ANTEROGRADE AMNESIA

• trouble learning new information

• trouble remembering old information that preceded the brain injury

• thiamine deficiency, caused by alcoholism
• deterioration of mammillary bodies

• profound anterograde amnesia

• intact intellect
• old learning generally OK, although some retrograde amnesia
• immediate verbal memory OK, but verbal learning is impaired (e.g., new slang)
• no personality change (unlike Phineas Gage)
• socially appropriate
• not easily bored

Pre-illness memory

• intact basic knowledge (intellectual, social, linguistic)
• motor/cognitive skills
• personal preferences

• Motor learning - mirror-drawing task
• Repetition priming
• word-stems
• stimulus fragments
• Psychophysiological responses
• electrodermal response
• classical conditioning
• Operant conditioning
• Evaluative responses
• emotional responses preserved as implicit learning (e.g., pin in doctor’s hand)
• "liking" ratings
• staff member association with "generosity"

1) hippocampus is not the site of long-term memory storage, nor is it needed to access long-term memories

2) hippocampus is not the site of immediate (short-term) memory storage

3) hippocampus is involved in converting short-term memories to long-term

DECLARATIVE MEMORIES

• can be consciously recalled as facts, events, or stimuli (explicit)

• not conscious, operate automatically, don’t include facts, but they control behaviors (implicit)

• showed list of words
• then asked for recall (explicit) or showed first few letters and asked to say the first word that came to mind (implicit)
• amnesic subjects’ explicit memory was <50% of controls’, but they performed equally on the implicit task

• can be damaged by anoxia (lack of oxygen)
• contains many NMDA receptors
• various metabolic disturbances cause excessive release of glutamate, resulting in too much calcium in the cells
• this begins to destroy the neurons

• radial maze tasks
• rats with lesions of the hippocampus can’t remember which arms they had already visited
• these rats COULD learn to avoid certain arms that never contained food (this is what type of learning?)

• Morris milk maze
• rats with hippocampal lesions perform poorly when having to use visual cues
• these rats will swim directly for the platform, however, if it is in view (this is what type of learning?)

• recorded from individual pyramidal cells in the hippocampus
• found different neurons had different spatial receptive fields – responding to visual cues/relationships
• information is provided by pattern of cell responding, neural networks
• even deaf, blind rats can navigate the maze, but not when they’re dizzy!
• study with normal rats in 8-arm radial maze, let them learn the maze, then had them in the dark
• their "place cells" no longer could provide the mental map, but if light turned on briefly and then back off, the rats knew their way around

• excitability of hippocampal formation neurons increased by exposure to enriched environment (long-term potentiation)

• Carlson’s breakfast example
• asking what he had for breakfast stimulates language association area
• which then triggers hippocampus to "complete the pattern" by pulling the other bits of information which are stored in various parts of association cortex

Broca’s aphasia

• inability to speak due to damage to the inferior left frontal lobe and underlying subcortical white matter

• speech is slow, non-fluent
• hard time with "function" words (e.g., a, the, in)
• can say "content" words (e.g., nouns, verbs, adjectives)

• 3 types of speech deficits produced by damage to Broca’s area:

2. anomia - word-finding difficulty

3. articulation problems - mispronunciations

• can comprehend speech much better than they can speak, but still have deficits
• deficits parallel production problems
• understanding grammar, sequence of commands

• inability to understand due to damage to middle and posterior portions of the superior temporal gyrus of the left hemisphere

• poor speech comprehension; can’t repeat
• production of meaningless speech which is fluent and unlabored
• uses function words but few content words
• they seem unaware of their deficit (unlike Broca’s) Why?

• 3 types of speech deficits associated with Wernicke’s aphasia:

• can recognize other sounds (doorbell, etc.)
• can read and write or read people’s lips
• can speak sensibly
• auditory system of left hemisphere specialized for recognition of short sounds and right hemisphere for long sounds. How do we know that?

• damage to this area alone produces "transcortical sensory aphasia"
• people with this disorder can repeat - they can recognize words
• they cannot comprehend the meaning of what they hear and repeat

• people with Wernicke’s aphasia and those with transcortical sensory aphasia cannot speak sensibly

• Wernicke’s aphasia essentially is the combination of pure word deafness and transcortical sensory aphasia

• damage to particular areas creates specific kinds of aphasias
• inability to identify body parts, spatial relationships (e.g., "down"), etc.

• damage to arcuate fasciculus, which connects Broca’s and Wernicke’s areas

• meaningful, fluent speech
• relatively good comprehension - but can they repeat?
• very poor repetition
• arcuate fasciculus is pathway to repeat unfamiliar words
• another pathway exists to frontal area from association areas, based on the meaning of the word, not the sounds

• generally occur from damage to left temporal/parietal lobes, without involving Wernicke’s area

• may be considered a partial amnesia for words
• can have specific anomias resulting from damage to particular cortical areas

Pure Alexia

• alexia without agraphia;
• lesions that prevent visual information from reaching the visual association cortex of the left hemisphere

• can recognize words if spelled aloud to them
• it is a perceptual disorder, like pure word deafness
• not the same as visual agnosia - people with visual agnosia can still read, people with pure alexia can identify objects

• whole-word reading - direct recognition of the word as a whole
• phonetic reading - sounding word out

1. surface dyslexia

• deficit in whole-word reading
• make errors based on "surface" of word - how it looks, rather than its "deeper" meaning

• can read by whole-word method, but can’t sound out words

• have deficits in both whole-word and phonetic reading
• but still recognize letters and can read words if they say each letter aloud

• like transcortical sensory aphasia, except with written words

• can read aloud, but cannot understand what they are reading

• cannot read
• but can pick correct answer from among choices of labels for a picture
• even though cannot name picture or read aloud the choices

• opposite of direct dyslexia

1. problems with motor control

• e.g., can write numbers but not letters, consonants but not vowels, etc.

• audition (sounding things out in your head)
• phonological dysgraphia - can’t write unfamiliar words or pronounceable nonwords
• visual image (picturing the word in your head)
• orthographic dysgraphia - can only sound out words, not picture them - trouble writing irregular words