Right Medial Thalamic Lesion causes Isolated

Retrograde Amnesia(Miller, Caine, Harding,

Thompson, Large & Watson, 2001)

Soomi Kim PSYC 260

IntroductionWhat is amnesia?

Temporary or/and permanent loss of memory.

There are two types of amnesia.AnterogradeRetrograde

Types of AmnesiaAnterograde Amnesia Retrograde AmnesiaShort term memory loss

e.g. black out after excessive alcohol consumption.

Long term memory losse.g. wedding day

HypothesisThe right mediodorsal thalamic nucleus and

immediately surrounding areas are responsible for central processing mechanisms such as recalling cortically stored memories, which are suggested by McClelland (1994) and Markowitsch (1995).

Case PresentationJG is a 33 years old, right-handed, healthy

male patient.He has isolated retrograde amnesia caused by

right medial thalamic lesionNormal day to day memoryTrouble recalling:

Autobiographical information Procedure memory Knowledge of famous people and events

Case PresentationHe said “I don’t remember anything”.He had no memory of where he worked and

what he was supposed to do at work.

Neurological FindingsCT scan showed the patient’s brain is normal.MRI showed that there are three lesions in

the patient’s thalamus.Right:

More anterior and mediodorsal thalamic nuclei (a) More posterior part of mediodorsal nucleus (b)

Left: Posterior part of the mediodorsal nucleus and

paraventricular nucleus (c)

Neurological FindingsAnterior

Right Left

Posterior

Neuropsychological AssessmentsInitial Assessment

JG’s recognition ability for autobiographical material “Major Life Events Test” Recognizing a familiar face among the picture of

three strangers Matching Christian names with each photograph of

his family members or friendsResults:

He was unable to correctly identify faces of people in his past.

But he identified people whom he recently met.

Neuropsychological AssessmentsJG’s non-autobiographical information

“Famous People Test” “Famous Events Test”

Results: His performance was at near-chance level when

compared with three men without any known neurological disorders.

No significant differences between recognizing famous people’s names and faces before and during his life time.

He barely remembered any of famous events regardless of time.

Neuropsychological AssessmentsFamous People Test

Neuropsychological AssessmentsFamous Events Test

Neuropsychological AssessmentsFollow-up Assessment

JG showed no improvements in Recalling of personal events and semantic details

from childhood His memory of distant past autobiographical events Recalling famous events that occurred before the

onset of his lesionJG showed improvements in recognition of

famous people whom he recently saw. But he could not match faces with names.

Neuropsychological AssessmentsProcedural Memory

JG kept long-standing procedural memories. e.g. driving and playing golf

However, JG’s procedural knowledge was slightly impaired. e.g. using a cash register at the shop he worked a

few weeks before his admission

DiscussionJG’ severe and chronic retrograde amnesia

was found to be caused by the recent lesion.Posterior part of the mediodorsal nucleus and

paraventricular nucleus (c)JG’s symptoms are due to other related

cortical area dysfunctions as well.He had difficulties accessing more distant

memories, which are stored in neocortex.

DiscussionKnowledge of people, events and other

unique material differs form other factual knowledge and they are also correlated with personal experiences.

ConclusionThe results are consistent with McClellend

and Markowitsch’s finding that the right mediodorsal thalamic nucleus and the surrounding regions engage in central procession mechanism such as recalling cortically stored memories.

My OpinionStrengths WeaknessesIt is heuristic

It can provide background information for future study.

Combined method and result sections make hard to reproduce.Confusing

The conclusion is hard to generalize to the entire population.