W7 Lecture 2 - Hemispheric Lateralisation & Memory

# W7 Lecture 2 ## Hemispheric Lateralisation **Differences between the hemispheres** * **Right hemisphere**: * Receives sensory input from the left * Controls motor skills on the left * **Left hemisphere**: * Vice versa **Hemispheric dominance**: One hemisphere is better than the oth...

# W7 Lecture 2 ## Hemispheric Lateralisation **Differences between the hemispheres** * **Right hemisphere**: * Receives sensory input from the left * Controls motor skills on the left * **Left hemisphere**: * Vice versa **Hemispheric dominance**: One hemisphere is better than the other. **Example**: Right/ left hand preference * Language also applies here as well. * Left hemisphere is dominant for language speaking and comprehension **Evidence for this**: Aphasia after stroke, both hemispheres showed an effect on the left side of the brain ## Speech Areas ### Broca's Area * Lower posterior region of the left frontal lobe * Damage here impacts speech but can generally understand speech * Problems with talking, but not singing or writing, but not drawing. Deaf signers can lose their ability to sign. ### Wernicke's Area * Posterior region of the temporal lobe * Damage causes problems with comprehension of speech * Produce fluent but meaningless speech. * Cannot read. ## The Split Brain * Lateralisation of function is not usual because of shared info between right and left hemispheres. * Some patients split their brain to treat epilepsy. * Split brain patients can still walk, talk, suffer little to no impairments. **Roger Sperry** was a major researcher. **Findings of lateral brained people:** * Patients can name an object in their right hand but not their left. **Functions in the right hemisphere:** * Right side can comprehend simple language. * Right side contributes more than the left to adding and interpreting emotional content to speech. * Right brain better than the left at producing and interpreting facial expressions. ## Memory & Hippocampus **Hippocampus**: Best memory structure in the brain. * Core of the temporal lobe. **Henry Molaison**: Had brain surgery to help severe epilepsy, and had hippocampus removed! * Amygdalae and surrounding cortex. **Hippocampus continued:** * Removal of the hippocampus helped seizures, but caused him to have severe amnesia. ## Hippocampal Amnesia * Brenda Miller studied HM for many years. * HM's older memories were spared - **Autrograde amnesia** * Couldn't learn anything new **Deficit specific to declarative learning and memory:** * Patients like HM can show procedural learning even though they can't recall having done the task before. * **Declarative memory** doesn't work. * **Procedural memory** does. ## Wernicke Korsakoff Syndrome **Amnesia** due to diseases and brain damage. * Severe deficiency in Vitamin B1 (thiamine) in chronic alcoholics triggers **Wernicke encephalopathy** (confusion, etc.) * Untreated, WE leads to **Korsakoff Psychosis**, characterized by **retrograde amnesia** and some **anterograde amnesia** (confabulation). * Amnesia due to irreversible damage to **mammillary bodies** and part of the **thalamus**. ## Alzheimers * Progressive degenerative disease characterized by: * Loss of newly learned information * Followed by loss of distant memories * Factual knowledge, and finally procedural skills * **Abnormal neural tissue** present in the brain, especially prevalent in the cortex and the hippocampus: * Senile plaques * Neurofibrillary tangles (abnormal tissues)