Anterior Cortical Lesions Research Articles

Ipsilateral hippocampal proteomics reveals mitochondrial antioxidative stress impairment in cortical-lesioned chronic mild stressed rats.

In this study, a two-dimensional gel-based proteomic approach was applied to profile the protein alterations underlying the significant adverse effects from post-stroke depression (PSD). In view of the close association between left prefrontal cortical dysfunction and PSD, a PSD rat model was constructed through a left anterior cortical lesion followed by chronic mild stress (CMS) for three weeks. Through sucrose preference testing, PSD rats displayed depression-like behavior during the entire CMS period. In contrast, stroke rats displayed depression-like behavior in the first week post-stroke and recovered in the second week post-stroke. To investigate the PSD-induced protein expression changes, ipsilateral hippocampal protein expression in stroke, PSD, and control rats were comparatively analyzed. 46 differential proteins were identified, 22 of which were regulated in opposing directions by stroke and post-stroke stress. The majority of these 22 proteins were involved in neurogenesis, cytoskeletal remodeling, and energy metabolism. Additional proteins were functionally related to mitochondrial antioxidative stress systems. The differential proteins expressed in opposing directions by stroke and post-stroke stress may play a role in self-repair after adult brain lesions, suggesting that stroke induces self-repair mechanisms, while post-stoke stress mitigates them, in the rat hippocampus. Among these differential proteins dysregulated in opposing directions, three mitochondrial proteins involved in mitochondrial antioxidative stress - heat shock 70 kDa protein 9, peroxiredoxin-6, and prohibitin - were validated and may play an important role in stroke-injury self-repair and PSD-induced injury of hippocampal neurons. These findings offer new insight into deciphering the molecular mechanisms underpinning PSD's adverse effects on stroke recovery.

Lesion characteristics related to treatment improvement in object and action naming for patients with chronic aphasia

Few studies have examined the relationship between degree of lesion in various locations and improvement during treatment in stroke patients with chronic aphasia. The main purpose of this study was to determine whether the degree of lesion in specific brain regions was related to magnitude of improvement over the course of object and action naming treatments. Participants and methodsFifteen left hemisphere stroke patients with aphasia participated in treatments for object and/or action naming. Two raters assessed extent of lesion in 18 left hemisphere cortical and subcortical regions of interest (ROIs) on CT or MRI scans. Correlations were calculated between composite basal ganglia, anterior cortical, and posterior cortical lesion ratings, on the one hand, and both pretreatment scores and treatment change for both object and action naming, on the other hand. ResultsUnexpectedly, greater anterior cortical lesion extent was highly correlated with better object and action naming scores prior to treatment and with greater improvement during treatment when partial correlations controlled for total basal ganglia lesion extent (r ranging from .730 to .858). Greater total basal ganglia lesion extent was highly correlated with worse object and action naming scores prior to treatment and with less improvement during treatment when partial correlations controlled for total anterior lesion extent (r ranging from −.623 to −.785). Correlations between degree of posterior cortical lesion and naming indices generally were not significant. No consistent differences were found between the correlations of ROI lesion ratings with object naming versus action naming scores. ConclusionLarge anterior cortical lesions and intactness of the basal ganglia may both contribute to more efficient reorganization of language functions.

Behavioural effects of neocortical and cingulate lesions in the Mongolian gerbil

The experiments examine the effects of cortical lesions on a variety of behaviours in the Mongolian gerbil ( Meriones unguiculatus). Gerbils with either large anterior or posterior lesions were compared with normal gerbils by administering a battery of tests of rodent behaviours such as grooming, eating, social interaction, ventral marking and foot-stomping. In a second experiment, a more detailed investigation was carried out of the effects of focal cortical lesions on ventral marking. The results of these experiments suggest that anterior cortical lesions in gerbils give rise to a number of different deficits in behaviour. The results further suggest that cingulate cortex is part of the neural substrate for ventral marking behaviour. The implications of these results for contemporary theories of frontal lobe function are discussed.

Development of paw preference in rats following unilateral cortical ablations in infancy.

Rats which received unilateral anterior cortical lesions in infancy manifested a preference for the paw contralateral to the intact hemisphere when tested at 5 wk. and at 10 wk. of age. That this effect was locus specific and was not due to a change in the over-all balance of activity between the hemispheres was indicated by the fact that similar lesions made in the posterior cortex did not influence which paw the animals subsequently preferred. The posterior lesions, however, may have lowered the frequency of ambidexterity, a finding interpreted in terms of theoretical arguments concerning bilateral symmetry and the discrimination and memory of left and right.

Cortical lesions: flavor illness and noise-shock conditioning

We studied the effects of neocortical lesions in rats upon (a) aversive conditioning where a flavor is paired with a subsequent illness, and (b) aversive conditioning where a noise is followed by a foot shock. Lesions of the anterior cortex produced deficits in both paradigms, regardless of whether the gustatory cortex was damaged or spared. Lesion size was more important than location for taste aversion acquisition. Gustatory cortical lesions, as well as other cortical lesions, produced “intersession memory” deficits between training days in the noise-shock paradigm. Within sessions, the acquisition slopes were similar for control and lesioned rats. These data favor a general learning effect for any anterior cortical lesion rather than a specific effect of gustatory lesions on flavor-illness conditioning.

Avoidance behavior in rats as a function of the size and location of anterior cingulate cortex lesions

In 1967, Trafton found that lesions in the anterior midline cortex led to extreme deficits in conditioned avoidance response (CAR) learning in rats. The present study varied the placement and size of anterior cortical lesions in an attempt to further define the areas which are critical in producing the learning deficit. The results indicate a significant correlation between the size of the lesion and the degree of learning deficit in a shuttlebox. The placement of the lesion within the anterior cingulate area was not found to be associated with CAR performance in any predictable manner.

Influence of Anterior Cortical Lesions upon the Cer to Auditory Stimulus under Non-Extinction

The mo:or and autonomic activity of 72 rats was observed in a grill-box under several combinations of auditory and electric shock stimulation. Post-operative observations carried out under conditions of non-extinction showed sham operations to be as effective as bilateral anterior cortical lesions in producing a change in the motor facet of the CER. In line with earlier reports, high defecation scores produced and maintained by brief electric shock to the feet did not show any apparent alteration in frequency as a result of surgery.