Higher cortical functions in man

https://is.muni.cz/el/1423/podzim2011/PSY221_P11/um/27733942/Milner__1965_.pdf

Visually-guided maze learning in man: effects of bilateral hippocampal, bilateral frontal, and unilateral cerebral lesions

In 1899 Bechterew3demonstrated a case of bilateral softening of the gyrus uncinatus and cornu ammonis before members of the St. Petersburg Clinic and drew attention to the prominent memory disturbances. Over 50 years later, Glees and Griffith8described an instance of dementia with bilateral destruction of the hippocampus and hippocampal gyrus in which recent memory impairment was an early and prominent symptom. They concluded on the basis of the necropsy material that the integrity of the region of the hippocampus is necessary for the maintenance of recent memory. Since then, a series of clinical studies has provided corroborative evidence and has extended these findings. In 1954, Scoville35reported a grave loss of recent memory in one epileptic and one psychotic patient after bilateral surgical removal of the uncus, hippocampus, and hippocampal gyrus. Formal memory and intelligence testing of eight similar patients again indicated impairment in recent

Learning and Retention in Monkeys After Amygdala- Hippocampus Resection

Horseradish peroxidase (HRP) was injected in relatively massive amounts to cover most, or portions, of opercular striate cortex in four macaques. Absence of transcallosal or circumventricular labelling, plus discrete and consistent retrograde labelling in other areas in the four cases, assured the validity and specificity of the observations. Numerous labelled cells in regions directly bordering striate cortex, however, were excluded from the analysis because of the possibility of uptake consequent to physical diffusion. With this exception, all labelled cells were counted at roughly 2-mm intervals for one case with extensive unilateral injection of HRP. Even excluding the closely circumstriate population, the totals indicate that more than 30% of the afferent input to striate cortex arises from nongeniculate sources. Four areas of neocortex together make up about one-fourth of the total afferents: superior temporal sulcus 17.1%; inferior occipital area, 6.1%; intraparietal sulcus, 0.4%; and parahippocampal gyrus, 0.3%. Other areas projecting to striate cortex include claustrum, pulvinar, nucleus paracentralis, raphe system, locus coeruleus, and the nucleus basalis of Meynert. Cells of the latter were particularly striking with their very heavy uptake of HRP, and, even in cases of minimal effective injection, were scattered throughout an extensive area from the posterior edge of the globus pallidus passing rostrally beyond the chiasm and into the nucleus of the diagonal band. On the basis of their distribution and known cholinergic affinity, it is argued that this group also includes the cells labelled in and around lateral hypothalamus and cerebral peduncle, and that as a whole the group constitutes a cholinergic counterpart of the diffusely projecting monoaminergic systems. It seems possible that the basalis projection at first follows a fornical-subcallosal pathway to reach striate cortex via callosoperforant fibers.

Nongeniculate afferents to striate cortex in macaques.

The present chapter deals with the possibility that some behavioral manifestations of brain damage can be modified by general environmental conditions. Specifically, it examines the hypothesis that brain-lesion effects might be increased or decreased in severity as a function of the level of environmental stimulation before or after damage, or between successive injuries. It might be expected that marked changes in brain lesion symptomatology would follow severe deprivation or exposure to aberrant or very restrictive stimulus conditions. However, deprivation effects, while interesting in their own right, shed only indirect light on how maximum recovery might be achieved. In contrast, exposure to stimulating environments could reveal more information about the recovery potential of an organism after a specific brain lesion. Hence, the effects of enhanced stimulation will be emphasized in this review.

J. Orbach

Papers

"Functions" of striate cortex and the problem of mass action.