hippocampus and memory for exam 3 Flashcards
Bartolomero Eustachi (Eustachius)
1552: created the first illustration of the hippocampus
Paper not published until 1714!!!!
Even used fancy scaling equivalent to what is used in current brain atlases
Camillo Golgi
Late 19th century
Chief medical officer at a psychiatric hospital
Metal impregnation of neurons
Lorento de Nó
Lorento de Nó named CA1-4
Structure of the Hippocampus
history of hippocampus continued
- ____ studies in ___(animal)
- Temporal lobe resections in humans
- ____ and ____ studies found :
- Refinement of temporal lobe resections for epilepsy treatment
- Isolated to _____ lobe
Lesion studies in monkeys
Temporal lobe resections in humans
Lesion and resection studies found placidity, bulimia, hypersexuality, loss of sensation… even seizures
Refinement of temporal lobe resections for epilepsy treatment
Isolated to medial temporal lobe
- 1950s: finally able to come up with structure-function relationships with regards to hippocampal _____
- 1952:
1950s: finally able to come up with structure-function relationships with regards to hippocampal epilepsy
* 1952: Brenda Milner at McGill University under the direction of Donald Hebb
Brenda Milner at McGill University under the direction of Donald Hebb
-names of patients - what was up with their brains?
*Encountered two patients (P.B. and F.C.) who had become severely amnesic following unilateral removal of the medial structures of the left temporal lobe for the treatment of epileptic seizures (Penfield and Milner, 1958).
It was proposed that in each case there had been a preexistent, but unsuspected, atrophic lesion in the medial temporal lobe of the opposite hemisphere.
Unilateral surgery would have resulted in a bilateral lesion, an idea that was confirmed at autopsy some years later for patient P.B.
After the two cases were presented at the 1955 meeting of the American Neurological Association, Wilder Penfield (the neurosurgeon in both cases) received a call from William Scoville, a neurosurgeon in Hartford, Connecticut. Brenda Milner sent to see this patient (HM)
HM
*what part of brain is affected and why was it affected?
- Most famous bilateral temporal lobe resection patient
- Knocked down by a bicycle at the age of 7, began to have minor seizures at age 10, and had major seizures after age 16.
- At the age of 27 he had become so incapacitated by his seizures, despite high doses of anticonvulsant medication, that he could not work or lead a normal life.
- Offered H.M. an experimental procedure that he had carried out previously in psychotic patients, and the surgery was then performed with the approval of the patient and his family.
the first papers said that No Hippo, No Memory (forgetting that other regions are missing)
- Early papers incorrectly cited stating the hippocampus is important for memory
- Surgeon’s description, included the hippocampus, amygdala, and the adjacent parahippocampal gyrus.
- Milner: “Despite the use of the word ‘hippocampal’ in the titles of my papers with Scoville and Penfield, I have never claimed that the memory loss was solely attributable to the hippocampal lesions” (Milner, 1998).
- “It is concluded that the anterior hippocampus and hippocampal gyrus, either separately or together, are critically concerned in the retention of current experience. It is not known whether the amygdala plays any part in this mechanism, since the hippocampal complex has not been removed alone, but always together with uncus and amygdala.”
H.M. and the Types of Memory
-what is the factor(s) that determine how long patients like HM can retain information in memory
- Time is not the key factor that determines how long patients like H.M. can retain information in memory.
- The relevant factors are the CAPACITY OF IMMEDIATE MEMORY AND ATTENTION, i.e., the amount of material that can be held in mind and how successfully it can be rehearsed.
- Psychological distinction between immediate memory and long-term memory is a prominent feature of how the brain has organized its memory functions.
3 Principles from H.M. and other patients
- Memory is a distinct cerebral ability separate from other cognitive functions
- Short-term memory and long-term memory are distinct
- Medial temporal love structures are not the ultimate repository of long-term memory
H.M. gives us the animal model of hippocampal function
-what animal is studied now?
*Now we have a region of the brain to target
Hippocampus fairly well conserved across mammals
Lesions studies in rats became popular
Results of Rat Studies (in regards to memory and hippocampus)
*Rats with hippocampal lesions failed to replicate the deficits seen in H.M.
reasons for mistake in thinking that the animal models would result in the same as HM
(2 things)
*1960s and 1970s, not understood that memory and learning could be supported by different brain regions and systems.
- Humans and experimental animals approach similar tasks with different strategies
- Example: Visual Discrimination Tasks/Learning
- -Monkeys learn task gradually over trials by habit learning (basal ganglia-based)
- -Rats perform like monkeys
- -Humans learn task by memorization
Animals are People Too… Except When It Comes to _____
Animals are People Too… Except When It Comes to Behavior
- To relate behavioral and learning tasks between humans and other animals species, you must be very careful when designing tasks
- Animal analogs of human tests that show deficits
- One-trial visual learning/Match-to-sample with delay
- Delayed nonmatch-to-sample
Since the 1970s
LTP (1973)
Place cells (1978)
Grid cells
Adult Neurogenesis
