Comparison of neuronal firing rates in somatosensory and posterior parietal cortex during prehension

Neurons in posterior parietal cortex (PPC) may serve both proprioceptive and exteroceptive functions during prehension, signaling hand actions and object properties. To assess these roles, we used digital video recordings to analyze responses of 83 hand-manipulation neurons in area 5 as monkeys grasped and lifted objects that differed in shape (round and rectangular), size (large and small spheres), and location (identical rectangular blocks placed lateral and medial to the shoulder). The task contained seven stages—approach, contact, grasp, lift, hold, lower, relax—plus a pretrial interval. The four test objects evoked similar spike trains and mean rate profiles that rose significantly above baseline from approach through lift, with peak activity at contact. Although representation by the spike train of specific hand actions was stronger than distinctions between grasped objects, 34% of these neurons showed statistically significant effects of object properties or hand postures on firing rates. Somatosensory input from the hand played an important role as firing rates diverged most prominently on contact as grasp was secured. The small sphere—grasped with the most flexed hand posture—evoked the highest firing rates in 43% of the population. Twenty-one percent distinguished spheres that differed in size and weight, and 14% discriminated spheres from rectangular blocks. Location in the workspace modulated response amplitude as objects placed across the midline evoked higher firing rates than positions lateral to the shoulder. We conclude that area 5 neurons, like those in area AIP, integrate object features, hand actions, and grasp postures during prehension.

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Neurophysiology of Prehension. I. Posterior Parietal Cortex and Object-Oriented Hand Behaviors

Journal of Neurophysiology ◽

10.1152/jn.00558.2006 ◽

2007 ◽

Vol 97 (1) ◽

pp. 387-406 ◽

Cited By ~ 78

Author(s):

Esther P. Gardner ◽

K. Srinivasa Babu ◽

Shari D. Reitzen ◽

Soumya Ghosh ◽

Alice S. Brown ◽

...

Keyword(s):

Parietal Cortex ◽

Posterior Parietal Cortex ◽

Related Area ◽

Firing Rates ◽

Sensorimotor Transformations ◽

Area 5 ◽

On Line ◽

Posterior Parietal ◽

Neuronal Spike Trains ◽

Task Goals

Hand manipulation neurons in areas 5 and 7b/anterior intraparietal area (AIP) of posterior parietal cortex were analyzed in three macaque monkeys during a trained prehension task. Digital video recordings of hand kinematics synchronized to neuronal spike trains were used to correlate firing rates of 128 neurons with hand actions as the animals grasped and lifted rectangular and round objects. We distinguished seven task stages: approach, contact, grasp, lift, hold, lower, and relax. Posterior parietal cortex (PPC) firing rates were highest during object acquisition; 88% of task-related area 5 neurons and 77% in AIP/7b fired maximally during stages 1, 2, or 3. Firing rates rose 200–500 ms before contact, peaked at contact, and declined after grasp was secured. 83% of area 5 neurons and 72% in AIP/7b showed significant increases in mean rates during approach as the fingers were preshaped for grasp. Somatosensory signals at contact provided feedback concerning the accuracy of reach and helped guide the hand to grasp sites. In error trials, tactile information was used to abort grasp, or to initiate corrective actions to achieve task goals. Firing rates declined as lift began. 41% of area 5 neurons and 38% in AIP/7b were inhibited during holding, and returned to baseline when grasp was relaxed. Anatomical connections suggest that area 5 provides somesthetic information to circuits linking AIP/7b to frontal motor areas involved in grasping. Area 5 may also participate in sensorimotor transformations coordinating reach and grasp behaviors and provide on-line feedback needed for goal-directed hand movements.

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Dopamine influences attentional rate modulation in Macaque posterior parietal cortex

10.1101/2020.05.15.097675 ◽

2020 ◽

Author(s):

Jochem van Kempen ◽

Christian Brandt ◽

Claudia Distler ◽

Mark A. Bellgrove ◽

Alexander Thiele

Keyword(s):

Spatial Attention ◽

Parietal Cortex ◽

Posterior Parietal Cortex ◽

Rhesus Macaques ◽

D1 Receptor ◽

Attention Task ◽

Attentional Processing ◽

Firing Rates ◽

Pupil Light Reflex ◽

Posterior Parietal

AbstractSelective attention facilitates the prioritization of task-relevant sensory inputs over those which are irrelevant. Although cognitive neuroscience has made great strides in understanding the neural substrates of attention, our understanding of its neuropharmacology is incomplete. Cholinergic and glutamatergic contributions have been demonstrated, but emerging evidence also suggests an important influence of dopamine (DA). DA has historically been investigated in the context of frontal/prefrontal function arguing that dopaminergic receptor density in the posterior/parietal cortex is sparse. However, this notion was derived from rodent data, whereas in primates DA innervation in parietal cortex matches that of many prefrontal areas. We recorded single- and multi-unit activity whilst iontophoretically administering dopaminergic agonists and antagonists to posterior parietal cortex of rhesus macaques engaged in a spatial attention task. Out of 88 neurons, 50 showed modulation of activity induced by drug administration. Dopamine inhibited firing rates across the population according to an inverted-U shaped dose-response curve. D1 receptor antagonists diminished firing rates in broad-spiking units according to a monotonically increasing function. Additionally, dopamine modulated attentional signals in broad, but not narrow-spiking cells. Finally, both drugs modulated the pupil light reflex. These data show that dopamine plays an important role in shaping neuronal responses and modulates attentional processing in macaque parietal cortex.Significance statementDopamine is critically involved in high-level cognitive functions, and dopaminergic dysfunctions pertain to ageing and neurological and psychiatric disorders. Most previous studies focused on dopaminergic effects on prefrontal activity or its role in basal ganglia circuitry. The effects of dopamine in other brain areas such as parietal cortex, despite its well-established role in cognition and cognitive dysfunction, have largely been overlooked. This study is the first to show dopaminergic modulation of parietal activity in general, and specific to spatial attention in the non-human primate, revealing cell-type specific effects of dopamine on attentional modulation.

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Neural Representation of Hand Kinematics During Prehension in Posterior Parietal Cortex of the Macaque Monkey

Journal of Neurophysiology ◽

10.1152/jn.90942.2008 ◽

2009 ◽

Vol 102 (6) ◽

pp. 3310-3328 ◽

Cited By ~ 25

Author(s):

Jessie Chen ◽

Shari D. Reitzen ◽

Jane B. Kohlenstein ◽

Esther P. Gardner

Keyword(s):

Parietal Cortex ◽

Muscle Activation ◽

Posterior Parietal Cortex ◽

Macaque Monkey ◽

Neural Representation ◽

Firing Rates ◽

Hand Kinematics ◽

Object Properties ◽

Area 5 ◽

Posterior Parietal

Studies of hand manipulation neurons in posterior parietal cortex of monkeys suggest that their spike trains represent objects by the hand postures needed for grasping or by the underlying patterns of muscle activation. To analyze the role of hand kinematics and object properties in a trained prehension task, we correlated the firing rates of neurons in anterior area 5 with hand behaviors as monkeys grasped and lifted knobs of different shapes and locations in the workspace. Trials were divided into four classes depending on the approach trajectory: forward, lateral, and local approaches, and regrasps. The task factors controlled by the animal—how and when he used the hand—appeared to play the principal roles in modulating firing rates of area 5 neurons. In all, 77% of neurons studied (58/75) showed significant effects of approach style on firing rates; 80% of the population responded at higher rates and for longer durations on forward or lateral approaches that included reaching, wrist rotation, and hand preshaping prior to contact, but only 13% distinguished the direction of reach. The higher firing rates in reach trials reflected not only the arm movements needed to direct the hand to the target before contact, but persisted through the contact, grasp, and lift stages. Moreover, the approach style exerted a stronger effect on firing rates than object features, such as shape and location, which were distinguished by half of the population. Forty-three percent of the neurons signaled both the object properties and the hand actions used to acquire them. However, the spread in firing rates evoked by each knob on reach and no-reach trials was greater than distinctions between different objects grasped with the same approach style. Our data provide clear evidence for synergies between reaching and grasping that may facilitate smooth, coordinated actions of the arm and hand.

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Posterior parietal cortex mediates encoding processes in change blindness

PsycEXTRA Dataset ◽

10.1037/e520562012-977 ◽

2009 ◽

Author(s):

Philip Tseng ◽

Cassidy Sterling ◽

Adam Cooper ◽

Bruce Bridgeman ◽

Neil G. Muggleton ◽

...

Keyword(s):

Parietal Cortex ◽

Posterior Parietal Cortex ◽

Change Blindness ◽

Posterior Parietal

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The Grasp Cell Hypothesis: Near-miss effect points to common neurological machinery in posterior parietal cortex for controllable objects and concepts

10.31234/osf.io/4awrz ◽

2018 ◽

Author(s):

Imogen M Kruse

Keyword(s):

Parietal Cortex ◽

Posterior Parietal Cortex ◽

Near Miss ◽

Illusion Of Control ◽

Gambling Behaviour ◽

Drug Seeking ◽

Spatial Influence ◽

Reward Probability ◽

Posterior Parietal ◽

Action Value

The near-miss effect in gambling behaviour occurs when an outcome which is close to a win outcome invigorates gambling behaviour notwithstanding lack of associated reward. In this paper I postulate that the processing of concepts which are deemed controllable is rooted in neurological machinery located in the posterior parietal cortex specialised for the processing of objects which are immediately actionable or controllable because they are within reach. I theorise that the use of a common machinery facilitates spatial influence on the perception of concepts such that the win outcome which is 'almost complete' is perceived as being 'almost within reach'. The perceived realisability of the win increases subjective reward probability and the associated expected action value which impacts decision-making and behaviour. This novel hypothesis is the first to offer a neurological model which can comprehensively explain many empirical findings associated with the near-miss effect as well as other gambling phenomena such as the ‘illusion of control’. Furthermore, when extended to other compulsive behaviours such as drug addiction, the model can offer an explanation for continued drug-seeking following devaluation and for the increase in cravings in response to perceived opportunity to self-administer, neither of which can be explained by simple reinforcement models alone. This paper therefore provides an innovative and unifying perspective for the study and treatment of behavioural and substance addictions.

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