Lawrence M. Parsons

Cerebellum implicated in sensory acquisition and discrimination rather than motor control.

Recent evidence that the cerebellum is involved in perception and cognition challenges the prevailing view that its primary function is fine motor control. A new alternative hypothesis is that the lateral cerebellum is not activated by the control of movement per se, but is strongly engaged during the acquisition and discrimination of sensory information. Magnetic resonance imaging of the lateral cerebellar output (dentate) nucleus during passive and active sensory tasks confirmed this hypothesis. These findings suggest that the lateral cerebellum may be active during motor, perceptual, and cognitive performances specifically because of the requirement to process sensory data.

Interregional connectivity to primary motor cortex revealed using MRI resting state images

The topographic organization of cortical neurons is traditionally examined using histological procedures. Functional magnetic resonance imaging (fMRI) offers the potential noninvasively to detect interregional connectivity of human brain. In the brain, there is spontaneous firing of neurons even in the resting state. Such spontaneous firing will increase local blood flow, cause MRI signal fluctuations, and affect remotely located neurons through the efferent output. By calculating covariance of each voxel referenced to the time course of a selected brain region, it is possible to detect the neurons connected to the selected region. Using this covariance method, neural connectivity to primary motor cortex was assessed during a resting state in six healthy right‐handed volunteers. This interregional connectivity is similar to connectivity established by other anatomical, histochemical, and physiological techniques. This method may offer in vivo noninvasive measurements of neural projections. Hum. Brain Mapping 8:151–156, 1999.

Passive music listening spontaneously engages limbic and paralimbic systems

In this PET study, non-musicians passively listened to unfamiliar instrumental music revealed afterward to elicit strongly pleasant feelings. Activations were observed in the subcallosal cingulate gyrus, prefrontal anterior cingulate, retrosplenial cortex, hippocampus, anterior insula, and nucleus accumbens. This is the first observation of spontaneous responses in such limbic and paralimbic areas during passive listening to unfamiliar although liked music. Activations were also seen in primary auditory, secondary auditory, and temporal polar areas known to respond to music. Our findings complement neuroimaging studies of aesthetic responses to music that have used stimuli selected by subjects or designed by experimenters. The observed pattern of activity is discussed in terms of a model synthesizing emotional and cognitive responses to music.

Music and language side by side in the brain: a PET study of the generation of melodies and sentences

Parallel generational tasks for music and language were compared using positron emission tomography. Amateur musicians vocally improvised melodic or linguistic phrases in response to unfamiliar, auditorily presented melodies or phrases. Core areas for generating melodic phrases appeared to be in left Brodmann area (BA) 45, right BA 44, bilateral temporal planum polare, lateral BA 6, and pre‐SMA. Core areas for generating sentences seemed to be in bilateral posterior superior and middle temporal cortex (BA 22, 21), left BA 39, bilateral superior frontal (BA 8, 9), left inferior frontal (BA 44, 45), anterior cingulate, and pre‐SMA. Direct comparisons of the two tasks revealed activations in nearly identical functional brain areas, including the primary motor cortex, supplementary motor area, Brocas area, anterior insula, primary and secondary auditory cortices, temporal pole, basal ganglia, ventral thalamus, and posterior cerebellum. Most of the differences between melodic and sentential generation were seen in lateralization tendencies, with the language task favouring the left hemisphere. However, many of the activations for each modality were bilateral, and so there was significant overlap. While clarification of this overlapping activity awaits higher‐resolution measurements and interventional assessments, plausible accounts for it include component sharing, interleaved representations, and adaptive coding. With these and related findings, we outline a comparative model of shared, parallel, and distinctive features of the neural systems supporting music and language. The model assumes that music and language show parallel combinatoric generativity for complex sound structures (phonology) but distinctly different informational content (semantics).

Integrating cognitive psychology, neurology and neuroimaging

In the last decade, there has been a dramatic increase in research effectively integrating cognitive psychology, functional neuroimaging, and behavioral neurology. This new work is typically conducting basic research into aspects of the human mind and brain. The present review features as examples of such integrations two series of studies by the author and his colleagues. One series, employing object recognition, mental motor imagery, and mental rotation paradigms, clarifies the nature of a cognitive process, imagined spatial transformations used in shape recognition. Among other implications, it suggests that when recognizing a hands handedness, imagining ones body movement depends on cerebrally lateralized sensory-motor structures and deciding upon handedness depends on exact match shape confirmation. The other series, using cutaneous, tactile, and auditory pitch discrimination paradigms, elucidates the function of a brain structure, the cerebellum. It suggests that the cerebellum has non-motor sensory support functions upon which optimally fine sensory discriminations depend. In addition, six key issues for this integrative approach are reviewed. These include arguments for the value and greater use of: rigorous quantitative meta-analyses of neuroimaging studies; stereotactic coordinate-based data, as opposed to surface landmark-based data; standardized vocabularies capturing the elementary component operations of cognitive and behavioral tasks; functional hypotheses about brain areas that are consistent with underlying microcircuitry; an awareness that not all brain areas implicated by neuroimaging or neurology are necessarily directly involved in the associated cognitive or behavioral task; and systematic approaches to integrations of this kind.

The Role of the Insular Cortex in Pitch Pattern Perception: The Effect of Linguistic Contexts

Auditory pitch patterns are significant ecological features to which nervous systems have exquisitely adapted. Pitch patterns are found embedded in many contexts, enabling different information-processing goals. Do the psychological functions of pitch patterns determine the neural mechanisms supporting their perception, or do all pitch patterns, regardless of function, engage the same mechanisms? This issue is pursued in the present study by using 150-water positron emission tomography to study brain activations when two subject groups discriminate pitch patterns in their respective native languages, one of which is a tonal language and the other of which is not. In a tonal language, pitch patterns signal lexical meaning. Native Mandarin-speaking and English-speaking listeners discriminated pitch patterns embedded in Mandarin and English words and also passively listened to the same stimuli. When Mandarin listeners discriminated pitch embedded in Mandarin lexical tones, the left anterior insular cortex was the most active. When they discriminated pitch patterns embedded in English words, the homologous area in the right hemisphere activated as it did in English-speaking listeners discriminating pitch patterns embedded in either Mandarin or English words. These results support the view that neural responses to physical acoustic stimuli depend on the function of those stimuli and implicate anterior insular cortex in auditory processing, with the left insular cortex especially responsive to linguistic stimuli.

Location-Probability Profiles for the Mouth Region of Human Primary Motor-Sensory Cortex: Model and Validation

The mouth representation of the human, primary motor cortex (M1) is not reliably identified by surface anatomy but may be reliably localized by means of spatial coordinates. For this report, three quantitative metanalyses were performed which jointly described the mean location, location variability and location-probability profiles of the human M1-mouth representation. First, a literature metanalysis of intersubject functional-area variability was performed using eleven, per-subject studies, each of which reported a coordinate-referenced measure of intersubject variability for one or more brain areas. From these data, a weighted-mean value for intersubject variability was computed, which proved to be small (5.6 mm, standard deviation), consistent across coordinate axes (x, y, z), and consistent across brain areas. Second, a literature metanalysis of the location of M1-mouth was performed using seven, coordinate-referenced, group-mean studies (71 subjects in all), each of which reported a grand-average location for M1-mouth. From this, a weighted-mean location and weighted values for total variability (interlaboratory plus interindividual) were determined. Using these two literature metanalyses as input data, location-probability profiles were computed for the cardinal axes (x, y, and z) of the reference space, using the functional volumes modeling (FVM) statistical model. Third, an original-data metanalysis was performed on in-house PET data from 30 normal subjects performing overt-speech tasks. M1-mouths mean location, location variability, and location-probability profiles were consistent with those conjointly modeled by FVM from the two literature metanalyses. Collectively, these observations provide a detailed, consensus probabilistic description of the location of the human M1-mouth representation in standardized coordinates.

Beyond the single study: Function/location metanalysis in cognitive neuroimaging

Cognitive neuroimaging maps the brain locations of mental operations. This process is iterative, as no single study can fully characterize a mental operation or its brain location. This iterative discovery process, in combination with the location-reporting standard (i.e. spatial coordinates) of the cognitive neuroimaging community, has engendered a new form of metanalysis. Response locations from multiple studies have been analyzed collectively so as to better describe the spatial distribution of brain activations, with promising results. New hypotheses regarding elementary mental operations and their respective brain locations are being generated and refined via metanalysis. These hypotheses are being tested and confirmed by subsequent, prospective experiments. Function/location metanalysis is an important new tool for hypothesis generation in cognitive neuroimaging. This form of metanalysis is fundamentally different from the effect-size metanalyses prevalent in other literatures, with unique advantages and challenges.

The brain basis of piano performance

Performances of memorized piano compositions unfold via dynamic integrations of motor, perceptual, cognitive, and emotive operations. The functional neuroanatomy of such elaborately skilled achievements was characterized in the present study by using (15)0-water positron emission tomography to image blindfolded pianists performing a concerto by J.S. Bach. The resulting brain activity was referenced to that for bimanual performance of memorized major scales. Scales and concerto performances both activated primary motor cortex, corresponding somatosensory areas, inferior parietal cortex, supplementary motor area, motor cingulate, bilateral superior and middle temporal cortex, right thalamus, anterior and posterior cerebellum. Regions specifically supporting the concerto performance included superior and middle temporal cortex, planum polare, thalamus, basal ganglia, posterior cerebellum, dorsolateral premotor cortex, right insula, right supplementary motor area, lingual gyrus, and posterior cingulate. Areas specifically implicated in generating and playing scales were posterior cingulate, middle temporal, right middle frontal, and right precuneus cortices, with lesser increases in right hemispheric superior temporal, temporoparietal, fusiform, precuneus, and prefrontal cortices, along with left inferior frontal gyrus. Finally, much greater deactivations were present for playing the concerto than scales. This seems to reflect a deeper attentional focus in which tonically active orienting and evaluative processes, among others, are suspended. This inference is supported by observed deactivations in posterior cingulate, parahippocampus, precuneus, prefrontal, middle temporal, and posterior cerebellar cortices. For each of the foregoing analyses, a distributed set of interacting localized functions is outlined for future test.

The boundaries of language and thought in deductive inference

Is human thought fully embedded in language, or do some forms of thought operate independently? To directly address this issue, we focus on inference-making, a central feature of human cognition. In a 3T fMRI study we compare logical inferences relying on sentential connectives (e.g., not, or, if … then) to linguistic inferences based on syntactic transformation of sentences involving ditransitive verbs (e.g., give, say, take). When contrasted with matched grammaticality judgments, logic inference alone recruited “core” regions of deduction [Brodmann area (BA) 10p and 8m], whereas linguistic inference alone recruited perisylvian regions of linguistic competence, among others (BA 21, 22, 37, 39, 44, and 45 and caudate). In addition, the two inferences commonly recruited a set of general “support” areas in frontoparietal cortex (BA 6, 7, 8, 40, and 47). The results indicate that logical inference is not embedded in natural language and confirm the relative modularity of linguistic processes.