Recruitment of the premotor cortex during arithmetic operations by the monkey.

Arithmetic operations are complex mental processes rooted in the abstract concept of numerosity. Despite the significance, the neural architecture responsible for these operations has remained largely uncharted. In this study, we explored the presence of specific neuronal activity in the dorsal premotor cortex of the monkey dedicated to numerical addition and subtraction. Our findings reveal that many of these neural activities undergo a transformation, shifting their coding from arithmetic to motor representations. These motor representations include information about which hand to use and the number of steps involved in the action. We consistently observed that cells related to the right-hand encoded addition, while those linked to the left-hand encoded subtraction, suggesting that arithmetic operations and motor commands are intertwining with each other. Furthermore, we used a multivariate decoding technique to predict the monkey's behaviour based on the activity of these arithmetic-related cells. The classifier trained to discern arithmetic operations, including addition and subtraction, not only predicted the arithmetic decisions but also the subsequent motor actions of the right and left-hand. These findings imply a cognitive extension of the motor cortex's function, where inherent neural systems are repurposed to facilitate arithmetic operations.

Extensive extracranial growth of spheno-orbital meningioma: illustrative case.

BACKGROUND: Spheno-orbital meningioma (SOM) typically presents with a classic triad of symptoms (i.e., proptosis, visual impairment, and ocular paresis), resulting from intraorbital tumor invasion. The authors present a very rare case of SOM in which the chief complaint was swelling of the left temporal region, which, to the best of their knowledge, has not been reported previously. OBSERVATIONS: The patient presented with marked extracranial extension to the left temporal region but unremarkable intraorbital extension, even on radiological examination. Physical examination of the patient showed almost no exophthalmos or restriction of left eye movement, consistent with the radiological findings. Four separate meningioma specimens were removed by extraction (i.e., one each from the intracranial, extracranial, and intraorbital segments of the tumor and one from the skull). The World Health Organization grade was 1 and the MIB-1 index was less than 1%, indicating a diagnosis of a benign tumor. LESSONS: SOM may be present even in patients with only temporal swelling and few ocular-related symptoms, and detailed imaging evaluations may be required to identify the tumor.

Microvascular Decompression for Glossopharyngeal Neuralgia in the Semi-Sitting Position: A Report of Two Cases.

The semi-sitting position is well known to neurosurgeons. However, there are few reports of microvascular decompression surgery for glossopharyngeal neuralgia performed using the semi-sitting position. The semi-sitting position is not widely adopted in Japan, but it is considered to be a very useful neurosurgical position. Microvascular decompression surgery for glossopharyngeal neuralgia is a relatively rare procedure, and the semi-sitting position is very effective, considering the possibility of intraoperative cardiac arrest and postoperative complications of lower cranial nerve palsy. This report describes two cases of glossopharyngeal neuralgia operated in the semi-sitting position. Microvascular decompression was performed on both patients, and postoperative pain controls were good and no complications were observed. We show that the use of the semi-sitting position to perform microvascular decompression for glossopharyngeal neuralgia provides an excellent surgical view of the brainstem.

Limitations of median nerve somatosensory evoked potential monitoring during carotid endarterectomy.

OBJECTIVE: Hypoperfusion during carotid artery cross-clamping (CC) for carotid endarterectomy (CEA) may result in the major complication of perioperative stroke. Median nerve somatosensory evoked potential (MNSSEP) monitoring, which is an established method for the prediction of cerebral ischemia, has low sensitivity in detecting such hypoperfusion. In this study the authors sought to explore the limitations of MNSSEP monitoring compared to tibial nerve somatosensory evoked potential (TNSSEP) monitoring for the detection of CC-related hypoperfusion. METHODS: The authors retrospectively analyzed data from patients who underwent unilateral CEA with routine shunt use. All patients underwent preoperative magnetic resonance angiography and were monitored for intraoperative cerebral ischemia by using MNSSEP, TNSSEP, and carotid stump pressure during CC. First, the frequency of MNSSEP and TNSSEP changes during CC were analyzed. Subsequently, variables related to stump pressure were determined by using linear analysis and those related to each of the somatosensory evoked potential (SSEP) changes were determined by using logistic regression analysis. RESULTS: A total of 94 patients (mean age 74 years) were included in the study. TNSSEP identified a greater number of SSEP changes during CC than MNSSEP (20.2% vs 11.7%; p < 0.05). Linear regression analysis demonstrated that hypoplasia of the contralateral proximal segment of the anterior cerebral artery (A1 hypoplasia) (p < 0.01) and hypoplasia of the ipsilateral precommunicating segment of the posterior cerebral artery (P1 hypoplasia) (p = 0.02) independently and negatively correlated with stump pressure. Both contralateral A1 hypoplasia (OR 26.25, 95% CI 4.52-152.51) and ipsilateral P1 hypoplasia (OR 8.75, 95% CI 1.83-41.94) were independently related to the TNSSEP changes. However, only ipsilateral P1 hypoplasia (OR 8.76, 95% CI 1.61-47.67) was independently related to MNSSEP changes. CONCLUSIONS: TNSSEP monitoring appears to be superior to MNSSEP in detecting CC-related hypoperfusion. Correlation with stump pressure and SSEP changes indicates that TNSSEP, and not MNSSEP monitoring, is a reliable indicator of cerebral ischemia in the territory of the anterior cerebral artery.

Representation of the Numerosity 'zero' in the Parietal Cortex of the Monkey.

Zero is a fundamental concept in mathematics and modern science. Empty sets are considered a precursor of the concept of numerosity zero and a part of numerical continuum. How is numerosity zero (the absence of visual items) represented in the primate cortex? To address this question, we trained monkeys to perform numerical operations including numerosity zero. Here we show a group of neurons in the posterior parietal cortex of the monkey activated in response to numerosity 'zero'. 'Zero' neurons are classified into exclusive and continuous types; the exclusive type discretely encodes numerical absence and the continuous type encodes numerical absence as a part of a numerical continuum. "Numerosity-zero" neurons enhance behavioral discrimination of not only zero numerosity but also non-zero numerosities. Representation of numerosity zero in the parietal cortex may be a precursor of non-verbal concept of zero in primates.

Goal-oriented, flexible use of numerical operations by monkeys.

Previous studies have shown that elementary aspects of numerical abilities have developed in non-human primates. In the present study, we explored the potential for the development of a novel ability in the use of numerical operations by macaque monkeys (Macaca fuscata): adequate selection of a series of numerical actions toward achieving a behavioral goal. We trained monkeys to use a pair of devices to selectively add or subtract items to/from a digital array in order to match a previously viewed sample array. The monkeys determined whether to add or subtract on the basis of the feedback about numerosity given to the monkeys, which was displayed as an outcome of each step of the numerical operation. We also found that monkeys adapted flexibly to changes in the numerical rule that determined the relationship between device use and numerical operation. Our model analysis found that the numerosity-based model was a better fit for the monkeys' performance than was the reward-expectation-based model. Such a capacity for goal-oriented selection of numerical operations suggests a mechanism by which monkeys use numerical representations for purposeful behaviors.

[A case of cranial fasciitis induced by trauma].

We present a 20-month-old boy with a rapid growing occipital mass after head trauma, that was pathologically diagnosed as cranial fasciitis. Cranial fasciitis, first described as a specific entity by Lauer and Enzinger in 1980, is a benign fibroblastic lesion occurring in children that resembles nodular fasciitis pathologically. Nodular fasciitis also shows benign proliferation of fibroblasts and myofibroblasts in the subcutaneous tissues. This disease was firstly reported in 1955. This lesion is arising in the upper and lower extremities and trunk in adult commonly. The rapid growth, abundant cellularity, and mitotic activity cause these lesions to be misdiagnosed as sarcomas frequently. However, these lesions recur rarely, do not develop metastases, and are readily cured only by surgical excision. Cranial fasciitis is similar to nodular fasciitis in clinical cause and pathology. Therefore cranial fasciitis should be considered a variant of nodular fasciitis, although it differs from noduler fasciitis in its frequent site and age. Cranial fasciitis occurs in skull bone and in childhood. The cause of them are still unknown. However, we speculate on the relationship between head trauma and cranial fasciitis making reference to the fact that 5-15% of nodular fasciitis were caused by trauma. So we investigated this relationship in cranial fasciitis, then 8 cases of 40 cases(20%), that we could trace in the world literatures, had histories of previous head trauma. From this result, head trauma is one of a cause of cranial fasciitis probably.