G.A. Carlesimo, L. Serra, L. Fadda, A. Cherubini, M. Bozzali, C. Caltagirone

1. Bilateral damage to the mammillo-thalamic tract impairs recollection but not familiarity in the recognition process: A single case investigation G.A. Carlesimo, L. Serra, L. Fadda, A. Cherubini, M. Bozzali, C. Caltagirone Neuropsychologia 45 (2007) 2467-2479 Presentation by Adam Bregman

2. Who is this person? • G.P. is a 38 year old right handed man. • He was a lawyer with a prominent company in Italy

3. What went wrong? • While walking, fell unconscious in February 2001. • Was taken to the hospital where he regained consciousness a few hours later with anterograde and retrograde amnesia. • A few days later he had enduring problems with anterograde LTM

4. Neuroanatomy Background Info • MTL injuries- poor episodic memory with either recall or recognition. Show normal scores on STM, semantic, procedural memory. • Caused by thalamic lesions which is from disconnection between MTL structures and anterior thalamus

5. Background continued • Mammillo-thalamic tract: connects hippocampus of MTL to mamillary bodies and the medial and lateral nuclei of mamillary bodies to anterior thalamic nuclei, which project to limbic cortical areas such as cingulate cortex. • VAF pathway: intrathalamic portion of pathway from amygdala and perirhinal cortex to MD thalamus.

6. Diagram of mammillo-thalamic tract

7. Clinical Connections • Claim that some structures in MTL involved in only recall of recent episodic memory, others in recognition • Recognition: evidence that perirhinal cortex in parahippocampal gyrus impt. Receives input from all sensory areas of brain and is important in recgonition of episodic memory • Recall: Hippocampus receives cortical inputs from parahippocampal gyrus and then projects to cortical and subcortical regions. • Aggleton and Brown (1999): damage to MTT and anterior thalamus cause severe and selective damage to recall • Damage to MD to thalamus or VAF, problems to recognition

8. What’s the Nature of the damage • Bilateral thalamic damage. • MRI showed two ischemic lesions in anterior medial thalamus. • Lesion volumes were 316 and 217mL on right, and 57 and 22mL on left for two different scans. • Right thalamic lesion involved MTT • Left thalamic lesion involved MTT and ventral anterior thalamic nucleus. • MD nucleus spared

9. MRI of Ischemic Lesions

11. Aspects of memory impaired • Battery of neuropsychological tests all normal with exception of recognition tests compared to age matched controls • Problems with block design and object assembly and object decision subtest. • Normal STM, immediate memory intact but delayed episodic is poor • WAIS IQ=110 • WAIS verbal subtest=133 • Overall: impaired declarative episodic memory for verbal and visuo-spatial material. Normal recognition on two choice tests, but poor on yes/no and multiple choice tests. Preserved recognition.

12. Discussion and Implications • Visuo-spatial problems could be due to larger damage to right hemisphere. • MD nucleus spared, which is important in recognition • Only damage to MTT, so only problems with recall. • Hippocampus only: problems with recall • Hippocampus and parahippocampal gyrus: recall and recognition problems