Andrew Mayes

Associative encoding of pictures activates the medial temporal lobes

It remains unresolved whether the medial temporal lobe activations found in recent neuroimaging studies are mediated by novelty detection alone, by specific kinds of encoding or consolidation operations, or both. This study attempted to see whether associative encoding or consolidation is sufficient to cause such activation by matching for novelty across conditions. Using single‐photon emission computer tomography (SPECT) (with Tc99mHMPAO), we compared the activation patterns produced by the associative encoding and the perceptual matching of novel complex scenes in 10 normal subjects using both statistical parametric mapping (SPM) and a regions‐of‐interest (ROI) approach. During the encoding condition, significant activations were detected in the left hippocampal/parahippocampal region, the left cingulate cortex, and the right prefrontal cortex, using both statistical techniques. Additionally, activation was found in the right cingulate cortex, and a trend towards activation was found in the right hippocampal/parahippocampal region using the ROI approach. In contrast, no medial temporal activations were found during the matching condition, which produced bilateral occipito‐parietal and right posterior inferior parietal (supramarginal gyrus) activations. These results not only confirm that the associative encoding and/or consolidation of complex scenes is partially mediated by medial temporal lobe structures, but also demonstrate, for the first time, that associative encoding/consolidation is sufficient to produce such an activation. The implications of the high degree of consistency revealed by the results of the SPM and ROI comparison are discussed. Hum. Brain Mapping 6:85–104, 1998.

Rate of forgetting in amnesia: I. Recall and recognition of prose.

Three experiments explored the rate at which amnesic participants free recall, cued recall, and recognition of prose declined over short filled delays. In Experiment 1, after performance had been matched to that of controls at 15s, amnesics showed accelerated forgetting over delays of up to 10 min in a free-recall condition, whereas recognition performance declined normally over delays of up to 1 hr. This pattern of results was replicated in Experiment 2, which showed that amnesic rate of forgetting on a test of cued recall was influenced by level of cuing. Experiment 3 showed that excessive sensitivity to interference was unlikely to be the cause of the amnesic patients accelerated forgetting rate, which is instead explained in terms of storage deficit accounts of amnesia.

A comparison of egocentric and allocentric spatial memory in medial temporal lobe and Korsakoff amnesics

Two patients with medial temporal lobe damage, seven Korsakoff amnesics and fourteen healthy control subjects were tested on three conditions of a spatial memory test (short delay, allocentric and egocentric). The task required subjects to recall the position of a single spot of light presented on a board after various delays. The short delay condition tested memory over very short, unfilled intervals. The other two conditions used longer, filled delays. The allocentric condition required subjects to move to a different place around the board before recalling the position of the light. In the egocentric condition stimuli were presented in darkness, which eliminated allocentric cues. The Korsakoff amnesics were impaired at all delays of the short delay tasks, suggesting poor encoding. On the allocentric and egocentric tasks the Korsakoff amnesics showed a comparable impairment in the two conditions, which worsened with delay. This accelerated forgetting suggested that the Korsakoff amnesics also had impaired memory for allocentric and egocentric information. The patients with medial temporal lobe damage were unimpaired in the short delay condition suggesting intact encoding and short-term memory of spatial information. However, they were impaired in the allocentric condition and showed accelerated loss of allocentric spatial information. In the egocentric condition, while the performance of one patient was impaired, the performance of the other was as good as controls. This result suggests that, in contrast to allocentric spatial memory, which is sensitive to medial temporal lobe damage, an intact medial temporal lobe need not be necessary for successful performance on an egocentric spatial memory task.

The Relationship between Retrograde and Anterograde Amnesia in Patients with Typical Global Amnesia

An extensive battery of tests of anterograde amnesia and remote memory was given to ten amnesics with lesions either to the medial temporal lobes of the diencephalon. These showed that the patients had anterograde amnesia with deficits in verbal and non-verbal recall and recognition, but preservation of word stem completion and intelligence. Mild impairments on executive tests and digit span performance were largely caused by the poor performance of the Korsakoff patients. The amnesics also showed remote memory deficits for personal and public domain information, and temporal gradients were observed for some of the tests. These deficits probably arose because the patients anterograde amnesia was more severe than their retrograde amnesia even for the recent pre-morbid past. They were more impaired in the recall of details about famous names in their ability to recognize such names. There was also a suggestion that performance on anterograde tests did not relate strongly to that on tests of retrograde amnesia of the remote pre-morbid past. However, this effect was less apparent with memory for personal information when the format and the information tapped were matched on pre- and post-morbid tests.

Rate of forgetting in amnesia: II. Recall and recognition of word lists at different levels of organization.

Amnesic rate of decline of free recall, cued recall, and recognition of word lists with different levels of organization was investigated in 2 experiments. In Experiment 1, it was found that amnesic free recall of semantically related word lists declined at an accelerated rate, whereas free recall of lists of unrelated words declined at a normal rate. Cued recall and recognition performance of both kinds of word lists appeared to decline at a normal rate. In Experiment 2, the results of the free-recall and recognition conditions were replicated using an improved experimental design. The observed amnesic forgetting pattern is interpreted as arising from an impairment in consolidation of long-term memory for complex associations between 2 or more items and their study context that is caused by extended hippocampal system lesions.

A meta-analysis of indirect memory tests for novel material in organic amnesics

A meta-analysis was conducted on studies of implicit memory for novel and familiar information in organic amnesic patients and healthy controls. Across studies, the amnesics performed equivalently to the controls on indirect memory tests for familiar information. However, the controls performed better than amnesics for indirect memory tests for novel item and novel associative information. This is in accord with memory theories which suggest that medial temporal lobe structures are essential for encoding and storing arbitrary associations between items or events.

Jazz, guitar, and neurosurgery: the Pat Martino case report.

OBJECTIVEnWe present the case of a professional jazz guitarist with temporal lobe epilepsy secondary to an arteriovenous cerebral malformation.nnnCASE DESCRIPTIONnThe patient underwent a left temporal lobectomy in 1980. After surgery, he presented with severe retrograde amnesia and complete loss of musical interest and capabilities. The patients musical abilities recovered over time, and he regained his previous virtuoso status. In 2007, his medical history, neuropsychologic functions, and structural magnetic resonance imaging study were examined and revealed a remarkable degree of recovery of memory and musical abilities in the context of extensive temporal lobe resection. The neuropsychologic findings and neuroanatomic features of the magnetic resonance imaging study were analyzed to try to understand the high degree of recovery of both long-term memory and musical processing abilities in this musician.nnnCONCLUSIONSnThis case reveals the possibility of an unusual degree of cerebral plasticity and reorganization. Additionally, it emphasizes the question of musical virtuosity. This report shows that the musical capabilities of professional musicians, in specific cases, can completely recover even when much of the left temporal lobe has been removed.

Storage of verbal associations is sufficient to activate the left medial temporal lobe

Neuroimaging studies have shown that memory encoding activates the medial temporal lobe (MTL). Many believe that these activations are related to novelty but it remains unproven which is critical - novelty detection or the rich associative encoding it triggers. We examined MTL activation during verbal associative encoding using functional magnetic resonance imaging. First, associative encoding activated left posterior MTL more than single word encoding even though novelty detection was matched, indicating not only that associative encoding activates the MTL particularly strongly, but also that activation does not require novelty detection. Moreover, it remains to be convincingly shown that novelty detection alone does produce such activation. Second, repetitive associative encoding produced less MTL activation than initial associative encoding, indicating that priming of associative information reduces MTL activation. Third, re-encoding familiar associations in a well-established way had a minimal effect on both memory and MTL activation, indicating that MTL activation reflects storage of associations, not merely their initial representation.

The Paradoxical Brain: Abbreviations

Acknowledgements Preface Foreword Oliver Sacks Author affiliations Abbreviations 1. The paradoxical nature of nature Narinder Kapur, Alvaro Pascual-Leone, Tom Manly and Jonathan Cole 2. Paradoxical effects of sensory loss Alvaro Pascual-Leone, Souzana Obretenova and Lotfi B. Merabet 3. Paradoxical functional facilitation and recovery in neurological and psychiatric conditions Narinder Kapur 4. Paradoxes in neurorehabilitation Tom Manly, Ian H. Robertson and Narinder Kapur 5. The paradoxical self Vilayanur Ramachandran and William Hirstein 6. Paradoxical psychological functioning in early child development David J. Lewkowicz and Asif A. Ghazanfar 7. Cognitive ageing: a positive perspective Shira Zimerman, Lynn Hasher and David Goldstein 8. Paradoxes of learning and memory Henry L. Roediger, III and Andrew C. Butler 9. The paradox of human expertise: why experts get it wrong Itiel E. Dror 10. Paradoxes in Parkinsons disease and other movement disorders Ashwani Jha and Peter Brown 11. Paradoxical phenomena in epilepsy Steven C. Schachter 12. Paradoxical creativity and adjustment in neurological conditions Indre V. Viskontas and Bruce L. Miller 13. Paradoxical functional facilitation with noninvasive brain stimulation Umer Najib and Alvaro Pascual-Leone 14. Unexpected benefits of allergies and cigarette smoking: two examples of paradox in neuroepidemiology Judith Schwartzbaum, Linda Karavodin, Narinder Kapur and James L. Fisher 15. The paradox of autism: why does disability sometimes give rise to talent? Simon Baron-Cohen, Emma Ashwin, Chris Ashwin, Teresa Tavassoli and Bhismadev Chakrabarti 16. Paradoxes in creativity and psychiatric conditions Jonathan Hurlow and James H. MacCabe 17. The paradox of psychosurgery to treat mental disorders Perminder S. Sachdev 18. The paradox of electroconvulsive therapy Angela Merkl and Malek Bajbouj 19. Paradoxes of comparative cognition Howard C. Hughes 20. Paradoxical phenomena in brain plasticity Bryan Kolb and G. Campbell Teskey 21. Immature neurons in the adult brain. Breaking all the rules J. Martin Wojtowicz 22. The paradoxical hippocampus: when forgetting helps learning Howard Eichenbaum 23. Paradoxical effects of drugs on cognitive function: the neuropsychopharmacology of the dopamine and other neurotransmitter systems Roshan Cools, Esther Aarts and Mitul A. Mehta 24. The paradoxical brain - so what? Narinder Kapur, Tom Manly, Jonathan Cole and Alvaro Pascual-Leone Index.

The Paradoxical Brain: Contents

Acknowledgements Preface Foreword Oliver Sacks Author affiliations Abbreviations 1. The paradoxical nature of nature Narinder Kapur, Alvaro Pascual-Leone, Tom Manly and Jonathan Cole 2. Paradoxical effects of sensory loss Alvaro Pascual-Leone, Souzana Obretenova and Lotfi B. Merabet 3. Paradoxical functional facilitation and recovery in neurological and psychiatric conditions Narinder Kapur 4. Paradoxes in neurorehabilitation Tom Manly, Ian H. Robertson and Narinder Kapur 5. The paradoxical self Vilayanur Ramachandran and William Hirstein 6. Paradoxical psychological functioning in early child development David J. Lewkowicz and Asif A. Ghazanfar 7. Cognitive ageing: a positive perspective Shira Zimerman, Lynn Hasher and David Goldstein 8. Paradoxes of learning and memory Henry L. Roediger, III and Andrew C. Butler 9. The paradox of human expertise: why experts get it wrong Itiel E. Dror 10. Paradoxes in Parkinsons disease and other movement disorders Ashwani Jha and Peter Brown 11. Paradoxical phenomena in epilepsy Steven C. Schachter 12. Paradoxical creativity and adjustment in neurological conditions Indre V. Viskontas and Bruce L. Miller 13. Paradoxical functional facilitation with noninvasive brain stimulation Umer Najib and Alvaro Pascual-Leone 14. Unexpected benefits of allergies and cigarette smoking: two examples of paradox in neuroepidemiology Judith Schwartzbaum, Linda Karavodin, Narinder Kapur and James L. Fisher 15. The paradox of autism: why does disability sometimes give rise to talent? Simon Baron-Cohen, Emma Ashwin, Chris Ashwin, Teresa Tavassoli and Bhismadev Chakrabarti 16. Paradoxes in creativity and psychiatric conditions Jonathan Hurlow and James H. MacCabe 17. The paradox of psychosurgery to treat mental disorders Perminder S. Sachdev 18. The paradox of electroconvulsive therapy Angela Merkl and Malek Bajbouj 19. Paradoxes of comparative cognition Howard C. Hughes 20. Paradoxical phenomena in brain plasticity Bryan Kolb and G. Campbell Teskey 21. Immature neurons in the adult brain. Breaking all the rules J. Martin Wojtowicz 22. The paradoxical hippocampus: when forgetting helps learning Howard Eichenbaum 23. Paradoxical effects of drugs on cognitive function: the neuropsychopharmacology of the dopamine and other neurotransmitter systems Roshan Cools, Esther Aarts and Mitul A. Mehta 24. The paradoxical brain - so what? Narinder Kapur, Tom Manly, Jonathan Cole and Alvaro Pascual-Leone Index.