Memory, LTP, and Protein Synthesis

• Memory involves cellular and molecular mechanisms.
• Durability of Long-Term Potentiation (LTP) is a key aspect of memory.

S-LTP vs. L-LTP:

• Short-Term LTP (S-LTP) is temporary and doesn't require new protein synthesis.
• Long-Term LTP (L-LTP) lasts longer and requires protein synthesis for maintenance.

De Novo Protein Synthesis Hypothesis:

• Long-term maintenance requires translation of new proteins, even though initial LTP changes are supported by modifications.
• Studies show that blocking translation after high-frequency stimulation (HFS) prevents L-LTP but still allows S-LTP.
• Local mRNA translation in dendrites is crucial for sustaining LTP.

Local mRNA Translation in Dendrites:

• Sutton & Schuman (2006) found that L-LTP still occurred when dendrites were cut off from the soma.
• Local protein synthesis in dendrites can maintain LTP on its own.
• Bradshaw (2003) found that blocking translation in dendrites prevented L-LTP, while blocking it in the soma did not.
• mRNA translation in dendrites is necessary for LTP.

Genomic Signaling Hypothesis:

• Transcription factors (e.g., CREB) help produce the mRNA needed for L-LTP.
• Strong depolarization triggers a cascade that enhances transcription of key proteins.

CREB Activation Mechanisms:

• Molecules activated at the synapse travel to the soma and phosphorylate CREB.
• Calcium influx in the soma directly activates CREB, which is faster and more efficient.

Key Molecules in LTP:

• BDNF is released alongside glutamate.
• BDNF enhances local mRNA translation in dendritic spines.
• BDNF is essential for LTP maintenance.
• Arc is quickly transcribed and translated after synaptic activity.
• Arc helps stabilize synaptic changes by regulating actin.

Synaptic Tag and Capture Hypothesis:

• Active synapses get a "tag" that allows them to capture plasticity molecules.
• Strong stimulation provides both a tag and the ability to translate molecules.
• Weak stimulation only provides a tag but can capture molecules from other synapses.
• This allows efficient use of available plasticity molecules.
• This integrates weak inputs into long-term memory.

Encoding and Attention in Memory:

• Attention focuses on important information while ignoring distractions.
• Working Memory is a short-term memory system that processes and stores information temporarily.
• Encoding is the process of taking in and organizing new information for long-term storage.

Brain Regions Involved:

• Parietal Cortex combines sensory information (e.g., vision and touch).
• Prefrontal Cortex (PFC) controls focus, decision-making, and planning.
• Anterior Cingulate Cortex (ACC) helps switch attention and adapt to new information.

Key Experiments:

• Wisconsin Card Sorting Task (WCST) tests problem-solving and flexibility (related to the PFC, ACC, and parietal cortex).
• Visual Paired Comparison Task (VPC) tests recognition memory by measuring attention to new images.
• Novel Object Recognition (NOR) Task tests how animals recognize new vs. familiar objects (perirhinal cortex & hippocampus).

Types of Attention:

• Selective Attention: Focuses on one thing while ignoring distractions.
• Inattentional Blindness: Failing to see something obvious because attention is elsewhere.
• Selective Inattention: Ignoring stressful or unnecessary stimuli.

Good or Bad?

• Can be helpful for focus or harmful if it causes one to miss important details.

Working Memory Components:

• Phonological Loop processes verbal info (e.g., remembering a phone number).
• Visuospatial Sketchpad stores visual and spatial information (e.g., mental maps).
• Central Executive controls attention and decides what's important.
• Episodic Buffer connects working memory to long-term memory.

Schemas and Memory Organization:

• Schemas are mental "folders" that group related ideas.
• Stronger schemas lead to better memory.
• Assimilation: Adding new info to an existing schema.
• Accommodation: Changing a schema to fit new info.

Levels of Processing (Memory Strength):

• Shallow Processing involves basic features (e.g., capital letters).
• Intermediate Processing involves sound-based features (e.g., rhymes).
• Deep Processing involves meaning-based understanding and is best for memory.

Memory Strategies:

• Maintenance Rehearsal: Repeating information (good for short-term memory).
• Elaborative Rehearsal: Connecting new info to existing knowledge (best for long-term memory).

Working Memory and Cognitive Load:

• Sensory Memory (SM) holds raw sensory input briefly.
• Short-Term Memory (STM) holds small amounts of info temporarily.
• Long-Term Memory (LTM) stores information for extended periods.
• Working Memory links SM and LTM, helping to process new info and retrieve old info.

Multitasking and Task Performance:

• Multitasking is a myth, reducing accuracy and speed, as the brain switches between tasks.
• Multitasking leads to lower performance and increased fatigue.

Automatic vs. Cognitive Tasks:

• Automatic Task + Automatic Task is easy (e.g., walking + chewing gum).
• Automatic Task + Cognitive Task is possible (e.g., driving + music).
• Cognitive Task + Cognitive Task is hard (e.g., texting while driving).

Cognitive Load Theory (CLT):

• Intrinsic Load is task difficulty (e.g., complex math problems).
• Extraneous Load consists of unnecessary distractions (e.g., noisy environment).
• Germane Load is the effort to connect new info with existing knowledge.

Element Interactivity:

• Low Interactivity involves simple tasks (e.g., memorizing a list).
• High Interactivity involves complex tasks with multiple steps (e.g., writing an essay).

Effects of Noise:

• Physical Noise (e.g., loud music) impacts learning.
• Cognitive Noise (e.g., complicated instructions) impacts learning.
• Too much noise makes learning harder.

How To Reduce Cognitive Load While Studying:

• Extraneous Load: Remove distractions by finding a quiet study space.
• Intrinsic Load: Break difficult material into smaller sections.
• Germane Load: Use old notes to connect new info.

The Serial Position Effect:

• Primacy Effect: Remembering the first items on a list (long-term memory).
• Recency Effect: Remembering the last items (short-term memory).
• Von Restorff Effect: Unusual or different items stand out.

Memory consolidation involves cellular mechanisms like Long-Term Potentiation (LTP). Short-Term LTP is temporary, while Long-Term LTP requires new protein synthesis. Local mRNA translation in dendrites is crucial for sustaining LTP, enabling it to occur even when dendrites are isolated from the soma.