Handout



Handout 7 Learning/Memory and Language

Nature of learning (synaptic plasticity)

Definition: experiences producing change in the brain

a. Perceptual: ability to identify and categorize objects through senses

b. Motor: ability to identify and categorize things through our motor systems

c. Stimulus-response: establishing an association between a stimulus perception and a motor response

Examples:

|Classical/Pavlovian conditioning |Instrumental/Operant learning |

|a. hungry dog |a. you study |

|b. present food (unconditioned stimulus), dog salivates |b. you get an A |

|(unconditioned response) |c. reward will increase probability of studying again |

|c. turn on light (conditioned stimulus) before presenting food | |

|d. dog salivates to light (conditioned response) | |

d. Relational: the relationships among individual stimuli (spatial, episodic, observational)

Nature of memory

Definition: changes in the brain as a result of experiences retained for a period of time & ability to retain learned information and knowledge of past events and experiences and to be able to retrieve that information.

Common Model of Memory processes

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Squire’s taxonomy of memory

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Hippocampus

What is it? Structure in the medial temporal lobe

Functions:

- consolidation of memory (STM ( LTM)

- acts as the “pointer” and as “links” sensory info together

- spatial and contextual memory (taxi driver studies showed that hippocampal volume correlated with

the experience)

- detection of novel stimuli

- neurogenesis (even as adult)

Malfunctions:

- Severe anterograde amnesia: when you can’t form new memories

- Mild retrograde amnesia: can’t remember past memories

- Problems navigating space

- Seizures

- most common origin is in the medial temporal lobe

- why? Because it is a positive feed-forward circuit

- Susceptible to Alzheimer’s disease (first symptom of Alzheimer’s is the loss of STM)

- Hippocampus and depression

- smaller hippocampus in clinically depressed individuals due increased levels of cortisol (stress hormone)

Neuroanatomy

- Trisynaptic circuit

[pic] [pic]

Place cells

- cells that map out the environment

- cells get sensory input, respond to locations that are associated with a certain place

Activity Dependent Synaptic Plasticity

- increased strengthening is how associations are made

- neuroanatomical changes

- increased number of receptors (NMDA receptors)

- increased sensitization of NT

- increase amount of NT

- longer lasting change = shape of the neuron changes, gets bigger

Language

Methods of communications:

-gestures, speech, body language, writing

What is the importance of communication?

a. Allows for cultural evolution

b. Allows for knowledge to be passed down from generation to generation

Language acquisition

a. Is language genetic or is it learned?

a. Chomsky: first to suggest that there is an unique set of systems designed for learning language

b. Is it unique to humans?

a. Yes. Other animals have language too but not what we consider to be language.

c. Are language and thought interrelated?

a. Possibly. Do babies “think”? Yes, but their idea of thinking is different from our ideas about thinking. Babies are highly adaptable to learning languages and are even able to detect a universal language

d. Universal language?

a. Yes, but we eventually become specialized in a specific language so we aren’t able to detect other languages as easily

Birdsong

- The anatomy of birdsong (bird “language”) is similar to that in human systems. They have a productive language.

- Acquisition of birdsong suggests that there is a critical period for developing language. Birds that aren’t exposed to their species’ birdsong will not be able to detect it in the future.

- Neurogenesis occurs every Spring when they learn different versions of songs

Non-human primates (our close relative)

- There have been many efforts to teach speech/symbols/language to apes

- Their system is highly inflexible, static

- Vocalizations are preprogrammed meaning “AH”= snake and will always mean snake (AH is a made up vocalization)

- Slight lateralization

- There is a limit to what they can learn!! Adult monkeys know the same amount of words as a young child.

- There is debate whether or not they have the ability to learn language

o Savage-Rumbaugh believes chimps can understand speech, and they can do more than we think

o Pinker believes they just don’t understand language

What is language?

a. Includes grammar (phonetics, morphology, syntax, semantics)

b. Symbol usage (letters)

c. Ability to represent real-world situations

d. Ability to articulate something new

e. Intention to communicate

f. Infinite system of communication

Why is language important?

a. Humans are the only species to use language with syntactic (rules governing word order) and productive properties

a. The dog bit the man vs. The man bit the dog

i. Different order of words changes meaning completely

b. Language comprehension is rapid and automatic (something we take for granted)

a. Stroop task (takes a lot longer to state the color of the words rather than the word itself)

c. Language production is rapid and involves dynamic systems

a. Alex the parrot could learn new sounds and manipulate words into a distinct order

Lateralization

|Left hemisphere responsibilities |Right hemisphere responsibilities |

|-analysis of sequences of stimuli that occur quickly but |-analysis of space/shapes/forms |

|sequentially |-understanding prosody, jokes, tone of voice |

|-language (because of faster CPU) |-visual-spatial skills |

Language Disorders

- General knowledge

o Language disorders can be caused by many things

o Language disorders most commonly result from damage to the left hemisphere

o To test language dominance: use Wada test!

▪ You inject sodium amytal into one hemisphere of the brain. It puts that one hemisphere to sleep and if language is affected you’ll know that that side of the brain is responsible for language

- Types

o Paraphasia: substitution of a word by a sound, and incorrect word

o Neologism: paraphasia with a completely new word

o Non-fluent speech: talking with considerable effort

o Agraphia: impairment in writing

o Alexia: impairment in reading

Aphasias

|Broca’s |Wernicke’s |

|Where: lesions in the left inferior frontal region |Where: left superior temporal gyrus, extending to adjacent parietal cortex |

|Symptoms: |Symptoms: |

|-Nonfluent, labored speech (articulation) |-Fluent but nonsensical speech |

|-Cannot name persons or subjects (anomia) |-Cannot understand what they read or hear |

|-Can utter automatic or overlearned speech |-Difficulty with content words |

|-Have difficulty with function words (agrammatism) |-Cannot really repeat words |

|-Comprehension intact |-No hemiplegia |

|-Hemiplegia | |

- Global aphasia: total loss of language

- Damage to arcuate fasciculus (fibers that connect Broca’s and Wernicke’s areas) causes inability to repeat spoken words

Language pathways

1. Repeating a spoken word

a. A1 ( Wernicke’s ( Arcuate fasciculus (Broca’s ( Motor cortex

2. Repeating a written word

a. V1 ( angular gyrus/Wernicke’s (Broca’s ( Motor cortex

Sign languages

Do they work the same way?

- Sort of! Damage to Broca’s or Wernicke’s can cause signer aphasia

- Suggests that these areas are for language in general not just spoken/written word

- Circuitry is the same

Other languages

- Evidence suggests all languages rely on same circuits

- Kids learn languages way easier than adults

Dyslexia

- Problem reading, more common in males who are left-handed

- Switch phonemes around (telephone becomes enohpelet)

- Acquired dyslexia = alexia

- Deep dyslexia = problems with seeing the whole picture

William’s Syndrome

- Genetic disorder (chromosome 7)

- Extremely good at language but can’t do basic tasks, tend to be highly social

- Almost a mirror image of an autistic child

- This suggests that you can dissociate intelligence from language; they are independent processes

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