We present a patient with right-hemispheric speech lateralization who exhibited severe recognition and naming deficits for unique objects (famous faces and landmarks) and grossly normal recognition and naming performances for nonunique objects (animals and man-made objects) following an anterior right temporal lobe (TL) resection of a ganglioglioma. While recognition deficits have been reported for famous faces following right temporal pole lesions, and for landmarks and geographic regions following right TL damage in general, this is the first reported case of both recognition and naming deficits for these objects resulting from a single lesion. These results are consistent with research suggesting that the neuroanatomic substrates for the recognition and naming of unique objects lie in the anterior TL regions. Left temporal pole lesions have been associated with naming deficits for unique objects while right temporal pole lesions have been associated with recognition deficits for unique objects. However, these findings suggest that the substrates of naming can be located in homotopic regions of the right hemisphere when language lateralization is atypical. As various object categories appear to have different neuroanatomical representations in the TLs, we discuss the possible benefits of sampling a wider array of objects during cortical stimulation mapping of language.

Objective

Based upon Damasio's “Convergence Zone” model of semantic memory, we predicted that epilepsy surgical patients with anterior temporal lobe (TL) seizure onset would exhibit a pattern of category-specific naming and recognition deficits not observed in patients with seizures arising elsewhere.

Methods

We assessed epilepsy patients with unilateral seizure onset of anterior TL or other origin (n = 22), pre- or postoperatively, using a set of category-specific items and a conventional measure of visual naming (Boston Naming Test: BNT).

Results

Category-specific naming deficits were exhibited by patients with dominant anterior TL seizure onset/resection for famous faces and animals, while category-specific recognition deficits for these same categories were exhibited by patients with nondominant anterior TL onset/resection. Patients with other seizure onset did not exhibit category-specific deficits. Naming and recognition deficits were frequently not detected by the BNT, which samples only a limited range of stimuli.

Interpretation

Consistent with the “convergence zone” framework, results suggest that the nondominant anterior TL plays a major role in binding sensory information into conceptual percepts for certain stimuli, while dominant TL regions function to provide a link to verbal labels for these percepts. Although observed category-specific deficits were striking, they were often missed by the BNT, suggesting that they are more prevalent than recognized in both pre- and postsurgical epilepsy patients. Systematic investigation of these deficits could lead to more refined models of semantic memory, aid in the localization of seizures, and contribute to modifications in surgical technique and patient selection in epilepsy surgery to improve neurocognitive outcome.

The oral version of the Trail Making Test (OTMT) is a neuropsychological measure that provides an assessment of sequential set-shifting without the motor and visual demands of the written TMT (WTMT). Originally purposed to serve as an oral analog of the WTMT, the OTMT provides a means to evaluate patients with physical restrictions. However, formal validity studies and available normative data remain sparse. In a sample of healthy adults (n = 81), a strong correlation was observed between OTMT-B and its written counterpart (r = .62), but the correlations were weak between OTMT-A and either written version of the TMT. OTMT-B was significantly correlated with age but not with education or gender, whereas OTMT-A was not significantly correlated with demographic factors. The WTMT to OTMT ratios observed in the current study were generally lower than previously reported and varied across age groups, suggesting that the recommended use of a uniform conversion factor to predict one performance based on the other should be cautiously undertaken. Normative data that have been stratified by age are provided as well as suggestions for using both versions of the TMT in tandem to better elucidate the nature of cognitive deficits and to aid in the localization of cerebral dysfunction.

We present a 56 year-old, right-handed, congenitally deaf, female who exhibited a partial Balint's syndrome accompanied by positive visual phenomena restricted to her lower right visual quadrant (e.g., color band, transient unformed visual hallucinations). Balint's syndrome is characterized by a triad of visuo-ocular symptoms that typically occur following bilateral parieto-occipital lobe lesions. These symptoms include the inability to perceive simultaneous events in one's visual field (simultanagnosia), an inability to fixate and follow an object with one's eyes (optic apraxia), and an impairment of target pointing under visual guidance (optic ataxia). Our patient exhibited simultanagnosia, optic ataxia, left visual-field neglect, and impairment of all complex visual-spatial tasks, yet demonstrated normal visual acuity, intact visual-fields, and an otherwise normal neurocognitive profile. The patient's visuo-ocular symptoms were noticed while she was participating in rehabilitation for a small right pontine stroke. White matter changes involving both occipital lobes had been incidentally noted on the CT scan revealing the pontine infarction. As the patient relied upon sign language and reading ability for communication, these visuo-perceptual limitations hindered her ability to interact with others and gave the appearance of aphasia. We discuss the technical challenges of assessing a patient with significant barriers to communication (e.g., the need for a non-standardized approach, a lack of normative data for such special populations), while pointing out the substantial contributions that can be made by going beyond the standard neuropsychological test batteries.

Objective

The purpose of this investigation was to determine whether clinical speech deficits following brain injury were associated with functional speech reorganization.

Methods

Across an 18 year interval, 11 patients with mild to moderate speech deficits underwent language mapping as part of their treatment for intractable epilepsy. These ‘aphasics’ were compared to 14 matched ‘controls’ with normal speech also undergoing epilepsy surgery. Neuroanatomical data were compared to quantitative language profiles and clinical variables.

Results

Cortical lesions were evident near speech areas in all aphasia cases. As expected, aphasics and controls were distinguished by quantitative language profiles. The groups were further distinguished by the anatomical distribution of their speech sites. A significantly higher proportion of frontal speech sites was found in patients with prior brain injury, consistent with frontal site recruitment. The degree of frontal recruitment varied as a function of patient age at the time of initial brain injury—earlier injuries were associated with greater recruitment. The overall number of speech sites remained the same following injury. Significant associations were found between the number of the speech sites, naming fluency and the lesion proximity in the temporal lobe.

Conclusions

Language maps in aphasics demonstrated evidence for age-dependent functional recruitment in the frontal, but not temporal, lobe. The proximity of cortical lesions to temporal speech sites predicted the overall extent of temporal lobe speech representation and performance on naming fluency. These findings have implications for neurosurgical planning in patients with preoperative speech deficits.

Patients with frontal lobe dysfunction (e.g., Huntington’s Disease) reportedly benefit more from cueing on measures of semantic fluency than do patients with damage to temporal lobe structures (e.g., Alzheimer’s disease). This differential benefit from cueing suggests that different neurocognitive functions are impaired in these two groups. Patients with frontal lobe dysfunction are presumed to have difficulty with the executive aspects of this generative fluency task while patients with temporal lobe impairment are limited by deficits in semantic memory. We studied the performance of patients with complex partial seizures of frontal or temporal lobe onset as determined by video-EEG monitoring on standard and cued measures of semantic fluency administered in a counterbalanced sequence across groups. These groups did not differ significantly in terms of age, education, gender, age of seizure onset, total number of antiepileptic drugs, or IQ, and all patients subsequently underwent surgery for intractable epilepsy. FL patients performed significantly worse than TL patients on the standard semantic fluency paradigm (TL M = 18.4, SD = 4.7; FL M = 11.1, SD = 5.3), t (27) = −3.75, p < .001. Nevertheless, results of an ANCOVA demonstrated that the FL patients showed significantly greater performance improvement than the TL patients when provided with a cued semantic fluency format even after controlling for baseline differences in ability on the standard semantic fluency task (TL M = 0.45, SD = 3.8; FL M = 9.4, SD = 5.1), F (1, 29) = 12.37, p = .002. These findings support previous research suggesting that frontal and temporal structures contribute uniquely to semantic generative fluency and suggest that using a combination of standard and cued semantic fluency tasks may help confirm localization of seizure onset in partial epilepsy by localizing the associated cognitive dysfunction