5b - Brain and Behaviour (26.02.2020) Flashcards
Stages of memory
- Registration: Input from our senses into the memory system
- Encoding: Processing and combining of received information
- Storage: Holding of that input in the memory system
- Retrieval: Recovering stored information from the memory system (remembering)
=> different diseases may cause problems in different parts of this.
Memory Theory - Duration
- Conceptual divisions in memory systems
- Sensory
- Working or short term memory (only last few minutes)
- Long-term memory
A model of memory
- see notes/presentation
Memory Types
see notes/slides
Episodic Memory
Involves the medial temporal lobes including the hippocampus, entorhinal cortex, mammilary bodies, and parahippocampal cortex
Memory systems
Semantic - Knowledge Procedural – how to do things Working – short term
Memory disorders
- Total amnesia is rare, especially isolated amnesia with otherwise preserved cognition
- Numerous neurological conditions can affect memory with varying lesion sites
- Varying aspects of memory - e.g. episodic, semantic, anterograde, retrograde etc. – are affected in different ways by different disorders
- Implicit memory or learning often intact in memory disorders (e.g. drawing skills improve even though not remembering doing ti before)
Clive Wearing
- Musician,composer, scholar
- Herpes simplex encephalitis at age 46.
- Temporallobedamage.
- Severe amnesia.
- Permanent state of just having woken up.
Memory: Modality
- Left hemisphere: Mainly concerned with verbal information processing
- Right hemisphere: Mainly concerned with non-verbal information
Remembering: serial position effect
- primacy effect
- recency effect
commonly you remember the first few (primacy) and the last few (recency effects) if you hear a list of words.
in Alzeheimers you have an absence of primacy effect, only the recency effect.
What is the probability of recalling a word is related to…
Order in the list Personal salience of words Number of words Chunking or other encoding strategy Delay time Distraction
Clinical implications of memory theories
- Give important information at beginning and end of consultation
- Emphasise and repeat important information
- Make salient to the person
- Chunk information into meaningful categories
- Avoid overloading with information
=> make sure of what information you want someone to take away
MNEMONIC EXAMPLE: UNKNOWN CAUSE OF MEMORY PROBLEMS
- Vascular
- Infectious
- Toxic-Metabolic
- Autoimmune
- Metastases/Neoplasm
- Iatrogenic
- Neurodegenerative
- Systemic
A mnemonic can be a rhyme, acronym, image, phrase to sentence.
Language
• ‘A system of symbols and rules that enable us to communicate.’ (Harley, 2008)
• No humans yet discovered without language
• On-going debate: innate (e.g. Chomsky) or
exposure (e.g. Putnam)?
• Both organic and environmental factors important
Structure of language
• Phoneme: the smallest unit of speech sound in a language that can signal a difference in meaning
– Humans can produce just over 100 phonemes; English language consists of 44 phonemes, there are only 11 in Rotokas and as many as 112 in !Xóõ (including four tones) -> language from Botswana)
• Morphemes: the smallest units of meaning in a language
– Typically consist of one syllable
– Morphemes are combined into words
Phoneme
the smallest unit of speech sound in a language that can signal a difference in meaning
Morphemes
= the smallest units of meaning in a language
– Typically consist of one syllable
– Morphemes are combined into words
Syntax
- Rules and principles which govern the way in which morphemes and words can be combined to communicate meaning in a particular language
- Theory of ‘universal grammar’ widely accepted: that under normal conditions human beings will develop language with particular properties (e.g. distinguishing nouns from verbs)
- Pinker (1984) - children of speakers of pidgin languages which lack basic grammatical structures develop languages which are fully grammatical
- An innate property of the brain that results in this?
Language development
- 1-3 months: cooing
- 4-6 months: babbling
- 7-11 months: begins to imitate word sounds
- 12 months: First recognizable words typically spoken as one-word utterances to name familiar people or objects (e.g da-da)
- 12-18 months: Child increases knowledge of word meanings and begins to use single words to express whole phrases or requests
- 18-24 months: Vocabulary expands to between 50-100 words. First rudimentary sentences appear, usually consisting of two words (e.g. “more milk!”) with little or no use of articles (the,a), conjunctions (and) or auxiliary verbs (can, will). This condensed or telegraphic speech is characteristic of first sentences throughout the world.
- 2-4 years: vocabulary expands rapidly at the rate of several hundred words every 6 months. Two-word sentences give way to longer sentences that, though often grammatically incorrect, exhibit basic language syntax. Child begins to express concepts with words and to use language to describe imaginary objects and ideas. Sentences become more correct syntactically.
- 4-5 years: child has learned the basic grammatical rules for combining nouns, adjectives, articles conjunctions and verbs into meaningful sentences.
Language Development: Environment
What if children raised without exposure to language?
– ‘Genie’ -was deprived of social interaction from birth until discovered aged thirteen
– She was completely without language, and after seven years of rehabilitation still lacked linguistic competence.
‘Critical Period’ in Language Acquisition
- from ages 5.to puberty the language acquisition gets harder
- easier early on, later language development required more effort
Language acquisition
• Exposure to other people using language required
• Between ages 5 to puberty language acquisition becomes more difficult, based on:
– Feral children
– Brain injury at different ages – Second language acquisition (easily learn the second language generally)
Brain Structures Underlying language
- Hemispheric specialization / dominance for language.
- 95% of right-handed people have left- hemisphere dominance for language, 18.8% of left-handed people have right-hemisphere dominance for language function.
- Additionally, 19.8% of the left-handed have bilateral language functions.
- many left handed people also have left-handed language dominance.
Broca’s (expressive) Aphasia
Characteristics: • Non-fluent speech • Impaired repetition • Poor ability to produce syntactically correct sentences • broadly Intact comprehension
Wernicke’s (receptive) Aphasia
- Problems in comprehending speech (input or reception of language)
- Fluent meaningless speech
- Paraphasias – errors in producing specific words
- Semantic paraphasias – substituting words similar in meaning (“barn” –“house”)
- Phonemic paraphasias – substituting words similar in sound (“house” –“mouse”)
- Neologisms – non words (“galump”)
- Poor repetition
- Impairment in writing
Expressive aphasia - where is the problem?
Broca’s area (generally left hemisphere)
-> very effortful speech
Receptive aphasia - where is the problem?
Wernicke’s area
Language circuit
- Information abou t the sound is analysed in the !* auditory cortex and transmitted to wernickes area
- WA analyses the sound information to determine the word that was said.
- This information from WA is transmitted through the arcuate fascicles to Broca’s area
- BA forms a motor plant to repeat the word and sends that information to motor cortex
- motor cortex implements the plan, manipulating the larynx and related structures to say the word.
Lesions of the arcuate fasciculus disrupt the transfer from WA to BA so the patient thas difficulty repeating son words but may retain comprehension of spoken language (because of intact WA) and may still be able to speak spontaneously (because of intact BA)
Types of aphasia
- fluency
- comprehension
- repeats
- global
- mixed transcortical
- broca’s
- transcortical motor
- wercicke’s
- transcortical sensory
- conduction
- anomic
Conditions associated with aphasia
• Lesions to the dominant hemisphere can be caused by:
– Stroke
– Traumatic brain injury
– Cerebral tumour
– Progressive neurodegenerative conditions
Newer model of language neurobiology
= more complex than just Broca’s and Wernicke’s
- Modern findings show that rather than there being one key connective tract relevant to language function, there are many (uncinate fasciculus, the inferior front-occipital fasciculus, the middle longitudinal fasciculus, inferior longitudinal fasciculus)
- Tremblay & Dick conclude that language function is incredibly widely distributed through the brain, “extend[ing] far beyond ‘Broca’s’ and ‘Wernicke’s areas’,” involving areas “in the frontal, parietal, and temporal lobes, in the medial hemispheres of the brain, as well as in the basal ganglia, thalamus and cerebellum”
Dysexecutive Syndrome
- Dysexecutive syndrome involves the disruption of executive function and is closely related to frontal lobe damage
- Executive functioning skills are the mental processes that enable us to plan, focus attention, remember instructions, and juggle multiple tasks successfully.
- Dysexecutive syndrome encompasses cognitive, emotional, and behavioural symptoms
- Dysexecutive syndrome can result from many causes, including head trauma, tumours, degenerative diseases, and cerebrovascular disease, as well as in several psychiatric conditions
Behavioural & Emotional Aspects of Dysexecutive Syndrome
- Hypoactivity
- Lack of drive
- Apathetic
- Poor initiation of tasks
- Emotional bluntness
- Theory of mind difficulties
- Reduced empathy
- Hyperactivity
- Impulsive
- Disinhibited
- Perseverative
- Emotional dysregulation
- Socially inappropriate
- Rude,crass,proneto swearing
=> usually it falls under one or the other category
Cognitive aspects of dysexecutive syndrome
- Attentional and working memory difficulties
- Poor planning & organisation
- Difficulty coping with novel situations and unstructured tasks
- Difficulty switching from task to task
- Difficulty keeping track of multiple tasks
- Difficulty with complex/abstract thinking
Deficits associated with specific regions of the frontal lobes
– Orbito-frontal
• Impulsivity, disinhibition
– Medial
• Loss of spontaneity, initiation (akinetic mutism)
– Lateral
• Inability to formulate and carry out plans
something about differentiation from depression.
Pre-Frontal Cortex & Subcortical Structures
Sometimes changes in subcritical regions appear to be like cortical changes
apathy in PD because of clear connections to frontal regions.
