |title=The discovery of long-term potentiation |journal=[[Philosophical Transactions of the Royal Society B]] |volume=358 |issue=1432 |year=2003 |pages=617–620 |pmid=12740104 |doi=10.1098/rstb.2002.1226 |pmc=1693150}}</ref> Since then technical advances have made these sorts of experiments much easier to carry out, and thousands of studies have been made that have clarified the mechanism of synaptic change, and uncovered other types of activity-driven synaptic change in a variety of brain areas, including the cerebral cortex, hippocampus, basal ganglia, and cerebellum.<ref>{{cite journal |last1=Malenka |first1=R |last2=Bear |first2=M |title=LTP and LTD: an embarrassment of riches |journal=Neuron |volume=44 |issue=1 |pages=5–21 |year=2004 |pmid=15450156 |doi=10.1016/j.neuron.2004.09.012|s2cid=79844 |doi-access=free }}</ref> Brain-derived neurotrophic factor ([[BDNF]]) and [[physical activity]] appear to play a beneficial role in the process.<ref name="AirpollutionPhysicalactivity">{{cite journal|last1=Bos|first1=I|last2=De Boever|first2=P|last3=Int Panis|first3=L|last4=Meeusen|first4=R|year=2004|title=Physical Activity, Air Pollution and the Brain|url=https://www.researchgate.net/publication/264793941|journal=Sports Medicine|volume=44|issue=11|pages=1505–1518|doi=10.1007/s40279-014-0222-6|pmid=25119155 |s2cid=207493297}}</ref>

Neuroscientists currently distinguish several types of learning and memory that are implemented by the brain in distinct ways:

* '''[[Working memory]]''' is the ability of the brain to maintain a temporary representation of information about the task that an animal is currently engaged in. This sort of dynamic memory is thought to be mediated by the formation of [[Hebbian theory|cell assemblies]]—groups of activated neurons that maintain their activity by constantly stimulating one another.<ref>{{Cite journal |last1=Curtis |first1=CE |last2=D'Esposito |first2=M |title=Persistent activity in the prefrontal cortex during working memory |journal=Trends in Cognitive Sciences |volume=7 |pages=415–423 |year=2003 |pmid=12963473 |doi=10.1016/S1364-6613(03)00197-9 |issue=9 |citeseerx=10.1.1.457.9723|s2cid=15763406 }}</ref>
* '''[[Episodic memory]]''' is the ability to remember the details of specific events. This sort of memory can last for a lifetime. Much evidence implicates the hippocampus in playing a crucial role: people with severe damage to the hippocampus sometimes show [[amnesia]], that is, inability to form new long-lasting episodic memories.<ref>{{cite journal |title=Episodic and declarative memory: role of the hippocampus |journal=Hippocampus |year=1998 |volume=8 |pages=198–204 |pmid=9662134 |last1=Tulving |first1=E |last2=Markowitsch |first2=HJ |doi=10.1002/(SICI)1098-1063(1998)8:3<198::AID-HIPO2>3.0.CO;2-G |issue=3|s2cid=18634842 |doi-access=free }}</ref>
* '''[[Semantic memory]]''' is the ability to learn facts and relationships. This sort of memory is probably stored largely in the cerebral cortex, mediated by changes in connections between cells that represent specific types of information.<ref>{{cite journal |title=Semantic memory and the brain: structures and processes |journal=Current Opinion in Neurobiology |year=2001 |volume=11 |pages=194–201 |pmid=11301239 |last1=Martin |first1=A |last2=Chao |first2=LL |doi=10.1016/S0959-4388(00)00196-3 |issue=2|s2cid=3700874 }}</ref>
* '''[[Operant conditioning|Instrumental learning]]''' is the ability for rewards and punishments to modify behavior. It is implemented by a network of brain areas centered on the basal ganglia.<ref>{{cite journal |title=The integrative function of the basal ganglia in instrumental learning |journal=Behavioural Brain Research |volume=199 |pages=43–52 |year=2009 |pmid=19027797 |last1=Balleine |first1=BW |last2=Liljeholm |first2=Mimi |last3=Ostlund |first3=SB |doi=10.1016/j.bbr.2008.10.034 |issue=1|s2cid=36521958 }}</ref>
* '''[[Motor learning]]''' is the ability to refine patterns of body movement by practicing, or more generally by repetition. A number of brain areas are involved, including the [[premotor cortex]], basal ganglia, and especially the cerebellum, which functions as a large memory bank for microadjustments of the parameters of movement.<ref>{{cite journal |last=Doya |first=K |title=Complementary roles of basal ganglia and cerebellum in learning and motor control |journal=Current Opinion in Neurobiology |year=2000 |volume=10 |pages=732–739 |pmid=11240282 |doi=10.1016/S0959-4388(00)00153-7 |issue=6|s2cid=10962570 }}</ref>