Performance on visual delayed nonmatching-to-sample was assessed in rhesus monkeys with combined and separate ablations of the perirhinal entorhinal cortex, as well unoperated controls. Combined (i.e., rhinal cortex) lesions yielded a striking impairment this task, one almost severe that seen after amygdalohippocampal removals included some subjacent cortex (Mishkin, 1978; Murray Mishkin, 1984). Ablations alone produced deficit nearly found lesions, whereas only mild deficit. Contrary to...

Goal-directed actions are guided by expected outcomes of those actions. Humans with bilateral damage to ventromedial prefrontal cortex, or the amygdala, deficient in their ability use information about positive and negative guide choice behavior. Similarly, rats monkeys orbital amygdala have been found be impaired responses changing values outcomes. In present study, we tested whether direct, functional interaction between cortex is necessary for guiding behavior based on Unlike control...

The orbital prefrontal cortex (PFo) operates as part of a network involved in reward-based learning and goal-directed behavior. To test whether the PFo is necessary for guiding behavior based on value expected reward outcomes, we compared four rhesus monkeys with two-stage bilateral removals six unoperated controls their responses to reinforcer devaluation, task that assesses monkeys' abilities alter choices objects when underlying food has changed. For comparison, same were tested standard...

The ipsilateral corticocortical connections of the somatosensory fields lateral sulcus macaques were examined with both anterograde and retrograde axonal transport methods. In most cases, field interest was identified prior to injection tracer substance by recording neuronal responses somatic stimulation. results show that second area (S2) is reciprocally connected retroinsular (Ri), 7b, granular (Ig) dysgranular (Id) insular fields. Ri also Ig. Previously reported confirmed between S2 areas...

Monkeys were trained preoperatively on a one-trial learning task in which they required to associate memory novel object and the place it had just appeared. After level of 80% correct responses, received bilateral ablations either hippocampal formation or amygdaloid complex. The monkeys with amygdalectomy showed small drop performance initially but then regained their preoperative level. By contrast, hippocampectomy dropped near-chance levels remained there throughout postoperative testing....

Earlier work indicated that combined but not separate removal of the amygdala and hippocampus, together with cortex underlying these structures, leads to a severe impairment in visual recognition. More recent work, however, has shown rhinal cortex, region subjacent rostral yields nearly same as original removal. This raises possibility earlier results were attributable damage caudal portions rather than hippocampal To test this possibility, we trained rhesus monkeys on delayed...

Abstract The retrograde axonal transport method has been employed to identify the cell bodies of cortical neurons projecting directly spinal cord in monkey. investigation focused on aspects laminar, columnar, and somatotopic organization corticospinal within each cytoarchitectural functional subdivisions sensorimotor cortex. principle findings these experiments are that: (i) regions containing first motor cortex (area 4), somatic sensory (areas 3a, 3b, 1, 2), part immediately adjacent...

The present experiment tested predictions of a 'perceptual-mnemonic/feature conjunction' (PMFC) model perirhinal cortex function. predicts that lesions should disrupt complex visual discriminations with high degree 'feature ambiguity', property discrimination problems can emerge when features an object are rewarded they part one object, but not another. As feature ambiguity is thought to be the critical factor, such effects independent number objects discriminated. This was directly, by...

Aspiration lesions of the amygdala were found previously to produce a severe impairment in visual discrimination learning for auditory secondary reinforcement rhesus monkeys (Gaffan and Harrison, 1987). To determine whether excitotoxic would also this effect, we trained four naive on same task. The required learn 40 new problems per session situation which choices guided by an reinforcer that had been associated with food reward. Bilateral no effect rate reinforcement. We tested...

Abstract Seven cynomolgus monkeys ( Macaca fascicularis ) performed a series of tasks designed to assess their visual memory and ability identify stimuli. Preoperatively they were trained tested in delayed simultaneous matching‐to‐sample, both with large stimulus set small set; there ∼500 million possible stimuli the set, which effectively means that trial‐unique this while only four stimuli, appeared repeatedly every session training set. Three then had cortex within adjacent rhinal sulcus...

Rhesus monkeys learned 10 visual stimulus-stimulus association, or paired associates. They then received bilateral removals of either the amygdaloid complex and underlying cortex, hippocampal formation both combined, they were retained as unoperated controls. After surgery rest, tested for their retention preoperatively set associates, well ability to learn new associations same type. Both controls hippocampectomized relearned trained associates almost immediately. By contrast, with amygdala...

Abstract The thalamocortical relations of the somatic fields in and around lateral sulcus macaque were studied following cortical injections tritated amino acids horseradish peroxidase (HRP). Special attention was paid to second somatosensory area (S2), connections which also by means thalamic isotope retrograde degeneration. S2 shown receive its major input from ventroposterior inferior nucleus (VPI) not, as previously reported, caudal division (VPLc). Following small or HRP into hand...

Monkeys trained on both visual and tactual versions of an object memory task (delayed nonmatching-to-sample) received bilateral ablations either the amygdaloid complex or hippocampal formation brain. Although groups performed well two intramodal (visual-to-visual tactual-to-tactual), amygdalectomized monkeys were severely impaired relative to hippocampectomized a crossmodal version (tactual-to-visual). The findings suggest that amygdala is critical for certain forms association loss such...