Cognitive Functions

Cognitive Functions

Localised Cognitive Functions

·        Dominant hemisphere:

o   Speech, reading and writing

o   Calculation

o   Praxis (higher motor control of learned movement)

·        Non-dominant hemisphere:

o   Neglect: visual, auditory, tactile

o   Dressing or constructional apraxia

o   Visuo-perceptual: object recognition (fragmented drawings) and faces (Prosopagnosia)

o   Prosody: Expressive aspects of speech

Attention/Concentration

·        Depends on the reticular activating system, thalamus, frontal and medial temporal lobes

·        Test: orientation in time and place, serial subtractions, spelling WORLD backwards etc

Memory

·        Implicit: learned responses, reflexes and motor skills

·        Explicit:

o   Episodic:

§  Left hippocampus: verbal, right visuo-spatial, faces, etc

§  Temporally specific personal experiences

§  Lost in diffuse brain disease (dementia) and bilateral limbic disease (amnesic syndrome)

o   Semantic:

§  Facts, concepts, words, meanings (eg object naming, what do you cut bread with, etc)

§  In the temporal neocortex (left)

§  Lost in dementia

·        Working memory:

o   Very short term recall: words, numbers, melodies

o   Under frontal lobe executive control: important for dual task performance

o   Patients can have damage to just one of working or long term memory (eg Korsakov)

o   Psychosis patients have normal working memory, but cannot make:

§  New memories (anteriograde): Word list learning

§  Retrieve long-term memories: recall public events, autobiographical details

Higher Cognitive Function/Executive Function

·        Situated in the pre-frontal area (non-motor frontal lobes)

·        Functioning best established from informants and observation

·        Clinical features of frontal lobe lesions:

o  Poor planning: can‟t initiate and carry out a sequence of actions to complete a goal, can‟t do two things at once

o  Can‟t control impulses: irritable, irascible

o  Deterioration of personal relationships, social habits and hygiene

o  Dulling of curiosity and vitality, jocular, puerile

o  Lack energy