2. What is Brain Damage:Dysfunction?.docx

CRITICAL READING: CORNELL NOTES What is Brain Damage/Dysfunction? Name: Date: 25 August 2023 Section: Lecture 2 Period: Questions/Main Ideas/Vocabulary Notes/Answers/Definitions/Examples/Sentences Cortex Cerebral hemispheres: Left and right cortex Outermost layer: grey matter is...

CRITICAL READING: CORNELL NOTES What is Brain Damage/Dysfunction? Name: Date: 25 August 2023 Section: Lecture 2 Period: Questions/Main Ideas/Vocabulary Notes/Answers/Definitions/Examples/Sentences Cortex Cerebral hemispheres: Left and right cortex Outermost layer: grey matter is convoluted. Sulci: grooves/fissures. Gyri: convolutions/folds. Highly organised. Localised functions. Organisation of the Cortex Lateral organisation: Left and right hemispheres. Symmetrical organisation: Mirror-image. E.g., motor and sensory processes. Tendency for contra-lateral control. Asymmetrical organisation: Language, visuo-spatial. Longitudinal organisation: Longitudinal plane: back (posterior) to front (anterior). Divided into 4 lobes on each side: occipital, parietal, temporal, frontal. Lobes are made up of primary, secondary and tertiary areas. Primary processing areas: Basic sensory and motor functions. Association/secondary areas: Process information from primary processing areas. Adjacent to primary processing areas. High-order processing. Tertiary areas: Between association areas. Combine information from association areas – higher-level processing. General Organisation Posterior regions: Occipital, parietal and temporal lobes. Input. Anterior regions: Frontal lobes. Output. Regions connected by: Short fibres: connect one part of a lobe to another. Association fibres: connect lobes located on the same side of the brain. Commissures: fibres that link the two hemispheres. Occipital Lobes Posterior part of the brain. Involved in visual processing. Primary visual cortex: Basic visual processing (colour, shape, size, orientation, etc). Visual information to the left of fixation, goes to right visual cortex (and vice versa). Visual association areas: Adjacent to primary visual cortex. Receives information from primary visual cortex. Synthesises different types of visual information. Undertakes higher-level visual processing, enabling us to perceive and recognise objects. Cortical blindness: Blind spot/blindness – side opposite to damage. Blindsight: Extensive damage, person reports being blind but still has very basic visual processing. Blindsight – Case The ability of cortically blind subjects to perform visually mediated tasks without conscious awareness of vision is known as blindsight. Case D.B. – was cortically blind in his left visual field following surgical removal of his right occipital lobe. The patient had no awareness of “seeing” in his blind field, but: He could reach for visual stimuli with considerable accuracy. Could differentiate the orientation of a vertical line from a horizontal or diagonal line. Could differentiate the letters “X” and “O”. He was questioned repeatedly about his vision and his most common response was that he saw nothing at all. When he was shown his results, he expressed surprise and insisted that he thought he was just “guessing”. When he was shown a video film, he was openly astonished. Visual Anosognosia Anosognosia: Lack of awareness. Cortically blind person denies being blind and tries to behave as it sighted. Confabulation: ‘Make up’ excuses why bump into things. Visual Agnosia Agnosia: Loss of knowledge. Problems are specific to visual processing. Can recognise things using other senses such as sound and touch. Person may perceive the object in its parts (piecemeal). Or may perceive the whole object but not recognise what it is. Different types of visual agnosia: Object agnosia. Inability to recognise common objects. Different Types of Visual Agnosia Object agnosia: Inability to recognise everyday objects. Colour agnosia: Inability to distinguish between colours or to relate colours to objects. Prosopagnosia: Inability to recognise faces. Parietal Lobes – Primary Somatosensory Cortex Located along post-central gyrus. Receives somatosensory information like touch/pressure, temperature, pain, limb position/movement. Information is received from the opposite side of the body (contra-lateral input). Highly organised (somatosensory homunculus). Parietal Lobes –Somatosensory Association Area Adjacent to the primary somatosensory area. Integrates sensory information: Combining and analysing sensory information. Recognition of objects by touch. Parietal Lobes – Tertiary Processing Area Integrates different types of sensory information. Visual, auditory, tactile and spatial information processed together. Damage to the Primary Somatosensory Cortex Loss of sensation – sensory anaesthesia. Loss of sensation felt on side opposite to damage. Part of the body affected depends on site and amount of damage. Damage to the Somatosensory Association Area Tactile agnosia (astereognosis): Inability to recognise things via touch. Visual neglect/hemi-inattention. Apraxia: Disorder affecting voluntary movement. Not attributable to motor/physical problems, problems comprehending or motivation. Dressing apraxia: Specific form of apraxia. Person unable to coordinate movements to dress.