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End of Memory, Language and Attention

Retrograde Amnesia

Deficit in memory for information learned before the onset of Amnesia, Impairment is often temporally graded, old memories are well preserved.

Anterograde Amnesia

Hallmark feature of organic amnesia, failure to form new memories, Short delay leads to remember short prose piece, long delay leads to harder to remember, Short term memory is intact, significant forgetting, learning deficits occur for verbal and spatial

Primacy Effects

Reflects transfer from short term memory to long term memory

Recency Effect

Reflects retention in Short term memory

Amnesics

Don't show primacy effect but have recency effect a.k.a. Remember words at the end of the list.

H.M.

Case study of Amnesia, Surgical Removal of Hippocampus and Surrounding cortex, Severe new learning deficit (anterograde amnesia) Some loss of events 1-3 years prior to surgery (retrograde amnesia) Intact IQ, language, attention, knowledge base, childhood memories

Cerebellum

Procedural Memory

Pre-Frontal Cortex

Short Term Memory, working memory

Frontal and Temporal Lobes

Long Term Memory, semantic and episodic

Amygdala

Emotional Memories

Hippocampus

Responsible for the formation of Long Term Memories leads to consolidations, important for relational memory

Korsakoffs Syndrome

Damage to the thalamus and mammillary bodies, Retrograde and Anterograde amnesia and other symptoms due to thimone deficiency.

Herpes Simplex Encephalitis

...

Temporal Lobectomy

Used to treat epilepsy, damage to temporal lobs

Anoxia

Damage to Hippocampus

Anterior Communication Artery Aneurysm

Damage to Basal Fore Brain

Animal Models of Amnesia

The neuro anatomy of the medial temporal lobe is similar in many mammals.

Delayed non-matched sample task

Task: pick opposite location relative to where reward was last seen so monkeys sees reward then screen down , reward

Declarative vs. Non Declarative

Medial temporal lobe, amnesics showed spared procedural learning and perceptual priming

Semantic vs. Episodic

Patient KC severe anterograde and retrograde amnesia partially for episodic and source memories. KC could learn some new semantic information

Recall

Type of memory retrieval in which the information to be retrieved must be pulled from memory with very few external cues

Retrieval Failure

Recall has failed (tip of the tongue)

Recognition

The ability to match

Semantic vs. Episodic

Hear a list of related words, asked to look at a list of test words, decide which ones you've seen and which ones you hadn't

Relational Memory

Making an association between object information with spatial information

Three Layers of the Hippocampus

CA1 Pyramidal Cells, Granual Cells, CA3 Pyramidal Cells

Long Term Potentiation

response to stimulation over time will increase in the granule cells, post synaptic potential are graded

Hebb's Law

Neurons that fire together wire together

Cooperativity

more than one input must be active simultaneously

Associvity

Weak inputs are strengthened with the co-occur with stronger input

Specificity

Only stimulated synapses are potentiated8

NMDA Receptors

Gated by glutamate and Mg2, excited by MDA and glutamate, usually blocked by magnesium Ion, Weak stimulus don't cause it to open

Magnesium

Prevents currents from flowing through

Aphasia

inability to recognize the meaning of words

Tonal Agnosia

can't tell the differences between different worlds.

Mental Lexicon

Storage of words and concepts, a mental store of information about words that includes semantic information ,Synaptic Information, Word forms. Like dictionary but no fixed content meaning words can be learned and more frequently used words can be accessed more quickly

Perceptual Analysis of linguistic input

speech comprehension and reading

Language

Damage to Basal Fore Brain

Orthographic

Written/seen

Phonological

Pronounced/Heard

Organization of Language

Sounds then Phonemes then Morphemes then Words then Sentences

Phonemes

Smallest unit of sound that makes a difference in meaning

Morphemes

Smallest meaningful unit in grammar

Syntax

...

Mental Lexicon

Concept, Lemma, Lexeme

Concept

Semantic Representation

Lemma

Synaptic representation

Lexeme

Phonological Representation

Semantic Priming Effect

Facilitation of Word Recognition due to semantic associations

Naming Task

Reading target word out loud

Lexical Decision task

Is the target word a word or a non word

Wernicke's Aphasia Patients

Make semantic paraphrases e.g. horse instead of cow

Deep Dyslexia

Similar errors in reading

Progressive Semantic Dementia

Progressive damage to temporal lobs, impairment in conceptual systems

Category specific semantic Deficits

Deficits for Living things. vs. Non living thing. Production and comprehension following left temporal lobe.

Warington et. al.

Knowledge about different classes of things depends to varying degrees on visual vs. functional properties, computation model can account for apparent category specific deficits with property based account

Caramezza and Shelton

Linguistics materials in previous studies poorly controlled conceptual categories

Language Comprehension

Difficult Problem-Variability in signal: speech sounds vary as a function of context. Unlike written input, identification of word boundaries is different in spoken input

Cohort Model of Speech Comprehension

time dependent process, speech processing starts with the very first phoneme all words beginning with that phoneme then become activated, as more phonemes are processed, non-matching word reps are eliminated form the cohort until only one remains, model is too simplistic -also competition between words that don't match

Speech v. Non Speech Sounds

Speech sounds activate more than tone. Areas that activate more strongly to words and non0words are almost entirely lateralized to the left hemisphere

Pick Up Electric (EEG) or Magnetic (MEG)

Signals that stem from large populations of neurons

EEG

Not good at localization but good at temporal resolution difference in activities on a fine time scale. To derive a signal related to a particular event, need to average over many trials aligned on a particular event (called ERPs in EEG)

EEG-uses

use EEG to detect current pattern characteristics of seizure activity, good temporal resolution

Inverse Problem

Any given pattern observed on the surface of the scalp can result from many possibly locations of underlying neural generators.

Forward Solution

A single dipolar change simulates an active neuronal population inside and result in a distinct pattern of signals

Magnetencephalograhy (MEG)

Better at the inverse problems so better spatial resolution, Magnetic field not as distorted as electrical signal but best signal comes from sulci, where pyramidal neurons are orientated parallel to skull surface

Comparison of Methods,fMRI and EEG or MEG

fMRI is good at spatial resolution, PET isn't as good. EEG or MEG excellent temporal resolution

Left Occipital Temporal Cortex

Shows preferential responses to letter strings vs. other visual stimuli. If damaged, can suffer from alexia

Alexia

Word recognition specific deficit

Deep Dyslexia

Patients can't read non-words but can read irregular words. Problem with grapheme-phomeme conversion

Surface Dyslexia

Patients read everything by regularizing pronunciation. Problems with the direct rout.

Semantics (word recognition)

Semantically incongruous words elicit a negative ERP wave of 400 ms after stimulus onset: N400 Wave. Observed for many different manipulations. Independent of modality language. Indicates that by 400ms afterwords onset the words.

Syntax

Grammar; the system of rules by which worlds are combined into phrases and phrases into sentences

Semantic Analysis

Proceeds even for meaningless sentences

Garden Path Model (Syntax)

Sentences are processed in a way to minimize the amount of time spent on a assignment of syntactic structures, sentences have a preferred interpretation which is determined by minimal attachment and late closure

Minimal Attachment (GPM)

Minimize the number of syntactic nodes to be computed

Late Closure (GPM)

Attempt to assign incoming words to syntactic phrase currently being computed

Garden Path Effect

an incorrect interpretation of a sentence due to an inappropriate synaptic parsing. The model is Modular-Syntactic processing is encapsulated: cannot be influenced by other sources of information except after it is completed.

Brocas Area

activates more strongly to complex than single syntactic structure.

Agrammatic Aphsis

After lesions to brocas area or ant. STG produce short

P600

Positive ERP wave 600 ms after syntactic violation, also observed in sentencess with the garden path affect

Tip of the Tongue Phenomena

Failure to retrieve phonological rep despite access to semantic rep

Anomia

Deficit in naming (extreme version of TOT)

Brocas Area (speech production)

May be specific to phonological encoding but posterior Broca's also involved in articulation

Left Basal Temporal

Cortical stimulation produces speech arrest

Acute Fasciculus

Connects Brocas and Wericke areas together

Brocas Aphasia

Difficulty in speech production to problems in programming articulation or control over articulatory muscles, also agrammatism; syntactic processing impaired, damage to classical brocas area

Wernickes Aphasis

Difficult in accessing semantic and phonological representations for spoken output, persistent with aphasics requires lesions in surrounding post. Temporal inferior parietal cortex.

Attention

Higher Level process, directing cognitive resources towards processing. Limited ability to process thing in our environment on a deep level, withdrawing resources.

Stimulus independent affects

Neural correlates of delaying attention without stimulus (expectation)

Reflexive

Exogenous/Automatic. Attention drawn to a something that stands out. Spot color

Voluntary

Endogenous. Focus on unopened flowed. Something ordinary in the picture.

Characteristics of Attention

Can be reflexive or voluntary, limited capacity, no eye movement or head turning required.

Covernt Visual Attention

Ability to direct attention to a given location without eye movements to this location. Don't' turn your head or eyes away but still notice something

Selective attention

Ability to selectively process only a subset of information

Attention

Speeds up processing and make it more accurate.

Spatial Attention in the Brain

ERPs during spatial cuing task. Attentional effect found 70-100ms after stimulus-PL component Modulates activity in retinotopic cortex. Upper part is more active.

"Spotlight" spatial attention

increased activity in regions of retinotopic cortex, that represents the attended location

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