Albert E. Roberts

Modulations in cerebral hemodynamics under three response requirements while solving language-based problems: A transcranial Doppler study

This experiment used transcranial Doppler ultrasound to measure blood flow velocity in the middle, anterior or posterior cerebral artery (MCA, ACA and PCA, respectively) while separate groups of college students (each n = 20) solved anagrams and constructed new words using letters of a target word, each while viewing, speaking or writing the responses. The silent viewing requirement affected global velocities only while constructing words: velocities in both the MCA and ACA were faster than in the PCA. Speaking the solutions during both types of problems yielded faster overall velocities in the MCA than in the PCA. Finally, writing the solutions while constructing words led to faster velocities in the MCA compared to both the ACA and PCA. Time-course patterns to velocity changes from the thinking periods showed elevations in MCA velocity at the beginning and end of the periods, while PCA velocity typically slowed below baseline in the middle of the periods. These data show that the kind of language-based problem-solving task and the specific response requirement arranged to accomplish a task selectively affected velocity in three cerebral arteries.

Spatial Perception and Mental Rotation Produce Gender Differences in Cerebral Hemovelocity

Abstract We sought to determine if gender differences in cerebral blood flow velocity emerge while persons performed cognitive tasks known to favor men, e.g., tests of spatial abilities. Bilateral measures were obtained simultaneously from the middle cerebral artery (VMCA) by transcranial Doppler sonography while men and women college students performed 31-s thinking tasks. Tests of spatial ability included (1) three spatial visualizing tasks (finding words among sets of letters, locating pictures hidden within a complex scene, and finding embedded geometric patterns), and (2) a mental rotation task. Two nonspatial visualizing control tasks were looking at (1) a list of words and (2) a set of pictures. Women had significantly faster global VMCAs than men during all tasks except looking at pictures. Two tasks (looking at pictures, mental rotation) produced hemispheric asymmetry (right > left) in women only. Gender differences in the number of correct responses occurred for finding words (women > men) and m...

Making a “Successful” Course: Faculty and Student Perspectives

Faculty and students agree on the value of communication skills, but they differ on the value of intellectual and practical outcomes.

Caffeine can affect velocity in the middle cerebral artery during hyperventilation, hypoventilation, and thinking: a transcranial Doppler study.

This study examined possible caffeine‐mediated changes in blood flow velocity in the middle cerebral artery (VMCA) induced by tests of cerebrovascular responsiveness. Transcranial Doppler (TCD) sonography provided simultaneous bilateral VMCA measures while healthy college students hypoventilated, hyperventilated, and performed cognitive activities (short‐term remembering, generating an autobiographical image, solving problems), each in 31‐second tests. VMCA measures were obtained from the same persons, in separate testing sessions, when they were noncaffeinated and under two levels of caffeine: a smaller amount (from a cola, 45 mg/12 oz) and a larger amount (from coffee, 117 mg/8 oz). Compared with the no‐caffeine control condition, a smaller amount of caffeine had no significant effects on global VMCA, but a larger amount suppressed VMCA by 5.8%. Time‐course analyses showed that VMCA (1) followed a triphasic pattern to increase over baselines during hypoventilation regardless of caffeine condition, (2) slowed below baselines during hyperventilation (with the degree of slowing attenuated under caffeine), and (3) increased over baselines during all cognitive activities (ranges 3.8‐6.9%). It is concluded that a large amount of caffeine can suppress VMCA, and this possibility should be anticipated when TCD is used to assess cerebral hemovelocity.

Acquisition and maintenance of Sidman avoidance with paired rat subjects

Rat Ss were used to study the acquisition and maintenance of Sidman avoidance as a function of either single or paired training. Ss receiving paired training failed to acquire the leverpress response even after a block of individual training sessions. Within the paired training condition, Ss that were housed separately evidenced better acquisition than Ss housed as pairs. When Ss that were efficiently avoiding under individual training conditions were paired, avoidance was severely disrupted.

Cognitive activities modulate cerebral hemovelocities

We report three studies in which one of three cerebral arteries (MCA, ACA, or PCA) was insonated while subjects remembered sets of three letters, made decisions that were based on ethics and item-evaluation scenarios, and solved problems (anagrams, constructed new words from the letters of a target word, mathematics). Accelerations in blood flow velocity occurred during the cognitive tasks, but specific changes were bound to (1) the cerebral artery that was insonated (VMCA and VACA showed identical modulations during the tasks, but VPCA was not affected); (2) the specific task that was provided (only the letter-recall and math tasks sustained accelerations throughout the cogitation period); (3) the mode of task presentation (visually presented tasks led to stronger accelerations initially than tasks presented verbally); and (4) whether the subjects completed the task requirement during the cogitation period, in which case velocity decelerated to baseline levels.

Transcranial Doppler Monitoring of Middle Cerebral Artery Blood Flow Velocities During Three Memory Tasks

Bilateral transcranial Doppler ultrasound measures of blood flow velocities in the middle cerebral artery of college students were taken during three 90‐second memory tasks: generating and maintaining images, remembering letters, and answering general knowledge questions. Blood flow velocities in the middle cerebral artery during each task increased significantly over their respective 30‐second baseline period. Differences in blood flow velocities due to the kind of memory task, the middle cerebral artery sampled (right or left), or subject gender were not significant.

TCD neurosonology : a window to view thinking

Bilateral transcranial Doppler ultrasound measures of blood flow velocities in the middle cerebral artery (MCA) were taken from college students during three 45-sec cognitive activities. Each activity (remembering letters, decision making, and solving problems) was preceded by a 60-sec baseline period and involved three different 15-sec tasks. MCA blood flow velocities increased significantly over baseline throughout the letter recall and problem-solving tasks but not during decision making. Within-task indices were biphasic; initially, velocities were elevated markedly, but then they lessened. Velocities were maintained above baseline by the letter recall and problem-solving tasks, but they diminished to match baseline in the final portions of the decision-making task. Velocity differences due to the hemisphere insonated (right or left) were not reliable.

Free Operant Avoidance Behavior of Hooded Rats: Some Notes on Within- and Between-Session Stability

Free operant avoidance of rats was studied in two experiments. In Experiment 1, within-session avoidance behavior (with R-S = 15 sec.) was examined in blocks of 60-, 90- and 120-min. sessions. Experiment 2 looked at within-session avoidance using rats separately trained under R-S intervals of 10, 15, 20 and 30 sec. Three levels of avoidance proficiency were found in each experiment: good, poor, and nonavoidance. Within a session, the performance of “good” avoiders was characterized by a distinct warm-up period followed by stable and proficient avoidance, while the avoidance of “poor” avoiders improved only gradually. Experiment 1 also showed that postwarm-up measures (both within and between sessions) were not altered by changes in session length. Both experiments yielded considerable interanimal differences in within-session response rate trends. These differences illustrated the difficulty in describing “typical” postwarm-up performance and suggested that the avoidance schedule had minimal control over the response rate it produced.

Cerebral blood flow velocities modulate during cognitive tasks using vision and vision-like requirements: A TCD study

Blood flow velocities in the anterior, middle, and posterior cerebral arteries (VACAs, VMCAs, VPCAs) of three separate groups of healthy volunteers (n = 22–24) were obtained noninvasively with a transcranial Doppler procedure during rest and during sets of 24-sec cognitive tasks that had varied visual requirements: remembering seen and heard items; generating autobiographical images; and visualizing and mentally rotating stimuli. Both global and time-course velocity values (averaged and for each of eight measures, respectively, from a thinking period) were analyzed. Global VMCA increased bilaterally over baseline during recalling; global VACA was not affected; and global VPCA increased after the subjects saw but not after they heard the items. Global VMCA and VACA elevated bilaterally during imaging, but VPCA did not. Visualizing, but not mentally rotating, stimuli increased all three global velocities bilaterally. Task-dependent time-course modulations in velocities appeared during the thinking periods. Velocities hyperelevated temporarily at the outset of all periods, except for VPCA during tasks not requiring direct vision. VACA slowed to baseline during recollection of the heard items, and all velocities slowed during the visualizing tasks but remained above baseline.