Overview
This lecture covers higher mental functions in the central nervous system (CNS), focusing on roles of the cerebral cortex in reasoning, memory, language, learning, emotion, and associated brain regions and disease states.
Higher Mental Functions of the CNS
- Higher functions include reasoning, planning, memory, learning, social behavior, personality, and processing stimuli.
- These functions are mainly carried out by the cerebral cortex.
Localization of Function in the Cortex
- Parietal lobe: responsible for spatial awareness and attention.
- Temporal lobe: involved in recognition of stimuli, such as faces.
- Prefrontal cortex: key for personality, reasoning, planning, inhibition, and integrating information.
- Damage to specific regions leads to changes in personality or cognitive abilities.
- Cognitive functions can be lateralized (more dominant in one hemisphere).
Diseases Affecting Higher Functions
- Dementia: progressive memory loss and cognitive decline; most drugs only slow progression.
- Alzheimer's disease: characterized by neuron degeneration, synaptic loss, plaques, and tangles; early sign is memory loss.
- Vascular dementia: caused by loss of blood supply to brain regions, leading to variable symptoms.
- Lewy body dementia: marked by inclusions in neurons, memory impairment, hallucinations, and Parkinson-like symptoms.
- Pick's disease: early-onset frontotemporal dementia with personality and behavior changes; diagnosis is difficult.
Language and the Brain
- Language requires both understanding (comprehension) and speech formation (motor).
- Wernicke's area (left temporal lobe): processes auditory and visual language.
- Broca's area (left frontal lobe): plans and executes speech (motor component).
- Aphasia: loss of language function due to damage in Broca's (speech production) or Wernicke's (comprehension) areas.
Learning and Memory
- Declarative memory: conscious recall of facts (e.g., for tests).
- Non-declarative memory: unconscious skills and motor tasks (e.g., riding a bike).
- Memory stages: immediate (seconds), short-term (minutes), and long-term (days to lifetime).
- Declarative immediate/short-term stored in hippocampus; long-term consolidated in cerebral cortex, especially prefrontal cortex.
- Memory consolidation and long-term potentiation strengthen connections for long-term storage.
- Non-declarative memory involves motor cortex, cerebellum, and basal nuclei.
Emotion and the Brain
- Emotions arise from complex associations between perceptual, cognitive, and visceral brain regions.
- Limbic system (including hippocampus, cingulate gyrus, amygdala) and hypothalamus are central to emotion.
- Amygdala links memories and perceptions to emotional responses.
Key Terms & Definitions
- Cerebral cortex — outer brain layer involved in higher mental functions.
- Prefrontal cortex — region for reasoning, planning, and personality.
- Aphasia — language impairment from brain area damage.
- Declarative memory — explicit, factual memory.
- Non-declarative memory — implicit, skill-based memory.
- Limbic system — brain structures involved in emotion and memory.
- Amygdala — processes and links emotional responses.
Action Items / Next Steps
- Review brain lobe functions and associated pathologies.
- Memorize locations and roles of Broca's and Wernicke's areas.
- Prepare for upcoming lectures on CNS roles in sensation and movement.