Deficits In Transfer Research Articles

Incomplete split-brain syndrome in a patient with chronic Marchiafava-Bignami disease

A 40-year-old male patient is presented who survived Marchiafava-Bignami disease and recovered sufficiently to be assessed neurologically and neuropsychologically in some detail. Besides dementia, lack of initiative, and psychomotor retardation here ascribed to extracallosal damage, he showed a number of symptoms of hemispheric disconnection such as left-sided apraxia, poor bimanual coordination in specific laboratory tests, and deficits in the interhemispheric transfer of somaesthetic information. Other commissural functions, such as interhemispheric transfer of tactile, visual and auditory information as well as bilateral coordination in previously overlearned tasks, were nearly intact. The observed dysarthria could be meaningfully discussed in relationship to postcallosotomy mutism. It is concluded, that the partial interhemispheric disconnection syndrome in Marchiafava-Bignami disease lacks functional compensation which is different from the usual course in partial commissural section.

Dissociations among memory measures in memory-impaired subjects: evidence for a processing account of memory.

Deficits in conceptual transfer on both implicit and explicit memory tests were obtained for memory-impaired temporal lobe epileptic (TLE) subjects in three studies. In Experiment 1, in which a generate-read paradigm was employed, memory-impaired TLEs failed to show normal generation effects on conceptually driven tests of semantic cued recall and general knowledge questions, although their data-driven memory as measured by word-fragment completion and graphemic cued recall tasks was normal. In Experiment 2, memory-impaired patients having left temporal lobe seizure foci were tested on these four tasks and compared with nonimpaired TLEs having right temporal foci. The left TLEs showed deficits on conceptually driven tasks and normal memory for data-driven tests. These findings were extended in Experiment 3, in which left TLE patients failed to show any benefit from blocked study, as compared with random study, on category production and semantic cued-recall tests, although right TLEs and normal controls showed blocking effects on both tasks. These findings may be accommodated by a processing framework of memory in which memory-impaired patients are characterized as having deficits in conceptual, but not in data-driven, processing capabilities.

Effects of unilateral thalamic lesion upon interocular transfer of visual discrimination in pigeons. II: lesion in the untrained hemisphere (sensory deficits)

In a previous study, rotundal lesions in the 'trained' hemisphere caused deficits in interocular transfer of visual discrimination when the lesion was made after acquisition of the monocular learning, but not when the lesion was made before the monocular learning. In the present study, a rotundal lesion was made in the 'untrained' hemisphere before and after monocular training. The lesion caused deficits in transfer regardless of the temporal relation between the lesion and the training. Such deficits are likely to be 'sensory deficits' since visual information from the eye goes to the damaged rotundus when tested with the untrained eye. The relation between the 'sensory' versus 'mnemonic' deficits from damage to nucleus rotundus in the trained hemisphere are discussed.

Effects of unilateral thalamic lesion upon interocular transfer of visual discrimination in pigeons. I. Lesion in the trained hemisphere (memory access deficits)

Two groups of pigeons received a unilateral thalamic lesion in the hemisphere contralateral to the eye used for monocular training of a line orientation discrimination. The first group was trained monocularly on the discrimination after the lesion, and the second group received the lesion after the birds were successfully trained on the discrimination task. Then both groups were trained on the same task with their previously untrained eye to examine interocular transfer of discrimination. Lesion in the nucleus rotundus before monocular discrimination retarded acquisition of the original monocular learning but did not cause deficits in interocular transfer, whereas the rotundal lesion after the monocular discrimination learning resulted in deficits in interocular transfer. These results suggest (1) the bird could learn monocular discrimination with the hemisphere ipsilateral to the viewing eye when the contralateral hemisphere was not accessable, and (2) the bird learned monocular discrimination with the hemisphere contralateral to the viewing eye when both hemispheres were intact. Lesion in OPT did not cause deficits in interocular transfer. This result suggests a crucial role of the tecto-fugal pathway in interocular transfer.

Two Brains, One Child: Interhemispheric Information Transfer Deficits and Confabulatory Responding in Children Aged 4, 7, 10

In an investigation of developmental trends in the ability to transfer information between the cerebral hemispheres, 138 children, ages 4, 7, and 10, viewed pictures presented to either the right or left hemisphere and were asked to describe what was viewed. Responses were scored for the number of accurate pictorial features reported (inclusion score), confabulation (erroneous embellishment), perceptual, semantic, and syntactic errors. Misses (failure to provide a response) were also noted. A preponderance of errors were found, such that 4-year olds engaged in a significant degree of confabulatory responding following right vs. left presentation. A significant inverse relationship was found between inclusion and confabulation such that the larger the gap in information reported the greater was the tendency to insert (confabulate) erroneous material. In addition, all children were given a tactile-shape recognition task employing both transfer and non-transfer conditions and requiring tactile exploration and visual recognition. Significantly more errors were found on the transfer vs. non transfer task among the 4-year olds only. In that deficits in information transfer were not complete but only partial, and given that significant intra-hemispheric (non-transfer) errors were also discovered, it was concluded that the hemispheres of children age 4 are not completely but only partially disconnected, and that intra-hemispheric (cortical) immaturity plays a significant role in the production of processing deficits.

Interhemispheric transfer of stereognostic information in chronic schizophrenics.

Ten chronic schizophrenic in-patients and ten matched normal controls were tested on a cross-hemispheric stereognostic task, using both meaningful objects and non-meaningful shapes of wood, under four different retention intervals. The main finding was that the schizophrenic group but not the control group displayed deficits in intermanual transfer of tactual material, as compared to the same task performed within hands. The implications of this result are discussed in relation to the possibility that some basic neurological disorder may accompany schizophrenia.

Lateralized deficits in complex visual discrimination and bilateral transfer of reminiscence following unilateral temporal lobectomy

Differential deficits in complex visual discrimination and bilateral reminiscence in symbolic learning were assessed after left as compared with right temporal lobectomy in man. A deficit in the ability to discriminate between fragmented concentric circle patterns was found in the right temporal lobectomy group. The left temporal group exhibited a selectively lower left to right hand performance increment in inverted alphabet printing with interpolated rest. Stimulus complexity was inferred to be more effective than the level of visuospatial integration required by the task for eliciting deficits in visually guided behavior after right temporal lobectomy. Differences between the groups in the rate of interhemispheric dissipation of inhibitory effects in symbolic learning was postulated to account for the lower magnitude of bilateral reminiscence observed after left temporal lobectomy.