Embodied higher cognition: insights from Merleau-Ponty’s interpretation of motor intentionality

This paper clarifies Merleau-Ponty’s original account of “higher-order” cognition as fundamentally embodied and enacted. Merleau-Ponty’s philosophy inspired theories that deemphasize overlaps between conceptual knowledge and motor intentionality or, on the contrary, focus exclusively on abstract thought. In contrast, this paper explores the link between Merleau-Ponty’s account of motor intentionality and his interpretations of our capacity to understand and interact productively with cultural symbolic systems. I develop my interpretation based on Merleau-Ponty’s analysis of two neuropathological modifications of motor intentionality, the case of the brain-injured war veteran Schneider, and a neurological disorder known as Gerstmann’s syndrome. Building on my analysis of Schneider’s sensorimotor compensatory performances in relation to his limitations in the domains of algebra, geometry, and language usage, I demonstrate a strong continuity between the sense of embodiment and enaction at all these levels. Based on Merleau-Ponty’s interpretations, I argue that “higher-order” cognition is impaired in Schneider insofar as his injury limits his sensorimotor capacity to dynamically produce comparatively more complex differentiations of any given phenomenal structure. I then show how Merleau-Ponty develops and specifies his interpretation of Schneider’s intellectual difficulties in relation to the ambiguous role of the body, and in particular the hand, in Gerstmann’s syndrome. I explain how Merleau-Ponty defends the idea that sensorimotor and quasi-representational cognition are mutually irreducible, while maintaining that symbol-based cognition is a fundamentally enactive and embodied process.

A-62 Case of Gerstmann’s Syndrome Due to Brain Tumor of Unknown Etiology

Objective Gerstmann’s syndrome is a rare neurological condition that is characterized by agraphia, acalculia, finger agnosia, and right–left confusion. Gerstmann’s syndrome most commonly occurs due to stroke in parietal region of the brain. This case demonstrates the clinical presentation of Gerstmann’s syndrome in a patient due to a brain tumor in the parietal lobe. Method The patient is a 50-year-old, right-handed, Hispanic male with 16 years of education who reported memory changes over the last 10 months. His medical history is notable for two brain tumors of unknown etiology which have been present for 10 months. He has completed multiple biopsies and magnetic resonance imaging prior to his neuropsychological evaluation. Initial scans showed two tumors, one in the right medial occipital parietal lobe and one in the left parietal extending into the corpus callosum. The right medial occipital parietal lobe tumor has not been visualized for the past six months. Results His neurocognitive profile was characterized by impairments in verbal memory (both stories and word list), arithmetic, semantic fluency, and executive functioning. Across memory measures, he performed in the borderline to impaired range, and did not benefit from recognition items. Arithmetic performance was also in the borderline range and did not show improvement with additional time. Conclusions This case demonstrates the classical findings of Gerstmann’s syndrome with additional neurocognitive impairments in the areas of memory and executive functioning. This case is also unique in that the lesions of the parietal lobe are due to brain tumor with unknown etiology.

Parietal association deficits in patients harboring parietal lobe gliomas: a prospective study

OBJECTIVEAlthough the parietal lobe is a common site for glioma formation, current literature is scarce, consists of retrospective studies, and lacks consistency with regard to the incidence, nature, and severity of parietal association deficits (PADs). The aim of this study was to assess the characteristics and incidence of PADs in patients suffering from parietal lobe gliomas through a prospective study and a battery of comprehensive neuropsychological tests.METHODSBetween 2012 and 2016 the authors recruited 38 patients with glioma confined in the parietal lobe. Patients were examined for primary and secondary association deficits with a dedicated battery of neuropsychological tests. The PADs were grouped into 5 categories: visuospatial attention, gnosis, praxis, upper-limb coordination, and language. For descriptive analysis tumors were divided into high- and low-grade gliomas and also according to patient age and tumor size.RESULTSParietal association deficits were elicited in 80% of patients, thus being more common than primary deficits (50%). Apraxia was the most common PAD (47.4%), followed by anomic aphasia and subcomponents of Gerstmann’s syndrome (34.2% each). Other deficits such as hemineglect, stereoagnosia, extinction, and visuomotor ataxia were also detected, albeit at lower rates. There was a statistically nonsignificant difference between PADs and sex (72.2% males, 85% females) and age (77.8% at ≤ 60 years, 80% at age > 60 years), but a statistically significant difference between the > 4 cm and the ≤ 4 cm diameter group (p = 0.02, 94.7% vs 63.2%, respectively). There was a tendency (p = 0.094) for low-grade gliomas to present with fewer PADs (50%) than high-grade gliomas (85.7%). Tumor laterality showed a strong correlation with hemineglect (p = 0.004, predilection for right hemisphere), anomia (p = 0.001), and Gerstmann’s symptoms (p = 0.01); the last 2 deficits showed a left (dominant) hemispheric preponderance.CONCLUSIONSThis is the first study to prospectively evaluate the incidence and nature of PADs in patients with parietal gliomas. It could be that the current literature may have underestimated the true incidence of deficits. Dedicated neuropsychological examination detects a high frequency of PADs, the most common being apraxia, followed by anomia and subcomponents of Gerstmann’s syndrome. Nevertheless, a direct correlation between the clinical deficit and its anatomical substrate is only possible to a limited extent, highlighting the need for intraoperative cortical and subcortical functional mapping.

Gerstmann's syndrome and unilateral optic ataxia in the emergency department

ABSTRACT. A 75-year-old right-handed woman presented to the emergency department with simultanagnosia and right unilateral optic ataxia. Moreover, the patient had agraphia, acalculia, digital agnosia and right-left disorientation, consistent with complete Gerstmann's syndrome. This case highlights the concurrence of Gerstmann's syndrome and unilateral optic ataxia in the acute phase of a left middle cerebral artery stroke.