Hippocampus and memory

Animal studies of the hippocampus

Delayed non-match to sample (DNMS)

• Rhineland cortex damaged—a control lesion to show deficit due to hippocampus and not the Rhinal cortex

  • Came back to remove the hippocampus—-monkey memory fine but the rhinal cortext wasn’t—-memory not in the hippocampus (dependent)

  • RC for object memory, no that hippocampus

Place Cells

• Type of neuron in the hippocapus

• Stable in the sark

Place Field

• A region involving spatial memory and navigation that selectively fires at ___ location within an environment

Place Activity —-Walk

• Theta rhythm

  • brain wave pattern that helps coordinate brain activity, especially in the hippocampus

  • Low frequency for learning, memory and social cognition

  • 4-5 H.z.

Place Activity —-still

• Sharp wave ripples (SWRs)

• 150-250 Hz

• bursts of synchronized neuronal activity in the hippocampus that occur during sleep and when awake

• Memory consolidation and retrieval

• Planning and decision-making

What other tasks depend on the hippocampus

1. Context fear condition

   1. Similar to fear condition but be scared of a place—depends of the place hippocampus

   2. Does fear context depend on the hippocampus?

      1. Mirrors water maze—context + tone = shock—lesion

      2. New place—fear of the place on the hippocampus (fear of cue not need to learn)

   3. Trace conditions—easier in humans