Lesson 36 - The Brain

36: the brain Wednesday, April 24, 2024 1:26 PM the brain • 3 major regions ○ forebrain: complex processing, smell, sleep, learning ○ midbrain: routing of sensory information ○ hindbrain: involuntary activities, motor activities • size of regions related to importance of function • cerebrum: ○ forebrain ○ center for learning, emotion, memory, perception ○ voluntary motor function • cerebellum: ○ hindbrain ○ movement, motor skills, visual, and auditory input • diencephalon: ○ forebrain ○ thalamus: sensory input to cerebrum ○ hypothalamus: internal regulation • brainstem: ○ midbrain and hindbrain ○ integrates hearing, visual reflexes ○ medulla and pons: automatic functions, coordinated movement • brainstem: ○ midbrain and hindbrain ○ integrates hearing, visual reflexes ○ medulla and pons: automatic functions, coordinated movement the cerebral cortex • outer layer of cerebrum evolution of cognition in vertebrates • in humans: ○ the cerebral cortex is 80% of human brain mass ○ the brain uses 20-25% of basal metabolism • other vertebrates use 2-8% metabolic energy • evolution has led to different strategies for example brain function ○ mammals have a convoluted cortex ○ birds have neurons clustered in a structure called the pallium biological clock - circadian rhythm • periodic gene expression and cellular activity ○ arousal and sleep cycles, body temperature • daily cycles usually triggered by light and dark • coordinated by the suprachiasmatic nucleus ○ located in the hypothalamus biological clock - circadian rhythm • periodic gene expression and cellular activity ○ arousal and sleep cycles, body temperature • daily cycles usually triggered by light and dark • coordinated by the suprachiasmatic nucleus ○ located in the hypothalamus ○ signals the pineal gland to produce melatonin • disrupted by changes in light/dark cycle ○ jet lag, artificial light, devices language • language integration takes place in the left hemisphere for 90% of right-handed people and nearly 66% of left-handed people • temporal lobe: wernicke's area ○ language comprehension (written and spoken) ○ thought to speech • frontal lobe: broca's area ○ production of speech loss of language: aphasia • inability to understand or formulate language due to brain injury ○ stroke, head trauma, brain tumors, or infections • language cognition, not mechanics of speech • can be diffused or localized damage ○ broca's aphasia → comprehension intact, language production limited memory and learning • learning ○ lasting change in behavior due to experience • memory ○ retention of learned information ○ short-term: memory and learning • learning ○ lasting change in behavior due to experience • memory ○ retention of learned information ○ short-term: § holds information briefly, lost if not important § temporary links in hippocampus ○ long-term: § more secure information retention § connections in cerebral cortex • neuronal plasticity ○ associated with learning ○ useful synapses stay active, useless ones are lost ○ synapses added or removed ○ existing synapses strengthened or weakened • different ways to learn different things ○ motor skills learned by repetition, become unconscious tasks ○ more complex skills lead to the production of new synapses ○ memorization may rely on changes in strength of existing synapses why are long- and short-term memories formed differently? a. the brain has limited capacity in the cerebral cortex, so less important information is placed in an alternate location (hippocampus) b. regional specialization memory loss: alzheimer's disease • neurodegenerative disease ○ early stages: short-term memory loss, learning impairment memory loss: alzheimer's disease • neurodegenerative disease ○ early stages: short-term memory loss, learning impairment ○ late stages: dementia, mood swings, loss of bodily functions • changes in structures within brain ○ loss of neurons and synapses in the cerebral cortex ○ formation of plaque and neurofibrillary tangles ○ heritable