Memory and Synaptic Changes

• Learning is the acquisition of new information.
• Memory is the persistence of learning, retrievable later.
• Memory is a system that encodes, stores, and retrieves data, defined as 'the retention of information' that evolves.
• The brain converts meaningless information into meaningful patterns.
• Various brain regions store different types of experiences.
• Memories are not stored in one specific location, rather they are diffusely stored.

Synaptic Changes & Memory

• Synapses form the neural basis for brain changes during memory storage.
• Memories initiate as impulses through brain circuits, leaving a trace.
• Long-term potentiation describes the increased potential strength a neuron gains with memory utilization.
• Long-term potentiation (LTP) gradually strengthens neuronal pathways through repetitive stimulation.
• LTP increases neural transmission efficiency at synapses over time.
• LTP is a basis for learning and memory, commonly found in the hippocampus.
• Hebb's Law states "Neurons that fire together, wire together".
• Donald Hebb, a Canadian researcher, explored how brain cells change during learning.
• Consistent stimulation between brain cells leads to metabolic and physical changes, strengthening neuronal pathways.
• Memory is linked to activity at the cellular level, and behavior can be studied from neurons to the entire brain.

Brain Structures & Memory

• The hippocampus and amygdala (both in the midbrain) are involved in memory.
• The hippocampus aids in recalling events and is involved in consolidation, moving information from working memory to long-term memory.
• The hippocampus also date/time stamps memories.
• The amygdala aids in recalling emotions linked to events and strengthens memories with strong emotional connections.
• MRI scans indicate that experienced London taxi drivers have significantly larger posterior hippocampi compared to non-taxi drivers.

Hormones & Memory

• Strong emotions strengthen memories.
• Emotional arousal leads to the release of epinephrine and norepinephrine.
• Excess cortisol interferes with memory.
• Estrogen improves working memory.

Memory Deterioration

• Memory decline typically begins after age 65.
• Alzheimer's disease is the primary cause of dementia, accounting for 50-60% of cases.
• Symptoms of Alzheimer's include memory and language loss, consistent with cortical loss.

Multistore Model of Memory

• The Multistore Model (Atkinson & Shiffrin, 1968) describes the flow of information through three units:
  • Sensory store: Holds raw sensory input.
  • Short-term store (STS): Retains stimuli for seconds.
  • Long-term store (LTS): Stores information for future use.

Sensory Memory

• Sensory memory is the shortest type of memory.
• It briefly holds incoming information, with each sense having its own form.
• Iconic memory holds visual stimuli for about one second.
• Echoic memory holds auditory stimuli for 5-10 seconds.
• Sensory memory holds a vast amount of information, much of which doesn't reach conscious awareness.
• Attention selects which information passes to short-term memory (STM).

Sperling's Test

• Letters flashed briefly; people recalled about half.
• Recall accuracy improved when signaled to recall a specific row immediately after.

Short-Term Memory (STM)

• STM is a memory system for retaining information for brief periods, about 5-20 seconds.
• STM holds approximately 7 pieces of information for adults.
• Rehearsal extends the duration of STM information.
• Chunking organizes information into meaningful groups, extending STM span.

Interference with STM

• Information is lost in STM through decay (fading over time) and interference (competition from other information).
• Retroactive interference: New information hinders previously learned information.
• Proactive interference: Earlier learning hinders new learning.

Long-Term Memory (LTM)

• LTM is a relatively enduring store of information, including facts, experiences, and skills, that may last a lifetime.
• LTM errors are often semantic (meaning-related), while STM errors tend to be acoustic.
• LTM has subsystems: declarative (explicit) and non-declarative (implicit) memory.
• Both types decline with age, but declarative memory declines more, especially with dementia.

Subsystems of Long-Term Memory

• Declarative (Explicit) memory includes conscious, intentionally remembered memories, divided into:
  • Episodic memory: Personally experienced events.
  • Semantic memory: Facts and information.
• Non-declarative (Implicit) memory includes unconscious, automatic memories, divided into:
  • Procedural memory: How to perform tasks (motor skills, habits).
  • Priming: Exposure to stimuli influences subsequent responses without conscious awareness.

Working Memory

• Working memory allows an individual to "work" with information.
• It is a mental workspace for cognitive operations and temporary storage, often thought of as a workspace for operations, information storage, and decision-making.
• Working memory is limited by capacity and duration and is likely located in the frontal cortex.

Event Memory

• Personal, social, and cultural factors influence memory organization.
• Event memory is the long-term memory for events.
• Children from individualistic cultures recall events from their own perspective, focusing on personal goals.
• Children from collectivist cultures focus on social aspects of events.

Autobiographical Memory

• Autobiographical memory is the ability to recall early experiences.
• Possible explanations for weak autobiographical memories:
  • Infants' inability to encode information verbally.
  • Underdeveloped brain areas involved in memory formation.
  • Use of scripts: Generalized events for young children.