The brain and the subjective experience of time. A voxel based symptom-lesion mapping study

Temporal judgments of actions following unilateral brain damage

Sense of time is a complex construct, and its neural correlates remain to date in most part unknown. To complicate the frame, physical attributes of the stimulus, such as its intensity or movement, influence temporal perception. Although previous studies have shown that time perception can be compromised after a brain lesion, the evidence on the role of the left and right hemispheres are meager. In two experiments, the study explores the ability of temporal estimation of multi-second actions and non-biological movements in 33 patients suffering from unilateral brain lesion. Furthermore, the modulatory role of induced embodiment processes is investigated. The results reveal a joint contribution of the two hemispheres depending not only on different durations but also on the presence of actions. Indeed, the left hemisphere damaged patients find it difficult to estimate 4500 ms or longer durations, while the right hemisphere damaged patients fail in 3000 ms durations. Furthermore, the former fail when a biological action is shown, while the latter fail in non-biological movement. Embodiment processes have a modulatory effect only after right hemisphere lesions. Among neuropsychological variables, only spatial neglect influences estimation of non-biological movement.

Time perception changes in stroke patients: A systematic literature review

Introduction

Time perception comprises the subjective experience of passing of time and of the duration of an event. Although already described in some neurological and psychiatric conditions, there is a paucity of details regarding this neurocognitive change in stroke patients. We aimed to describe time perception dysfunction in stroke patient.

Methods

We performed a systematic review of the literature in Pubmed, PsycInfo and EMBASE including manuscripts from their inception until December 2020. We collected data regarding the type of time perception that was detected, type of stroke, most common location of lesions, evaluation tests that were used and time of evaluation after stroke onset.

Results

A total of 27 manuscripts were selected, concerning a total of 418 patients (n = 253 male; 60.5%). Most manuscripts (n = 21) evaluated patients with ischaemic lesions (n = 407; 97.4%). The majority referred to evaluations between 2 months and seven years after stroke. Underestimation in temporal evaluation in sub- and supra-second was the most common dysfunction (n = 165; 41.7%). Overestimation of time (n = 116; 27.8%) and impaired time interval comparison (n = 88; 22.2%) were also found. Most patients had right hemisphere lesions (n = 219 patients; 52.4%). Common reported lesion locations included the thalamus, insula, basal ganglia, dorsolateral prefrontal cortex, parietal cortex including supramarginal, angular gyrus and right inferior parietal cortex and cerebellum.

Conclusion

There are multiple stroke locations associated with time perception dysfunction, which highlights the complex system involved in time perception. There is still scarce knowledge about specific time perception deficits after stroke. Most studies rely in psychometric analysis without clear clinical and functional translation, namely regarding impact on daily activities.

Uncoupling Sensation and Perception in Human Time Processing

Timing emerges from a hierarchy of computations ranging from early encoding of physical duration (time sensation) to abstract time representations (time perception) suitable for storage and decisional processes. However, the neural basis of the perceptual experience of time remains elusive. To address this, we dissociate brain activity uniquely related to lower-level sensory and higher-order perceptual timing operations, using event-related fMRI. Participants compared subsecond (500 msec) sinusoidal gratings drifting with constant velocity (standard) against two probe stimuli: (1) control gratings drifting at constant velocity or (2) accelerating gratings, which induced illusory shortening of time. We tested two probe intervals: a 500-msec duration (Short) and a longer duration required for an accelerating probe to be perceived as long as the standard (Long—individually determined). On each trial, participants classified the probe as shorter or longer than the standard. This allowed for comparison of trials with an “Objective” (physical) or “Subjective” (perceived) difference in duration, based on participant classifications. Objective duration revealed responses in bilateral early extrastriate areas, extending to higher visual areas in the fusiform gyrus (at more lenient thresholds). By contrast, Subjective duration was reflected by distributed responses in a cortical/subcortical areas. This comprised the left superior frontal gyrus and the left cerebellum, and a wider set of common timing areas including the BG, parietal cortex, and posterior cingulate cortex. These results suggest two functionally independent timing stages: early extraction of duration information in sensory cortices and Subjective experience of duration in a higher-order cortical–subcortical timing areas.

Impaired decision-making and time perception in individuals with stroke: Behavioral and neural correlates

Several studies have demonstrated that stroke subjects present impairment of functions related to decision-making and timing, involving the information processing in the neural circuits of the cerebellum in association with the prefrontal cortex. This review is aimed to identify the gaps, and demonstrate a better understanding of decision-making and timing functions in the patients with stroke. Electronic literature database was searched and the findings of relevant studies were used to explore the mechanisms of decision-making and timing in patients with stroke, as well as the circuit connections in timing mediated by prefrontal cortex and cerebellum. A literature review was conducted with 65 studies that synthesized findings on decision-making and time perception in individuals with stroke. Types of neurobiological modalities in this study included: Relationships among decision-making, time perception, related cognitive aspects (such as discrimination tasks, verbal estimation, bisection tasks, time production and motor reproduction), and motor control. We demonstrate that the timing processes are important for the performance in cognitive tasks and that the cerebellum and prefrontal cortex are involved in decision-making and time perception. In the context, the decision-making is impaired in stroke patients has a great impact on executive functions, and this seems to be important in determining neurobiological aspects relevant to the time interval interpretation.

Does the insula contribute to emotion-related distortion of time? A neuropsychological approach

The literature points to a large distributed brain network involved in the estimation of time. Among these regions, the role of the insular cortex is still poorly understood. At the confluence of emotional, interoceptive, and environmental signals, this brain structure has been proposed to underlie awareness of the passage of time and emotion related time dilation. Yet, this assumption has not been tested so far. This study aimed at exploring how a lesion of the insula affects subjective duration, either in an emotional context or in a non-emotional context. Twenty-one patients with a stroke affecting the insula, either left or right, were studied for their perception of sub and supra second durations. A verbal estimation task and a temporal bisection task were used with either pure tones or neutral and emotional sounds lasting between 300 and 1500 ms and presented monaurally. Results revealed that patients with a right insular lesion, showed less temporal sensitivity than both control participants and patients with a left insular lesion. Unexpectedly, emotional effects were similar in patients and control participants. Altogether, these results suggest a specific role of the right insula in the discrimination of durations, but not in emotion related temporal distortion. In addition, an ear × emotion interaction in control participants suggests that temporal processing of positive and negative sounds may be lateralized in the brain.

Neural substrates of internally-based and externally-cued timing: An activation likelihood estimation (ALE) meta-analysis of fMRI studies

A dynamic interplay exists between Internally-Based (IBT) and Externally-Cued (ECT) time processing. While IBT processes support the self-generation of context-independent temporal representations, ECT mechanisms allow constructing temporal representations primarily derived from the structure of the sensory environment. We performed an activation likelihood estimation (ALE) meta-analysis on 177 fMRI experiments, from 79 articles, to identify brain areas involved in timing; two individual ALEs tested the hypothesis of a neural segregation between IBT and ECT. The general ALE highlighted a network involving supplementary motor area (SMA), intraparietal sulcus, inferior frontal gyrus (IFG), insula (INS) and basal ganglia. We found evidence of a partial dissociation between IBT and ECT. IBT relies on a subset of areas also involved in ECT, however ECT tasks activate SMA, right IFG, left precentral gyrus and INS in a significantly stronger way. Present results suggest that ECT involves the detection of environmental temporal regularities and their integration with the output of the IBT processing, to generate a representation of time which reflects the temporal metric of the environment.